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Background: Maple is an important ornamental plant in China. With the increasing use of maple trees in landscaping, a symptom of shoot dieback has been observed in Henan province, China., Results: In this study, 28 Diaporthe isolates were obtained from symptomatic shoots of maple trees between 2020 and 2023. Phylogenetic analyses based on five loci (ITS, TEF, CAL, HIS and TUB) coupled with morphology of 12 representative isolates identified three known species (D. eres, D. pescicola and D. spinosa) and one new species, namely D. pseudoacerina sp. nov. Koch's postulates confirmed that all these species were pathogenic. Additionally, D. pseudoacerina was able to infect China wingnut (Pterocarya stenoptera), pear (Pyrus sp.), and black locust (Robinia pseudoacacia). This study marks the first report of Diaporthe spinosa and D. pescicola pathogens infecting maple trees., Conclusions: These findings enhance the existing knowledge of the taxonomy and host diversity of Diaporthe species as, while also providing valuable information for managing of maple shoot dieback in Henan Province, China., (© 2024. The Author(s).)

Background: Cotton is an important economic crop and a host of Liriomyza sativae. Pectin methylesterase (PME)-mediated pectin metabolism plays an indispensable role in multiple biological processes in planta. However, the pleiotropic functions of PME often lead to unpredictable effects on crop resistance to pests. Additionally, whether and how PME affects susceptibility to Liriomyza sativae remain unclear., Results: Here, we isolated GhPME36, which is located in the cell wall, from upland cotton (Gossypium hirsutum L.). Interestingly, the overexpression of GhPME36 in cotton caused severe susceptibility to Liriomyza sativae but increased leaf biomass in Arabidopsis. Cytological observations revealed that the cell wall was thinner with more demethylesterified pectins in GhPME36-OE cotton leaves than in WT leaves, whereas the soluble sugar content of GhPME36-OE cotton leaf cell walls was accordingly higher; both factors attracted Liriomyza sativae to feed on GhPME36-OE cotton leaves. Metabolomic analysis demonstrated that glucose was significantly differentially accumulated. Transcriptomic analysis further revealed DEGs enriched in glucose metabolic pathways when GhPME36 was overexpressed, suggesting that GhPME36 aggravates susceptibility to Liriomyza sativae by affecting both the structure and components of cell wall biosynthesis. Moreover, GhPME36 interacts with another pectin-modifying enzyme, GhC/VIF1, to maintain the dynamic stability of pectin methyl esterification., Conclusions: Taken together, our results reveal the cytological and molecular mechanisms by which GhPME36 aggravates susceptibility to Liriomyza sativae. This study broadens the knowledge of PME function and provides new insights into plant resistance to pests and the safety of genetically modified plants., (© 2024. The Author(s).)

Drought dramatically affects plant growth and yield. A previous study indicated that endophytic fungus Phomopsis liquidambaris can improve the drought resistance of peanuts, which is related with the root arbuscular mycorrhizal fungi (AMF) community; however, how root endophytes mediate AMF assembly to affect plant drought resistance remains unclear. Here, we explored the mechanism by which endophytic fungus recruits AMF symbiotic partners via rhizodeposits to improve host drought resistance. The results showed that Ph. liquidambaris enhanced peanut drought resistance by enriching the AMF genus Claroideoglomus of the rhizosphere. Furthermore, metabolomic analysis indicated that Ph. liquidambaris significantly promoted isoformononetin and salicylic acid (SA) synthesis in rhizodeposits, which were correlated with the increase in Claroideoglomus abundance following Ph. liquidambaris inoculation. Coinoculation experiments confirmed that isoformononetin and SA could enrich Claroideoglomus etunicatum in the rhizosphere, thereby improving the drought resistance. This study highlights the crucial role of fungal consortia in plant stress resistance.

Background: Septoria tritici blotch (STB) disease causes yield losses of up to 50 per cent in susceptible wheat cultivars and can reduce wheat production. In this study, genomic architecture for adult-plant STB resistance in a Septoria Association Mapping Panel (SAMP) having 181 accessions and genomic regions governing STB resistance in a South Asian wheat panel were looked for., Results: Field experiments during the period from 2019 to 2021 revealed those certain accessions, namely BGD52 (CHIR7/ANB//CHIR1), BGD54 (CHIR7/ANB//CHIR1), IND92 (WH 1218), IND8 (DBW 168), and IND75 (PBW 800), exhibited a high level of resistance. Genetic analysis revealed the presence of 21 stable quantitative trait nucleotides (QTNs) associated with resistance to STB (Septoria tritici blotch) on all wheat chromosomes, except for 2D, 3A, 3D, 4A, 4D, 5D, 6B, 6D, and 7A. These QTNs were predominantly located in chromosome regions previously identified as associated with STB resistance. Three Quantitative Trait Loci (QTNs) were found to have significant phenotypic effects in field evaluations. These QTNs are Q.STB.5A.1, Q.STB.5B.1, and Q.STB.5B.3. Furthermore, it is possible that the QTNs located on chromosomes 1A (Q.STB.1A.1), 2A (Q.STB_DH.2A.1, Q.STB.2A.3), 2B (Q.STB.2B.4), 5A (Q.STB.5A.1, Q.STB.5A.2), and 7B (Q.STB.7B.2) could potentially be new genetic regions associated with resistance., Conclusion: Our findings demonstrate the importance of Asian bread wheat as a source of STB resistance alleles and novel stable QTNs for wheat breeding programs aiming to develop long-lasting and wide-ranging resistance to Zymoseptoria tritici in wheat cultivars., (© 2024. The Author(s).)

Aims: The objective of this study was to elucidate the role and mechanism of changes in the rhizosphere microbiome following Arthrobotrys oligospora treatment in the biological control of root-knot nematodes and identify the key fungal and bacterial species that collaborate with A. oligospora to biocontrol root-knot nematodes., Methods and Results: We conducted a pot experiment to investigate the impact of A. oligospora treatment on the biocontrol efficiency of A. oligospora against Meloidogyne incognita infecting tomatoes. We analyzed the rhizosphere bacteria and fungi communities of tomato by high-throughput sequencing of the 16S rRNA gene fragment and the internal transcribed spacer (ITS). The results indicated that the application of A. oligospora resulted in a 53.6% reduction in the disease index of M. incognita infecting tomato plants. The bacterial diversity of rhizosphere soil declined in the A. oligospora-treated group, while fungal diversity increased. The A. oligospora treatment enriched the tomato rhizosphere with Acidobacteriota, Firmicutes, Bradyrhizobium, Sphingomonadales, Glomeromycota, and Purpureocillium. These organisms are involved in the utilization of rhizosphere organic matter, nitrogen, and glycerolipids, or play the role of ectomycorrhiza or directly kill nematodes. The networks of bacterial and fungal co-occurrence exhibited a greater degree of stability and complexity in the A. oligospora treatment group., Conclusions: This study demonstrated the key fungal and bacterial species that collaborate with the A. oligospora in controlling the root-knot nematode and elaborated the potential mechanisms involved. The findings offer valuable insights and inspiration for the advancement of bionematicide based on nematode-trapping fungi., (© The Author(s) 2024. Published by Oxford University Press on behalf of Applied Microbiology International.)

Sclerotinia disease is one of the most devastating fungal diseases worldwide, as it reduces the yields of many economically important crops. Pathogen-secreted effectors play crucial roles in infection processes. However, key effectors of Ciboria shiraiana, the pathogen primarily responsible for sclerotinia disease in mulberry (Morus spp.), remain poorly understood. In this study, we identified and functionally characterized the effector Cs02526 in C. shiraiana and found that Cs02526 could induce cell death in a variety of plants. Moreover, Cs02526-induced cell death was mediated by the central immune regulator brassinosteroid insensitive 1-associated receptor kinase 1, dependent on a 67-amino acid fragment. Notably, Cs02526 homologs were widely distributed in hemibiotrophic and necrotrophic phytopathogenic fungi, but the homologs failed to induce cell death in plants. Pretreatment of plants with recombinant Cs02526 protein enhanced resistance against both C. shiraiana and Sclerotinia sclerotiorum. Furthermore, the pathogenicity of C. shiraiana was diminished upon spraying plants with synthetic dsRNA-Cs02526. In conclusion, our findings highlight the cell death-inducing effector Cs02526 as a potential target for future biological control strategies against plant diseases., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists.)

Plant growth-promoting rhizobacteria (PGPR) have been reported to suppress various diseases as potential bioagents. It can inhibit disease occurrence through various means such as directly killing pathogens and inducing systemic plant resistance. In this study, a bacterium isolated from soil showed significant inhibition of Valsa mali. Morphological observations and phylogenetic analysis identified the strain as Pseudomonas thivervalensis, named K321. Plate confrontation assays demonstrated that K321 treatment severely damaged V. mali growth, with scanning electron microscopy (SEM) observations showing severe distortion of hyphae due to K321 treatment. In vitro twigs inoculation experiments indicated that K321 had good preventive and therapeutic effects against apple Valsa canker (AVC). Applying K321 on apples significantly enhanced the apple inducing systemic resistance (ISR), including induced expression of apple ISR-related genes and increased ISR-related enzyme activity. Additionally, applying K321 on apples can activate apple MAPK by enhancing the phosphorylation of MPK3 and MPK6. In addition, K321 can promote plant growth by solubilizing phosphate, producing siderophores, and producing 3-indole-acetic acid (IAA). Application of 0.2% K321 increased tomato plant height by 53.71%, while 0.1% K321 increased tomato fresh weight by 59.55%. Transcriptome analysis revealed that K321 can inhibit the growth of V. mali by disrupting the integrity of its cell membrane through inhibiting the metabolism of essential membrane components (fatty acids) and disrupting carbohydrate metabolism. In addition, transcriptome analysis also showed that K321 can enhance plant resistance to AVC by inducing ISR-related hormones and MAPK signaling, and application of K321 significantly induced the transcription of plant growth-related genes. In summary, an excellent biocontrol strain has been discovered that can prevent AVC by inducing apple ISR and directly killing V. mali. This study indicated the great potential of P. thivervalensis K321 for use as a biological agent for the control of AVC., Competing Interests: Declaration of competing interest The authors declare no competing interests (financial and nonfinancial interests)., (Copyright © 2024 Elsevier Inc. All rights reserved.)

As the third active gas signal molecule in plants, hydrogen sulfide (H 2 S) plays important roles in physiological metabolisms and biological process of fruits and vegetables during postharvest storage. In the present study, the effects of H 2 S on enhancing resistance against soft rot caused by Botryosphaeria dothidea and the involvement of jasmonic acid (JA) signaling pathway in kiwifruit during the storage were investigated. The results showed that 20 μL L -1 H 2 S fumigation restrained the disease incidence of B. dothidea-inoculated kiwifruit during storage, and delayed the decrease of firmness and the increase of soluble solids (SSC) content. H 2 S treatment increased the transcription levels of genes related to JA biosynthesis (AcLOX3, AcAOS, AcAOC2, and AcOPR) and signaling pathway (AcCOI1, AcJAZ5, AcMYC2, and AcERF1), as well as the JA accumulation. Meanwhile, H 2 S promoted the expression of defense-related genes (AcPPO, AcSOD, AcGLU, AcCHI, AcAPX, and AcCAT). Correlation analysis revealed that JA content was positively correlated with the expression levels of JA biosynthesis and defense-related genes. Overall, the results indicated that H 2 S could promote the increase of endogenous JA content and expression of defense-related genes by regulating the transcription levels of JA pathway-related genes, which contributed to the inhibition on the soft rot occurrence of kiwifruit., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Masson SAS.)

Cotton (Gossypium hirsutum, Malvaceae) is the most important fiber crop in the world. There are published records of many fungal pathogens attacking Gossypium spp., causing numerous diseases, including powdery mildews. Recently, in 2022, non-cultivated spontaneous G. hirsutum plants bearing powdery mildews symptoms were found at roadsides in two municipalities of the state of Minas Gerais (Brazil): Varginha and Ubá. Such localities are situated ca. 260 km apart, suggesting a broader distribution of this fungus-host association in Brazil. Samples were taken to the laboratory, and an Ovulariopsis-like, asexual stage of Phyllactinia, was identified forming amphigenous colonies, that were more evident, white and cottony, abaxially. Morphological and molecular data- of the ITS and LSU regions- have shown that colonies from those two samples were of the same fungus species, belonging to a previously unknown species of Erysiphaceae (Ascomycota). The fungus fits into the Phyllactinia clade and is described herein as the new species Phyllactinia gossypina sp. nov. This new species belongs to the 'basal Phyllactinia group', a lineage that includes species known only from the Americas. This report expands the list of pathogenic fungi on cotton. It is early to anticipate whether this new powdery mildew represents a threat to cultivated cotton, which is a major crop in Brazil. Nevertheless, further studies about its infectivity to commercial cotton varieties are recommended, since all known Erysiphaceae are specialized obligate plant parasites and several species cause major losses to important crops., (© 2024. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

Ultraviolet (UV) irradiation below 300 nm may control powdery mildew in numerous crops. Depending on disease pressure, wavelength, and crop growth stage, one to three applications of 100-200 J/m2 per week at night are as effective or better than the best fungicides. Higher doses may harm the plants and reduce yields. Although red light alone or in combination with UV has a suppressive effect on powdery mildew, concomitant or subsequent exposure to blue light or UV-A strongly reduces the efficacy of UV treatments. To be effective, direct exposure of the pathogen/infection sites to UV/red light is important, but there are clear indications for the involvement of induced resistance in the host. Other pathogens and pests are susceptible to UV, but the effective dose may be phytotoxic. Although there are certain limitations, this technology is gradually becoming more used in both protected and open-field commercial production systems.

Rose black spot disease, caused by Marssonina rosae (syn. Diplocarpon rosae), is one of the most widespread diseases of field-grown roses worldwide. Pathogens have been found to interfere with or stimulate plant immune responses by secreting effectors. However, the molecular mechanism involved in inhibition of the rose immune response by M. rosae effectors remains poorly understood. Here, we identified the effector MrSEP43, which plays a pivotal role in promoting the virulence of M. rosae and enhancing rose susceptibility to infection by reducing callose deposition, H2O2 accumulation, and the expression of defense genes in the jasmonic acid signaling pathway. Yeast two-hybrid, bimolecular fluorescence complementation, and split luciferase assays showed that MrSEP43 interacted with the rose orphan protein RcBROG. RcBROG, a positive regulator of defense against M. rosae, enhanced rose resistance by increasing callose deposition, H2O2 accumulation, and the expression of RcERF1 in the ethylene signaling pathway. Overall, our findings suggest that the M. rosae virulence effector MrSEP43 specifically targets the orphan protein RcBROG to suppress the rose immune response to M. rosae. These results provide new insights into how M. rosae manipulates and successfully colonizes rose leaves, and are essential for preventing the breakdown of resistance to rose black spot disease., (Published by Oxford University Press on behalf of the Society for Experimental Biology 2024.)

Symbiotic microorganisms that reside on the host skin serve as the primary defense against pathogens in vertebrates. Specifically, the skin microbiome of bats may play a crucial role in providing resistance against Pseudogymnoascus destructans ( Pd ), the pathogen causing white-nose syndrome. However, the epidermis symbiotic microbiome and its specific role in resisting Pd in highly resistant bats in Asia are still not well understood. In this study, we collected and characterized skin microbiota samples of 19 Myotis pilosus in China and explored the differences between Pd -positive and negative individuals. We identified inhibitory effects of these bacteria through cultivation methods. Our results revealed that the Simpson diversity index of the skin microbiota for positive individuals was significantly lower than that of negative individuals, and the relative abundance of Pseudomonas was significantly higher in positive bats. Regardless of whether individuals were positive or negative for Pd , the relative abundance of potentially antifungal genera in skin microbiota was high. Moreover, we successfully isolated 165 microbes from bat skin and 41 isolates from positive individuals able to inhibit Pd growth compared to only 12 isolates from negative individuals. A total of 10 genera of Pd -inhibiting bacteria were screened, among which the genera Algoriella , Glutamicibacter , and Psychrobacter were newly discovered as Pd -inhibiting genera. These Pd -inhibiting bacteria metabolized a variety of volatile compounds, including dimethyl trisulfide, dimethyl disulfide, propylene sulfide, 2-undecanone, and 2-nonanone, which were able to completely inhibit Pd growth at low concentrations.IMPORTANCERecently, white-nose syndrome has caused the deaths of millions of hibernating bats, even threatening some with regional extinction. Bats in China with high resistance to Pseudogymnoascus destructans can provide a powerful reference for studying the management of white-nose syndrome and understanding the bats against the pathogen's intrinsic mechanisms. This study sheds light on the crucial role of host symbiotic skin microorganisms in resistance to pathogenic fungi and highlights the potential for harnessing natural defense mechanisms for the prevention and treatment of white-nose syndrome. In addition, this may also provide promising candidates for the development of bioinsecticides and fungicides that offer new avenues for addressing fungal diseases in wildlife and agricultural environments., Competing Interests: The authors declare no conflict of interest.

Propagule dispersal is a crucial aspect of the survival and reproduction of sessile organisms, such as plants and fungi. As such, the colours of fleshy fruits serve as a visual cue for animal dispersers. However, little is known about how, or whether, specific traits of fungal fruiting bodies, such as colour or shape, attract animal dispersers, and additionally the identities of fungal dispersers are poorly understood. Globally, most truffle-like fungi are dull-coloured, subterranean, and likely have scents that are attractive to mammalian dispersers. In Aotearoa-New Zealand, however, brightly coloured truffle-like fungi that emerge from the forest floor have seemingly proliferated. This proliferation has prompted the hypothesis that they are adapted to dispersal by a bird-dominated fauna. In our study, we used the literature and citizen science data (GBIF) to explore whether colourful species occur at a higher proportion of the total truffle-like fungi flora in Aotearoa-New Zealand than elsewhere in the world. In addition, we tested for a relationship between biotic factors (avian frugivory and forest cover) and abiotic factors (precipitation, radiation, and temperature) and the prevalence of brightly coloured truffle-like fungi across the world. The most colourful truffle-like fungi are in three defined regions: Australia, South and Central America and the Caribbean, and Aotearoa-NZ. Potential dispersers and the environment both relate to the distribution of truffle-like fungi: we found that increasing levels of frugivory were associated with higher proportions of colourful truffle-like fungi. This finding provides new insights into drivers of certain fungal traits, and their interactions between birds and fungi. Unique ecosystems, such as Aotearoa-NZ's bird-dominated biota, provide fascinating opportunities to explore how plants and fungi interact with the sensory systems of animals., (© 2024. The Author(s).)

Key Message: Developing genetically resistant soybean cultivars is key in controlling the destructive Sclerotinia Stem Rot (SSR) disease. Here, a GWAS study in Canadian soybeans identified potential marker-trait associations and candidate genes, paving the way for more efficient breeding methods for SSR. Sclerotinia stem rot (SSR), caused by the fungal pathogen Sclerotinia sclerotiorum, is one of the most important diseases leading to significant soybean yield losses in Canada and worldwide. Developing soybean cultivars that are genetically resistant to the disease is the most inexpensive and reliable method to control the disease. However, breeding for resistance is hampered by the highly complex nature of genetic resistance to SSR in soybean. This study sought to understand the genetic basis underlying SSR resistance particularly in soybean grown in Canada. Consequently, a panel of 193 genotypes was assembled based on maturity group and genetic diversity as representative of Canadian soybean cultivars. Plants were inoculated and screened for SSR resistance in controlled environments, where variation for SSR phenotypic response was observed. The panel was also genotyped via genotyping-by-sequencing and the resulting genotypic data were imputed using BEAGLE v5 leading to a catalogue of 417 K SNPs. Through genome-wide association analyses (GWAS) using FarmCPU method with threshold of FDR-adjusted p-values < 0.1, we identified significant SNPs on chromosomes 2 and 9 with allele effects of 16.1 and 14.3, respectively. Further analysis identified three potential candidate genes linked to SSR disease resistance within a 100 Kb window surrounding each of the peak SNPs. Our results will be important in developing molecular markers that can speed up the breeding for SSR resistance in Canadian grown soybean., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Powdery mildew (PM), triggered by Oidium neolycopersici, represents a significant threat and a major concern for the productivity of tomato plants (Solanum lycopersicum L.). The presence of susceptibility (S) genes in plants facilitates pathogen proliferation and their dysfunction can lead to a recessively inherited broad-spectrum and durable type of resistance. Past studies have demonstrated that disrupting the function of DND1 (Defense No Death 1) increases plant resilience against various pathogens, such as powdery mildew (PM), but this comes at the cost of negatively affecting the overall health and vigor of the plant. To investigate the possibility of minimizing the adverse effects of the dnd1 mutation while boosting disease resistance, a CRISPR-Cas9 construct with four single guide RNAs targeting three exons of SlDND1 (Solyc02g088560.4.1) was designed and introduced into the tomato variety Moneymaker (MM) through Agrobacterium tumefaciens-mediated transformation. Three T 1 lines (named E1, E3 and E4) were crossed with MM and then selfed to produce T F2 families. All the T F2 plants in homozygous state dnd1/dnd1, showed reduced PM symptoms compared to the heterozygous (DND1/dnd1) and wild type (DND1/DND1) ones. Two full knock-out (KO) mutant events (E1 and E4) encoding truncated DND1 proteins, exhibited clear dwarfness and auto-necrosis phenotypes, while mutant event E3 harbouring deletions of 3 amino acids, showed normal growth in height with less auto-necrotic spots. Analysis of the 3D structures of both the reference and the mutant proteins revealed significant conformational alterations in the protein derived from E3, potentially impacting its function. A dnd1/dnd1 TF2 line (TV181848-9, E3) underwent whole-genome sequencing using Illumina technology, which confirmed the absence of off-target mutations in selected genomic areas. Additionally, no traces of the Cas9 gene were detected, indicating its elimination through segregation. Our findings confirm the role of DND1 as an S-gene in tomato because impairment of this gene leads to a notable reduction in susceptibility to O. neolycopersici. Moreover, we provide, for the first time, a dnd1 mutant allele (E3) that exhibits fitness advantages in comparison with previously reported dnd1 mutant alleles, indicating a possible way to breed with dnd1 mutants., (© 2024. The Author(s).)

Epiphytic microbes are those that live for some or all of their life cycle on the surface of plant leaves. Leaf surfaces are a topologically complex, physicochemically heterogeneous habitat that is home to extensive, mixed communities of resident and transient inhabitants from all three domains of life. In this review, we discuss the origins of leaf surface microbes and how different biotic and abiotic factors shape their communities. We discuss the leaf surface as a habitat and microbial adaptations which allow some species to thrive there, with particular emphasis on microbes that occupy the continuum between epiphytic specialists and phytopathogens, groups which have considerable overlap in terms of adapting to the leaf surface and between which a single virulence determinant can move a microbial strain. Finally, we discuss the recent findings that the wheat pathogenic fungus Zymoseptoria tritici spends a considerable amount of time on the leaf surface, and ask what insights other epiphytic organisms might provide into this pathogen, as well as how Z. tritici might serve as a model system for investigating plant-microbe-microbe interactions on the leaf surface., (© 2024. The Author(s).)

In order to provide a highly feasible research pathway for the control of larch shoot blight, healthy larch branches and leaves were collected from 13 sampling sites in 8 provinces in China. The antagonistic endophytic bacteria obtained from the screening were used to carry out disease control experiments in potted seedlings. The safety evaluation test was conducted on the antagonistic bacteria. Subsequently, the strains with better preventive effect and high safety were identified by morphological and molecular methods. A total of 391 strains of endophytic bacteria were isolated from healthy larch branches and leaves. Seventy-eight strains of larch endophytic bacteria with antagonistic effect were obtained by primary sieving. Ten strains of endophytic bacteria with obvious antagonism were further obtained by secondary sieving, and all of them had an inhibition rate of more than 57%. Among them, strains YN 2, JL 6, NMG 23, and JL 54 showed the highest inhibition rate of 63.16%-65.08%, which was significantly different from the other treatments. The results of the pot test showed that 14 days after inoculation with the pathogen, strains YN 2 and JL 54 were more effective in the control of larch shoot blight, with the preventive effects reaching 57.7% and 50.0%, respectively. Strains JL 6 and JL 54 were biologically safe in the safety evaluation test. Therefore, strain JL 54 was selected for identification. It was identified as Bacillus amyloliquefaciens through morphological observation, 16S rDNA sequence, gyrB gene sequence and 16S rDNA- gyrB tandem feature sequence analysis., Importance: Larch shoot blight is a widely distributed, damaging, and rapidly spreading fungal disease of forest trees that poses a serious threat to larch plantations. Endophytic bacteria have biological effects on host plants against pests and diseases, and they have a growth-promoting effect on plants. In this paper, we investigated for the first time the biocontrol effect of endophytic bacteria on larch shoot blight by screening endophytic bacteria with the function of antagonizing dieback fungi. Bacillus amyloliquefaciens JL 54 has a better prospect of biocontrol against larch shoot blight, which lays the foundation for the application of this bacterium in the future., Competing Interests: The authors declare no conflict of interest.

Background: Septoria tritici blotch (STB), caused by the foliar fungus Zymoseptoria tritici, is one of the most damaging disease of wheat in Europe. Genetic resistance against this fungus relies on different types of resistance from non-host resistance (NHR) and host species specific resistance (HSSR) to host resistance mediated by quantitative trait loci (QTLs) or major resistance genes (Stb). Characterizing the diversity of theses resistances is of great importance for breeding wheat cultivars with efficient and durable resistance. While the functional mechanisms underlying these resistance types are not well understood, increasing piece of evidence suggest that fungus stomatal penetration and early establishment in the apoplast are both crucial for the outcome of some interactions between Z. tritici and plants. To validate and extend these previous observations, we conducted quantitative comparative phenotypical and cytological analyses of the infection process corresponding to 22 different interactions between plant species and Z. tritici isolates. These interactions included four major bread wheat Stb genes, four bread wheat accessions with contrasting quantitative resistance, two species resistant to Z. tritici isolates from bread wheat (HSSR) and four plant species resistant to all Z. tritici isolates (NHR)., Results: Infiltration of Z. tritici spores into plant leaves allowed the partial bypass of all bread wheat resistances and durum wheat resistance, but not resistances from other plants species. Quantitative comparative cytological analysis showed that in the non-grass plant Nicotiana benthamiana, Z. tritici was stopped before stomatal penetration. By contrast, in all resistant grass plants, Z. tritici was stopped, at least partly, during stomatal penetration. The intensity of this early plant control process varied depending on resistance types, quantitative resistances being the least effective. These analyses also demonstrated that Stb-mediated resistances, HSSR and NHR, but not quantitative resistances, relied on the strong growth inhibition of the few Z. tritici penetrating hyphae at their entry point in the sub-stomatal cavity., Conclusions: In addition to furnishing a robust quantitative cytological assessment system, our study uncovered three stopping patterns of Z. tritici by plant resistances. Stomatal resistance was found important for most resistances to Z. tritici, independently of its type (Stb, HSSR, NHR). These results provided a basis for the functional analysis of wheat resistance to Z. tritici and its improvement., (© 2024. The Author(s).)

Septoria nodorum blotch (SNB), caused by Parastagonospora nodorum, is a disease of durum and common wheat initiated by the recognition of pathogen-produced necrotrophic effectors (NEs) by specific wheat genes. The wheat gene Snn1 was previously cloned, and it encodes a wall-associated kinase that directly interacts with the NE SnTox1 leading to programmed cell death and ultimately the development of SNB. Here, sequence analysis of Snn1 from 114 accessions including diploid, tetraploid, and hexaploid wheat species revealed that some wheat lines possess two copies of Snn1 (designated Snn1-B1 and Snn1-B2) approximately 120 kb apart. Snn1-B2 evolved relatively recently as a paralog of Snn1-B1, and both genes have undergone diversifying selection. Three point mutations associated with the formation of the first SnTox1-sensitive Snn1-B1 allele from a primitive wild wheat were identified. Four subsequent and independent SNPs, three in Snn1-B1 and one in Snn1-B2, converted the sensitive alleles to insensitive forms. Protein modeling indicated these four mutations could abolish Snn1-SnTox1 compatibility either through destabilization of the Snn1 protein or direct disruption of the protein-protein interaction. A high-throughput marker was developed for the absent allele of Snn1, and it was 100% accurate at predicting SnTox1-insensitive lines in both durum and spring wheat. Results of this study increase our understanding of the evolution, diversity, and function of Snn1-B1 and Snn1-B2 genes and will be useful for marker-assisted elimination of these genes for better host resistance., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.)

Pecan ( Carya illinoinensis ) is a valuable crop in the southern United States. Scab (caused by Venturia effusa ) is a major biotic constraint to pecan production in the southeastern region and requires 10 to 15 or more fungicide applications for control. Spray application relies on large standard radial airflow air blast sprayers (SSs). Some SSs have been adapted to include a volute on one side to project spray higher into the canopy because of a decline in coverage with height. A grower-designed and engineered double volute-generated focused airflow air blast sprayer (DVS) was assessed for scab control and spray coverage compared with an SS. Over three seasons, on foliage and fruit, scab control was either equal to or superior using the DVS sprayer. On mature fruit, in 2017, scab severity on the control was 9.07%, on the DVS it was 0.19%, and on the SS it was 0.24%; in 2018 severity was 84.4, 18.4, and 29.1%, respectively; and in 2019 it was 32.7, 7.0, and 11.6%, respectively. There were no discernable gradients in scab severity with tree height with either sprayer in 2017, but in 2018 the difference was significant, with the DVS having a shallower gradient, and in 2019 the DVS slope was numerically less steep compared with the SS. Mature fruit weight was significantly greater on trees treated using the DVS compared with the SS in 2017 and 2018 but was not different in 2019. Spray coverage studies showed that the DVS sprayer had significantly more coverage at heights >13.8 m (up to 19.0 m), ranging from 18.4 to 14.1%, compared with coverage using the SS, which ranged from 7.9 to 2.9%. The slope in decline of spray coverage with height was significantly shallower with the DVS sprayer, and spray profiles reflected these differences. Disease control was improved overall when using the DVS, and the DVS provided greater spray coverage at heights >13.8 m when compared with the SS sprayer. The DVS design may offer economical, superior scab control in pecan orchards where trees are >13.8 m tall., Competing Interests: The author(s) declare no conflict of interest.

Wheat blast caused by Pyricularia oryzae pathotype Triticum (MoT) has been transmitted from South America to Bangladesh and Zambia and is now spreading in these countries. To prepare against its further spread to Asian countries, we introduced Rmg8 , a gene for resistance to wheat blast, into a Japanese elite cultivar, Chikugoizumi (ChI), through recurrent backcrosses and established ChI near-isogenic lines, #2-1-10 with the Rmg8 / Rmg8 genotype and #4-2-10 with the rmg8 / rmg8 genotype. A molecular analysis suggested that at least 96.6% of the #2-1-10 genome was derived from the recurrent parent ChI. The #2-1-10 line was resistant to MoT not only in primary leaves at the seedling stage but also in spikes and flag leaves at the heading stage. The strength of the resistance in spikes of this Rmg8 carrier was comparable to that of a carrier of the 2NS segment, which has been the only genetic resource released to farmers' fields for wheat blast resistance. On the other hand, the 2NS resistance was not expressed on leaves at the seedling stage nor flag leaves at the heading stage. Considering that leaf blast has been increasingly reported and regarded as an important inoculum source for spike blast, Rmg8 expressed at both the seedling and heading stages, or more strictly in both leaves and spikes, is suggested to be useful to prevent the spread of MoT in Asia and Africa., Competing Interests: The author(s) declare no conflict of interest.

Stripe rust and powdery mildew are serious diseases that severely decrease the yield of wheat. Planting wheat cultivars with powdery mildew and stripe rust resistance genes is the most effective way to control these two diseases. Introducing disease resistance genes from related species into the wheat genome via chromosome translocation is an important way to improve wheat disease resistance. In this study, nine novel T1RS.1AL translocation lines were developed from the cross of wheat cultivar Chuannong25 (CN25) and a Chinese rye Qinling. The results of non-denaturing fluorescence in situ hybridization and PCR showed that all new lines were homozygous for the T1RS.1AL translocation. These new T1RS.1AL translocation lines exhibited strong resistance to stripe rust and powdery mildew. The cytogenetics results indicated that the resistance of the new lines was conferred by the 1RS chromosome arms, which came from Qinling rye. The genetic analysis indicated that there were new dominant resistance genes on the 1RS chromosome arm resistant to stripe rust and powdery mildew, and their resistance patterns were different from those of Yr9, Pm8 , and Pm17 genes. In addition, the T1RS.1AL translocation lines generally exhibited better agronomic traits in the field relative to CN25. These T1RS.1AL translocations have great potential in wheat-breeding programs in the future., Competing Interests: The author(s) declare no conflict of interest.

Stem rot caused by Sclerotinia sclerotiorum is a serious and sometimes devastating disease of lupin ( Lupinus spp.). A total of 236 lupin accessions from across 12 Lupinus species were screened against the prevalent S. sclerotiorum isolate MBRS-1 (pathotype 76). L. angustifolius accession 21655 and L. albus var. albus accession 20589 showed immune and "near-immune" responses, respectively. Thirteen accessions of L. angustifolius , three accessions each of L. albus and L. albus var. albus , and a single accession each of L. albus var. graecus , L. mutabilis , L. palaestinus , and L. pilosus (totaling ∼4%) showed a highly resistant (HR) response. A further 19 accessions of L. angustifolius , 2 accessions each of L. albus and L. pilosus , and a single accession of L. mutabilis (totaling ∼10%) showed a resistant (R) response. The reactions of 16 (15 L. angustifolius , 1 L. digitatus ) of these 236 accessions were also compared with their reactions to a different isolate, Walkaway-3 (WW-3; pathotype 10). Against this isolate, five L. angustifolius accessions showed an HR response and four showed an R response, and the L. digitatus accession showed a moderate resistance response. Overall, isolate WW-3 caused significantly ( P < 0.05) smaller lesions than MBRS-1 across tested accessions in common. In addition, 328 plants in a "wild" naturalized field population of L. cosentinii were screened in situ in the field against isolate MBRS-1. Five (∼1.5%) of the 328 plants of wild lupin showed an immune response, 63 (∼19%) showed an HR response, and 146 (∼45%) showed an R response. We believe this is the first examination of diverse Lupinus spp. germplasm responses to a prevalent pathotype of S. sclerotiorum . Lupin genotypes exhibiting high-level resistance to Sclerotinia stem rot identified in this study can be used as parental lines for crosses in lupin breeding programs and/or directly as improved cultivars to reduce the adverse impact of this disease on lupin crops., Competing Interests: The author(s) declare no conflict of interest.

Didymella macrostoma P2 was isolated from rapeseed ( Brassica napus ), and it is an endophyte of rapeseed and an antagonist of three rapeseed pathogens, Botrytis cinerea , Leptosphaeria biglobosa , and Sclerotinia sclerotiorum . However, whether P2 has a suppressive effect on infection of rapeseed by the clubroot pathogen Plasmodiophora brassicae remains unknown. This study was conducted to detect production of antimicrobials by P2 and to determine the efficacy of the antimicrobials and P2 pycnidiospores in suppression of rapeseed clubroot. The results showed that cultural filtrates (CFs) of P2 in potato dextrose broth and the substances in pycnidiospore mucilages exuded from P2 pycnidia were inhibitory to P. brassicae . In the indoor experiment, seeds of the susceptible rapeseed cultivar Zhongshuang No. 9 treated with P2 CF and the P2 pycnidiospore suspension (P2 SS, 1 × 10 7 spores/ml) reduced clubroot severity by 31 to 70% on the 30-day-old seedlings compared with the control (seeds treated with water). P2 was reisolated from the roots of the seedlings in the treatment of P2 SS; the average isolation frequency in the healthy roots (26%) was much higher than that (5%) in the diseased roots. In the field experiment, seeds of another susceptible rapeseed cultivar, Huayouza 50 (HYZ50), treated with P2 CF, P2 CE (chloroform extract of P2 CF, 30 μg/ml), and P2 SS reduced clubroot severity by 29 to 48% on 60-day-old seedlings and by 28 to 59% on adult plants (220 days old) compared with the control treatment. The three P2 treatments on HYZ50 produced significantly ( P < 0.05) higher seed yield than the control treatment on this rapeseed cultivar, and they even generated seed yield similar to that produced by the resistant rapeseed cultivar Shengguang 165R in one of the two seasons. These results suggest that D. macrostoma P2 is an effective biocontrol agent against rapeseed clubroot., Competing Interests: The author(s) declare no conflict of interest.

In the field, necrosis area induced by pathogens is usually surrounded by a red circle in apple fruits. However, the underlying molecular mechanism of this phenomenon remains unclear. In this study, we demonstrated that accumulated salicylic acid (SA) induced by fungal infection promoted anthocyanin biosynthesis through MdNPR1-MdTGA2.2 module in apple (Malus domestica). Inoculating apple fruits with Valsa mali or Botryosphaeria dothidea induced a red circle surrounding the necrosis area, which mimicked the phenotype observed in the field. The red circle accumulated a high level of anthocyanins, which was positively correlated with SA accumulation stimulated by fungal invasion. Further analysis showed that SA promoted anthocyanin biosynthesis in a dose-dependent manner in both apple calli and fruits. We next demonstrated that MdNPR1, a master regulator of SA signaling, positively regulated anthocyanin biosynthesis in both apple and Arabidopsis. Moreover, MdNPR1 functioned as a co-activator to interact with and enhance the transactivation activity of MdTGA2.2, which could directly bind to the promoters of anthocyanin biosynthetic and regulatory genes to promote their transcription. Suppressing expression of either MdNPR1 or MdTGA2.2 inhibited coloration of apple fruits, while overexpressing either of them significantly promoted fruit coloration. Finally, we revealed that silencing either MdNPR1 or MdTGA2.2 in apple fruits repressed SA-induced fruit coloration. Therefore, our data determined that fungal-induced SA promoted anthocyanin biosynthesis through MdNPR1-MdTGA2.2 module, resulting in a red circle surrounding the necrosis area in apple fruits., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

The McMurdo Dry Valleys in Southern Victoria Land, Antarctica, are known for their extreme aridity, cold, and nutrient-poor conditions. These valleys provide a valuable comparison to environments on Mars. The survival of microorganisms in these areas hinges on their ability to withstand dehydration due to the limited availability of liquid water. Some microorganisms have adapted to survive extended periods of metabolic inactivity and dehydration, a physiological response to the harsh conditions in which they exist. This adaptation is significant for astrobiology studies as it allows for testing the resilience of microorganisms under extraterrestrial conditions, exploring the boundaries and potential for life beyond Earth. In this study, we examined the survivability, metabolic activity, cellular membrane integrity, and ultrastructural damage of Cryomyces antarcticus, a eukaryotic organism used for astrobiological studies, following two dehydration processes. We conducted a fast dehydration process, simulating what happens on the surface of Antarctic rocks under typical environmental conditions, and a slow dehydration process, which is commonly used in astrobiological experiments. Our findings revealed a higher percentage of damaged cells following slow dehydration treatments, confirming that rapid dehydration reflects the adaptability of microorganisms to respond to sudden and drastic changes in the Antarctic environment., (© 2024 The Author(s). Environmental Microbiology Reports published by John Wiley & Sons Ltd.)

Gentians ( Gentiana spp.) as floriculture crops are constantly exposed to several fungal and viral pathogens in the field. Among the fungal diseases afflicting gentian production, gentian sclerotial flower blight caused by Ciborinia gentianae incurs economic losses, as it affects flowers before and after harvest. Currently, preventive measures for this disease are limited, and no resistant cultivars have been reported. This is partly because of the lack of a reliable infection system that could promote research on this plant-fungus interaction. In this study, Gentiana plant tissue culture material was inoculated with C. gentianae culture filtrate. We successfully demonstrated non-ascospore-mediated infection of C. gentianae . Inoculation of individual hyphal structures present in the culture filtrate suggested that sclerotial primordia are the main agents of this infection. Interestingly, our results indicated that primary infection of C. gentianae occurs in petals rather than leaves, which enables systemic infection and therefore mirrors the fungus's infection strategy observed in the field. Moreover, we showed that (i) non-ascospore hyphal structures can also cause disease in flowers grown in the field, and (ii) ascosporic infection can also be observed using the in vitro system, opening possibilities for both practical and basic research aimed to combat gentian sclerotial flower blight disease., Competing Interests: The author(s) declare no conflict of interest.

Verticillium dahliae, a soil-borne fungal pathogen, compromises host innate immunity by secreting a plethora of effectors, thereby facilitating host colonization and causing substantial yield and quality losses. The mechanisms underlying the modulation of cotton immunity by V. dahliae effectors are predominantly unexplored. In this study, we identified that the V. dahliae effector Vd6317 inhibits plant cell death triggered by Vd424Y and enhances PVX viral infection in Nicotiana benthamiana. Attenuation of Vd6317 significantly decreased the virulence of V. dahliae, whereas ectopic expression of Vd6317 in Arabidopsis and cotton enhanced susceptibility to V. dahliae infection, underscoring Vd6317's critical role in pathogenicity. We observed that Vd6317 targeted the Arabidopsis immune regulator AtNAC53, thereby impeding its transcriptional activity on the defense-associated gene AtUGT74E2. Arabidopsis nac53 and ugt74e2 mutants exhibited heightened sensitivity to V. dahliae compared to wild-type plants. A mutation at the conserved residue 193L of Vd6317 abrogated its interaction with AtNAC53 and reduced the virulence of V. dahliae, which was partially attributable to a reduction in Vd6317 protein stability. Our findings unveil a hitherto unrecognized regulatory mechanism by which the V. dahliae effector Vd6317 directly inhibits the plant transcription factor AtNAC53 activity to suppress the expression of AtUGT74E2 and plant defense., (© 2024 Society for Experimental Biology and John Wiley & Sons Ltd.)

The rice blast fungus Magnaporthe oryzae poses a significant challenge to maintaining rice production. Developing rice varieties with resistance to this disease is crucial for its effective control. To understand the genetic variability of blast isolates collected between 2015 and 2017, the 27 monogenic rice lines that carry specific resistance genes were used to evaluate blast disease reactions. Based on criteria such as viability, virulence, and reactions to resistance genes, 20 blast isolates were selected as representative strains. To identify novel resistance genes, a quantitative trait locus analysis was carried out utilizing a mixture of the 20 representative rice blast isolates and a rice population derived from crossing the blast-resistant cultivar 'Cheongcheong' with the blast-susceptible cultivar 'Nagdong'. This analysis revealed a significant locus, RM1227-RM1261 on chromosome 12, that is associated with rice blast resistance. Within this locus, 12 disease resistance-associated protein genes were identified. Among them, OsDRq12 , a member of the nucleotide-binding, leucine-rich repeat disease resistance family, was chosen as the target gene for additional computational investigation. The findings of this study have significant implications for enhancing rice production and ensuring food security by controlling rice blast and developing resistant rice cultivars., Competing Interests: The author(s) declare no conflict of interest.

Wheat blast caused by Pyricularia oryzae pathotype Triticum has spread to Asia (Bangladesh) and Africa (Zambia) from the endemic region of South America. Wheat varieties with durable resistance are needed, but very limited resistance resources are currently available. After screening tetraploid wheat accessions, we found an exceptional accession St19 ( Triticum dicoccum , KU-114). Primary leaves of St19 were resistant not only to Brazilian isolate Br48 (a carrier of Type eI of AVR-Rmg8 ) but also to Br48ΔA8, an AVR-Rmg8 disruptant of Br48, even at 30°C, suggesting that the resistance of St19 is tolerant to high temperature and controlled by a gene or genes other than Rmg8 . When an F 2 population derived from a cross between St19 and St30 (a susceptible accession of T. paleocolchicum , KU-191) was inoculated with Br48, resistant and susceptible seedlings segregated in a 3:1 ratio, indicating that resistance of St19 is conferred by a single gene. We designated this gene Rmg11 . Molecular mapping revealed that the RMG11 locus is located on the short arm of chromosome 7A. Rmg11 is effective not only against other two Brazilian isolates (Br5 and Br116.5) but also against Bangladeshi isolates (T-108 and T-109) at the seedling stage. At the heading stage, lines containing Rmg11 were highly susceptible to the Bangladeshi isolates but moderately resistant to the Brazilian isolates. Stacking of Rmg11 with Rmg8 and the 2NS segment is highly recommended to achieve durable wheat blast resistance., Competing Interests: The author(s) declare no conflict of interest.

Sclerotinia sclerotiorum (Lib.) de Bary, an economically devastating soilborne fungal pathogen known to cause disease across a wide range of plants, produces long-term inoculum called sclerotia that can germinate either carpogenically by ascospores infecting aboveground plant parts or myceliogenically to infect stem base and roots. Typically, for research purposes, S. sclerotiorum diseases are initiated by direct contact methods, using S. sclerotiorum mycelium agar plugs wrapped around the stem or sclerotia placed directly beneath root mass. However, reproducible noncontact methods leading to basal stem infection are not currently available. Therefore, the objective of this study was to develop effective noncontact protocols that consistently generate basal plant stem infection from S. sclerotiorum in the soil. Using three host plant species (canola, lupin, and lettuce), we determined two methods that reliably produced basal stem infection. The first method, where mycelial agar plugs were positioned just below the soil surface at a distance of 5 mm from each seedling, led to 100% infection in all plants. The second method used pathogen-infested soil by mixing the soil with dry inoculum in the form of a powder prepared from mycelium-colonized organic substrates. Four substrates consistently produced 100% seedling infection at 4 days after inoculation (DAI): wheat bran, wheat grain, red rice, and hulled millet. In contrast, chia, canary, sesame, and ryegrass seed substrates resulted in less than 50% seedling infection at 10 DAI, and infection levels did not progress further. The two soil inoculation methods outlined in this study will enhance future research on the progression of S . sclerotiorum diseases, with the potential to screen disease-resistant host genotypes to basal S . sclerotiorum infection and, in particular, to test the effectiveness of soil applications of fungicides or biocontrol agents against S . sclerotiorum basal infection., Competing Interests: The author(s) declare no conflict of interest.

Global chickpea production is restricted by Ascochyta blight caused by the necrotrophic fungi Ascochyta rabiei . Developing locally adapted disease-resistant cultivars is an economically and environmentally sustainable approach to combat this disease. However, the lack of genetic variability in cultivated chickpeas and breeder-friendly markers poses a significant challenge to Ascochyta blight-resistant breeding efforts in chickpeas. In this study, we screened the mini-core germplasm of Cicer reticulatum against a local pathotype of A. rabiei . A modified mini-dome screening approach resulted in the identification of five accessions showing a high level of resistance. The mean disease score of resistant accessions ranged between 1.75 ± 0.3 and 2.88 ± 0.4 compared to susceptible accessions, where the mean disease score ranged between 3.59 ± 0.62 and 8.86 ± 0.14. Genome-wide association study revealed a strong association on chromosome 5 , explaining ∼58% of the phenotypic variance. The underlying region contained two candidate genes ( Cr&#95;14190.1&#95;v2 and Cr&#95;14189.1&#95;v2 ), the characterization of which showed the presence of a DNA-binding domain (cl28899 and cd18793) in Cr&#95;14190.1&#95;v2 and its orthologs in C. arietinum , whereas Cr&#95;14190.1&#95;v2 carried an additional N-terminal domain (cl31759). qPCR expression analysis in resistant and susceptible accessions revealed ∼3- and ∼110-fold higher transcript abundance for Cr&#95;14189.1 and Cr&#95;14190.1 , respectively., Competing Interests: One of the co-authors (K. S. Gill) is the CEO and co-owner of the company where the work was performed.

Plant-pathogenic fungi produce toxins as virulence factors in many plant diseases. In Cercospora leaf blight of soybean caused by Cercospora cf. flagellaris , symptoms are a consequence of the production of a perylenequinone toxin, cercosporin, which is light-activated to produce damaging reactive oxygen species. Cercosporin is universally toxic to cells, except to the cells of the producer. The current model of self-resistance to cercosporin is largely attributed to the maintenance of cercosporin in a chemically reduced state inside hyphae, unassociated with cellular organelles. However, in another perylenequinone-producing fungus, Phaeosphaeria sp., the toxin was specifically sequestered inside lipid droplets (LDs) to prevent reactive oxygen species production. This study hypothesized that LD-based sequestration of cercosporin occurred in C . cf. flagellaris and that lipid-inhibiting fungicides could inhibit toxin production. Confocal microscopy using light-cultured C . cf. flagellaris indicated that 3-day-old hyphae contained two forms of cercosporin distributed in two types of hyphae. Reduced cercosporin was uniformly distributed in the cytoplasm of thick, primary hyphae, and, contrary to previous studies, active cercosporin was observed specifically in the LDs of thin, secondary hyphae. The production of hyphae of two different thicknesses, a characteristic of hemibiotrophic plant pathogens, has not been documented in C . cf. flagellaris . No correlation was observed between cercosporin production and total lipid extracted, and two lipid-inhibiting fungicides had little effect on fungal growth in growth-inhibition assays. This study lays a foundation for exploring the importance of pathogen lifestyle, toxin production, and LD content in the pathogenicity and symptomology of Cercospora ., Competing Interests: The author(s) declare no conflict of interest.

Flax ( Linum usitatissimum ) grown under controlled conditions displayed genotype-dependent resistance to powdery mildew ( Oidium lini ) following COS-OGA (comprising chitosan- and pectin-derived oligomers) elicitor application. The present study reveals a two-step immune response in plants preventively challenged with the elicitor: an initial, rapid response characterized by the transcription of defense genes whose protein products act in contact with or within the cell wall, where biotrophic pathogens initially thrive, followed by a prolonged activation of cell wall peroxidases and accumulation of secondary metabolites. Thus, dozens of genes encoding membrane receptors, pathogenesis-related proteins, and wall peroxidases were initially overexpressed. Repeated COS-OGA treatments had a transient effect on the transcriptome response while cumulatively remodeling the metabolome over time, with a minimum of two applications required for maximal metabolomic shifts. Secondary metabolites, in particular terpenoids and phenylpropanoids, emerged as major components of this secondary defense response alongside pathogenesis-related proteins and wall peroxidases. The sustained accumulation of secondary metabolites, even after cessation of elicitation, contrasted with the short-lived transcriptomic response. Wall peroxidase enzyme activity also exhibited cumulative effects, increasing strongly for weeks after a third elicitor treatment. This underscores the plasticity of the plant immune response in the face of a potential infection, and the need for repeated preventive applications to achieve the full protective potential of the elicitor., Competing Interests: G. van Aubel, G. Métillon, E. Van Cutsem, and P. Van Cutsem are members of FytoFend S.A., which manufactures the COS-OGA product tested in this manuscript.

Pear ring rot, caused by Botryosphaeria dothidea, is the most serious disease of pear (Pyrus spp.) trees. However, the molecular mechanisms underlying pear resistance to B. dothidea remain elusive. In this study, we demonstrated that the pear AuTophagy-related Gene 1a (PbrATG1a) plays a key role in autophagic activity and resistance to B. dothidea. Stable overexpression of PbrATG1a enhanced resistance to B. dothidea in pear calli. Autophagy activity was greater in PbrATG1a-overexpressing calli than in wild-type calli. We used yeast 1-hybrid screening to identify a transcription factor, related to ABI3 and VP1 (Pbr3RAV2), that binds the promoter of PbrATG1a and enhances pear resistance to B. dothidea by regulating autophagic activity. Specifically, the overexpression of Pbr3RAV2 enhanced resistance to B. dothidea in pear calli, while transient silencing of Pbr3RAV2 resulted in compromised resistance to B. dothidea in Pyrus betulifolia. In addition, we identified Transparent Testa Glabra 1 (PbrTTG1), which interacts with Pbr3RAV2. Pathogen infection enhanced the interaction between Pbr3RAV2 and PbrTTG1. The Pbr3RAV2-PbrTTG1 complex increased the binding capacity of Pbr3RAV2 and transcription of PbrATG1a. In addition to providing insights into the molecular mechanisms underlying pear disease resistance, these findings suggest potential genetic targets for enhancing disease resistance in pear., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Proanthocyanidins (PAs) are an important group of flavonoids that contribute to astringency, color, and flavor in grapes (Vitis vinifera) and wines. They also play a crucial role in enhancing plant resistance to various stresses. However, the underlying regulatory mechanism governing PAs biosynthesis, particularly in relation to conferring resistance to powdery mildew, has not been extensively explored. This study focused on identifying a key player in PAs biosynthesis, namely the plant U-box (PUB) E3 ubiquitin ligase VvPUB26. We discovered that overexpression of VvPUB26 in grapes leads to a significant increase in PAs content, whereas interfering with VvPUB26 has the opposite effect. Additionally, our findings demonstrated that overexpression of VvPUB26 in transgenic grapevines enhances defense against powdery mildew while interfering with VvPUB26 results in increased susceptibility to the pathogen. Interestingly, we observed that VvPUB26 interacts with the WRKY transcription factor VvWRKY24, thereby facilitating ubiquitination and degradation processes. Through RNA-Seq analysis, we found that VvWRKY24 primarily participates in secondary metabolites biosynthesis, metabolic pathways, and plant-pathogen interaction. Notably, VvWRKY24 directly interacts with the promoters of dihydroflavonol-4-reductase (DFR) and leucoanthocyanidin reductase (LAR) to inhibit PAs biosynthesis. Meanwhile, VvWRKY24 also influences the expression of MYB transcription factor genes related to PAs synthesis. In conclusion, our results unveil a regulatory module involving VvPUB26-VvWRKY24-VvDFR/VvLAR that plays a fundamental role in governing PAs biosynthesis in grapevines. These findings enhance our understanding of the relationship between PAs biosynthesis and defense mechanisms against powdery mildew., Competing Interests: Conflict of interest statement. The authors have no conflict of interest to declare., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Plant nucleotide-binding leucine-rich repeat receptors (NLRs) sense pathogen effectors and activate effector-triggered immunity (ETI). Many plant NLRs form pairs with other NLRs to recognize effectors and initiate ETI. PIRICULARIA ORYZAE RESISTANCE IN BL1 (Pib), an NLR protein in rice (Oryza sativa), activates resistance by recognizing the rice blast effector AvrPib. The activation of Pib is suppressed by SH3 DOMAIN-CONTAINING PROTEIN 2 (OsSH3P2) in the absence of AvrPib. However, how Pib triggers defense responses and whether Pib pairs with another NLR are not clear. In this study, we identified Pib by map-based cloning and showed that a homolog of Pib, PIB HOMOLOGUE 8 (PibH8), interacts with Pib. Pib and PibH8 mediate resistance to the Magnaporthe oryzae isolate Guy11, a rice blast strain carrying AvrPib. Interestingly, the pib/pibh8 double mutant exhibited enhanced susceptibility to Guy11 compared to the single mutant. Furthermore, PibH8 can oligomerize through its coiled-coil (CC) domain, which also contributes to the Pib-PibH8 interaction, suggesting that Pib and PibH8 may form a complex to recognize AvrPib. OsSH3P2 inhibited the interaction of Pib and PibH8 through association with the CC domain of PibH8. Taken together, these results indicate that both Pib and PibH8 are required for rice blast resistance to M. oryzae carrying AvrPib, which is negatively regulated by OsSH3P2. This study not only identifies an NLR that functions in rice blast resistance but also reveals a possible complex immune strategy in which homologous NLR proteins may regulate the complete activation of plant immunity., Competing Interests: Conflict of interest statement. None declared., (© The Author(s) 2024. Published by Oxford University Press on behalf of American Society of Plant Biologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)

Verticillium dahliae is a kind of pathogenic fungus that brings about wilt disease and great losses in cotton. The molecular mechanism of the effectors in V. dahliae regulating cotton immunity remains largely unknown. Here, we identified an effector of V. dahliae, VdPHB1, whose gene expression is highly induced by infection. The VdPHB1 protein is localized to the intercellular space of cotton plants. Knock-out of the VdPHB1 gene in V. dahliae had no effect on pathogen growth, but decreased the virulence in cotton. VdPHB1 ectopically expressed Arabidopsis plants were growth-inhibited and significantly susceptible to V. dahliae. Further, VdPHB1 interacted with the type II metacaspase GhMC4. GhMC4 gene-silenced cotton plants were more sensitive to V. dahliae with reduced expression of pathogen defense-related and programmed cell death genes. The accumulation of GhMC4 protein was concurrently repressed when VdPHB1 protein was expressed during infection. In summary, these results have revealed a novel molecular mechanism of virulence regulation that the secreted effector VdPHB1 represses the activity of cysteine protease for helping V. dahliae infection in cotton., (© The Author(s) 2024. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site–for further information please contact journals.permissions@oup.com.)

Background: Sclerotinia spp. are generalist fungal pathogens, infecting over 700 plant hosts worldwide, including major crops. While host resistance is the most sustainable and cost-effective method for disease management, complete resistance to Sclerotinia diseases is rare. We recently identified soft basal stem as a potential susceptibility factor to Sclerotinia minor infection in lettuce (Lactuca sativa) under greenhouse conditions., Results: Analysis of stem and root cell wall composition in five L. sativa and one L. serriola accessions with varying growth habits and S. minor resistance levels revealed strong association between hemicellulose constituents, lignin polymers, disease phenotypes, and basal stem mechanical strength. Accessions resistant to basal stem degradation consistently exhibited higher levels of syringyl, guaiacyl, and xylose, but lower levels of fucose in stems. These findings suggest that stem cell wall polymers recalcitrant to breakdown by lignocellulolytic enzymes may contribute to stem strength-mediated resistance against S. minor., Conclusions: The lignin content, particularly guaiacyl and syringyl, along with xylose could potentially serve as biomarkers for identifying more resistant lettuce accessions and breeding lines. Basal stem degradation by S. minor was influenced by localized microenvironment conditions around the stem base of the plants., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Ascochyta blights cause yield losses in all major legume crops. Spring black stem (SBS) and leaf spot disease is a major foliar disease of Medicago truncatula and Medicago sativa (alfalfa) caused by the necrotrophic fungus Ascochyta medicaginicola. This present study sought to identify candidate genes for SBS disease resistance for future functional validation. We employed RNA-seq to profile the transcriptomes of a resistant (HM078) and susceptible (A17) genotype of M. truncatula at 24, 48, and 72 h post inoculation. Preliminary microscopic examination showed reduced pathogen growth on the resistant genotype. In total, 192 and 2,908 differentially expressed genes (DEGs) were observed in the resistant and susceptible genotype, respectively. Functional enrichment analysis revealed the susceptible genotype engaged in processes in the cell periphery and plasma membrane, as well as flavonoid biosynthesis whereas the resistant genotype utilized calcium ion binding, cell wall modifications, and external encapsulating structures. Candidate genes for disease resistance were selected based on the following criteria; among the top ten upregulated or downregulated genes in the resistant genotype, upregulated over time in the resistant genotype, hormone pathway genes, plant disease resistance genes, receptor-like kinases, contrasting expression profiles in QTL for disease resistance, and upregulated genes in enriched pathways. Overall, 22 candidate genes for SBS disease resistance were identified with support from the literature. These genes will be sources for future targeted mutagenesis and candidate gene validation potentially helping to improve disease resistance to this devastating foliar pathogen., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Key Message: A total of 65 SNPs associated with resistance to tan spot and septoria nodorum blotch were identified in a panel of 180 cultivated emmer accessions through association mapping Tan spot and septoria nodorum blotch (SNB) are foliar diseases caused by the respective fungal pathogens Pyrenophora tritici-repentis and Parastagonospora nodorum that affect global wheat production. To find new sources of resistance, we evaluated a panel of 180 cultivated emmer wheat (Triticum turgidum ssp. dicoccum) accessions for reactions to four P. tritici-repentis isolates Pti2, 86-124, 331-9 and DW5, two P. nodorum isolate, Sn4 and Sn2000, and four necrotrophic effectors (NEs) produced by the pathogens. About 8-36% of the accessions exhibited resistance to the four P. tritici-repentis isolates, with five accessions demonstrating resistance to all isolates. For SNB, 64% accessions showed resistance to Sn4, 43% to Sn2000 and 36% to both isolates, with Spain (11% accessions) as the most common origin of resistance. To understand the genetic basis of resistance, association mapping was performed using SNP (single nucleotide polymorphism) markers generated by genotype-by-sequencing and the 9 K SNP Infinium array. A total of 46 SNPs were significantly associated with tan spot and 19 SNPs with SNB resistance or susceptibility. Six trait loci on chromosome arms 1BL, 3BL, 4AL (2), 6BL and 7AL conferred resistance to two or more isolates. Known NE sensitivity genes for disease development were undetected except Snn5 for Sn2000, suggesting novel genetic factors are controlling host-pathogen interaction in cultivated emmer. The emmer accessions with the highest levels of resistance to the six pathogen isolates (e.g., CItr 14133-1, PI 94634-1 and PI 377672) could serve as donors for tan spot and SNB resistance in wheat breeding programs., (© 2024. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Background: Powdery mildew (caused by Blumeria graminis f. sp. tritici (Bgt)) and leaf rust (caused by Puccinia triticina (Pt)) are prevalent diseases in wheat (Triticum aestivum L.) production. Thinopyrum ponticum (2n = 10x = 70, E e E e E b E b E x E x StStStSt) contains genes that confer high levels of resistance to these diseases., Results: An elite wheat-Th. ponticum disomic substitution line, DS5Ag(5D), was developed in the Bainong Aikang 58 (AK58) background. The line was assessed using genomic in situ hybridization (GISH), oligo-nucleotide probe multiplex (ONPM) fluorescence in situ hybridization (FISH), and molecular markers. Twenty eight chromosome-specific molecular markers were identified for the alien chromosome, and 22 of them were co-dominant. Additionally, SNP markers from the wheat 660 K SNP chip were utilized to confirm chromosome identification and they provide molecular tools for tagging the chromosome in concern. The substitution line demonstrated high levels of resistance to powdery mildew throughout its growth period and to leaf rust at the adult stage. Based on the resistance evaluation of five F 5 populations between the substitution lines and wheat genotypes with different levels of sensitivity to the two diseases. Results showed that the resistance genes located on 5Ag confered stable resistance against both diseases across different backgrounds. Resistance spectrum analysis combined with diagnostic marker detection of known resistance genes of Th. ponticum revealed that 5Ag contained two novel genes, Pm5Ag and Lr5Ag, which conferred resistance to powdery mildew and leaf rust, respectively., Conclusions: In this study, a novel wheat-Th. ponticum disomic substitution line DS5Ag(5D) was successfully developed. The Th. ponticum chromosome 5Ag contain new resistance genes for powdery mildew and leaf rust. Chromosomic-specific molecular markers were generated and they can be used to track the 5Ag chromosome fragments. Consequently, this study provides new elite germplasm resources and molecular markers to facilitate the breeding of wheat varieties that is resistant to powdery mildew and leaf rust., (© 2024. The Author(s).)

Background: Septoria tritici blotch (STB) is considered to be one of the most destructive foliar wheat diseases and is caused by Zymoseptoria tritici. The yield losses are severe and in Northwestern Europe can reach up to 50%. The efficacy of fungicides is diminishing due to changes in the genetic structure of the pathogen. Therefore, resistance breeding is the most effective strategy of disease management. Recently, genome-wide association studies (GWAS) have become more popular due to their robustness in dissecting complex traits, including STB resistance in wheat. This was made possible by the use of large mapping populations and new sequencing technologies. High-resolution mapping benefits from historical recombination and greater allele numbers in GWAS., Results: In our study, 217 wheat genotypes of diverse origin were phenotyped against five Z. tritici isolates (IPO323, IPO88004, IPO92004, IPO86036 and St1-03) and genotyped on the DArTseq platform. In polytunnel tests two disease parameters were evaluated: the percentage of leaf area covered by necrotic lesions (NEC) and the percentage of leaf area covered by lesions bearing pycnidia (PYC). The disease escape parameters heading date (Hd) and plant height (Ht) were also measured. Pearson's correlation showed a positive effect between disease parameters, providing additional information. The Structure analysis indicated four subpopulations which included from 28 (subpopulation 2) to 79 genotypes (subpopulation 3). All of the subpopulations showed a relatively high degree of admixture, which ranged from 60% of genotypes with less than 80% of proportions of the genome attributed to assigned subpopulation for group 2 to 85% for group 4. Haplotype-based GWAS analysis allowed us to identify 27 haploblocks (HBs) significantly associated with analysed traits with a p-value above the genome-wide significance threshold (5%, which was -log10(p) > 3.64) and spread across the wheat genome. The explained phenotypic variation of identified significant HBs ranged from 0.2% to 21.5%. The results of the analysis showed that four haplotypes (HTs) associated with disease parameters cause a reduction in the level of leaf coverage by necrosis and pycnidia, namely: Chr3A&#95;HB98&#95;HT2, Chr5B&#95;HB47&#95;HT1, Chr7B&#95;HB36&#95;HT1 and Chr5D&#95;HB10&#95;HT3., Conclusions: GWAS analysis enabled us to identify four significant chromosomal regions associated with a reduction in STB disease parameters. The list of valuable HBs and wheat varieties possessing them provides promising material for further molecular analysis of resistance loci and development of breeding programmes., (© 2024. The Author(s).)

Background: Since the 1980s, soils in a 22-km 2 area near Lake Neuchâtel in Switzerland have been recognized for their innate ability to suppress the black root rot plant disease caused by the fungal pathogen Thielaviopsis basicola. However, the efficacy of natural disease suppressive soils against insect pests has not been studied., Results: We demonstrate that natural soil suppressiveness also protects plants from the leaf-feeding pest insect Oulema melanopus. Plants grown in the most suppressive soil have a reduced stress response to Oulema feeding, reflected by dampened levels of herbivore defense-related phytohormones and benzoxazinoids. Enhanced salicylate levels in insect-free plants indicate defense-priming operating in this soil. The rhizosphere microbiome of suppressive soils contained a higher proportion of plant-beneficial bacteria, coinciding with their microbiome networks being highly tolerant to the destabilizing impact of insect exposure observed in the rhizosphere of plants grown in the conducive soils. We suggest that presence of plant-beneficial bacteria in the suppressive soils along with priming, conferred plant resistance to the insect pest, manifesting also in the onset of insect microbiome dysbiosis by the displacement of the insect endosymbionts., Conclusions: Our results show that an intricate soil-plant-insect feedback, relying on a stress tolerant microbiome network with the presence of plant-beneficial bacteria and plant priming, extends natural soil suppressiveness from soilborne diseases to insect pests. Video Abstract., (© 2024. The Author(s).)

Millions of hibernating bats across North America have died from white-nose syndrome (WNS), an emerging disease caused by a psychrophilic (cold-loving) fungus, Pseudogymnoascus destructans , that invades their skin. Mechanisms of P. destructans invasion of bat epidermis remain obscure. Guided by our in vivo observations, we modeled hibernation with a newly generated little brown bat ( Myotis lucifugus ) keratinocyte cell line. We uncovered the stealth intracellular lifestyle of P. destructans , which inhibits apoptosis of keratinocytes and spreads through the cells by two epidermal growth factor receptor (EGFR)-dependent mechanisms: active penetration during torpor and induced endocytosis during arousal. Melanin of endocytosed P. destructans blocks endolysosomal maturation, facilitating P. destructans survival and germination after return to torpor. Blockade of EGFR aborts P. destructans entry into keratinocytes.

The electrical potential of the mycelia of a cord-forming wood decay fungus, Pholiota brunnescens, was monitored for over 100 days on a plain agar plate during the colonization onto a wood bait. Causality analyses of the electrical potential at different locations of the mycelium revealed a clear and stable causal relationship with the directional flow of the electrical potential from the hyphae at the bait location to other parts of the mycelium. However, this causality disappeared after 60 days of incubation, coinciding with the onset of slow electrical oscillation at the bait location, which occurred over one week per oscillation cycle. We speculated that the hyphae that initially colonized the bait may act as a temporary activity center, which generates electrical signals to other parts of the mycelium, thereby facilitating the colonization of the entire mycelial body to the bait. The week-long electrical oscillation represents the longest oscillation period ever recorded in fungi and warrants further investigation to elucidate its function and stability in response to environmental stimuli., (© 2024. The Author(s).)

With climate warming and economic globalization, insect-microbe assemblages are becoming increasingly responsible for various devastating forest diseases worldwide. Japanese larch (Larix kaempferi) is extensively cultivated in China because of its high survival rate, rapid maturation and robust mechanical properties. Endoconidiophora fujiensis, an ophiostomatoid fungus associated with Ips subelongatus, has been identified as a lethal pathogen of L. kaempferi in Japan. However, there is a dearth of research on the pathogenicity of E. fujiensis in larches in China. Therefore, we investigated the pathogenicity of E. fujiensis in introduced L. kaempferi and indigenous larch (Larix olgensis) trees and compared the induced resistance responses to the pathogen in both tree species in terms of physiology and gene expression. Five-year-old saplings and 25-year-old adult trees of L. olgensis and L. kaempferi were inoculated in parallel during the same growing season. Endoconidiophora fujiensis exhibited high pathogenicity in both larch species, but particularly in L. kaempferi compared with L. olgensis adult trees; adult L. olgensis was more resistant to E. fujiensis than adult L. kaempferi, which was reflected in higher accumulation of defensive monoterpenes, such as myrcene, 3-carene and limonene and the earlier induction of defense genes catalase (CAT) and pathogenesis-related protein 1 (PR1). This study contributes to our understanding of the interactions between bark beetle-associated ophiostomatoid fungi and host larches, from phenotypic responses to alterations in secondary metabolites via defense- and metabolism-related gene activation, providing a valuable foundation for the management of larch diseases and pests in the future., (© The Author(s) 2024. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Powdery mildew, caused by Blumeria graminis f. sp. tritici ( Bgt ), is a serious disease that threatens wheat production globally. It is imperative to explore novel resistance genes to control this disease by developing and planting resistant varieties. Here, we identified a wheat- Dasypyrum villosum 3V (3D) disomic substitution line, NAU3815 (2 n = 42), with a high level of powdery mildew resistance at both the seedling and adult-plant stages. Subsequently, NAU3815 was used to generate recombination between chromosomes 3V and 3D. Through genomic in situ hybridization (GISH), fluorescence in situ hybridization (FISH), and 3VS- and 3VL-specific markers analysis, four introgression lines were developed from the selfing progenies of 3V and 3D double monosomic line NAU3816, which was derived from the F 1 hybrids of NAU3815/NAU0686. There were t3VS (3D) ditelosomic substitution line NAU3817, t3VL (3D) ditelosomic substitution line NAU3818, homozygous T3DL·3VS translocation line NAU3819, and homozygous T3DS·3VL translocation line NAU3820. Powdery mildew tests of these lines confirmed the presence of an all-stage and broad-spectrum powdery mildew resistance gene, Pm3VS , located on chromosome arm 3VS. When compared with the recurrent parent NAU0686 plants, the T3DL·3VS translocation line NAU3819 showed no obvious negative effect on yield-related traits. However, the introduction of the T3DL·3VS translocated chromosome had a strong effect on reducing the flag-leaf length. Consequently, the T3DL·3VS translocation line NAU3819 provides a new germplasm in breeding for both resistance and plant architecture., Competing Interests: The author(s) declare no conflict of interest.

Sclerotinia sclerotiorum is an economically damaging fungal pathogen that causes Sclerotinia stem rot in legumes, producing enormous yield losses. This pathogen is difficult to control due to its wide host spectrum and ability to produce sclerotia, which are resistant bodies that can remain active for long periods under harsh environmental conditions. Here, the biocontrol methods for the management of S. sclerotiorum in legumes are reviewed. Bacillus strains, which synthesized lipopeptides and volatile organic compounds, showed high efficacies in soybean plants, whereas the highest efficacies for the control of the pathogen in alfalfa and common bean were observed when using Coniothyrium minitans and Streptomyces spp., respectively. The biocontrol efficacies in fields were under 65%, highlighting the lack of strategies to achieve a complete control. Overall, although most studies involved extensive screenings using different biocontrol agent concentrations and application conditions, there is a lack of knowledge regarding the specific antifungal mechanisms, which limits the optimization of the reported methods., Competing Interests: The author(s) declare no conflict of interest.

Methyl jasmonate (MeJA) and salicylic acid (SA) are important in mediating plant responses to abiotic and biotic stresses. MeJA and SA can act as elicitors by triggering plant defense responses similar to those induced by pathogens and may even provide long-term protection against them. Thus, exogenous application of MeJA and SA could protect susceptible avocado plants against white root rot (WRR) disease caused by the necrotrophic fungus Rosellinia necatrix , one of the main diseases affecting avocado orchards. This work evaluates the effects of MeJA or SA on the physiological and molecular response of susceptible 'Dusa' avocado rootstock and their ability to provide some protection against WRR. The application of MeJA and SA in avocado increased photoprotective mechanisms (nonphotochemical chlorophyll fluorescence quenching) and upregulated the glutathione S-transferase , suggesting the triggering of mechanisms closely related to oxidative stress relief and reactive oxygen species scavenging. In contrast to SA, MeJA's effects were more pronounced at the morphoanatomical level, including functional traits such as high leaf mass area, high stomatal density, and high root/shoot ratio, closely related to strategies to cope with water scarcity and WRR disease. Moreover, MeJA upregulated a greater number of defense-related genes than SA, including a glu protease inhibitor , a key gene in avocado defense against R. necatrix . The overall effects of MeJA increased 'Dusa' avocado tolerance to R. necatrix by inducing a primed state that delayed WRR disease symptoms. These findings point toward the use of MeJA application as an environmentally friendly strategy to mitigate the impact of this disease on susceptible avocado orchards., Competing Interests: The author(s) declare no conflict of interest.