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Background: α-Hairpinins are a family of antimicrobial peptides, promising antimicrobial agents, which includes only 12 currently revealed members with proven activity, although their real number is supposed to be much higher. α-Hairpinins are short peptides containing four cysteine residues arranged in a specific Cys-motif. These antimicrobial peptides (AMPs) have a characteristic helix−loop−helix structure with two disulfide bonds. Isolation of α-hairpinins by biochemical methods is cost- and labor-consuming, thus requiring reliable preliminary in silico prediction. Methods: In this study, we developed a special algorithm for the prediction of putative α-hairpinins on the basis of characteristic motifs with four (4C) and six (6C) cysteines deduced from translated plant transcriptome sequences. We integrated this algorithm into the Cysmotif searcher pipeline and then analyzed all transcriptomes available from the One Thousand Plant Transcriptomes project. Results: We predicted more than 2000 putative α-hairpinins belonging to various plant sources including algae, mosses, ferns, and true flowering plants. These data make α-hairpinins one of the ubiquitous antimicrobial peptides, being widespread among various plants. The largest numbers of α-hairpinins were revealed in the Papaveraceae family and in Papaver somniferum in particular. Conclusions: By analyzing the primary structure of α-hairpinins, we concluded that more predicted peptides with the 6C motif are likely to have potent antimicrobial activity in comparison to the ones possessing 4C motifs. In addition, we found 30 α-hairpinin precursors containing from two to eight Cys-rich modules. A striking similarity between some α-hairpinin modules belonging to diverse plants was revealed. These data allowed us to assume that the evolution of α-hairpinin precursors possibly involved changing the number of Cys-rich modules, leading to some missing middle and C-terminal modules, in particular.

The use of plant growth-promoting rhizobacteria presents a promising addition to conventional mineral fertilizer use and an alternative strategy for sustainable agricultural crop production. However, genotypic variations in the plant host may result in variability of the beneficial effects from these plant–microbe interactions. This study examined growth promotion effects of commercial vegetable crop cultivars of tomato, cucumber and broccoli following application with five rhizosphere bacteria. Biochemical assays revealed that the bacterial strains used possess several nutrient acquisition traits that benefit plants, including nitrogen fixation, phosphate solubilization, biofilm formation, and indole-3-acetic acid (IAA) production. However, different host cultivars displayed genotype-specific responses from the inoculations, resulting in significant (p < 0.05) plant growth promotion in some cultivars but insignificant (p > 0.05) or no growth promotion in others. Gene expression profiling in tomato cultivars revealed that these cultivar-specific phenotypes are reflected in differential expressions of defense and nutrient acquisition genes, suggesting that plants can be categorized into “microbe-friendly” cultivars (with little or no defense responses against beneficial microbes) and “microbe-hostile” cultivars (with strong defense responses). These results validate the notion that “microbe-friendly” (positive interaction with rhizosphere microbes) should be considered an important trait in breeding programs when developing new cultivars which could result in improved crop yields.

The interaction between plant hosts and plant viruses is a very unique and complex process, relying on dynamically modulated intercellular redox states and the generation of reactive oxygen species (ROS). Plants strive to precisely control this state during biotic stress, as optimal redox levels enable proper induction of defense mechanisms against plant viruses. One of the crucial elements of ROS regulation and redox state is the production of metabolites, such as glutathione, or the activation of glutathione-associated enzymes. Both of these elements play a role in limiting the degree of potential oxidative damage in plant cells. While the role of glutathione and specific enzymes is well understood in other types of abiotic and biotic stresses, particularly those associated with bacteria or fungi, recent advances in research have highlighted the significance of glutathione modulation and mutations in genes encoding glutathioneassociated enzymes in triggering immunity or susceptibility against plant viruses. Apparently, glutathione-associated genes are involved in precisely controlling and protecting host cells from damage caused by ROS during viral infections, playing a crucial role in the host's response. In this review, we aim to outline the significant improvements made in research on plant viruses and glutathione, specifically in the context of their involvement in susceptible and resistant responses, as well as changes in the localization of glutathione. Analyses of essential glutathione-associated enzymes in susceptible and resistant responses have demonstrated that the levels of enzymatic activity or the absence of specific enzymes can impact the spread of the virus and activate host-induced defense mechanisms. This contributes to the complex network of the plant immune system. Although investigations of glutathione during the plant-virus interplay remain a challenge, the use of novel tools and approaches to explore its role will significantly contribute to our knowledge in the field. [ABSTRACT FROM AUTHOR]

Summary: Plant resistance (R) and pathogen avirulence (Avr) gene interactions play a vital role in pathogen resistance. Efficient molecular screening tools for crops lack far behind their model organism counterparts, yet they are essential to rapidly identify agriculturally important molecular interactions that trigger host resistance.Here, we have developed a novel wheat protoplast assay that enables efficient screening of Avr/R interactions at scale. Our assay allows access to the extensive gene pool of phenotypically described R genes because it does not require the overexpression of cloned R genes. It is suitable for multiplexed Avr screening, with interactions tested in pools of up to 50 Avr candidates.We identified Avr/R‐induced defense genes to create a promoter‐luciferase reporter. Then, we combined this with a dual‐color ratiometric reporter system that normalizes read‐outs accounting for experimental variability and Avr/R‐induced cell death. Moreover, we introduced a self‐replicative plasmid reducing the amount of plasmid used in the assay.Our assay increases the throughput of Avr candidate screening, accelerating the study of cellular defense signaling and resistance gene identification in wheat. We anticipate that our assay will significantly accelerate Avr identification for many wheat pathogens, leading to improved genome‐guided pathogen surveillance and breeding of disease‐resistant crops. [ABSTRACT FROM AUTHOR]

This article is a Commentary on Gfeller et al. (2024), 241: 2575–2588. [ABSTRACT FROM AUTHOR]

Key message: NOI10 and NOI11 are two RIN4-like/NOI proteins that participate in the immune response of the Arabidopsis plant and affect the RIN4-regulated mechanisms involving the R-proteins RPM1 and RPS2. The immune response in plants depends on the regulation of signaling pathways triggered by pathogens and herbivores. RIN4, a protein of the RIN4-like/NOI family, is considered to be a central immune signal in the interactions of plants and pathogens. In Arabidopsis thaliana, four of the 15 members of the RIN4-like/NOI family (NOI3, NOI5, NOI10, and NOI11) were induced in response to the plant herbivore Tetranychus urticae. While overexpressing NOI10 and NOI11 plants did not affect mite performance, opposite callose accumulation patterns were observed when compared to RIN4 overexpressing plants. In vitro and in vivo analyses demonstrated the interaction of NOI10 and NOI11 with the RIN4 interactors RPM1, RPS2, and RIPK, suggesting a role in the context of the RIN4-regulated immune response. Transient expression experiments in Nicotiana benthamiana evidenced that NOI10 and NOI11 differed from RIN4 in their functionality. Furthermore, overexpressing NOI10 and NOI11 plants had significant differences in susceptibility with WT and overexpressing RIN4 plants when challenged with Pseudomonas syringae bacteria expressing the AvrRpt2 or the AvrRpm1 effectors. These results demonstrate the participation of NOI10 and NOI11 in the RIN4-mediated pathway. Whereas RIN4 is considered a guardee protein, NOI10 and NOI11 could act as decoys to modulate the concerted activity of effectors and R-proteins. [ABSTRACT FROM AUTHOR]

Phenolic compounds (PCs) are a prominent class of secondary metabolites produced by plants and are essential for the natural role of the entire plant life cycle. PCs are formed in plants under both favorable and unfavorable conditions and have essential functions in signaling pathways, such as cell division, nutrient mineralization, hormone control, and reproduction. Under abiotic stress conditions, plants produce more polyphenols, which aid them in adapting to their environment. The phenylpropanoid biosynthetic pathway is activated under various environmental stress conditions, such as drought, heavy metal toxicity, salinity, and high/low temperatures, resulting in the deposition of compounds. These compounds can neutralize reactive oxygen species (ROS) produced in excessive amounts in crops under stressful conditions and adversely affect plants. It is imperative to investigate the functions of PCs in response to several abiotic stresses, as the phenylpropanoid pathway plays a crucial role in the metabolic pathway in crop plants, leading to the biosynthesis of a wide range of PCs. These compounds play various roles in plant growth, development, and response to environmental stress. Therefore, this review provides a comprehensive understanding of PCs and their exchanges with other cellular components, which is crucial for harnessing their potential to improve crop resilience to environmental stresses. [ABSTRACT FROM AUTHOR]

Laticifers – among the most common defensive reservoirs in plants – are hypothesized to benefit plant fitness by preventing microbes from entering wounds. I argue that while latex seals wounds, and can suppress microbial growth, direct evidence that these processes benefit plant fitness is scarce. I outline a roadmap for filling this knowledge gap. [ABSTRACT FROM AUTHOR]

Tomato torrado virus (ToTV) is a type member of the Torradovirus genus in the Secoviridae family known to cause severe necrosis in susceptible tomato varieties. ToTV also infects other Solanaceae plants, including Nicotiana benthamiana , where it induces distinctive disease symptoms: plant growth drop with the emergence of spoon-like malformed systemic leaves. Virus-induced post-transcriptional gene silencing (PTGS) is significant among plant defense mechanisms activated upon virus invasion. The PTGS, however, can be counteracted by suppressors of RNA silencing commonly found in viruses, which efficiently disrupt the antiviral defense of their host. Here, we addressed the question of PTGS antiviral activity and its suppression in N. benthamiana during ToTV infection—a phenomenon not described for any representative from the Torradovirus genus so far. First, we showed that neither the Vp26—a necrosis-inducing pathogenicity determinant of ToTV—nor other structural viral proteins limited the locally induced PTGS similar to p19, a well-characterized potent suppressor of RNA silencing of tombusviruses. Moreover, by employing wild-type and transgenic lines of N. benthamiana with suppressed Dicer-like 2 (DCL2), Dicer-like 4 (DCL4), Argonaute 2 and RNA-dependent RNA polymerase 6 (RDR6) proteins, we proved their involvement in anti-ToTV defense. Additionally, we identified DCL4 as the major processor of ToTV-derived siRNA. More importantly, our results indicate the essential role of the Suppressor of Gene Silencing 3 (SGS3)/RDR6 pathway in anti-ToTV defense. Finally, we conclude that ToTV might not require a potent RNA silencing suppressor during infection of the model plant N. benthamiana. [ABSTRACT FROM AUTHOR]

Mealybug wilt of pineapple (MWP) is a destructive disease worldwide caused by a parasitic complex that includes Pineapple Mealybug Wilt-associated Viruses (PMWaVs) and mealybugs (Dysmicoccus brevipes), which concurrently act as vectors for these viruses. Reducing the mealybug population is key to managing MWP, which is achieved in intensive production systems through the use of insecticides. SA (salicylic acid), ASM (acibenzolar-S-methyl), BABA (β-aminobutyric acid), and MeSA (methyl salicylate) are key components of systemic acquired resistance (SAR), the defense mechanism of plants against biotrophic agents such as mealybugs. In this study, these compounds were applied either as pure chemicals and/or as a major constituent of plant extracts. Both the Hawaiian hybrid MD-2 and Queen Victoria tissue culture plants, as well as suckers used for vegetative propagation, were treated with these compounds by direct application on the soil of pineapple pots. Subsequently, five mealybugs were released on each plant or each daughter plant in case of a transgenerational experiment; then, after 45 days, the number of mealybugs was counted. Exogenous SA, ASM, and MeSA reduced the population of mealybugs by a minimum of 50% and up to 80%. These SAR-inducing treatments could be an interesting alternative for controlling mealybugs and are already used in other pathosystems. The SAR mechanisms behind this effect are yet to be confirmed by molecular and enzymatic markers. ASM and MeSA are promising treatments for pineapples using tissue culture plants or traditional shoots. [ABSTRACT FROM AUTHOR]

Allelopathy is a natural phenomenon of competing and interfering with other plants or microbial growth by synthesizing and releasing the bioactive compounds of plant or microbial origin known as allelochemicals. This is a sub-discipline of chemical ecology concerned with the effects of bioactive compounds produced by plants or microorganisms on the growth, development and distribution of other plants and microorganisms in natural communities or agricultural systems. Allelochemicals have a direct or indirect harmful effect on one plant by others, especially on the development, survivability, growth, and reproduction of species through the production of chemical inhibitors released into the environment. Cultivation systems that take advantage of allelopathic plants' stimulatory/inhibitory effects on plant growth and development while avoiding allelopathic autotoxicity is critical for long-term agricultural development. Allelopathy is one element that defines plant relationships and is involved in weed management, crop protection, and microbial contact. Besides, the allelopathic phenomenon has also been reported in the forest ecosystem; however, its presence depends on the forest type and the surrounding environment. In the present article, major aspects addressed are (1) literature review on the impacts of allelopathy in agroecosystems and underpinning the research gaps, (2) chemical, physiological, and ecological mechanisms of allelopathy, (3) genetic manipulations, plant defense, economic benefits, fate, prospects and challenges of allelopathy. The literature search and consolidation efforts in this article shall pave the way for future research on the potential application of allelopathic interactions across various ecosystems. [ABSTRACT FROM AUTHOR]

Calcium is a universal messenger in different kingdoms of living organisms and regulates most physiological processes, including defense against pathogens. The threat of viral infections in humans has become very clear in recent years, and this has triggered detailed research into all aspects of host–virus interactions, including the suppression of calcium signaling in infected cells. At the same time, however, the threat of plant viral infections is underestimated in society, and research in the field of calcium signaling during plant viral infections is scarce. Here we highlight an emerging role of calcium signaling for antiviral protection in plants, in parallel with the known evidence from studies of animal cells. Obtaining more knowledge in this domain might open up new perspectives for future crop protection and the improvement of food security. [ABSTRACT FROM AUTHOR]

Epigenetics refers to dynamic chemical modifications to the genome that can perpetuate gene activity without changes in the DNA sequence. Epigenetic mechanisms play important roles in growth and development. They may also drive plant adaptation to adverse environmental conditions by buffering environmental variation. Grapevine is an important perennial fruit crop cultivated worldwide, but mostly in temperate zones with hot and dry summers. The decrease in rainfall and the rise in temperature due to climate change, along with the expansion of pests and diseases, constitute serious threats to the sustainability of winegrowing. Ongoing research shows that epigenetic modifications are key regulators of important grapevine developmental processes, including berry growth and ripening. Variations in epigenetic modifications driven by genotype–environment interplay may also lead to novel phenotypes in response to environmental cues, a phenomenon called phenotypic plasticity. Here, we summarize the recent advances in the emerging field of grapevine epigenetics. We primarily highlight the impact of epigenetics to grapevine stress responses and acquisition of stress tolerance. We further discuss how epigenetics may affect winegrowing and also shape the quality of wine. [ABSTRACT FROM AUTHOR]

Summary: Microbial mutualists can profoundly modify host species ecology and evolution, by extension altering interactions with other microbial species, including pathogens. Arbuscular mycorrhizal fungi (AMF) may moderate infections by pathogens, but the direction and strength of these effects can be idiosyncratic.To assess how the introduction of AMF impacts the incidence and severity of aboveground plant diseases (i.e. 'disease impact'), we conducted a meta‐analysis of 130 comparisons derived from 69 published studies. To elucidate the potential mechanisms underlying the influence of AMF on pathogens, we conducted three glasshouse experiments involving six non‐woody plant species, yielded crucial data on leaf nutrient composition, plant defense compounds, and transcriptomes.Our meta‐analysis revealed that the inoculation of AMF lead to a reduction in disease impact. More precisely, AMF inoculation was associated with a decrease in necrotrophic diseases, while no significant impact on biotrophic diseases. Chemical and transcriptome analyses suggested that these effects may be driven by AMF regulation of jasmonic acid and salicylic acid signaling pathways in glasshouse experiments. However, changes in plant nutritional status and secondary chemicals may also regulate disease impact.These results emphasize the importance of incorporating pathogen life history when predicting how microbial mutualisms affect disease impact. [ABSTRACT FROM AUTHOR]

Combined abiotic and biotic stresses modify plant defense signaling, leading to either the activation or suppression of defense responses. Although the majority of combined abiotic and biotic stresses reduce plant fitness, certain abiotic stresses reduce the severity of pathogen infection in plants. Remarkably, certain pathogens also improve the tolerance of some plants to a few abiotic stresses. While considerable research focuses on the detrimental impact of combined stresses on plants, the upside of combined stress remains hidden. This review succinctly discusses the interactions between abiotic stresses and pathogen infection that benefit plant fitness. Various factors that govern the positive influence of combined abiotic stress and pathogen infection on plant performance are also discussed. In addition, we provide a brief overview of the role of pathogens, mainly viruses, in improving plant responses to abiotic stresses. We further highlight the critical nodes in defense signaling that guide plant responses during abiotic stress towards enhanced resistance to pathogens. Studies on antagonistic interactions between abiotic and biotic stressors can uncover candidates in host plant defense that may shield plants from combined stresses. [ABSTRACT FROM AUTHOR]

Gut microbiomes profoundly influence insect health and mediate interactions between plant hosts and their environments. Insects, including aphids, harbour diverse obligate symbionts that synthesize essential nutrients and facultative symbionts that enhance host fitness in specific ecological contexts. Sorghum (Sorghum bicolor) is a significant cereal crop cultivated worldwide that has been negatively affected by the presence of an invasive piercing-sucking insect pest, the sugarcane aphid (SCA; Melanaphis sacchari). We previously identified SC265 and SC1345 as the resistant and susceptible sorghum lines, respectively, among the founder nested association mapping (NAM) population. Here, using these resistant and susceptible lines, we explored variations in the SCA gut microbiome when they feed on two different sorghum lines with varied resistance levels. Analyses after excluding the obligate endosymbiont Buchnera aphidicola from the dataset showed a significant difference in microbial diversity and composition between resistant and susceptible sorghum lines 7- and 14 days post aphid infestation. Our results indicate that the SCA fed on susceptible and resistant sorghum lines had Pseudomonadaceae and Rhizobiaceae, respectively, as the most abundant bacterial families. Differences in gut microbial community composition were underscored by alpha diversity metrics and beta diversity compositional analyses. These findings contribute to our understanding of the intricate interplay between plant and aphid microbiomes, shedding light on potential avenues to bolster sorghum resistance to SCA. [ABSTRACT FROM AUTHOR]

Main conclusion: Silencing of an ascorbate oxidase (AO) gene in N. benthamiana enhanced disease severity from cucumber mosaic virus (CMV), showing higher accumulation and expansion of the spreading area of CMV. A Nicotiana benthamiana ascorbate oxidase (NbAO) gene was found to be induced upon cucumber mosaic virus (CMV) infection. Virus-induced gene silencing (VIGS) was employed to elucidate the function of AO in N. benthamiana. The tobacco rattle virus (TRV)-mediated VIGS resulted in an efficient silencing of the NbAO gene, i.e., 97.5% and 78.8% in relative quantification as compared to the control groups (TRV::eGFP- and the mock-inoculated plants), respectively. In addition, AO enzymatic activity decreased in the TRV::NtAO-silenced plants as compared to control. TRV::NtAO-mediated NbAO silencing induced a greater reduction in plant height by 15.2% upon CMV infection. CMV titer at 3 dpi was increased in the systemic leaves of NbAO-silenced plants (a 35-fold change difference as compared to the TRV::eGFP-treated group). Interestingly, CMV and TRV titers vary in different parts of systemically infected N. benthamiana leaves. In TRV::eGFP-treated plants, CMV accumulated only at the top half of the leaf, whereas the bottom half of the leaf was “occupied” by TRV. In contrast, in the NbAO-silenced plants, CMV accumulated in both the top and the bottom half of the leaf, suggesting that the silencing of the NbAO gene resulted in the expansion of the spreading area of CMV. Our data suggest that the AO gene might function as a resistant factor against CMV infection in N. benthamiana. [ABSTRACT FROM AUTHOR]

SUMMARY: The membrane‐bound heterotrimeric G‐proteins in plants play a crucial role in defending against a broad range of pathogens. This study emphasizes the significance of Extra‐large Gα protein 2 (XLG2), a plant‐specific G‐protein, in mediating the plant response to Sclerotinia sclerotiorum, which infects over 600 plant species worldwide. Our analysis of Arabidopsis G‐protein mutants showed that loss of XLG2 function increased susceptibility to S. sclerotiorum, accompanied by compromised accumulation of jasmonic acid (JA) during pathogen infection. Overexpression of the XLG2 gene in xlg2 mutant plants resulted in higher resistance and increased JA accumulation during S. sclerotiorum infection. Co‐immunoprecipitation (co‐IP) analysis on S. sclerotiorum infected Col‐0 samples, using two different approaches, identified 201 XLG2‐interacting proteins. The identified JA‐biosynthetic and JA‐responsive proteins had compromised transcript expression in the xlg2 mutant during pathogen infection. XLG2 was found to interact physically with a JA‐responsive protein, Coronatine induced 1 (CORI3) in Co‐IP, and confirmed using split firefly luciferase complementation and bimolecular fluorescent complementation assays. Additionally, genetic analysis revealed an additive effect of XLG2 and CORI3 on resistance against S. sclerotiorum, JA accumulation, and expression of the defense marker genes. Overall, our study reveals two independent pathways involving XLG2 and CORI3 in contributing resistance against S. sclerotiorum. Significance Statement: XLG2 and CORI3 proteins interact to confer defense against Sclerotinia sclerotiorum, primarily through the JA pathway, while also suggesting the involvement of independent defense mechanisms. [ABSTRACT FROM AUTHOR]

SUMMARY: Carotenoids are isoprenoid pigments indispensable for photosynthesis. Moreover, they are the precursor of apocarotenoids, which include the phytohormones abscisic acid (ABA) and strigolactones (SLs) as well as retrograde signaling molecules and growth regulators, such as β‐cyclocitral and zaxinone. Here, we show that the application of the volatile apocarotenoid β‐ionone (β‐I) to Arabidopsis plants at micromolar concentrations caused a global reprogramming of gene expression, affecting thousands of transcripts involved in stress tolerance, growth, hormone metabolism, pathogen defense, and photosynthesis. This transcriptional reprogramming changes, along with induced changes in the level of the phytohormones ABA, jasmonic acid, and salicylic acid, led to enhanced Arabidopsis resistance to the widespread necrotrophic fungus Botrytis cinerea (B.c.) that causes the gray mold disease in many crop species and spoilage of harvested fruits. Pre‐treatment of tobacco and tomato plants with β‐I followed by inoculation with B.c. confirmed the effect of β‐I in increasing the resistance to this pathogen in crop plants. Moreover, we observed reduced susceptibility to B.c. in fruits of transgenic tomato plants overexpressing LYCOPENE β‐CYCLASE, which contains elevated levels of endogenous β‐I, providing a further evidence for its effect on B.c. infestation. Our work unraveled β‐I as a further carotenoid‐derived regulatory metabolite and indicates the possibility of establishing this natural volatile as an environmentally friendly bio‐fungicide to control B.c. Significance Statement: Plants rely on a wide range of metabolites to coordinate their growth and to respond to environmental stimuli. The family of carotenoid‐cleavage products, apocarotenoids, is emerging as a source of growth‐regulating and signaling molecules conferring protection against abiotic and biotic stresses. We show that the apocarotenoid, β‐ionone, is a regulatory metabolite that reshapes Arabidopsis transcriptome and hormone content, increasing resistance to the necrotrophic fungus Botrytis cinerea (B.c.) in Arabidopsis, tobacco and tomato plants. [ABSTRACT FROM AUTHOR]

Endophytic fungi are microorganisms known as plant-associated fungi and are typically found asymptomatically inside plant tissue. By directly generating secondary metabolites, endophytic fungi help their host plants grow and become more resistant to plant diseases. Furthermore, they can also biosynthesize bioactive compounds used for antimicrobials, which were previously believed to be produced only by the host plant. Medicinal plants as host plants for endophytic fungi which produce secondary metabolites and their ability as biological agents against pathogens. Calabash tree is a medicinal plant that contains active compounds that function as antifungal and antibacterial. This study aims to determine the antagonistic activity of endophytic fungi from calabash tree leaves against F. oxysporum Fos, the pathogen that causes fusarium wilt in shallot plants. Twelve endophytic fungi were obtained from isolation from the leaves of the calabash tree, namely EnM6C22, EnM11P2, EnM6A2, EnM5H21, EnM10H22, EnM12P, EnM11P, EnM111, EnM5H22, EnM9Pt22, EnM5H1 and EnM5K. Five of the twelve endophytic fungi of calabash tree leaves have been identified, as Fusarium sp., Rhizoctonia sp., Pestalotia sp., Colletotrichum sp., and Bipolaris sp. with inhibition percentages of 36.43%, 32.19%, 25.41%, 32.19%, and 27.53% respectively at 7 days after inoculation. [ABSTRACT FROM AUTHOR]

Neonicotinoid seed treatment (NST) is a routine practice used worldwide to control insect pests in a variety of crops, including maize (Zea mays mays L.). However, previous work indicates that systemic insecticides can compromise plant defenses, counteracting efforts to control insect pests. The goal of this study was to evaluate the effect of thiamethoxam-neonicotinoid seed treatment on the resistance of two maize genotypes (B73 and MC 4050) against the major non-target pest, fall armyworm Spodoptera frugiperda (Lepidoptera: Noctuidae). In preference and performance assays, we evaluated the effect of NST on fall armyworm behavior and biology. We also determined the influence of NST on induced plant defenses, quantifying phytohormone levels and plant volatile emissions, in treatments with and without fall armyworm herbivory. NST did not affect caterpillar host preference, however it reduced caterpillar performance on the genotype B73 across both maize growth stages (V4 and V6). NST-treated B73 plants also had lower induced volatile production (V4 stage) compared to untreated herbivore-damage plants and lower constitutive salicylic acid (V6 stage). In contrast, MC 4050 was not affected by the insecticide, regardless of growth stage. In conclusion, we found that the effects of NST on maize defenses vary by plant genotype and growth stage, suggesting growers may need to tailor their selection of plant genotypes to avoid negative impacts of NST on plant resistance and ultimately pest control. [ABSTRACT FROM AUTHOR]

Insect–plant interactions are less well studied than other types of herbivory on islands, precluding a comprehensive understanding of the evolutionary ecology of these interactions. Declines in native island plants and insects call for urgent attention to characterize these species' interactions for their conservation and to better understand evolution in these unique, insular ecosystems. In Hawai'i, the Kamehameha butterfly (Vanessa tameamea) is one of only two native butterflies, and larvae are specialists on native urticaceous plants. Using a no‐choice bioassay, we investigated performance of V. tameamea reared from egg hatching through eclosion on four native urticaceous host plants, Boehmeria grandis, Pipturus albidus, Touchardia latifolia, and Touchardia oahuensis, and one exotic urticaceous species, Cecropia obtusifolia. Performance varied significantly among the plant diets, with V. tameamea performing best on P. albidus and T. oahuensis among the performance metrics of survival, pupal and adult body mass, and development time. Larval responses to the exotic host plant C. obtusifolia varied among populations, with O'ahu caterpillars successfully completing development on it, but Hawai'i Island caterpillars rejecting it completely, suggesting a geographic mosaic for this novel species interaction. Characterization of a suite of nutritive and defensive plant traits revealed significant variability among plant species, but patterns did not align well with V. tameamea performance rankings, making it difficult to identify key drivers of host plant quality. Future work examining additional plant traits under natural conditions would provide new insights, contributing critical ecological information to conserve this charismatic island species. [ABSTRACT FROM AUTHOR]

N6-methyladenosine (m6A) is the most abundant eukaryotic mRNA modification and is involved in various biological processes. Increasing evidence has implicated that m6A modification is an important anti-viral defense mechanism in mammals and plants, but it is largely unknown how m6A regulates viral infection in plants. Here we report the dynamic changes and functional anatomy of m6A in Nicotiana benthamiana and Solanum lycopersicum during Pepino mosaic virus (PepMV) infection. m6A modification in the PepMV RNA genome is conserved in these two species. Overexpression of the m6A writers, mRNA adenosine methylase A (MTA), and HAKAI inhibit the PepMV RNA accumulation accompanied by increased viral m6A modifications, whereas deficiency of these writers decreases the viral RNA m6A levels but enhances virus infection. Further study reveals that the cytoplasmic YTH-domain family protein NbECT2A/2B/2C as m6A readers are involved in anti-viral immunity. Protein-protein interactions indicate that NbECT2A/2B/2C interact with nonsense-mediated mRNA decay (NMD)-related proteins, including NbUPF3 and NbSMG7, but not with NbUPF1. m6A modification-mediated restriction to PepMV infection is dependent on NMD-related factors. These findings provide new insights into the functionality of m6A anti-viral activity and reveal a distinct immune response that NMD factors recognize the m6A readers-viral m6A RNA complex for viral RNA degradation to limit virus infection in plants. [ABSTRACT FROM AUTHOR]

Plants employ a diverse array of responses to counteract and defend against stressors. Utilizing quantitative proteomic analysis allows for the exploration of global proteomic dynamics in cells and tissues at specific time points. In order to comprehend the intricate mechanisms underlying plant responses, we conducted a proteomic investigation of peanut hairy root cultures induced with a combination of chitosan (CHT), methyl jasmonate (MeJA), and cyclodextrin (CD) at multiple time points. The study identified 292, 317, and 327 differentially expressed proteins (DEPs) in hairy root tissues at 24-, 48-, and 72 h intervals post-elicitation, respectively. Principal component analysis (PCA) distinctly clustered each timepoint of treatment and the control group. Gene ontology (GO) enrichment analysis highlighted terms such as ''responding to biotic stimuli'' and ''defense response'' during the early response, with the upregulation of Heat shock cognate 70 kDa protein, Wound-induced protein 1, and Disease resistance-like protein. The 72 h time point specifically showed an upregulation of superoxide dismutase (SOD) and auxin response factor, indicating a delayed response and illustrating how hairy roots adapt to stress in later stages. Furthermore, GO enrichment at later stages implicated alterations in protein production, involving both synthesis and degradation processes. Proteolytic enzymes, including those in the ubiquitin/proteasome pathway, were identified as facilitating protein degradation. The detection of small molecular weight (MW) peptides in the culture medium of elicited hairy roots suggested their origin from the proteolytic cleavage of precursor proteins. The GO enrichment of culture medium peptides pointed towards involvement in signaling pathways. The suggested signaling cascade acts as a potential link that connects the recognition of stress to the initiation of appropriate response to external stressors. This approach delves into dynamic changes in protein expression and secretion patterns over various intervals, providing insights into the plant's adaptive response to external stress.

The rice receptor kinase XA21 confers broad-spectrum resistance to Xanthomonas oryzae pv. oryzae (Xoo), the causal agent of rice bacterial blight disease. To investigate the relationship between the expression level of XA21 and resulting resistance, we generated independent HA-XA21 transgenic rice lines accumulating the XA21 immune receptor fused with an HA epitope tag. Whole-genome sequence analysis identified the T-DNA insertion sites in sixteen independent T0 events. Through quantification of the HA-XA21 protein and assessment of the resistance to Xoo strain PXO99 in six independent transgenic lines, we observed that XA21-mediated resistance is dose dependent. In contrast, based on the four agronomic traits quantified in these experiments, yield is unlikely to be affected by the expression level of HA-XA21. These findings extend our knowledge of XA21-mediated defense and contribute to the growing number of well-defined genomic landing pads in the rice genome that can be targeted for gene insertion without compromising yield.

Root-knot nematodes are polyphagous parasitic nematodes that cause severe losses in the agriculture worldwide. They enter the root in the elongation zone and subtly migrate to the root meristem where they reach the vascular cylinder and establish a feeding site called gall. Inside the galls they induce a group of transfer cells that serve to nurture them along their parasitic stage, the giant cells. Galls and giant cells develop through a process of post-embryogenic organogenesis that involves manipulating different genetic regulatory networks within the cells, some of them through hijacking some molecular transducers of established plant developmental processes, such as lateral root formation or root regeneration. Galls/giant cells formation involves different mechanisms orchestrated by the nematode´s effectors that generate diverse plant responses in different plant tissues, some of them include sophisticated mechanisms to overcome plant defenses. Yet, the plant-nematode interaction is normally accompanied to dramatic transcriptomic changes within the galls and giant cells. It is therefore expected a key regulatory role of plant-transcription factors, coordinating both, the new organogenesis process induced by the RKNs and the plant response against the nematode. Knowing the role of plant-transcription factors participating in this process becomes essential for a clear understanding of the plant-RKNs interaction and provides an opportunity for the future development and design of directed control strategies. In this review, we present the existing knowledge of the TFs with a functional role in the plant-RKN interaction through a comprehensive analysis of current scientific literature and available transcriptomic data.

Inducible anti-herbivore defenses in plants are predominantly regulated by jasmonic acid (JA). The red spider mite Tetranychus evansi Baker & Pritchard, 1960 (Acari: Tetranychidae) is an invasive pest known for its detrimental impact on tomato plants and other Solanaceae crops. Here, we investigated the extent to which T. evansi and the predatory mite Phytoseiulus longipes Evans, 1968 (Acari: Phytoseiidae) are affected by induced JA-defenses. Initially, we artificially induced the JA-response in tomato plants using exogenous methyl jasmonate (MeJA) and subsequently assessed the effect of JA defenses on spider mite by evaluating mortality and oviposition rates. Our findings revealed a higher mortality and lower oviposition rates on plants treated with MeJA compared to non-treated control plants. Furthermore, we examined the predatory mite's predation rates on spider mite eggs produced on MeJA-treated and non-treated tomato plants. The results showed a reduced predation on T. evansi eggs derived from MeJA-treated plants, indicating a potential negative impact of JA-induced defenses on the predator's performance. Finally, we released five predatory females on T. evansi-infested tomato plants treated and non-treated with MeJA, monitoring the predator population density for three generations. Predator population was not affected, as the abundance of larvae and adults was not significantly different between treatments. These findings underscore the negative impact of JA defenses on herbivores and highlight the trade-off it may pose on natural enemies.

Abstract Plants regulate root exudates to form the composition of rhizosphere microbial community and resist disease stress. Many studies advocate intervention with biochar (BC) and exogenous microbe to enhance this process and improve plant defenses. However, the mechanism by which BC mediates exogenous microorganisms to enhance root exudate-soil microbial defensive feedback remains unclear. Here, a BC-based Bacillus subtilis SL-44 inoculant (BC@SL) was prepared to investigate the defensive feedback mechanism for plants, which enhanced plant growth and defense more than BC or SL-44 alone. BC@SL not only strengthened the direct inhibition of Rhizoctonia solani Rs by solving the problem of reduced viability of a single SL-44 inoculant but also indirectly alleviated the Rs stress by strengthening plant defensive feedback, which was specifically manifested by the following: (1) increasing the root resistance enzyme activities (superoxide dismutase up to 3.5 FC); (2) increasing the abundance of beneficial microbe in soil (0.38–16.31% Bacillus); and (3) remodeling the composition of root exudates (palmitic acid 3.95–6.96%, stearic acid 3.56–5.93%, 2,4 tert-butylphenol 1.23–2.62%, increasing citric acid 0.94–1.81%, and benzoic acid 0.97–2.13%). The mechanism reveals that BC@SL can enhance the positive regulatory effect between root exudates and microorganisms by optimizing their composition. Overall, BC@SL is a stable and efficient new solid exogenous soil auxiliary, and this study lays the foundation for the generalization and application of green pesticides. Graphical Abstract

Trichome is a hair-like structure involved in mechanical and chemical defenses of plants against herbivorous insects. Nicotiana benthamiana, a wild tobacco plant, has well-developed glandular trichomes that secrete sugar esters with potent repellent and insecticidal properties. However, there is a lack of information about the effectiveness of trichome extract in the control of plant-sapping insects. The objective of this study was to investigate the effects of N. benthamiana trichome exudates on Bemisia tabaci MED (Gennadius) (Hemiptera: Aleyrodidae), a highly destructive insect pest that poses significant threats to both vegetable and ornamental plants globally. First, we determined the host preference and mortality of B. tabaci adults using the choice test and feeding assay towards tomato and N. benthamiana plants. B. tabaci preferred tomato over N. benthamiana plants. Second, we extracted N. benthamiana trichome exudates by washing the leaves with either water or ethanol and evaluated their oral toxicities against B. tabaci adults using a parafilm feeding chamber containing 20% sucrose solution. Oral ingestion of both extracts significantly increased mortality in a concentration-dependent manner. Oral ingestion of ethanol-washed 10% trichome extract caused >60% mortality in B. tabaci adults after 36 h. Third, trichome exudates were concentrated by drying to obtain a powder form, which was more potent in killing whiteflies than the liquid form. Oral ingestion of 1% trichome powder was completely lethal to B. tabaci within 36 h. N. benthamiana trichome exudates are highly toxic to B. tabaci through oral ingestion, suggesting that N. benthamiana can be used as a potential natural pesticide for whitefly management.

Abstract The interaction between insects and plants is a classic case of coevolution. During the arms race that has continued for 400 million years, the mutualistic (such as pollination and defense assistance) and antagonistic relationships gradually formed and complicated under the selection pressure from phytophagous insects. Thus, plants have developed diverse defense strategies, constantly balancing the relationship between defense and growth. At the same time, insects have evolved the ability to adapt to and resist plant defenses. Throughout this process, phenotypic plasticity has continuously helped both groups adapt to new environments and niches. Epigenetic changes play an important role in the formation of plastic phenotype. These changes allow parental defense traits to be passed on to the offspring, helping the offspring resist insect feeding. Epigenetic changes and genetic variation provide the basis for the formation of new phenotypes, and plants can form stable defense traits under long-term insect feeding pressure. In this review, we summarize the defense strategies of plants and the counter-defense strategies of insects, suggest that phenotypic plasticity plays an important role in this interaction, and discuss the role of epigenetics in the formation of plastic phenotypes.

Abstract Background Two spotted spider mite, Tetranychus urticae (Acari: Tetranychidae) is one of the most important plant pests in the world. Due to increased resistance of mites to acaricides, it is necessary to use other methods such as inducing resistance in plants by natural compounds for pests' management. Polyamins such as spermine are effective in increasing plant resistance to biotic and abiotic stressors. In this research, the effect of spermine treatments in cucumber plants on life table parameters of T. urticae was investigated. Also, top-down effect of spermine and T. urticae on cucumber biochemical parameters was measured. In the experiments, 1, 2 and 3 mM spermine concentrations were used. Results Amongst the spermine treatments, those mites that fed on cucumbers which received 1 mM spermine showed the shortest protonymphal period and higher ovipositon period, fecundity, gross and net reproductive rates and life expectancy compare to control. Treatment with 2 mM spermine lead to the longest teleochrysalis period and shortest range of age-stage-specific fecundity period. In addition, 2 mM spermine lowered intrinsic and finite rate of population increase in T. urticae. The longest larval period of T. urticae was observed in 3 mM spermine. Feeding of T. urticae from cucumber plants increased hydrogen peroxide (H2O2), malondialdehyde (MDA) content, electrolyte leakage (EL) level and ascorbate peroxidase (APX) activity but inhibited catalase (CAT) activity in this plant. Infested cucumber plants treated with 2 mM spermine showed lower H2O2 and MDA content and highest activity of APX and CAT on day 1 and 3 compare to the others. The 3 mM spermine increased H2O2 content in infested plants during the whole experiment as well as non-infested plants in day 5 and 9 only. This treatment induced the highest MDA content and lowest catalase activity on day1, 3 and 5 of experiment in infested plants. Conclusion This study showed that 2 mM spermine was the only effective concentration that reduce cucumber sensitivity to T. urticae. The trend of changes in biochemical parameters, especially H2O2, in 3 mM spermine was abnormal, and this concentration could be considered toxic.

Microbes hold immense potential, based on the fact that they are widely acknowledged for their role in mitigating the detrimental impacts of chemical fertilizers and pesticides, which were extensively employed during the Green Revolution era. The consequence of this extensive use has been the degradation of agricultural land, soil health and fertility deterioration, and a decline in crop quality. Despite the existence of environmentally friendly and sustainable alternatives, microbial bioinoculants encounter numerous challenges in real-world agricultural settings. These challenges include harsh environmental conditions like unfavorable soil pH, temperature extremes, and nutrient imbalances, as well as stiff competition with native microbial species and host plant specificity. Moreover, obstacles spanning from large-scale production to commercialization persist. Therefore, substantial efforts are underway to identify superior solutions that can foster a sustainable and eco-conscious agricultural system. In this context, attention has shifted towards the utilization of cell-free microbial exudates as opposed to traditional microbial inoculants. Microbial exudates refer to the diverse array of cellular metabolites secreted by microbial cells. These metabolites enclose a wide range of chemical compounds, including sugars, organic acids, amino acids, peptides, siderophores, volatiles, and more. The composition and function of these compounds in exudates can vary considerably, depending on the specific microbial strains and prevailing environmental conditions. Remarkably, they possess the capability to modulate and influence various plant physiological processes, thereby inducing tolerance to both biotic and abiotic stresses. Furthermore, these exudates facilitate plant growth and aid in the remediation of environmental pollutants such as chemicals and heavy metals in agroecosystems. Much like live microbes, when applied, these exudates actively participate in the phyllosphere and rhizosphere, engaging in continuous interactions with plants and plant-associated microbes. Consequently, they play a pivotal role in reshaping the microbiome. The biostimulant properties exhibited by these exudates position them as promising biological components for fostering cleaner and more sustainable agricultural systems.

Small RNAs (sRNAs) are known to regulate pathogenic plant-microbe interactions. Emerging evidence from the study of these model systems suggests that microRNAs (miRNAs) can be translocated between microbes and plants to facilitate symbiosis. The roles of sRNAs in mutualistic mycorrhizal fungal interactions, however, are largely unknown. In this study, we characterized miRNAs encoded by the ectomycorrhizal fungus Pisolithus microcarpus and investigated their expression during mutualistic interaction with Eucalyptus grandis. Using sRNA sequencing data and in situ miRNA detection, a novel fungal miRNA, Pmic_miR-8, was found to be transported into E. grandis roots after interaction with P. microcarpus Further characterization experiments demonstrate that inhibition of Pmic_miR-8 negatively impacts the maintenance of mycorrhizal roots in E. grandis, while supplementation of Pmic_miR-8 led to deeper integration of the fungus into plant tissues. Target prediction and experimental testing suggest that Pmic_miR-8 may target the host NB-ARC domain containing transcripts, suggesting a potential role for this miRNA in subverting host signaling to stabilize the symbiotic interaction. Altogether, we provide evidence of previously undescribed cross-kingdom sRNA transfer from ectomycorrhizal fungi to plant roots, shedding light onto the involvement of miRNAs during the developmental process of mutualistic symbioses.

This article, titled "Editorial: Rhizospheric interactions: integrating plant-microbe signaling during stresses," explores the importance of understanding plant interactions and their impact on the ecosystem, particularly in the context of agricultural practices. The article emphasizes the need for eco-friendly and sustainable approaches to agriculture, highlighting the role of rhizospheric interactions in nutrient acquisition, stress resistance, and overall plant growth. It discusses the various ways in which rhizospheric microbes contribute to plant health and defense mechanisms, as well as the potential for these interactions to be utilized in sustainable agricultural practices. The article also mentions specific studies that have investigated the role of rhizospheric interactions in plant stress resistance and growth promotion. [Extracted from the article]

This study explores the impact of exogenous salicylic acid (SA) alongside conventional treatment by farmers providing positive (Mancozeb 80 % WP) and negative (water) controls on rice plants (Oryza sativa L.), focusing on antioxidant enzyme activities, phytohormone levels, disease resistance, and yield components under greenhouse and field conditions. In greenhouse assays, SA application significantly enhanced the activities of peroxidase (POX), polyphenol oxidase (PPO), catalase (CAT), and superoxide dismutase (SOD) within 12–24 h post-inoculation (hpi) with Magnaporthe oryzae. Additionally, SA-treated plants showed higher levels of endogenous SA and indole-3-acetic acid (IAA) within 24 hpi compared to the controls. In terms of disease resistance, SA-treated plants exhibited a reduced severity of rice blast under greenhouse conditions, with a significant decrease in disease symptoms compared to negative control treatment. The field study was extended over three consecutive crop seasons during 2021–2023, further examining the efficacy of SA in regular agricultural practice settings. The SA treatment consistently led to a reduction in rice blast disease severity across all three seasons. Yield-related parameters such as plant height, the number of tillers and panicles per hill, grains per panicle, and 1000-grain weight all showed improvements under SA treatment compared to both positive and negative control treatments. Specifically, SA-treated plants yielded higher grain outputs in all three crop seasons, underscoring the potential of SA as a growth enhancer and as a protective agent against rice blast disease under both controlled and field conditions. These findings state the broad-spectrum benefits of SA application in rice cultivation, highlighting its role not only in bolstering plant defense mechanisms and growth under greenhouse conditions but also in enhancing yield and disease resistance in field settings across multiple crop cycles. This research presents valuable insights into the practical applications of SA in improving rice plant resilience and productivity, offering a promising approach for sustainable agriculture practices.

Viral, bacterial, fungal, and nematode infections cause significant agricultural losses, with limited treatment options, necessitating novel approaches to enhance plant defense systems and protection against pathogens. Virus-like nanoparticles (VLPs), extensively used in animal and human therapies (e.g., vaccines and immune enhancers), hold potential for novel agricultural solutions and advancing plant nanotechnology. This study employed various methodologies, including VLP production, confocal microscopy, and real-time qPCR. Our findings demonstrated the presence of 30 nm Qβ-VLPs, fluorescently labeled, within the intercellular space of Nicotiana benthamiana leaves one hour post-infiltration. Furthermore, infiltration with Qβ-VLPs led to an upregulation of key defense genes (NbPR1a, NbPR5, NbNPR, NbERF1, NbMYC2, and NbLRR2) in treated plants. Using RT-qPCR, a significant increase in the relative expression levels of defense genes was observed, with sustained high levels of NbERF1 and NbLRR2 even after 24 h. These findings suggest that Qβ-VLPs effectively upregulate genes crucial for pathogen defense in N. benthamiana, initiating PAMP-triggered immunity and launching signaling cascades that enhance defense mechanisms. This innovative application of VLPs to activate plant defense programs advances plant nanobiotechnology, offering new agricultural solutions.

Plants face numerous environmental stresses that hinder their growth and productivity, including biotic agents, such as herbivores and parasitic microorganisms, as well as abiotic factors, such as cold, drought, salinity, and high temperature. To counter these challenges, plants have developed a range of defense strategies. Among these, plant antimicrobial proteins and peptides (APPs) have emerged as a promising solution. Due to their broad-spectrum activity, structural stability, and diverse mechanisms of action, APPs serve as powerful tools to complement and enhance conventional agricultural methods, significantly boosting plant defense and productivity. This review focuses on different studies on APPs, emphasizing their crucial role in combating plant pathogens and enhancing plant resilience against both biotic and abiotic stresses. Beginning with in vitro studies, we explore how APPs combat various plant pathogens. We then delve into the defense mechanisms triggered by APPs against biotic stress, showcasing their effectiveness against bacterial and fungal diseases. Additionally, we highlight the role of APPs in mitigating the abiotic challenges associated with climatic change. Finally, we discuss the current applications of APPs in agriculture, emphasizing their potential for sustainable agricultural practices and the need for future research in this area.

Cytochrome P450s (CYPs) are the most prominent family of enzymes involved in NADPH- and O2-dependent hydroxylation processes throughout all spheres of life. CYPs are crucial for the detoxification of xenobiotics in plants, insects, and other organisms. In addition to performing this function, CYPs serve as flexible catalysts and are essential for producing secondary metabolites, antioxidants, and phytohormones in higher plants. Numerous biotic and abiotic stresses frequently affect the growth and development of plants. They cause a dramatic decrease in crop yield and a deterioration in crop quality. Plants protect themselves against these stresses through different mechanisms, which are accomplished by the active participation of CYPs in several biosynthetic and detoxifying pathways. There are immense potentialities for using CYPs as a candidate for developing agricultural crop species resistant to biotic and abiotic stressors. This review provides an overview of the plant CYP families and their functions to plant secondary metabolite production and defense against different biotic and abiotic stresses.