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BackgroundSoybean cyst nematodes (SCN) as animal parasites of plants are not usually interested in killing the host but are rather focused on completing their life cycle to increase population, resulting in substantial yield losses. Remarkably, some agricultural soils after long-term crop monoculture show a significant decline in SCN densities and suppress disease in a sustainable and viable manner. However, relatively little is known about the microbes and mechanisms operating against SCN in such disease-suppressive soils.ResultsGreenhouse experiments showed that suppressive soils (S) collected from two provinces of China and transplantation soils (CS, created by mixing 10% S with 90% conducive soils) suppressed SCN. However, SCN suppressiveness was partially lost or completely abolished when S soils were treated with heat (80 °C) and formalin. Bacterial community analysis revealed that the specific suppression in S and CS was mainly associated with the bacterial phylum Bacteroidetes, specifically due to the enrichment of Chitinophaga spp. and Dyadobacter sp., in the cysts. SCN cysts colonized by Chitinophaga spp. showed dramatically reduced egg hatching, with unrecognizable internal body organization of juveniles inside the eggshell due to chitinase activity. Whereas, Dyadobacter sp. cells attached to the surface coat of J2s increased soybean resistance against SCN by triggering the expression of defence-associated genes. The disease-suppressive potential of these bacteria was validated by inoculating them into conducive soil. The Dyadobacter strain alone or in combination with Chitinophaga strains significantly decreased egg densities after one growing cycle of soybeans. In contrast, Chitinophaga strains alone required more than one growing cycle to significantly reduce SCN egg hatching and population density.ConclusionThis study revealed how soybean monoculture for decades induced microbiota homeostasis, leading to the formation of SCN-suppressive soil. The high relative abundance of antagonistic bacteria in the cyst suppressed the SCN population both directly and indirectly. Because uncontrolled proliferation will likely lead to quick demise due to host population collapse, obligate parasites like SCN may have evolved to modulate virulence/proliferation to balance these conflicting needs. Video Abstract.

Background: Botrytis cinerea a blueberry gray mold, is one of the main diseases affecting postharvest storage, causing significant losses. Several studies have shown that Bacillus tequilensis can prevent the growth of plant pathogens by producing various antibacterial substances, and can induce plant resistance. However, research on the biological management of post-harvest gray mold in blueberries using B. tequilensis remains unclear. Methods: To better control the postharvest gray mold of blueberry, the effects of B. tequilensis KXF6501 fermentation solution (YY) and KXF6501 cell-free supernatant (SQ) on the induction of disease resistance in blueberry fruits were studied using biochemical and transcriptomic analyses. Results: We found that YY controlled the conidial germination and mycelial growth of B. cinerea in vitro, followed by SQ. After 3 d of culture, the lesion diameter and incidence of gray mold in blueberry fruits inoculated with YY and SQ were smaller than those in the control group. Therefore, gray mold in blueberries was effectively controlled during the prevention period, and the control effect of YY was better than that of SQ. Transcription spectrum analysis of blueberry peel tissue showed that the YY- and SQ-induced phenylpropane metabolic pathways had more differentially expressed genes (DEGs) than other biological pathways. In addition, biochemical analyses showed that YY treatment effectively enhanced the activity of enzymes related to the phenylpropane pathway (phenylalanine ammonialyase [PAL], cinnamate 4-hydroxylase [C4H], 4-coumarate CoA ligase [4CL], and polyphenol oxidase [PPO]) and stimulated the synthesis of lignin, total phenols, and flavonoids, followed by SQ. Compared with the control, the YY and SQ treatments reduced the weight loss rate and better maintained the appearance and nutritional quality of the blueberry fruits. Conclusion: Our findings suggest that B. tequilensis KXF6501 is potentially useful as a suitable bio-control agent in harvested blueberries. [ABSTRACT FROM AUTHOR]

The endogenous stress metabolite β-aminobutyric acid (BABA) primes plants for enhanced resistance against abiotic and biotic stress by activating a complex phytohormone signaling network that includes abscisic acid (ABA), jasmonic acid (JA), salicylic acid (SA), and ethylene (ET). In this study, through stringent filtering, we identify 14 master regulatory transcription factors (TFs) from the DOF, AHL, and ERF families that potentially regulate the biosynthesis and signaling of these phytohormones. Transcriptional analysis of BABA-treated Arabidopsis thaliana and Hordeum vulgare suggests that DOF family TFs play a crucial role in stress response regulation in both species. BABA treatment in A. thaliana upregulates the TFs MNB1A and PBF and enhances the expression of the genes ICS1, EDS5, and WIN3 in the SA biosynthesis pathway, potentially boosting NPR1 and PR1 in the SA signaling pathway. Conversely, in H. vulgare, the BABA-induced upregulation of TF DOF5.8 may negatively regulate SA biosynthesis by downregulating ICS1, EDS5, and PR1. Additionally, in A. thaliana, BABA triggers the expression of TF PBF, which may result in the decreased expression of MYC2, a key gene in JA signaling. In contrast, H. vulgare exhibits increased expression of ERF2 TF, which could positively regulate the JA biosynthesis genes LOX and Tify9, along with the COI1 and JAZ genes involved in the JA signaling pathway. These findings offer new perspectives on the transcriptional regulation of phytohormones during plant priming. [ABSTRACT FROM AUTHOR]

Viral diseases of potatoes are among the main problems causing deterioration in the quality of tubers and loss of yield. The growth and development of potato plants largely depend on soil moisture. Prevention strategies require comprehensive protection against pathogens and abiotic stresses, including modeling the beneficial microbiome of agroecosystems combining microorganisms and immunostimulants. Chitosan and its derivatives have great potential for use in agricultural engineering due to their ability to induce plant immune responses. The effect of chitosan conjugate with caffeic acid (ChCA) in combination with Bacillus subtilis 47 on the transcriptional activity of PR protein genes and changes in the proteome of potato plants during potato virus Y (PVY) infection and drought was studied. The mechanisms of increasing the resistance of potato plants to PVY and lack of moisture are associated with the activation of transcription of genes encoding PR proteins: the main protective protein (PR-1), chitinase (PR-3), thaumatin-like protein (PR-5), protease inhibitor (PR-6), peroxidase (PR-9), and ribonuclease (PR-10), as well as qualitative and quantitative changes in the plant proteome. The revealed activation of the expression of marker genes of systemic acquired resistance and induced systemic resistance under the influence of combined treatment with B. subtilis and chitosan conjugate indicate that, in potato plants, the formation of resistance to viral infection in drought conditions proceeds synergistically. By two-dimensional electrophoresis of S. tuberosum leaf proteins followed by MALDI-TOF analysis, 10 proteins were identified, the content and composition of which differed depending on the experiment variant. In infected plants treated with ChCA, the synthesis of proteinaceous RNase P 1 and oxygen-evolving enhancer protein 2 was enhanced in conditions of normal humidity, and 20 kDa chaperonin and TMV resistance protein N-like was enhanced in conditions of lack of moisture. The virus coat proteins were detected, which intensively accumulated in the leaves of plants infected with potato Y-virus. ChCA treatment reduced the content of these proteins in the leaves, and in plants treated with ChCA in combination with Bacillus subtilis, viral proteins were not detected at all, both in conditions of normal humidity and lack of moisture, which suggests the promising use of chitosan derivatives in combination with B. subtilis bacteria in the regulation of plant resistance. [ABSTRACT FROM AUTHOR]

Global sorghum production has been significantly reduced due to the occurrence of sorghum root rot caused by the fungus Fusarium graminearum. The utilization of biocontrol microorganisms has emerged as an effective strategy. However, the underlying mechanisms remain unclear. Therefore, the aim of this study was to investigate the effectiveness of biocontrol bacteria in inducing sorghum resistance against sorghum root rot and explore the potential induced resistance mechanisms through metabolomics analysis. The results revealed that the biocontrol bacteria Lnkb100, identified as Serratia marcescens (GenBank: PP152264), significantly enhanced the resistance of sorghum against sorghum root rot and promoted its growth, leading to increased seed weight. Targeted metabolomics analysis demonstrated that the highest concentration of the hormone IAA (indole-3-acetic acid) was detected in the metabolites of Lnkb100. Treatment with IAA enhanced the activity of disease-related enzymes such as SOD, CAT, POD and PPO in sorghum, thereby improving its resistance against sorghum root rot. Further untargeted metabolomic analysis revealed that IAA treatment resulted in higher concentrations of metabolites involved in the resistance against F. graminearum, such as geniposidic acid, 5-L-Glutamyl-taurine, formononetin 7-O-glucoside-6″-O-malonate, as well as higher concentrations of the defense-related molecules volicitin and JA. Additionally, "secondary bile acid biosynthesis" and "glycerophospholipid metabolism" pathways were found to play significant roles in the defense response of sorghum against fungal infection. These findings provide a reliable theoretical basis for utilizing biocontrol microorganisms to control sorghum root rot. [ABSTRACT FROM AUTHOR]

Plant resistance and predators can influence density‐dependent survivorship and growth of herbivores, and their damage to plants. Although the independent effects of plant resistance and predators on herbivores and herbivory are well known, little is known about their interactive and density‐dependent effects on herbivores and the amount and distribution of damage on plants. These relationships are important for understanding how herbivore and plant populations influence each other. We used a laboratory density‐manipulation experiment to determine how plant resistance (three treatments: jasmonate‐insensitive, unmanipulated wild type, and jasmonate‐sprayed wild‐type plants) and predation (two treatments: predator or no predator) affect the survivorship and growth of an herbivore, as well as per capita damage and the distribution of damage on plants. We found evidence that the density dependence of herbivore survivorship was influenced by predators and an interactive effect of plant resistance and predation. Herbivore growth was reduced by higher plant resistance but was not density‐dependent nor affected by predation. Per capita plant damage was reduced by plant resistance, predation, and herbivore density. The within‐plant distribution of damage became more even with increasing herbivore density but was not affected by predation or the independent effect of plant resistance. The distribution of damage was also affected by an interaction between plant resistance and herbivore density; damage became less aggregated with density across all plant resistance treatments, but the decrease was strongest for the jasmonate‐insensitive plants. These results show that predators influence herbivore density dependence, and that plant resistance can affect the impact of predators on herbivores. Though plant resistance, predation, and herbivore density all reduced per capita herbivore damage to plants, only herbivore density and plant resistance affected the distribution of damage. Distributions of herbivory can influence plant success; documenting patterns of herbivory is an under‐appreciated avenue for integrating effects of plant resistance, predators, and herbivore density on plant–herbivore interactions. [ABSTRACT FROM AUTHOR]

Serine protease is an extracellular protease secreted by biocontrol fungi that can effectively control nematode diseases by degrading nematode eggshells and enhancing plant resistance. Trichoderma longibrachiatum T6, an important biocontrol fungus, has been demonstrated to effectively parasitize and degrade Heterodera avenae cysts, eggs, and second-stage juveniles (J2s). However, the genes that encoding serine protease and their functions in T. longibrachiatum T6 have not been thoroughly investigated. In this study, we successfully cloned and sequenced the serine protease gene TlSP1 in T. longibrachiatum T6. Our results revealed that the expression level of the TlSP1 gene was induced and significantly increased in T. longibrachiatum T6 after inoculation with H. avenae cysts. The full-length sequence of the coding region (CDS) of TlSP1 gene was 1230 bp and encoded a protein consisting of 409 amino acids. Upon the transformation of the TlSP1 gene into Pichia pastoris X33, the purified recombinant TlSP1 protein exhibited optimal activity at a temperature of 50 °C and pH 8.0. Following 4–10-day of treatment with the purified recombinant TlSP1 protein, the eggshells and content were dissolved and exuded. The number of nematodes invading wheat roots was reduced by 38.43% in the group treated with both TlSP1 and eggs on one side (P1+N) compared to the control group, while the number of nematodes invading wheat roots was reduced by 30.4% in the TlSP1 and eggs two-sided treatment group (P1/N). Furthermore, both the P1+N and P1/N treatments significantly upregulated genes associated with defense enzymes (TaPAL, TaCAT, TaSOD, and TaPOD), genes involved in the lignin synthesis pathway (TaC4H, Ta4CL2, TaCAD1, and TaCAD12), and salicylic acid (SA)-responsive genes (TaNPR1, TaPR1, and TaPR2) and led to the high expression of jasmonic acid (JA)-responsive genes (TaPR4, TaOPR3, and TaAOS2). This study has highlighted the significant role of the TlSP1 gene in facilitating H. avenae eggshells' dissolution, preventing nematode invasion in the host plant, and boosting plant resistance in wheat. [ABSTRACT FROM AUTHOR]

Perilla essential oil (PEO) is reported as an aromatic yellowish oily substance with a volatile odor extracted from perilla leaves. It exhibits various biological activities except anti-tobacco mosaic virus (TMV) activity. In this study, we investigated the main components and anti-TMV activity of PEO, identified its primary active components, and examined its mode of action. The results indicated that PEO exhibited anti-TMV activity (65.58%) at 800 μg/mL, with perillaldehyde identified as the main active component. The protective, curative, and inactivation activities of perillaldehyde at 800 μg/mL were 80.41%, 73.42%, and 34.93%, respectively. These values were significantly higher than those of the control drug (commercial chitosan oligosaccharide) and the protective and curative activities were superior to those of ningnanmycin. The results of the mode of action showed that perillaldehyde induced a hypersensitive response (HR) in tobacco. Transmission electron microscope (TEM) observation revealed that perillaldehyde had no direct effect on TMV particles. The treatment of Nicotiana glutinosa with perillaldehyde at 800 μg/mL indicated that perillaldehyde had significant induction activity (58.46%). The expression of three pathogenesis-related tobacco genes (PR genes), including nonexpressor of pathogenesis-related genes 1 (NPR1), pathogenesis-related protein 1 gene (PR1), and pathogenesis-related protein 5 gene (PR5), were induced and upregulated by perillaldehyde treatment. Perillaldehyde also induced the overexpression of the phenylalanine ammonia-lyase gene (PAL), respiratory burst oxidase homolog B gene (RBOHB), and protochlorophyllide oxidoreductase gene 1 (POR1). Furthermore, perillaldehyde increased the salicylic acid (SA) and H2O2 contents in tobacco leaves, and enhanced the activities of four defense enzymes: superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and phenylalanine ammonia-lyase (PAL). N. glutinosa was treated with perillaldehyde at 800 μg/mL for 24 h, and the results showed that the highest SA and H2O2 contents (1032.08 pmol/L and 23.40 μmol/g FW, respectively) were obtained in tobacco leaves. Defense enzyme activities also reached a maximum at 800 μg/mL, and the activities of CAT, PAL, POD, and SOD increased by 1.76, 1.95, 2.17, and 3.78 times, respectively, compared to the control. The results of the study showed that perillaldehyde may enhance resistance to pathogen infection by inducing systemic acquired resistance (SAR), which may contribute to the activation of SA signal transduction pathway. Therefore, perillaldehyde has the potential for application in agriculture as a novel antiviral agent and immune inducer. [ABSTRACT FROM AUTHOR]

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Peptides are important regulators that participate in the modulation of almost every physiological event in plants, including defense. Recently, many of these peptides have been described as defense elicitors, termed phytocytokines, that are released upon pest or pathogen attack, triggering an amplification of plant defenses. However, little is known about peptides sensing and inducing resistance activities in heterologous plants. In the present study, exogenous peptides from solanaceous species, Systemins and HypSys, are sensed and induce resistance to the necrotrophic fungus Plectosphaerella cucumerina in the taxonomically distant species Arabidopsis thaliana. Surprisingly, other peptides from closer taxonomic clades have very little or no effect on plant protection. In vitro bioassays showed that the studied peptides do not have direct antifungal activities, suggesting that they protect the plant through the promotion of the plant immune system. Interestingly, tomato Systemin was able to induce resistance at very low concentrations (0.1 and 1 nM) and displays a maximum threshold being ineffective above at higher concentrations. Here, we show evidence of the possible involvement of the JA-signaling pathway in the Systemin-Induced Resistance (Sys-IR) in Arabidopsis. Additionally, Systemin treated plants display enhanced BAK1 and BIK1 gene expression following infection as well as increased production of ROS after PAMP treatment suggesting that Systemin sensitizes Arabidopsis perception to pathogens and PAMPs. [ABSTRACT FROM AUTHOR]

Plant defence peptides are paramount endogenous danger signals secreted after a challenge, intensifying the plant immune response. The peptidic hormone Systemin (Sys) was shown to participate in resistance in several plant pathosystems, although the mechanisms behind Sys-induced resistance when exogenously applied remain elusive. We performed proteomic, metabolomic, and enzymatic studies to decipher the Sys-induced changes in tomato plants in either the absence or the presence of Botrytis cinerea infection. Sys treatments triggered direct proteomic rearrangement mostly involved in carbon metabolism and photosynthesis. However, the final induction of defence proteins required concurrent challenge, triggering priming of pathogen-targeted proteins. Conversely, at the metabolomic level, Sys-treated plants showed an alternative behaviour following a general priming profile. Of the primed metabolites, the flavonoids rutin and isorhamnetin and two alkaloids correlated with the proteins 4-coumarate-CoA-ligase and chalcone-flavanone-isomerase triggered by Sys treatment. In addition, proteomic and enzymatic analyses revealed that Sys conditioned the primary metabolism towards the production of available sugars that could be fuelling the priming of callose deposition in Sys-treated plants; furthermore, PR1 appeared as a key element in Sys-induced resistance. Collectively, the direct induction of proteins and priming of specific secondary metabolites in Sys-treated plants indicated that post-translational protein regulation is an additional component of priming against necrotrophic fungi. [ABSTRACT FROM AUTHOR]

[Objective] To explore the control effect and mechanism of Bacillus subtilis B579 on cucumber Fusarium wilt. [Method] Plate confrontation test and greenhouse pot experiment were used to detect the growth and morphological changes of the pathogen, plant growth, activity of defense enzymes in leaves and malondialdehyde content, and expression of defense-related related genes. [Result] The B. subtilis B579 had a strong inhibitory effect on cucumber Fusarium wilt, and the mycelium around the inhibition zone showed uneven thickness, swelling and breakage. Pot experiment demonstrated that B579 achieved the disease control efficiency against cucumber wilt, reaching 78.80%. The plant height, stem diameter, fresh weight, and dry weight of cucumber seedlings in B579 treatment increased by 13.87%, 4.17%, 15.15% and 12.77% compared with the control group, respectively. After pretreatment with B579, pathogen inoculation significantly increased the activities of phenylalanine ammonilyase（PAL）, polyphenol oxidase（PPO）, peroxidase（POD）, and catalase（CAT）and reduced the content of malondialdehyde（MDA）in cucumber leaves on day 4 and 7 compared with the control group. The results of real-time fluorescence quantitative PCR showed that the expressions of LOX, PR1, PR3 and CAT genes in cucumber leaves after inoculation with B579 and then challenge with pathogen were significantly higher than those in other treatments at 4 and 7 d. [Conclusion] B. subtilis B579 can control cucumber Fusarium wilt by directly inhibiting the growth of pathogen and inducing resistance in cucumber [ABSTRACT FROM AUTHOR]

Plants constantly face the environment that surrounds them and fight for survival against biotic and abiotic stress factors. To deal with harmful conditions, plants have developed a multilayer defence system, making them capable of recognising threats and promptly recovering from them. This phenomenon, which takes advantage of the "memory effect", is referred to as bio-priming and represents a new frontier in terms of crop protection. Here, we investigated the "indirect" protective mechanisms of a new yeast extract formulate in Vitis vinifera cv. Sangiovese plants at both the biochemical and genic levels. The formulate was applied once a week for three consecutive weeks, and grapevine leaves were sampled from the first to the fifth day after treatment (dat) at every week of the experiment. Increased levels of jasmonic acid (every week at 2 dat; +70% as average) and abscisic acid (at 1 dat of the first week, more than 1.7-fold higher than the control) and the underproduction of salicylic acid (from 2 dat; −18%) confirmed that these signalling molecules/"specialised compounds" are actively involved in the early activation of defence pathways in treated vines. In addition, pr2 and chit1b, two genes involved in regulating hormonal crosstalk, were significantly up-regulated (both in the first and second week of the trial) and were also found to underlie upstream molecular activation. The results obtained by this investigation confirm the use of this new product to prime and protect grapevines from a wide range of fungal and fungal-like plant pathogens through the induction of defence responses. [ABSTRACT FROM AUTHOR]

Abstract Background Soybean cyst nematodes (SCN) as animal parasites of plants are not usually interested in killing the host but are rather focused on completing their life cycle to increase population, resulting in substantial yield losses. Remarkably, some agricultural soils after long-term crop monoculture show a significant decline in SCN densities and suppress disease in a sustainable and viable manner. However, relatively little is known about the microbes and mechanisms operating against SCN in such disease-suppressive soils. Results Greenhouse experiments showed that suppressive soils (S) collected from two provinces of China and transplantation soils (CS, created by mixing 10% S with 90% conducive soils) suppressed SCN. However, SCN suppressiveness was partially lost or completely abolished when S soils were treated with heat (80 °C) and formalin. Bacterial community analysis revealed that the specific suppression in S and CS was mainly associated with the bacterial phylum Bacteroidetes, specifically due to the enrichment of Chitinophaga spp. and Dyadobacter sp., in the cysts. SCN cysts colonized by Chitinophaga spp. showed dramatically reduced egg hatching, with unrecognizable internal body organization of juveniles inside the eggshell due to chitinase activity. Whereas, Dyadobacter sp. cells attached to the surface coat of J2s increased soybean resistance against SCN by triggering the expression of defence-associated genes. The disease-suppressive potential of these bacteria was validated by inoculating them into conducive soil. The Dyadobacter strain alone or in combination with Chitinophaga strains significantly decreased egg densities after one growing cycle of soybeans. In contrast, Chitinophaga strains alone required more than one growing cycle to significantly reduce SCN egg hatching and population density. Conclusion This study revealed how soybean monoculture for decades induced microbiota homeostasis, leading to the formation of SCN-suppressive soil. The high relative abundance of antagonistic bacteria in the cyst suppressed the SCN population both directly and indirectly. Because uncontrolled proliferation will likely lead to quick demise due to host population collapse, obligate parasites like SCN may have evolved to modulate virulence/proliferation to balance these conflicting needs. Video Abstract

The protective effect and underlying mechanism of melatonin (MT) treatment against Rhizopus stolonifer in postharvest peach fruit (Prunus persica (L.) Batsch cv ‘Xiahui 8’) were studied. Freshly harvested peaches were inoculated with R. stolonifer following pretreatment with different concentrations of MT (0, 0.05, 0.10, 0.50 and 1.00 mmol/L) and then stored at 20 ℃ for up to 60 h. Disease development was measured to determine the most effective MT concentration. Subsequently, the effects of MT treatment on quality parameters, total phenol and lignin contents, disease resistance-related enzyme activity and gene expression in peaches during postharvest storage, and the in vitro growth of R. stolonifer were investigated. The results showed that 0.50 mmol/L MT treatment could most significantly reduce the occurrence of Rhizopus rot and maintain postharvest fruit quality. Furthermore, compared with either of them alone, R. stolonifer inoculation after MT treatment exhibited stronger disease resistance response, resulting in a marked increase in the activities of chitinase (CHI), β-1,3-glucanase (GLU), phenylalanine ammonia lyase (PAL), cinnamate 4-hydroxylase (C4H), 4-coumarate-CoA ligase (4CL), peroxidase (POD) and polyphenol oxidase (PPO), the contents of total phenols and lignin, and the expression levels of defense-related genes such as those encoding CHI (PpCHI), GLU (PpGLU), PAL (PpPAL) and POD (PpPOD). Moreover, MT treatment had no significant inhibitory effect on the growth of R. stolonifer in vitro. Taken together, these results indicate that MT can initiate defense responses to pathogenic infection indirectly by priming defense, thereby reducing the occurrence of peach postharvest diseases.

Abstract Tobacco mosaic virus (TMV) is widely recognized as one of the most important plant viruses, causing significant agricultural losses in terms of both quality and yield worldwide each year. This study demonstrated the biosynthesis of copper oxide nanoparticles (CuONPs) using orange peel extract for effective control of TMV infection both in vitro and in vivo. After treatment with CuONPs (100 mg/L) for 2 h, TMV particles exhibited evident fragmentation in vitro, reducing infectivity on tobacco plants. Similarly, the application of CuONPs on Nicotiana benthamiana (N. benthamiana) positively impeded viral replication and accumulation in vivo. Interestingly, the expression of systemic resistance-related genes (PR1, PR2, ERF1, and JAZ3) in the host plant was up-regulated by CuONPs treatment, supporting that CuONPs activated plant immunity to inhibit TMV. Importantly, the application of CuONPs (100 mg/L) did not exhibit any toxic effects on tobacco and, instead, resulted in the promotion of chlorophyll content, as well as an increase in the fresh weight and dry weight of the plant when compared to the control treatment. Overall, we proposed that the appropriate concentration of CuONPs (100 mg/L) can directly break viral particles by passivating, boost plant immunity by stimulating systemic acquired resistance (SAR), and provide nutritional supplements to promote plant growth.

Abstract [Objective] The study aims to investigate the differential efficacy of anti-leaf spot in barley (Hordeum vulgare L.) of various concentrations of exogenous methyl jasmonate (MeJA) and understand the underlying mechanisms, thereby providing a foundation for the application of MeJA in controlling barley leaf spot. [Methods] We used ‘Mengpimai 3’ (MP3) seedlings as materials and conducted three different treatments: Inoculating the barley leaves with sterile water without any Bipolaris sorokiniana (the causal agent of the disease), inoculating the barley leaves with sterile water after treatment, and treating the barley leaves with different concentrations (0.5, 1.0, 1.5, 2.0, 2.5 mmol/L) of methyl jasmonate (MeJA) before inoculation with the pathogen. The disease incidence was investigated at the three-leaf stage based on disease index to determine the optimal MeJA concentration. We measured antioxidant enzyme activities, anti-disease-related enzyme activities, malondialdehyde, proline, soluble sugar, and soluble protein contents, and the expression levels of related genes under no inoculating treatment, inoculation treatment, and inoculating + optimal MeJA concentration treatment. [Results] (1) Exogenous application of MeJA enhanced MP3 resistance against spot blotch, particularly at 1.5 mmol/L where there was a significant reduction of 19.03% (P

Tobacco mosaic virus (TMV) is widely recognized as one of the most important plant viruses, causing significant agricultural losses in terms of both quality and yield worldwide each year. This study demonstrated the biosynthesis of copper oxide nanoparticles (CuONPs) using orange peel extract for effective control of TMV infection both in vitro and in vivo. After treatment with CuONPs (100 mg/L) for 2 h, TMV particles exhibited evident fragmentation in vitro, reducing infectivity on tobacco plants. Similarly, the application of CuONPs on Nicotiana benthamiana (N. benthamiana) positively impeded viral replication and accumulation in vivo. Interestingly, the expression of systemic resistance-related genes (PR1, PR2, ERF1, and JAZ3) in the host plant was up-regulated by CuONPs treatment, supporting that CuONPs activated plant immunity to inhibit TMV. Importantly, the application of CuONPs (100 mg/L) did not exhibit any toxic effects on tobacco and, instead, resulted in the promotion of chlorophyll content, as well as an increase in the fresh weight and dry weight of the plant when compared to the control treatment. Overall, we proposed that the appropriate concentration of CuONPs (100 mg/L) can directly break viral particles by passivating, boost plant immunity by stimulating systemic acquired resistance (SAR), and provide nutritional supplements to promote plant growth. [ABSTRACT FROM AUTHOR]

Fusarium head blight (FHB) is a destructive disease caused by several species of Fusarium, such as Fusarium graminearum and F. asiaticum. FHB affects cereal crops, including wheat, barley, and rice, worldwide. Fusarium-infected kernels not only cause reduced yields but also cause quality loss by producing mycotoxins, such as trichothecenes and zearalenone, which are toxic to animals and humans. For decades, chemical fungicides have been used to control FHB because of their convenience and high control efficacy. However, the prolonged use of chemical fungicides has caused adverse effects, including the emergence of drug resistance to pathogens and environmental pollution. Biological control is considered one of the most promising alternatives to chemicals and can be used for integrated management of FHB due to the rare possibility of environment pollution and reduced health risks. In this study, Bacillus velezensis JCK-7158 isolated from rice was selected as an ecofriendly alternative to chemical fungicides for the management of FHB. JCK-7158 produced the extracellular enzymes protease, chitinase, gelatinase, and cellulase; the plant growth hormone indole-3-acetic acid; and the 2,3-butanediol precursor acetoin. Moreover, JCK-7158 exhibited broad antagonistic activity against various phytopathogenic fungi and produced iturin A, surfactin, and volatile substances as active antifungal compounds. It also enhanced the expression of PR1, a known induced resistance marker gene, in transgenic Arabidopsis plants expressing ß-glucuronidase (GUS) fused with the PR1 promoter. Under greenhouse conditions, treatments with the culture broth and suspension concentrate formulation of JCK-7158 at a 1,000-fold dilution inhibited the development of FHB by 50 and 66%, respectively. In a field experiment, treatment with the suspension concentrate formulation of JCK-7158 at a 1,000-fold dilution effectively controlled the development of FHB with a control value of 55% and reduced the production of the mycotoxin nivalenol by 40%. Interestingly, treatment with JCK-7158 enhanced the expression of plant defense-related genes in salicylic acid, jasmonic acid, ethylene, and reactive oxygen species (ROS) signaling pathways before and after FHB pathogen inoculation. Taken together, our findings support that JCK-7158 has the potential to serve as a new biocontrol agent for the management of FHB. [ABSTRACT FROM AUTHOR]

Terpenoids are defense metabolites that are induced upon infection or wounding. However, their role in systemic‐induced resistance (SIR) is not known. Here, we explored the role of terpenoids in this phenomenon at a very early stage in the interaction between Austrian pine and the tip blight and canker pathogen Diplodia pinea. We induced Austrian pine saplings by either wounding or inoculating the lower stems with D. pinea. The seedlings were then challenged after 12 h, 72 h, or 10 days with D. pinea on the stem 15 cm above the induction. Lesion lengths and terpenoids were quantified at both induction and challenge locations. Key terpenoids were assayed for antifungal activity in in vitro bioassays. SIR increased with time and was correlated with the inducibility of several compounds. α‐Pinene and a cluster of β‐pinene, limonene, benzaldehyde, dodecanol, and n‐dodecyl acrylate were positively correlated with SIR and were fungistatic in vitro, while other compounds were negatively correlated with SIR and appeared to serve as a carbon source for D. pinea. This study shows that, overall, terpenoids are involved in SIR in this system, but their role is nuanced, depending on the type of induction and time of incubation. We hypothesize that some, such as α‐pinene, could serve in SIR signaling. Summary statement: Trees can resist recurring pathogenic attacks using memory of successful prior encounters with pest or pathogens. Here we show that pathogenic induction results in systemic and selective accumulation of certain terpenoids and other non‐terpenoids in trees conferring higher resistance against newer infection. [ABSTRACT FROM AUTHOR]

Claviceptaceous endophytic fungi in the genus Epichloë mostly form a symbiotic relationship with cool-season grasses. Epichloë spp. are capable of producing bioactive alkaloids such as peramines, lolines, ergot alkaloids, and indole-diterpenes, which protect the host plant from herbivory by animals, insects, and nematodes. The host also benefits from enhanced tolerance to abiotic stresses, such as salt, drought, waterlogging, cold, heavy metals, and low nitrogen stress. The bioactive alkaloids produced can have both direct and indirect effects towards plant parasitic nematodes. Direct interaction with nematodes' motile stages can cause paralysis (nematostatic effect) or death (nematicidal effect). Indirectly, the metabolites may induce host immunity which inhibits feeding and subsequent nematode development. This review highlights the different mechanisms through which this interaction and the metabolites produced have been explored in the suppression of plant parasitic nematodes and also how the specific interactions between different grass genotypes and endophyte strains result in variable suppression of different nematode species. An understanding of the different grass–endophyte interactions and their successes and failures in suppressing various nematode species is essential to enable the proper selection of grass–endophyte combinations to identify the alkaloids produced, concentrations required, and determine which nematodes are sensitive to which specific alkaloids. [ABSTRACT FROM AUTHOR]

Plant pathogens and pests pose an increasing threat to worldwide food security. To improve and strengthen food security under increasingly difficult environmental, economic, and geopolitical conditions, the prospect of using microbial biocontrol agents becomes increasingly desirable. One of the most studied, and commercially used, biopesticide microorganisms is the entomopathogenic, gram-positive, soil bacterium Bacillus thuringiensis (Bt). While Bt has been known for many years as an insecticidal microorganism and used extensively in agriculture, its possible anti-phytopathogen and plant growth-promoting activities have received comparatively limited attention thus far. Here, we examine the ability of Bt to promote systemic immunity in tomato plants. We investigate how Bt influences plant immunity and disease resistance against several fungal and bacterial plant pathogens, as well as several arthropod pests. In order to determine which component of Bt (i.e., Bt spores or pure crystals) is responsible for the observed effects on pathogens or pests, we dissected the different fractions present in a commercial preparation and assessed their effects on pest and pathogen control. As previously reported in the Bt literature, our results indicate that proteins produced by Bt are likely the primary acting components against pests. In the case of pathogens, however, it appears that both the Bt spores and proteins directly act against pathogens such as the fungus Botrytis cinerea. Bt Spores and produced proteins also both induce plant immunity. Understanding the different Bt mode of action mechanisms will help in developing cost-effective and safe plant protection strategies for enhancing food security. Taken together, our findings suggest that Bt could be used in broad-spectrum pest and disease management strategies. Pending validation in agricultural settings, Bt products on the market could have additional uses in sustainable pest management and plant growth promotion. [ABSTRACT FROM AUTHOR]

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Imbibing watermelon seeds in 1 mM sodium tetraborate (Na2B4O7) for 24 h systemically protected plants against foliar infection by Stagonosporopsis cucurbitacearum in detached leaves and under greenhouse conditions. The treatment resulted in both a reduction in the overall percentage of leaf infection as well as in the size of lesions. Studies of the mechanisms by which Na2B4O7 protected watermelon showed that there was no direct effect on the S. cucurbitacearum mycelium growth in vitro. On the other hand, plants raised from seeds primed with Na2B4O7 showed a higher frequency of fluorescent epidermal cells compared to the plants treated with water. This indicates that a higher number of cells expressed the hypersensitive response after Na2B4O7 priming. In addition, there was an increase in peroxidase activity and an enhanced accumulation of a 45 kDa acidic peroxidase isoform during the early stages of infection in plants treated with Na2B4O7 compared to plants treated with water and this was positively correlated to the reduction of leaf infection caused by the pathogen. These results indicate that Na2B4O7 is able to induce systemic resistance in watermelon against S. cucurbitacearum by activating the hypersensitive reaction at penetration sites, increasing peroxidase activity and altering the peroxidase isozyme profile. Although each individual response may only have had a minor effect, their combined effects had a reducing effect on the disease. [ABSTRACT FROM AUTHOR]

The widespread use of pesticides poses significant challenges to the safety of agricultural products and the ecological environment. Levan‐type fructans have the ability to act as an induced resistance stimulus, enhancing plant disease resistance, which aligns with the principles of green development. This study showed that levan polysaccharide, produced by Halomonas smyrnnensis levansucrase, could induce the resistance of barley to Fusarium graminearum much better than inulin‐type fructans or low‐molecular‐weight chitosan oligosaccharide. Three different application methods of levan, namely seed soaking, leaf spraying or their combination, all decreased the necrotic areas caused by F. graminearum and Rhizoctonia solani. When inoculated with F. graminearum, the content of hydrogen peroxide, proline or jasmonic acid and the activities of peroxidase and ascorbate peroxidase in levan‐treated barley were higher than those in the control. In contrast, when inoculated with R. solani, the hydrogen peroxide content and peroxidase activity in levan‐treated leaves showed a faster induction than the control at the early priming and the content of proline and methyl salicylate was higher than that of the control. Thus, levan induces distinct pathways in response to different pathogens. [ABSTRACT FROM AUTHOR]

Autolysins are endogenous cell wall degrading enzymes (CWDEs) in bacteria that remodel the peptidoglycan layer of its own cell wall. In the Bacillus subtilis genome, at least 35 autolysin genes have been identified. However, the study of their roles in bacterial physiology has been hampered by their complexity and functional redundancy. B. subtilis GLB191 is an effective biocontrol strain against grape downy mildew disease, the biocontrol effect of which results from both direct effect against the pathogen and stimulation of the plant defense. In this study, we show that the autolysin N-acetylglucosaminidase LytD, a major autolysin of vegetative growth in B. subtilis, plays an important role in its biocontrol activity against grape downymildew. Disruption of lytD resulted in reduced suppression of the pathogen Plasmopara viticola and stimulation of the plant defense. LytD is also shown to affect the biofilm formation and colonization of B. subtilis on grape leaves. This is the first report that demonstrates the role of an endogenous CWDE in suppressing plant disease infection of a biological control microorganism. These findings not only expand our knowledge on the biological function of autolysins but also provide a new target to promote the biocontrol activity of B. subtilis. [ABSTRACT FROM AUTHOR]

The aim of this work was to study the effect of Bacillus subtilis strains VKM B-2604D and VKM B-2605D, which form the basis of the Vitaplan biological product, and their combinations with chitosan salicylate on antioxidant defense enzymes in the process of formation of resistance of wheat plants to infection with the dark brown blotch pathogen Bipolaris sorokiniana. In wheat plants treated with B. subtilis strains and their combinations with chitosan salicylate, upon subsequent infection, catalase and peroxidase are activated, which regulate the intensity of oxidative stress induced by the introduction of the pathogen. Taking the data we obtained into account, it can be assumed that the increase in plant resistance to the pathogen is realized through the control of the activity of antioxidant enzymes (in particular, catalase and peroxidase), which maintain the concentration of H2O2 at the level necessary for the neutralization of the phytopathogen in tissues, including the direct destruction of the invading pathogen and/or activation of crosslinking and lignification of the cell wall. These processes strengthen the cell wall and help contain the spread of the pathogen in the plant. At the same time, protective reactions are also switched on, leading to the development of induced resistance in wheat plants to dark brown spotting, which manifests itself in a decrease in the development of the disease by 25–45% relative to the infected control in the treated plants. The results indicate that the combination of active strains of microorganisms-antagonists of plant pathogens and chitosan salicylate is promising for increasing the biological efficiency and expanding the spectrum of action of the developed biological products. [ABSTRACT FROM AUTHOR]

The effect of chitosan conjugates with caffeic (ChCA) and ferulic (ChFA) acids in combination with Bacillus subtilis bacteria on the transcriptional activity of PR protein genes and proteome changes in potato plants during infection with Phytophthora infestans (Mont.) de Bary was studied. Plants grown from mini tubers of the Udacha variety were sprayed with solutions of ChCA and ChFA, a suspension of B. subtilis bacteria strains 26D and 11 VM, and conjugates of ChCA of ChFA together with bacteria. At 3 days after treatment, some plants were infected with P. infestans. A decrease in the degree of development of the late blight pathogen on potato leaves in all treatment options was revealed. The maximum protective effect was manifested when plants were treated with the B. subtilis strain 26D bacteria in combination with conjugates of chitosan and oxycinnamic acids. The mechanisms of increasing the resistance of potato plants to P. infestans were associated with the activation of transcriptional activity of genes encoding the main protective protein (PR-1), chitinase (PR-3), thaumatin-like protein (PR-5), protease inhibitor (PR-6), peroxidase (PR-9), and ribonuclease (PR-10). The revealed activation of the expression of marker genes of systemic acquired resistance and induced systemic resistance under the influence of joint treatment of plants with B. subtilis and chitin conjugates with hydroxycinnamic acids indicates the synergistic development of protective reactions in potato plants in this variant. Using the method of two-dimensional electrophoresis of S. tuberosum leaf proteins followed by MALDI-TOF analysis 12 proteins were identified; their presence in the leaves differed depending on the variant of the experiment. In all treatment variants, serine–threonine protein phosphatase activity was suppressed, reflecting the development of the hypersensitivity reaction. Different variants of the experiment formed weakly expressed clusters, which indicates multiple mechanisms of regulation of the synthesis of protective proteins involved in the reaction to treatment with bacteria, chitosan conjugates, and infection with P. infestans. [ABSTRACT FROM AUTHOR]

The biocontrol agent Pythium oligandrum, which is a member of the phylum Oomycota, can control diseases caused by a taxonomically wide range of plant pathogens, including fungi, bacteria, and oomycetes. However, whether P. oligandrum could control diseases caused by plant root-knot nematodes (RKNs) was unknown. We investigated a recently isolated P. oligandrum strain GAQ1, and the P. oligandrum strain CBS530.74, for the control of an RKN Meloidogyne incognita infection of tomato (Solanum lycopersicum L.). Initially, P. oligandrum culture filtrates were found to be lethal to M. incognita second-stage juveniles (J2s) with up to 84% mortality 24 h after treatment compared to 14% in the control group. Consistent with the lethality to M. incognita J2s, tomato roots treated with P. oligandrum culture filtrates reduced their attraction of nematodes, and the number of nematodes penetrating the roots was reduced by up to 78%. In a greenhouse pot trial, the P. oligandrum GAQ1 inoculation of tomato plants significantly reduced the gall number by 58% in plants infected with M. incognita. Notably, the P. oligandrum GAQ1 mycelial treatment significantly increased tomato plant height (by 36%), weight (by 27%), and root weight (by 48%). A transcriptome analysis of tomato seedling roots inoculated with the P. oligandrum GAQ1 strain identified ~2500 differentially expressed genes. The enriched GO terms and annotations in the up-regulated genes suggested a modulation of the plant hormone-signaling and defense-related pathways in response to P. oligandrum. In conclusion, our results support that P. oligandrum GAQ1 can serve as a potential biocontrol agent for M. incognita control in tomato. Multiple mechanisms appear to contribute to the biocontrol effect, including the direct inhibition of M. incognita, the potential priming of tomato plant defenses, and plant growth promotion. [ABSTRACT FROM AUTHOR]

Global agriculture is heavily dependent on sustainable plant protection. Worldwide, the concept of integrated pest management (IPM) is being followed. IPM utilizes a range of strategies, with chemical synthetic pesticides being employed only as a last resort. However, in agricultural practice, farmers continue to rely primarily on this option. To further reduce this dependence, new strategies are being sought to strengthen the use of biological control within the IPM approach including the identification of novel non-synthetic natural compounds. Here, we discuss and report on the state of the art in biological control research in areas such as biocontrol agents and application of ecological principles. These practices can help to establish sustainable plant protection systems, with the greatest impact achieved when they are used in appropriate combinations. We highlight the conditions that currently prevent or hinder the increased use of biocontrol measures. On the background of agroecological experiences, we discuss why additional advancements in plant protection practices are imperative to more effectively break the life cycles of pests, diseases and weeds. We emphasize the significance of a judicious application of chemical control technologies, adapted to local conditions. Additionally, we highlight the key role and expertise of operators in implementing these practices and their knowledge thereof. [ABSTRACT FROM AUTHOR]

Phytosanitary management on tomato crop is a challenge for organic and conventional growers. Whitefly Bemisia tabaci (Gennadius) and mite Tetranychus evansi Baker and Pritchard are among the major pests. Methyl-salicylate (MeSa) is a methyl ester from salicylic acid and activates secondary metabolism pathways in plants. Zingiberene (ZGB) is a secondary compound associated with resistance to B. tabaci. The aim of the study was to study the relationship between the exogenous MeSA spraying and zingiberene content in tomato leaves and adult whitefly and mite responses. MeSa concentrations [0 (control), 100, 200, 300, 400, 500 µg L−1)] were applied on tomato to evaluate the ZGB content and the relationship with whitefly and spider mite on plants. After the last ZGB analysis, plants were placed in B. tabaci-highly infested greenhouse. The number of adult whiteflies on plants was determined three days later. Tomato leaflets were collected from treated plants and infested with five T. evansi e females. The number of larvae emerging from eggs was evaluated after 96 and 120 h. Reduction of adult whiteflies (from 78 to 8%) was also observed in plants exogenously treated with MeSa [significant and negative correlation (0.88)]. The number of eggs and number of larvae were linearly reduced with increase of MeSa concentration. Positive correlation (0.97) between exogenous MeSa concentrations vs. ZGB contents was observed. Negative correlations (0.90, 0.89 and 0.94) were estimated, between MeSa concentration vs. tomato red spider mite oviposition and egg hatchability (96 and 120 h), respectively. These results indicate that exogenous MeSa applications increases ZGB content and plant resistance to B. tabaci and T. evansi. [ABSTRACT FROM AUTHOR]

Vanda tricolor is currently a protected species because is the occurrence of orchid late blight caused by the Fusarium sp. pathogenic fungus. The objective of this study was to investigate the effectiveness of Rhizoctonia mycorrhizae in inducing resistance against Fusarium sp., the causative agent of late blight, in V. tricolor. The research employed CRBD with three treatments and six replications. Rhizoctonia mycorrhizae were isolated and identified following the procedure outlined by Bayman. Pre-inoculation of Rhizoctonia mycorrhizae was conducted on PDA media, and mycorrhizae were subsequently inoculated onto the roots of V. tricolor seedlings derived from tissue culture. The presence of peloton structures on the roots was determined using the Nakano methods. The Saravanan method was employed to measure peroxidase activity. The results demonstrated that V. tricolor induced by Rhizoctonia mycorrhizae exhibited resistance against Fusarium sp. and displayed the formation of peroxidase enzymes, peloton structures, and lignification. In contrast, the non-induced orchids suffered significant damage to the epidermal tissue of the leaves, did not exhibit an increase in peroxidase enzymes, and failed to form peloton or lignified structures. The novelty of this research is the use of Rhizoctonia mycorrhizae to control orchid late blight diseases at Mount Merapi. [ABSTRACT FROM AUTHOR]

Abstract Plant resistance and predators can influence density‐dependent survivorship and growth of herbivores, and their damage to plants. Although the independent effects of plant resistance and predators on herbivores and herbivory are well known, little is known about their interactive and density‐dependent effects on herbivores and the amount and distribution of damage on plants. These relationships are important for understanding how herbivore and plant populations influence each other. We used a laboratory density‐manipulation experiment to determine how plant resistance (three treatments: jasmonate‐insensitive, unmanipulated wild type, and jasmonate‐sprayed wild‐type plants) and predation (two treatments: predator or no predator) affect the survivorship and growth of an herbivore, as well as per capita damage and the distribution of damage on plants. We found evidence that the density dependence of herbivore survivorship was influenced by predators and an interactive effect of plant resistance and predation. Herbivore growth was reduced by higher plant resistance but was not density‐dependent nor affected by predation. Per capita plant damage was reduced by plant resistance, predation, and herbivore density. The within‐plant distribution of damage became more even with increasing herbivore density but was not affected by predation or the independent effect of plant resistance. The distribution of damage was also affected by an interaction between plant resistance and herbivore density; damage became less aggregated with density across all plant resistance treatments, but the decrease was strongest for the jasmonate‐insensitive plants. These results show that predators influence herbivore density dependence, and that plant resistance can affect the impact of predators on herbivores. Though plant resistance, predation, and herbivore density all reduced per capita herbivore damage to plants, only herbivore density and plant resistance affected the distribution of damage. Distributions of herbivory can influence plant success; documenting patterns of herbivory is an under‐appreciated avenue for integrating effects of plant resistance, predators, and herbivore density on plant–herbivore interactions.

The perceived negative impacts of synthetic agrochemicals gave way to alternative, biological plant protection strategies. The deployment of induced resistance, comprising boosting the natural defense responses of plants, is one of those. Plants developed multi-component defense mechanisms to defend themselves against biotic and abiotic stresses. These are activated upon recognition of stress signatures via membrane-localized receptors. The induced immune responses enable plants to tolerate and limit the impact of stresses. A systemic cascade of signals enables plants to prime un-damaged tissues, which is crucial during secondary encounters with stress. Comparable stress tolerance mechanisms can be induced in plants by the application of carbohydrate elicitors such as chitin/chitosan, β-1,3-glucans, oligogalacturonides, cellodextrins, xyloglucans, alginates, ulvans, and carrageenans. Treating plants with carbohydrate-derived elicitors enable the plants to develop resistance appliances against diverse stresses. Some carbohydrates are also known to have been involved in promoting symbiotic signaling. Here, we review recent progresses on plant resistance elicitation effect of various carbohydrate elicitors and the molecular mechanisms of plant cell perception, cascade signals, and responses to cascaded cues. Besides, the molecular mechanisms used by plants to distinguish carbohydrate-induced immunity signals from symbiotic signals are discussed. The structure-activity relationships of the carbohydrate elicitors are also described. Furthermore, we forwarded future research outlooks that might increase the utilization of carbohydrate elicitors in agriculture in order to improve the efficacy of plant protection strategies.

A bacterial pustule caused by Xanthomonas axonopodis pv. glycines (Xag) is one of the main diseases of soybeans in Thailand. Beneficial microbes crucial to sustainable plant production were examined in this study. Soybean plants were sprayed with Pseudomonas fluorescens SP007s strain three times before Xag infection. The results showed a significant reduction in bacterial pustule disease severity by up to 85%, increased leaf accumulation of salicylic acid with 134% during the infection process of Xag. Furthermore, the Xag population size in soybean leaves was reduced by priming with SP007s. The mechanism of SP007s in the chemical structure of mesophyll was characterized by using the synchrotron radiation-based Fourier transform infrared (SR-FTIR) analysis. The SR-FTIR spectral changes from the mesophyll showed higher integral area groups of polysaccharides (peak of 900–1,200 cm−1). These biochemical changes were involved with the primed resistance of the soybean plants against the bacterial pustule disease as well as the polysaccharide signals that were linked to hypersensitive responses leading to a rapid death of plant cells to effectively restrict the growth of pathogens at the infected site. Therefore, we consider that SP007s can be a promising biocontrol agent by activating immunity of soybean plants.

This document is a corrigendum for an article titled "Arabidopsis plants sense non-self peptides to promote resistance against Plectosphaerella cucumerina." The corrigendum addresses an error in the picture legends of Figures 1 and 2, as well as Supplementary Figures 1, 2, and 3. The authors have updated the legends and removed the scale legend in the supplementary figures. They apologize for the error but state that it does not affect the scientific conclusions of the article. The original article has been updated. [Extracted from the article]

Abstract Background Poplar anthracnose, which is one of the most important tree diseases, is primarily caused by Colletotrichum gloeosporioides, which has been detected in poplar plantations in China and is responsible for serious economic losses. The characteristics of 84K poplar that have made it one of the typical woody model plants used for investigating stress resistance include its rapid growth, simple reproduction, and adaptability. Results In this study, we found that the resistance of 84K poplar to anthracnose varied considerably depending on how the samples were inoculated of the two seedlings in each tissue culture bottle, one (84K-Cg) was inoculated for 6 days, whereas the 84K-DCg samples were another seedling inoculated at the 6th day and incubated for another 6 days under the same conditions. It was showed that the average anthracnose spot diameter on 84K-Cg and 84K-DCg leaves was 1.23 ± 0.0577 cm and 0.67 ± 0.1154 cm, respectively. Based on the transcriptome sequencing analysis, it was indicated that the upregulated phenylpropanoid biosynthesis-related genes in 84K poplar infected with C. gloeosporioides, including genes encoding PAL, C4H, 4CL, HCT, CCR, COMT, F5H, and CAD, are also involved in other KEGG pathways (i.e., flavonoid biosynthesis and phenylalanine metabolism). The expression levels of these genes were lowest in 84K-Cg and highest in 84K-DCg. Conclusions It was found that PAL-related genes may be crucial for the induced resistance of 84K poplar to anthracnose, which enriched in the phenylpropanoid biosynthesis. These results will provide the basis for future research conducted to verify the contribution of phenylpropanoid biosynthesis to induced resistance and explore plant immune resistance-related signals that may regulate plant defense capabilities, which may provide valuable insights relevant to the development of effective and environmentally friendly methods for controlling poplar anthracnose.

Abstract Background Plant responses to a wide range of stresses are known to be regulated by epigenetic mechanisms. Pathogen-related investigations, particularly against RNA viruses, are however scarce. It has been demonstrated that Arabidopsis thaliana plants defective in some members of the RNA-directed DNA methylation (RdDM) or histone modification pathways presented differential susceptibility to the turnip mosaic virus. In order to identify genes directly targeted by the RdDM-related RNA Polymerase V (POLV) complex and the histone demethylase protein JUMONJI14 (JMJ14) during infection, the transcriptomes of infected mutant and control plants were obtained and integrated with available chromatin occupancy data for various epigenetic proteins and marks. Results A comprehensive list of virus-responsive gene candidates to be regulated by the two proteins was obtained. Twelve genes were selected for further characterization, confirming their dynamic regulation during the course of infection. Several epigenetic marks on their promoter sequences were found using in silico data, raising confidence that the identified genes are actually regulated by epigenetic mechanisms. The altered expression of six of these genes in mutants of the methyltransferase gene CURLY LEAF and the histone deacetylase gene HISTONE DEACETYLASE 19 suggests that some virus-responsive genes may be regulated by multiple coordinated epigenetic complexes. A temporally separated multiple plant virus infection experiment in which plants were transiently infected with one virus and then infected by a second one was designed to investigate the possible roles of the identified POLV- and JMJ14-regulated genes in wild-type (WT) plants. Plants that had previously been stimulated with viruses were found to be more resistant to subsequent virus challenge than control plants. Several POLV- and JMJ14-regulated genes were found to be regulated in virus induced resistance in WT plants, with some of them poisoned to be expressed in early infection stages. Conclusions A set of confident candidate genes directly regulated by the POLV and JMJ14 proteins during virus infection was identified, with indications that some of them may be regulated by multiple epigenetic modules. A subset of these genes may also play a role in the tolerance of WT plants to repeated, intermittent virus infections.

Cultivating vegetables in the hydroponic system is often exposed to biotic and abiotic stresses. The use of suitable plant growth-promoting bacteria (PGPB) that can alleviate the impact of biotic stress is urgently needed. This study aims to evaluate the role of Universitas Brawijaya educational forest (UB Forest) indigenous PGPB strains on the induction of plant resistance against plant pests or diseases and the promotion of lettuce growth in a Nutrient Film Technique (NFT) hydroponic system. This study used a randomized block design with 7 treatments and 3 replications. The results showed that the PGPB strain inoculation reduced plant damage caused by thrips, induced phenylalanine ammonia-lyase (PAL), peroxidase (PO), and polyphenol oxidase (PPO) enzyme accumulation in planta, and increased the growth and photosynthetic pigments of lettuce. However, the treatments had no effect on increasing total phenolic compounds. Pseudomonas lundensis UB-53 and Pseudomonas migulae UB-54 inoculations exhibited higher activity in suppressing plant damage caused by thrips, inducing enzymes related to plant defense, and increasing lettuce growth. Two PGPB strains, i.e. P. migulae UB-54 and P. lundensis UB-53, have a high potential to be developed as eco-friendly biocontrol agents to overcome biotic stress and boost lettuce crop growth in NFT hydroponic systems.

Background: Poplar anthracnose, which is one of the most important tree diseases, is primarily caused by Colletotrichum gloeosporioides, which has been detected in poplar plantations in China and is responsible for serious economic losses. The characteristics of 84K poplar that have made it one of the typical woody model plants used for investigating stress resistance include its rapid growth, simple reproduction, and adaptability. Results: In this study, we found that the resistance of 84K poplar to anthracnose varied considerably depending on how the samples were inoculated of the two seedlings in each tissue culture bottle, one (84K-Cg) was inoculated for 6 days, whereas the 84K-DCg samples were another seedling inoculated at the 6th day and incubated for another 6 days under the same conditions. It was showed that the average anthracnose spot diameter on 84K-Cg and 84K-DCg leaves was 1.23 ± 0.0577 cm and 0.67 ± 0.1154 cm, respectively. Based on the transcriptome sequencing analysis, it was indicated that the upregulated phenylpropanoid biosynthesis-related genes in 84K poplar infected with C. gloeosporioides, including genes encoding PAL, C4H, 4CL, HCT, CCR, COMT, F5H, and CAD, are also involved in other KEGG pathways (i.e., flavonoid biosynthesis and phenylalanine metabolism). The expression levels of these genes were lowest in 84K-Cg and highest in 84K-DCg. Conclusions: It was found that PAL-related genes may be crucial for the induced resistance of 84K poplar to anthracnose, which enriched in the phenylpropanoid biosynthesis. These results will provide the basis for future research conducted to verify the contribution of phenylpropanoid biosynthesis to induced resistance and explore plant immune resistance-related signals that may regulate plant defense capabilities, which may provide valuable insights relevant to the development of effective and environmentally friendly methods for controlling poplar anthracnose. [ABSTRACT FROM AUTHOR]

Background: Plant responses to a wide range of stresses are known to be regulated by epigenetic mechanisms. Pathogen-related investigations, particularly against RNA viruses, are however scarce. It has been demonstrated that Arabidopsis thaliana plants defective in some members of the RNA-directed DNA methylation (RdDM) or histone modification pathways presented differential susceptibility to the turnip mosaic virus. In order to identify genes directly targeted by the RdDM-related RNA Polymerase V (POLV) complex and the histone demethylase protein JUMONJI14 (JMJ14) during infection, the transcriptomes of infected mutant and control plants were obtained and integrated with available chromatin occupancy data for various epigenetic proteins and marks. Results: A comprehensive list of virus-responsive gene candidates to be regulated by the two proteins was obtained. Twelve genes were selected for further characterization, confirming their dynamic regulation during the course of infection. Several epigenetic marks on their promoter sequences were found using in silico data, raising confidence that the identified genes are actually regulated by epigenetic mechanisms. The altered expression of six of these genes in mutants of the methyltransferase gene CURLY LEAF and the histone deacetylase gene HISTONE DEACETYLASE 19 suggests that some virus-responsive genes may be regulated by multiple coordinated epigenetic complexes. A temporally separated multiple plant virus infection experiment in which plants were transiently infected with one virus and then infected by a second one was designed to investigate the possible roles of the identified POLV- and JMJ14-regulated genes in wild-type (WT) plants. Plants that had previously been stimulated with viruses were found to be more resistant to subsequent virus challenge than control plants. Several POLV- and JMJ14-regulated genes were found to be regulated in virus induced resistance in WT plants, with some of them poisoned to be expressed in early infection stages. Conclusions: A set of confident candidate genes directly regulated by the POLV and JMJ14 proteins during virus infection was identified, with indications that some of them may be regulated by multiple epigenetic modules. A subset of these genes may also play a role in the tolerance of WT plants to repeated, intermittent virus infections. [ABSTRACT FROM AUTHOR]

Phosphites (Phi) are inorganic salts widely used to protect plants from pathogens, especially oomycetes, on a wide range of horticultural crops. They were studied at the molecular level in different pathosystems; however, their mode of action is not completely understood. In this work, we investigate the participation of polyamine (PA) metabolism in the defence mechanism induced by Phi. To this aim, potato plants were treated with potassium phosphite (KPhi), and 3 days later, leaves were inoculated with Phytophthora infestans (P. infestans). The content of free PAs was analysed and showed that KPhi induced the accumulation of spermine (Spm), spermidine (Spd) and putrescine (Put). However, when treated leaves were detached and inoculated with P. infestans, their accumulation was even higher. In addition, the expression of genes implicated in PA synthesis and degradation was measured. Most of the genes involved in PA biosynthesis showed no changes in their expression upon KPhi treatment, except for those involved in Spm synthesis: Spm synthase and S-adenosyl-L-methionine decarboxylase (SPMS and SAMDC, respectively). On the other hand, the catabolism genes: diamine oxidase (DAO), and polyamine oxidases PAO1, PAO2 and PAO5, but not PAO4, decreased their expression after inoculation with P. infestans, and this was reverted by KPhi pretreatment. To investigate this effect, assays were carried out using a PA oxidase inhibitor showing that defence responses induced by KPhi do not require products of PA catabolism. Additionally, we analysed in silico phytohormone and stress-responsive cis-elements in PAO gene promoters, which might explain, at least in part, the different behaviour of PAO4. [ABSTRACT FROM AUTHOR]

BACKGROUND: The biocontrol potential of soil microbes can reduce the extensive use of hazardous synthetic fungicides. This study was designed to find a strain of rhizobacteria indigenous to Pakistan with potential biocontrol against early blight of tomato caused by Alternaria solani and to characterize its biocontrol mechanisms. RESULTS: Among 88 strains tested for antagonism against A. solani on agar media, S27, Dt10 and 423, identified by 16S rRNA sequencing as strains of Bacillus amyloliquefaciens, B. cereus and Stenotrophomonas rhizophila, respectively, were the most inhibitory. When applied to detached tomato leaflets in Petri dish assays, the strains reduced lesion development by over 30% compared to the control. In greenhouse pot trials, the bacterial strains reduced early blight severity by over 50%. In three field trials, all three strains applied to tomato foliage slowed early blight disease progress and reduced disease severity, with B. amyloliquefaciens S27 reducing the area under the disease progress curve by up to 70%. All three strains showed protease, catalase and oxidase activities in vitro, but none produced β‐1,3‐glucanase and only B. cereus Dt10 showed slight chitinase activity. In a greenhouse experiment in which the bacteria were applied to tomato foliage prior to pathogen inoculation, bacteria‐treated leaves had higher β‐1,3‐glucanase and chitinase levels than leaves inoculated only with the pathogen, indicating priming induction of response. CONCLUSION: Three rhizobacteria strains have the potential to control early blight of tomato under Pakistan's growing conditions, with B. amyloliquefaciens S27 being the most promising candidate for commercial development. Antagonism and induction of the priming response may be mechanisms of biocontrol by the bacterial strains. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

The European Green Deal aims to reduce the pesticide use, notably by developing biocontrol products to protect crops from diseases. Indeed, the use of significant amounts of chemicals negatively impact the environment such as soil microbial biodiversity or groundwater quality, and human health. Grapevine (Vitis vinifera) was selected as one of the first targeted crop due to its economic importance and its dependence on fungicides to control the main damaging diseases worldwide: grey mold, downy and powdery mildews. Chitosan, a biopolymer extracted from crustacean exoskeletons, has been used as a biocontrol agent in many plant species, including grapevine, against a variety of cryptogamic diseases such as downy mildew (Plasmopara viticola), powdery mildew (Erysiphe necator) and grey mold (Botrytis cinerea). However, the precise molecular mechanisms underlying its mode of action remain unclear: is it a direct biopesticide effect or an indirect elicitation activity, or both? In this study, we investigated six chitosans with diverse degrees of polymerization (DP) ranging from low to high DP (12, 25, 33, 44, 100, and 470). We scrutinized their biological activities by evaluating both their antifungal properties and their abilities to induce grapevine immune responses. To investigate their elicitor activity, we analyzed their ability to induce MAPKs phosphorylation, the activation of defense genes and metabolite changes in grapevine. Our results indicate that the chitosans with a low DP are more effective in inducing grapevine defenses and possess the strongest biopesticide effect against B. cinerea and P. viticola. We identified chitosan with DP12 as the most efficient resistance inducer. Then, chitosan DP12 has been tested against downy and powdery mildews in the vineyard trials performed during the last three years. Results obtained indicated that a chitosan-based biocontrol product could be sufficiently efficient when the amount of pathogen inoculum is quite low and could be combined with only two fungicide treatments during whole season programs to obtain a good protection efficiency. On the whole, a chitosan-based biocontrol product could become an interesting alternative to meet the chemicals reduction targeted in sustainable viticulture. [ABSTRACT FROM AUTHOR]

Summary: Verticillium dahliae is a widespread and destructive soilborne vascular pathogenic fungus that causes serious diseases in dicot plants. Here, comparative transcriptome analysis showed that the number of genes upregulated in defoliating pathotype V991 was significantly higher than in the non‐defoliating pathotype 1cd3‐2 during the early response of cotton. Combined with analysis of the secretome during the V991–cotton interaction, an elicitor VP2 was identified, which was highly upregulated at the early stage of V991 invasion, but was barely expressed during the 1cd3‐2‐cotton interaction. Full‐length VP2 could induce cell death in several plant species, and which was dependent on NbBAK1 but not on NbSOBIR1 in N. benthamiana. Knock‐out of VP2 attenuated the pathogenicity of V991. Furthermore, overexpression of VP2 in cotton enhanced resistance to V. dahliae without causing abnormal plant growth and development. Several genes involved in JA, SA and lignin synthesis were significantly upregulated in VP2‐overexpressing cotton. The contents of JA, SA, and lignin were also significantly higher than in the wild‐type control. In summary, the identified elicitor VP2, recognized by the receptor in the plant membrane, triggers the cotton immune response and enhances disease resistance. [ABSTRACT FROM AUTHOR]