Induced Disease Resistance Research Articles

Black shank-mediated alteration of the community assembly of rhizosphere soil bacteria in tobacco

IntroductionThere is a close and complex interaction between the elements in the aboveground-underground ecosystem during the growth and development of plants. Specifically, when the aboveground part of plants is infected by pathogens, it induces the plant rhizosphere to synthesize specific root exudates. Consequently, a group of beneficial rhizosphere soil bacteria is recruited to help plants resist diseases. However, the changes in the rhizosphere soil bacterial community of plants under infection by oomycete pathogens remain unknown.MethodsThree experimental treatments were set up in this experiment: soils inoculated with P. nicotianae, no-inoculation with P. nicotianae, and a control. The control treatment was composed of soils without transplanted tobacco plants, with the pathogen inoculated twice at an interval of eight days to ensure a successful P. nicotianae infection. P. nicotianae inoculation treatments were designed using the hyphal block inoculation method. In the non-inoculation treatment, tobacco plants were grown normally without pathogen inoculation. The tobacco plants were grown in a greenhouse.ResultsThis study demonstrates that tobacco plants recruit microorganisms at the rhizosphere level as a defense mechanism against disease after infection by the oomycete pathogen Phytophthora nicotianae. Specific rhizosphere soil bacteria were screened in vitro to promote tobacco growth in a biofilm-forming manner, which induced the systemic resistance of the plants to P. nicotianae. The recruitment of rhizosphere soil bacteria to the inter-root zone of tobacco plants after infection by P. nicotianae can help subsequently cultivated tobacco plants in the same soil resist pathogen infestation.DiscussionIn conclusion, the present study confirms that infestation caused by oomycete pathogens alters the composition of the plant rhizosphere soil bacterial community and recruits a specific group of beneficial microorganisms that induce disease resistance and promote plant growth, thereby maximizing the protection of progeny grown in the same soil against the disease.

Cloning and Expression Analysis of ATG8 (Autophagy-Related 8) Gene Family in Solanaceae.

The autophagy-related gene family ATG8 (Autophagy-related 8) plays an important role in plant growth, development, and stress response. In this study, 15 ATG8 gene family sequences were amplified from Solanaceae, namely tobacco, tomato, and pepper, using RT-PCR to evaluate their basic properties, protein structure, and function, as well as the role of ATG8 in autophagy. The physicochemical properties, the predicted secondary and tertiary protein structures, subcellular localisation, gene structures, conserved motifs, and phylogenetic relationships of the ATG8 genes were analysed using bioinformatic techniques, and their expression patterns under sericin-induced plant disease resistance were investigated by RT-qPCR. The lengths of these proteins ranged from 79 to 120 aa, while their predicted molecular weights and isoelectric points (PI) ranged from 9283.62 to 13,778.74 and 6.32 to 11.44, respectively. The majority of the proteins were localised in the nucleus or chloroplasts. Conserved protein motifs and various cis-regulatory elements in the protein, with a wide range of related functions, were identified. The ATG8 gene family members showed expression changes after treatment with osthole, which induces disease resistance in tobacco, tomato, and pepper. These findings provide a foundation for further analyses of the ATG8 gene family in Solanaceae and the mechanism underlying the response to adverse conditions.

Immunomodulating melatonin-decorated silica nanoparticles suppress bacterial wilt (Ralstonia solanacearum) in tomato (Solanum lycopersicum L.) through fine-tuning of oxidative signaling and rhizosphere bacterial community

BackgroundTomato (Solanum lycopersicum L.) production is severely threatened by bacterial wilt, caused by the phytopathogenic bacterium Ralstonia solanacearum. Recently, nano-enabled strategies have shown tremendous potential in crop disease management.ObjectivesThis study investigates the efficacy of biogenic nanoformulations (BNFs), comprising biogenic silica nanoparticles (SiNPs) and melatonin (MT), in controlling bacterial wilt in tomato.MethodsSiNPs were synthesized using Zizania latifolia leaves extract. Further, MT containing BNFs were synthesized through the one-pot approach. Nanomaterials were characterized using standard characterization techniques. Greenhouse disease assays were conducted to assess the impact of SiNPs and BNFs on tomato plant immunity and resistance to bacterial wilt.ResultsThe SiNPs and BNFs exhibited a spherical morphology, with particle sizes ranging from 13.02 nm to 22.33 nm for the SiNPs and 17.63 nm to 21.79 nm for the BNFs, indicating a relatively uniform size distribution and consistent shape across both materials. Greenhouse experiments revealed that soil application of BNFs outperformed SiNPs, significantly enhancing plant immunity and reducing bacterial wilt incidence by 78.29% in tomato plants by maintaining oxidative stress homeostasis via increasing the activities of antioxidant enzymes such as superoxide dismutase (31.81%), peroxidase (32.9%), catalase (32.65%), and ascorbate peroxidase (47.37%) compared to untreated infected plants. Additionally, BNFs induced disease resistance by enhancing the production of salicylic acid and activating defense-related genes (e.g., SlPAL1, SlICS1, SlNPR1, SlEDS, SlPD4, and SlSARD1) involved in phytohormones signaling in infected tomato plants. High-throughput 16 S rRNA sequencing revealed that BNFs promoted growth of beneficial rhizosphere bacteria (Gemmatimonadaceae, Ramlibacter, Microscillaceae, Anaerolineaceae, Chloroplast and Phormidium) in both healthy and diseased plants, while suppressing R. solanacearum abundance in infected plants.ConclusionOverall, these findings suggest that BNFs offer a more promising and sustainable approach for managing bacterial wilt disease in tomato plants.Graphical

Epsilon-poly-l-lysine and methyl jasmonate synergistically inhibit Pseudomonas tolaasii-caused brown spot disease in postharvest button mushroom (Agaricus bisporus)

The brown spot disease, caused by Pseudomonas tolaasii is a serious disease that significantly affects the quality of Agaricus bisporus. To develop a safe and effective method to protect mushrooms from disease, the effects of epsilon-poly-l-lysine (ε-PL) and methyl jasmonate (MeJA), either alone or in combination, on brown spot disease caused by P. tolaasii in A. bisporus were investigated. Our results showed that both ε-PL (100 mg L−1) and MeJA (100 μmol L−1) effectively reduced the incidence rate and disease index, inhibited the activity of polyphenol oxidase activated by P. tolaasii, and suppressed the production of malonaldehyde, and their combination achieved a more effective effect; the reason for this result was not due to their coordinated antibacterial activity in vitro, but rather the synergistic induction of disease resistance in mushrooms. The combined treatment of ε-PL and MeJA not only increased the content of pathogenesis-related proteins (PRs), the activities of defense enzymes and antioxidant enzymes, but also enhanced the activities of phenylpropanoid pathway-related enzymes and the accumulation of total phenolic and total flavonoid substances. Furthermore, the combined treatment was also more effective in increasing JA levels and the activities of lipoxygenase and allene oxide synthase compared to treatment with either ε-PL or MeJA alone. Correlation analysis further demonstrated the important role of defense-related enzymes and PRs as well as phenylpropanoid pathway-related enzymes and metabolites in the inhibition of ε-PL and MeJA alone or in combination on the incidence rate and disease index. Taken together, our results showed that ε-PL combined with MeJA treatment has good prospects for alleviating mushroom brown spot disease.

Induced resistance to control postharvest stem-end rot by methyl jasmonate in mango fruit

Induced resistance is an alternative disease control strategy for postharvest fruits and vegetables. Methyl jasmonate (MeJA) is a crucial phytohormone in the defense response to biotic and abiotic stresses. The effect and relevant mechanism of MeJA on the control of postharvest disease in mango fruit remain unclear. This study investigated the effect and possible mechanism of MeJA against stem-end rot caused by Lasiodiplodia theobromae in mango fruit. The results showed that MeJA significantly inhibited the lesion expansion on mango fruit inoculated with L. theobromae. 10 μM MeJA treatment effectively induced disease resistance against L. theobromae during postharvest storage. MeJA enhanced the activities of defense-related enzymes, including phenylalanine ammonia lyase (PAL), peroxidase (POD), β-1,3-glucanase (GLU), and chitinase (CHT), increased the accumulation of endogenous jasmonic acid (JA) and salicylic acid (SA) contents, up-regulated the expressions of the related genes on JA pathway (AOS, JAR1, MYC2, and COI1) and SA pathway (ICS, and PR1), stimulated the contents of total phenolics and flavonoids, and inhibited the accumulation of malondialdehyde (MDA). Furthermore, MeJA delayed the ripening and senescence of the fruit by inhibiting the peel yellowing, flesh softening and change in soluble solids content (SSC) of mango fruit. The results indicated that the enhanced resistance of MeJA-treated mango to stem-end rot was potentially due to the activation of defense responses induced by synergistic interaction between JA and SA pathways, as well as delayed postharvest ripening. The MeJA treatment is a promising strategy to control stem-end rot of mango fruit.

Molecular and metabolic insights into the mechanism of exogenous methyl jasmonate in enhancing the postharvest resistance of kiwifruit to Botrytis cinerea

Gray mold, caused by Botrytis cinerea infection, significantly impacts postharvest kiwifruit, leading to spoilage and food safety issues. Meanwhile, methyl jasmonate (MeJA) induces defense responses in plants. This study aimed to identify the optimal MeJA concentration to induce disease resistance in kiwifruits. Notably, various plant defense enzymes were detected in MeJA-treated kiwifruit. Moreover, 0.01 mol/L MeJA was found to enhance B. cinerea resistance in kiwifruit by increasing antioxidant enzyme activity. Widely targeted metabolomics analysis revealed 62–64 differentially expressed metabolites (DEMs) between the different treatment groups. Additionally, RNA-seq analysis revealed 930–2900 differentially expressed genes (DEGs), between these groups. Subsequently, combined DEG and DEM analysis highlighted phenylpropanoid biosynthesis and plant hormone signaling as key transduction pathway associated with MeJA-induced resistance. Overall, these findings identified the mechanism of MeJA-induced resistance in kiwifruit, providing a theoretical basis for the safe and effective control of postharvest diseases in kiwifruit.

The Past, Present, and Future of Plant Activators Targeting the Salicylic Acid Signaling Pathway.

Plant activators have emerged as promising alternatives to conventional crop protection chemicals for managing crop diseases due to their unique mode of action. By priming the plant's innate immune system, these compounds can induce disease resistance against a broad spectrum of pathogens without directly inhibiting their proliferation. Key advantages of plant activators include prolonged defense activity, lower effective dosages, and negligible risk of pathogen resistance development. Among the various defensive pathways targeted, the salicylic acid (SA) signaling cascade has been extensively explored, leading to the successful development of commercial activators of systemic acquired resistance, such as benzothiadiazole, for widespread application in crop protection. While the action sites of many SA-targeting activators have been preliminarily mapped to different steps along the pathway, a comprehensive understanding of their precise mechanisms remains elusive. This review provides a historical perspective on plant activator development and outlines diverse screening strategies employed, from whole-plant bioassays to molecular and transgenic approaches. We elaborate on the various components, biological significance, and regulatory circuits governing the SA pathway while critically examining the structural features, bioactivities, and proposed modes of action of classical activators such as benzothiadiazole derivatives, salicylic acid analogs, and other small molecules. Insights from field trials assessing the practical applicability of such activators are also discussed. Furthermore, we highlight the current status, challenges, and future prospects in the realm of SA-targeting activator development globally, with a focus on recent endeavors in China. Collectively, this comprehensive review aims to describe existing knowledge and provide a roadmap for future research toward developing more potent plant activators that enhance crop health.

Application and antagonistic mechanisms of atoxigenic Aspergillus strains for the management of fungal plant diseases.

This review covers, for the first time, all methods based on the use of Aspergillus strains as biocontrol agents for the management of plant diseases caused by fungi and oomycetes. Atoxigenic Aspergillus strains have been screened in a variety of hosts, such as peanuts, maize kernels, and legumes, during the preharvest and postharvest stages. These strains have been screened against a wide range of pathogens, such as Fusarium, Phytophthora, and Pythium species, suggesting a broad applicability spectrum. The highest efficacies were generally observed when using non-toxigenic Aspergillus strains for the management of mycotoxin-producing Aspergillus strains. The modes of action included the synthesis of antifungal metabolites, such as kojic acid and volatile organic compounds (VOCs), secretion of hydrolytic enzymes, competition for space and nutrients, and induction of disease resistance. Aspergillus strains degraded Sclerotinia sclerotiorum sclerotia, showing high control efficacy against this pathogen. Collectively, although two Aspergillus strains have been commercialized for aflatoxin degradation, a new application of Aspergillus strains is emerging and needs to be optimized.

Metagenomic and transcriptome insights into the disease resistance mechanisms in fresh-cut apple under pyridoxine treatment

Microbial spoilage poses a significant challenge to fresh-cut apples during storage, impacting quality and consumer health. This study explores pyridoxine’s (vitamin B6; VB6) potential mode of action to mitigate microbial spoilage in fresh-cut apples through physiological, transcriptomic, and metagenomic analysis. VB6 notably reduces microbial spoilage at room temperature by suppressing bacterial genera (Pseudomonas, Curtobacterium, Frigoribacterium) and fungal genera (Alternaria, Penicillium, Aureobasidium, Pseudogymnoascus) proliferation. Spoilage-causing identified biomarkers include species related to Pseudomonas, Curtobacterium, Frigoribacterium, and Penicillium. KEGG analysis suggests correlations of induced disease resistance with tropane alkaloids biosynthesis, plant-pathogen interaction, and phenylpropanoid biosynthesis pathways in fresh-cut apples. Moreover, VB6 treatment enhanced the antioxidant system via maintaining higher total phenolic contents, total flavonoid contents, and ascorbic acid under elevated catalase, superoxide dismutase, and ascorbate peroxidase enzymes activities, induced disease resistance under higher enzymes activities including phenylalanine ammonialyase, chitinase, cinnamate 4-hydroxylase, β-1,3-glucanase, and 4-coumarate: co-enzyme A ligase enzymes activities, maintained elevated VB6 contents, and reduced H2O2 accumulation. Notably, 6 elevated transcription factors involving WRKY, NAC and MYB might regulate disease resistance pathways in fresh-cut apples under VB6 treatment. This research establishes a theoretical and practical foundation for preserving post-processing quality of fresh-cut apples by restraining microbial proliferation through the proposed VB6-induced disease resistance regulatory mechanism.

Chitin nanofibers promote rhizobial symbiotic nitrogen fixation in Lotus japonicus

Chitin, an N-acetyl-D-glucosamine polymer, has multiple functions in living organisms, including the induction of disease resistance and growth promotion in plants. In addition, chitin oligosaccharides (COs) are used as the backbone of the signaling molecule Nod factor secreted by soil bacteria rhizobia to establish a mutual symbiosis with leguminous plants. Nod factor perception triggers host plant responses for rhizobial symbiosis. In this study, the effects of chitins on rhizobial symbiosis were examined in the leguminous plants Lotus japonicus and soybean. Chitin nanofiber (CNF), retained with polymeric structures, and COs elicited calcium spiking in L. japonicus roots expressing a nuclear-localized cameleon reporter. Shoot growth and symbiotic nitrogen fixation were significantly increased by CNF but not COs in L.japonicus and soybean. However, treatments with chitin and cellulose nanofiber, structurally similar polymers to CNF, did not affect shoot growth and nitrogen fixation in L.japonicus. Transcriptome analysis also supported the specific effects of CNF on rhizobial symbiosis in L.japonicus. Although chitins comprise the same monosaccharides and nanofibers share similar physical properties, only CNF can promote rhizobial nitrogen fixation in leguminous plants. Taking the advantages on physical properties, CNF could be a promising material for improving legume yield by enhancing rhizobial symbiosis.

The MiTGA1 stimulates MiPR1 expression and H2O2 production to enhance mango disease resistance in response to Bacillus siamensis treatment

Postharvest disease caused by fungi is a major issue that leads to quality decline and economic losses in mango fruit during storage and distribution. TGA transcription factors and pathogenesis-related proteins (PR) play crucial roles in modulating plant tolerance to pathogens. However, the roles of TGAs in the disease resistance of mango fruit remain unclear. Here, we investigated the impact of applying the antagonist Bacillus siamensis (N-1) on disease occurrence and the expression levels of MiTGA1 and MiPR1 genes in “Tainong No. 1” mango. We also explored the molecular mechanism of MiTGA1 interaction with MiPR1 gene. Results demonstrated that N-1 treatment significantly increased the level of hydrogen peroxide (H2O2) and effectively suppressed disease expansion during mango storage at 25 °C. Analyses of transcriptome data and qRT-PCR revealed the obvious up-regulation of MiTGA1 and MiPR1 genes in response to the N-1 treatment. Further subcellular localization identified the MiTGA1 protein as being located in the nucleus. Yeast one-hybrid (Y1H) and dual-luciferase reporter (DLR) assays confirmed that MiTGA1 could bind to the MiPR1 promoter and activate its transcription. Furthermore, transient over-expression of MiTGA1 in mango was found to enhance the accumulation of disease-resistant substances such as H2O2 by modulating MiPR1 expression, thereby bolstering the disease resistance of mango fruit. Our study suggests that MiTGA1 is a promising target gene and its interaction with MiPR1 may contribute to disease resistance induction and decay mitigation in postharvest mango fruit.

Effects of amino-oligosaccharides on induced disease resistance and biochemical indices of wolfberry

Effects of amino-oligosaccharides on induced disease resistance and biochemical indices of wolfberry

Molecular characterization revealed the role of thaumatin-like proteins of Rhizoctonia solani AG4-JY in inducing maize disease resistance.

The gene family of thaumatin-like proteins (TLPs) plays a crucial role in the adaptation of organisms to environmental stresses. In recent years, fungal secreted proteins (SP) with inducing disease resistance activity in plants have emerged as important elicitors in the control of fungal diseases. Identifying SPs with inducing disease resistance activity and studying their mechanisms are crucial for controlling sheath blight. In the present study, 10 proteins containing the thaumatin-like domain were identified in strain AG4-JY of Rhizoctonia solani and eight of the 10 proteins had signal peptides. Analysis of the TLP genes of the 10 different anastomosis groups (AGs) showed that the evolutionary relationship of the TLP gene was consistent with that between different AGs of R. solani. Furthermore, it was found that RsTLP3, RsTLP9 and RsTLP10 were regarded as secreted proteins for their signaling peptides exhibited secretory activity. Prokaryotic expression and enzyme activity analysis revealed that the three secreted proteins possess glycoside hydrolase activity, suggesting they belong to the TLP family. Additionally, spraying the crude enzyme solution of the three TLP proteins could enhance maize resistance to sheath blight. Further analysis showed that genes associated with the salicylic acid and ethylene pathways were up-regulated following RsTLP3 application. The results indicated that RsTLP3 had a good application prospect in biological control.

Effects of dietary β-sitosterol supplementation on growth performance, antioxidant ability, and disease resistance in largemouth bass Micropterus salmoides

β-sitosterol, as the most abundant phytosterol, has been shown to exert multiple biological roles in in vitro and in vivo animal studies. Largemouth bass (Micropterus salmoides) is an economical freshwater-farmed species widely cultivated in China due to its nutritious and delicious meat. This study investigated the effects of dietary β-sitosterol supplementation on largemouth bass farming. In the study, largemouth bass were fed with five levels of β-sitosterol (0, 20, 40, 80, and 160 mg/kg) supplementation in a commercial feed for four weeks. The growth performance, antioxidant ability, intestinal structure, immune-related gene expression, and resistance to pathogens such as Aeromonas hydrophila and largemouth bass virus (LMBRaV) were detected. The results revealed that β-sitosterol supplementation in feed increased the weight gain rate of largemouth bass, with 40 mg/kg supplementation displaying the best effect. The serum biochemical indices all showed an increase, including glucose and alkaline phosphatase. The intestinal villus length and muscularis propria thickness also increased, accompanied by elevated digestive enzyme activities, which promoted digestion and absorption of nutrients. Meanwhile, the levels of total cholesterol, aspartate aminotransferase, and alanine aminotransferase in serum decreased, indicating reduced liver damage. In addition, β-sitosterol supplementation effectively enhanced the antioxidant capacity of largemouth bass by decreasing malondialdehyde and elevating superoxide dismutase. Immune-related gene expression also changed. Pathogen infection tests revealed that β-sitosterol supplementation in feed had a certain protective effect against infection in largemouth bass, with the protection rate against A. hydrophila being higher than LMBRaV. The 40 mg/kg β-sitosterol supplementation group exhibited the best results. Collectively, the results revealed that the β-sitosterol can promote growth, improve enzyme activity, stimulate intestinal digestion, increase immune gene expression, and induce disease resistance in largemouth bass, with the optimal supplementation dosage being 40 mg/kg. β-sitosterol might be an excellent feed additive in aquaculture.

Lactic acid induced defense responses in tobacco against Phytophthora nicotianae

Induced resistance is considered an eco-friendly disease control strategy, which can enhance plant disease resistance by inducing the plant’s immune system to activate the defense response. In recent years, studies have shown that lactic acid can play a role in plant defense against biological stress; however, whether lactic acid can improve tobacco resistance to Phytophthora nicotianae, and its molecular mechanism remains unclear. In our study, the mycelial growth and sporangium production of P. nicotianae were inhibited by lactic acid in vitro in a dose-dependent manner. Application of lactic acid could reduce the disease index, and the contents of total phenol, salicylic acid (SA), jasmonic acid (JA), lignin and H2O2, catalase (CAT) and phenylalanine ammonia–lyase (PAL) activities were significantly increased. To explore this lactic acid-induced protective mechanism for tobacco disease resistance, RNA-Seq analysis was used. Lactic acid enhances tobacco disease resistance by activating Ca2+, reactive oxygen species (ROS) signal transduction, regulating antioxidant enzymes, SA, JA, abscisic acid (ABA) and indole-3-acetic acid (IAA) signaling pathways, and up-regulating flavonoid biosynthesis-related genes. This study demonstrated that lactic acid might play a role in inducing resistance to tobacco black shank disease; the mechanism by which lactic acid induces disease resistance includes direct antifungal activity and inducing the host to produce direct and primed defenses. In conclusion, this study provided a theoretical basis for lactic acid-induced resistance and a new perspective for preventing and treating tobacco black shank disease.

High-throughput sequencing-based analysis of the composition and diversity of the endophyte community in roots of Stellera chamaejasme

Stellera chamaejasme (S. chamaejasme) is an important medicinal plant with heat-clearing, detoxifying, swelling and anti-inflammatory effects. At the same time, it is also one of the iconic plants of natural grassland degradation in northwest China, playing a key role in the invasion process. Plant endophytes live in healthy plant tissues and can synthesize substances needed for plant growth, induce disease resistance in host plants, and enhance plant resistance to environmental stress. Therefore, studying the root endophytes of S. chamaejasme is of great significance for mining beneficial microbial resources and biological prevention and control of S. chamaejasme. This study used Illumina MiSeq high-throughput sequencing technology to analyze the composition and diversity of endophytes in the roots of S. chamaejasme in different alpine grasslands (BGC, NMC and XGYZ) in Tibet. Research results show that the main phylum of endophytic fungi in the roots of S. chamaejasme in different regions is Ascomycota, and the main phyla of endophytic bacteria are Actinobacteria, Proteobacteria and Firmicutes (Bacteroidota). Overall, the endophyte diversity of the NMC samples was significantly higher than that of the other two sample sites. Principal coordinate analysis (PCoA) and permutational multivariate analysis of variance (PERMANOVA) results showed significant differences in the composition of endophytic bacterial and fungal communities among BGC, NMC and XGYZ samples. Co-occurrence network analysis of endophytes showed that there were positive correlations between fungi and some negative correlations between bacteria, and the co-occurrence network of bacteria was more complex than that of fungi. In short, this study provides a vital reference for further exploring and utilizing the endophyte resources of S. chamaejasme and an in-depth understanding of the ecological functions of S. chamaejasme endophytes.

Assessment of different control means to protect grape berries from biotic injuries in postharvest

To find alternatives similar in effectiveness to conventional fungicides, two commercial disease resistance inducers, EP5-Protect (Phenom Biotech, Milan Italy; EP) and BioDea Flavor (BioDea, Arezzo, Italy; WD), and bioactive extracts (BCEs) from a strain of Streptomyces albidoflavus (CARA17), were compared to the fungicide fludioxonil in in vitro and in vivo trials to control postharvest decay on table grapes by Botrytis cinerea and Monilinia laxa. Disease severity and incidence were recorded by Mckinney index values of 0.0–5.0. On culture media, EP, BCEs, and fludioxonil significantly inhibited the growth of both pathogens by 100% for B. cinerea, and 79–100% for M. laxa, while WD inhibited both pathogens by 15–25%. Similar results were obtained from experimental trials with inoculated grape berries treated with these compounds after harvest. Fludioxonil was the most effective treatment to control both pathogens applied to uninoculated or inoculated grapes. EP was significantly but moderately effective to control both pathogens and the other saprophytic microorganisms, whereas the effectiveness of BCEs from S. albidoflavus was significantly less, and WD was the least effective treatment. Our results indicate EP and BCEs may be promising to control postharvest decay on grapes and other fresh products. They could conceivably be used to replace sulfur dioxide fumigation currently used to protect grapes after harvest, in particular when storage is not prolonged.

Enhancement of broad-spectrum disease resistance in wheat through key genes involved in systemic acquired resistance.

Systemic acquired resistance (SAR) is an inducible disease resistance phenomenon in plant species, providing plants with broad-spectrum resistance to secondary pathogen infections beyond the initial infection site. In Arabidopsis, SAR can be triggered by direct pathogen infection or treatment with the phytohormone salicylic acid (SA), as well as its analogues 2,6-dichloroisonicotinic acid (INA) and benzothiadiazole (BTH). The SA receptor non-expressor of pathogenesis-related protein gene 1 (NPR1) protein serves as a key regulator in controlling SAR signaling transduction. Similarly, in common wheat (Triticum aestivum), pathogen infection or treatment with the SA analogue BTH can induce broad-spectrum resistance to powdery mildew, leaf rust, Fusarium head blight, and other diseases. However, unlike SAR in the model plant Arabidopsis or rice, SAR-like responses in wheat exhibit unique features and regulatory pathways. The acquired resistance (AR) induced by the model pathogen Pseudomonas syringae pv. tomato strain DC3000 is regulated by NPR1, but its effects are limited to the adjacent region of the same leaf and not systemic. On the other hand, the systemic immunity (SI) triggered by Xanthomonas translucens pv. cerealis (Xtc) or Pseudomonas syringae pv. japonica (Psj) is not controlled by NPR1 or SA, but rather closely associated with jasmonate (JA), abscisic acid (ABA), and several transcription factors. Furthermore, the BTH-induced resistance (BIR) partially depends on NPR1 activation, leading to a broader and stronger plant defense response. This paper provides a systematic review of the research progress on SAR in wheat, emphasizes the key regulatory role of NPR1 in wheat SAR, and summarizes the potential of pathogenesis-related protein (PR) genes in genetically modifying wheat to enhance broad-spectrum disease resistance. This review lays an important foundation for further analyzing the molecular mechanism of SAR and genetically improving broad-spectrum disease resistance in wheat.

Inferring co-expression networks of Arabidopsis thaliana genes during their interaction with Trichoderma spp.

Fungi of the Trichoderma genus are called "biostimulants" because they promote plant growth and development and induce disease resistance. We used conventional transcriptome and gene co-expression analyses to understand the molecular response of the plant Arabidopsis thaliana to inoculation with Trichoderma atroviride or Trichoderma virens. The transcriptional landscape of the plant during the interaction with these fungi showed a reduction in functions such as reactive oxygen species production, defense mechanisms against pathogens, and hormone signaling. T. virens, as opposed to T. atroviride, was more effective at downregulating genes related to terpenoid metabolism, root development, and chemical homeostasis. Through gene co-expression analysis, we found functional gene modules that closely link plant defense with hypoxia. Notably, we found a transcription factor (locus AT2G47520) with two functional domains of interest: a DNA-binding domain and an N-terminal cysteine needed for protein stability under hypoxia. We hypothesize that the transcription factor can bind to the promoter sequence of the GCC-box that is connected to pathogenesis by positioned weight matrix analysis.

The volatile components from Bacillus cereus N4 can restrain brown rot of peach fruit by inhibiting sporulation of Monilinia fructicola and inducing disease resistance

Brown rot caused by Monilinia fructicola is one major disease in harvested peach fruit. Natural volatile compounds (VOCs) produced by antagonistic microorganisms have good biocontrol effects on postharvest fungal diseases. The present study showed the VOCs of Bacillus cereus N4 isolated from the orchard soil could significantly inhibit the sporulation and mycelial growth of M. fructicola. The expression levels of MfRGS2, MfRGS3 and MfLTF2α, which are unfavorable to the sporulation of M. fructicola were significantly induced by the VOCs of B. cereus N4. Moreover, the expression levels of MfRGS1, MfRGS4, MfREG1, MfPPOA and MfOPT1, which are beneficial to the sporulation of M. fructicola were markedly repressed. After fumigated with the VOCs of B. cereus N4 then inoculated with M. fructicola, peach fruit exhibited markedly lower disease incidence and lesion diameter than the control. Moreover, the activity of CHI and the expression level of PpCHI and PpPR1 of the fruit were significantly improved. 3-methyl-1-butanol, s-methyl butanethioate and 2-methyl-2-(methylthio)propane were the main antifungal substances in the VOCs of B. cereus N4 identified by gas chromatograph-mass spectrometer (GC-MS). Overall, the study provides natural candidates antibacterial agent from a biocontrol agent B. cereus N4 to restrain brown rot of peach fruit caused by M. fructicola.