Jasmonic Acid Pathway Research Articles

Arabidopsis GLYI4 Reveals Intriguing Insights into the JA Signaling Pathway and Plant Defense

Plant hormones play a central role in various physiological functions and mediate defense responses against (a)biotic stresses. Jasmonic acid (JA) has emerged as one of the key phytohormones involved in the response to necrotrophic pathogens. Under stressful conditions, plants can also produce small molecules, such as methylglyoxal (MG), a cytotoxic aldehyde. The enzymes glyoxalase I (GLYI) and glyoxalase II primarily detoxify MG. In Arabidopsis thaliana, GLYI4 has been recently characterized as having a crucial role in MG detoxification and emerging involvement in the JA pathway. Here, we investigated the impact of a GLYI4 loss-of-function on the Arabidopsis JA pathway and how MG affects it. The results showed that the glyI4 mutant plant had stunted growth, a smaller rosette diameter, reduced leaf size, and an altered pigment concentration. A gene expression analysis of the JA marker genes showed significant changes in the JA biosynthetic and signaling pathway genes in the glyI4 mutant. Disease resistance bioassays against the necrotroph Botrytis cinerea revealed altered patterns in the glyI4 mutant, likely due to increased oxidative stress. The MG effect has a further negative impact on plant performance. Collectively, these results contribute to clarifying the intricate interconnections between the GLYI4, MG, and JA pathways, opening up new avenues for further explorations of the intricate molecular mechanisms controlling plant stress responses.

ARGONAUTE4 and the DNA demethylase ROS1c mediate dehydroascorbate-induced intergenerational nematode resistance in rice.

Plants can transmit information to the next generation and modulate the phenotype of their offspring through epigenetic mechanisms. In this study, we demonstrate the activation of 'intergenerational acquired resistance' (IAR) in the progeny of rice (Oryza sativa) plants exogenously treated with dehydroascorbate (DHA). The offspring of lifelong DHA-treated plants (DHA-IAR) were significantly less susceptible to the root-knot nematode Meloidogyne graminicola and partially inherited the DHA-induced transcriptional response found in the parental plants. Phytohormone analyses on the DHA-IAR plants unveiled higher basal abscisic acid (ABA) levels and a primed induction of the jasmonic acid (JA) pathway. RNA-seq analysis on the embryonic tissues of immature seeds of DHA-treated plants revealed major shifts in the expression of genes associated with epigenetic pathways. We confirmed that DHA treatment leads to a significant but transient pattern of global DNA hypomethylation in the parental plants at 12 to 24 hours after treatment. The induction of resistance in the parental plants requires the DNA demethylase REPRESSOR OF SILENCING 1C (ROS1c) and ARGONAUTE 4 (AGO), suggesting a role for DNA demethylation and subsequent re-methylation in establishment of this phenotype. Confirming the transience of global hypomethylation upon DHA treatment, no significant change in global DNA methylation levels was observed in DHA-IAR versus naïve plants. Finally, DHA could not induce IAR in the Ros1c mutant line and in the ARGONAUTE 4 (ago4ab)-RNAi line. These data indicate that a controlled collaboration between transient DNA demethylation and remethylation underlies the induced resistance and IAR phenotypes upon DHA treatment.

Genome-Wide Analysis of the Serine Carboxypeptidase-like (SCPL) Protein Family of Bitter Gourd and Functional Validation of McSCPL22 in Fusarium oxysporum f. sp. Momordicae (FOM) Resistance.

Bitter gourd is increasingly being recognized for its value as a vegetable and medicinal use, but the molecular mechanisms of pathogen resistance remain relatively poorly understood. The serine carboxypeptidase-like (SCPL) protein family plays a key role in plant growth, pathogen defense, and so on. However, a comprehensive identification and functional characterization of the SCPL gene family has yet to be conducted in bitter melon. In this study, 32 SCPL genes were identified in bitter gourd and divided into three classes. The number of SCPL genes contained in the three clusters was 7, 7, and 18, respectively. Most SCPL gene promoters contain cis-acting elements with light, hormone, and stress responses. The RNA sequencing data showed that the expression of several SCPL genes changed significantly after pathogen infection. In particular, expression of the McSCPL4, 10, 17, 22, and 25 genes increased substantially in the resistant varieties after infection, and their expression levels were higher than those in the susceptible varieties. These results suggested that genes such as McSCPL4, 10, 17, 22, and 25 may play a significant role in conferring resistance to fungal infections. Moreover, the expression levels of the McSCPL10, 17, 22, 23, and 25 genes were likewise significantly changed after being induced by salicylic acid (SA) and jasmonic acid (JA). In situ hybridization showed that McSCPL22 was expressed in the vascular tissues of infected plants, which largely overlapped with the location of Fusarium oxysporum f. sp. Momordicae (FOM) infection and the site of hydrogen peroxide production. Our results showed that McSCPL22 may be involved in the regulation of the SA and JA pathways and enhance resistance to FOM in bitter gourd plants. This is the first study to perform SCPL gene family analysis in bitter gourd. McSCPL22 may have the potential to enhance FOM resistance in bitter gourd, and further investigation into its function is warranted. The results of this study may enhance the yield and molecular breeding of bitter gourd.

MdILL6 regulates xylem and vessel development to control internode elongation in spur-type apple.

Spur-type varieties play an important role in facilitating high-density plantings. However, the underlying mechanisms of internode elongation in spur-type varieties are poorly understood. In this research, we investigated the morphological phenotype of annual shoots in four spur-type varieties ('Miyazak', 'Jinfu 18', 'Yanfu No. 6', and 'Liquan spur') and four standard-type varieties ('Aomorifu', 'Shou Fuji', 'Yanfu No. 10', and 'Yanfu No. 3'). Compared with standard-type varieties, spur-type varieties had a shorter shoot length, an average internode length and a smaller xylem size. The content of Jasmonic acid (JA) and Jasmonic acid isoleucine (JA-Ile) significantly increased in spur-type varieties, accompanied by an increase in the expression of JA biosynthesis and signal transduction genes. Exogenous methyl jasmonate (MeJA) inhibited plant height, xylem size, and vessel area. Additionally, we identified an IAA-Leucine Resistant1-like Hydrolase family member, MdILL6, which was highly expressed in spur-type varieties and mature stems. MdILL6 was mainly expressed in the shoot tips and stem, and its protein was located on the endoplasmic reticulum. Overexpression of MdILL6 in apple inhibited plant height and average internode length by decreasing xylem size and vessel area. Our results revealed a molecular mechanism of spur-type variety development affected by the JA pathway and suggest strategies for genetic improvement and regulation of spur-type varieties.

Ascorbic acid treatment inhibits early wound healing in the fresh-cut potato by relegating jasmonic acid biosynthesis and signal transduction

Jasmonic acid (JA) is a wound hormone involved in plant defence responses. Ascorbic acid (AsA) treatment could inhibit early wound healing in fresh-cut potatoes (FCPs), but its regulation of JA pathway during this process remains unclear. We investigated the effects of AsA on JA biosynthesis and signal transduction in FCPs during wound healing. Results showed that AsA treatment decreased JA biosynthesis pathway-related enzyme activities and gene expression (StLOX3.1, StAOS1, StOPR1, StADH1, StKAT2, and StACOT13) at the wound site during healing. The JA content increased from 0.443 to 1.205 μg g−1 within 10 h but only increased to 0.535 μg g−1 with AsA. AsA treatment reduced jasmonic acid carboxyl methyltransferase and jasmonic acid-amido synthetase activities, StJMT and StJAR1 expressions, and methyl jasmonate and jasmonoyl-isoleucine contents. Moreover, AsA treatment upregulated StJAZ1 and downregulated StMYC2 expression. These findings suggested that AsA regulates wound healing in FCPs by suppressing JA biosynthesis and signal transduction.

Arabidopsis Actin-Binding Protein WLIM2A Links PAMP-Triggered Immunity and Cytoskeleton Organization.

Arabidopsis LIM proteins are named after the initials of three proteins Lin-11, Isl-1, and MEC-3, which belong to a class of transcription factors that play an important role in the developmental regulation of eukaryotes and are also involved in a variety of life processes, including gene transcription, the construction of the cytoskeleton, signal transduction, and metabolic regulation. Plant LIM proteins have been shown to regulate actin bundling in different cells, but their role in immunity remains elusive. Mitogen-activated protein kinases (MAPKs) are a family of conserved serine/threonine protein kinases that link upstream receptors to their downstream targets. Pathogens produce pathogen-associated molecular patterns (PAMPs) that trigger the activation of MAPK cascades in plants. Recently, we conducted a large-scale phosphoproteomic analysis of PAMP-induced Arabidopsis plants to identify putative MAPK targets. One of the identified phospho-proteins was WLIM2A, an Arabidopsis LIM protein. In this study, we investigated the role of WLIM2A in plant immunity. We employed a reverse-genetics approach and generated wlim2a knockout lines using CRISPR-Cas9 technology. We also generated complementation and phosphosite-mutated WLIM2A expression lines in the wlim2a background. The wlim2a lines were compromised in their response to Pseudomonas syringae Pst DC3000 but showed enhanced resistance to the necrotrophic fungus Botrytis cinereae. Transcriptome analyses of wlim2a mutants revealed the deregulation of immune hormone biosynthesis and signaling of salicylic acid (SA), jasmonic acid (JA), and ethylene (ET) pathways. The wlim2a mutants also exhibited altered stomatal phenotypes. Analysis of plants expressing WLIM2A variants of the phospho-dead or phospho-mimicking MAPK phosphorylation site showed opposing stomatal behavior and resistance phenotypes in response to Pst DC3000 infection, proving that phosphorylation of WLIM2A plays a crucial role in plant immunity. Overall, these data demonstrate that phosphorylation of WLIM2A by MAPKs regulates Arabidopsis responses to plant pathogens.

Molecular insights into Solanum sisymbriifolium’s resistance against Globodera pallida via RNA-seq

BackgroundThe presence of potato cyst nematodes (PCN) causes a significant risk to potato crops globally, leading to reduced yields and economic losses. While the plant Solanum sisymbriifolium is known for its resistance to PCN and can be used as a trap crop, the molecular mechanisms behind this resistance remain poorly understood. In this study, genes differentially expressed were identified in control and infected plants during the early stages of the S. sisymbriifolium - G. pallida interaction.ResultsGene expression profiles were characterized for two S. sisymbriifolium cultivars, Melody and Sis6001, uninfected and infected by G. pallida. The comparative transcriptome analysis revealed a total of 4,087 and 2,043 differentially expressed genes (DEGs) in response to nematode infection in the cultivars Melody and Sis6001, respectively. Gene ontology (GO) enrichment analysis provided insights into the response of the plant to nematode infection, indicating an activation of the plant metabolism, oxidative stress leading to defence mechanism activation, and modification of the plant cell wall. Genes associated with the jasmonic and salicylic acid pathways were also found to be differentially expressed, suggesting their involvement in the plant’s defence response. In addition, the analysis of NBS-LRR domain-containing transcripts that play an important role in hypersensitive response and programmed cell death led to the identification of ten transcripts that had no annotations from the databases, with emphasis on TRINITY_DN52667_C1_G1, found to be upregulated in both cultivars.ConclusionsThese findings represent an important step towards understanding the molecular basis underlying plant resistance to nematodes and facilitating the development of more effective control strategies against PCN.

A systematic regulatory network related to bulbil formation in Lilium lancifolium based on metabolome and transcriptome analyses

BackgroundLilium lancifolium is a special wild triploid species native to China and can produce abundant bulbils on its stem under natural conditions, which is very valuable to study bulbil organogenesis in plants. Although similar to the lateral and tillering principles, the molecular mechanism underlying bulbil formation has remained incompletely understood.ResultsThe metabolome and transcriptome of L. lancifolium bulbils across four development stages were analyzed. The pairwise comparison of metabolomes across the four stages identified 17 differential hormones, predominantly auxin (IAA), cytokinin (CK), and jasmonic acid (JA). Short Time-series Expression Miner (STEM) trend analysis of differential genes revealed four significant trends across these stages. The KEGG enrichment analysis of the four clusters highlighted pathways, such as plant hormone signal transduction, which were speculated to play a crucial role in development stages. these pathways were speculated to play a crucial role in development stages. To explore the key differential expressed genes and transcription factors associated with bulbil occurrence, two periods were focused on: Ll_UN and Ll_DN, which represented the stages with and without bulbils, respectively. Through correlation analysis and qRT-PCR analysis, 11 candidate differentially expressed genes and 27 candidate transcription factors were selected. By spraying exogenous hormones to validate these candidates, LlbHLH128, LlTIFY10A, LlbHLH93, and LlMYB108, were identified as the key genes for L. lancifolium bulbils.ConclusionA regulatory network of L. lancifolium bulbil development was predicted. LlTIFY10A and LlbHLH93 might be involved in the JA and auxin signal transduction pathways, which jointly formed a regulatory network to affect the occurrence of L. lancifolium bulbil. This study not only provided more information about the differentially expressed genes and metabolites through transcriptome and metabolomics analyses, but also provided a clearer understanding of the effect of hormones on bulbil formation in lily.

Combating wheat yellow mosaic virus through microbial interactions and hormone pathway modulations

BackgroundThe rhizosphere microbiome is critical for promoting plant growth and mitigating soil-borne pathogens. However, its role in fighting soil-borne virus-induced diseases, such as wheat yellow mosaic virus (WYMV) transmitted by Polymyxa graminis zoospores, remains largely underexplored. In this study, we hypothesized that during viral infections, plant microbiomes engage in critical interactions with plants, with key microbes playing vital roles in maintaining plant health. Our research aimed to identify microbial taxa that not only suppress the disease but also boost wheat yield by using a blend of techniques, including field surveys, yield assessments, high-throughput sequencing of plant and soil microbiomes, microbial isolation, hydroponic experiments, and transcriptome sequencing.ResultsWe found that, compared with roots and leaves, the rhizosphere microbiome showed a better performance in predicting wheat yield and the prevalence of P. graminis and WYMV across the three WYMV-impacted regions in China. Using machine learning, we found that healthy rhizospheres were marked with potentially beneficial microorganisms, such as Sphingomonas and Allorhizobium-Neorhizobium-Parararhizobium-Rhizobium, whereas diseased rhizospheres were associated with a higher prevalence of potential pathogens, such as Bipolaris and Fusicolla. Structural equation modeling showed that these biomarkers both directly and indirectly impacted wheat yield by modulating the rhizosphere microbiome and P. graminis abundance. Upon re-introduction of two key healthy rhizosphere biomarkers, Sphingomonas azotifigens and Rhizobium deserti, into the rhizosphere, wheat growth and health were enhanced. This was attributed to the up-regulation of auxin and cytokinin signaling pathways and the regulation of jasmonic acid and salicylic acid pathways during infections.ConclusionsOverall, our study revealed the critical role of the rhizosphere microbiome in combating soil-borne viral diseases, with specific rhizosphere microbes playing key roles in this process.9s7rr2_Gfui1KYKQgMf1m6Video

A new Bowman-Birk type protease inhibitor regulated by MeJA pathway in maize exhibits anti-feedant activity against the Ostrinia furnacalis.

Jasmonic acid (JA), an important plant hormone, plays a crucial role in defending against herbivorous insects. In this study, we have identified a new Bowman-Birk type protease inhibitor (BBTI) protein in maize that is regulated by the JA pathway and exhibits significant antifeedant activity, which is notably induced by exogenous Methyl Jasmonate and Ostrinia furnacalis feeding treatments. Bioinformatics analysis revealed significant differences in the BBTI protein among different maize inbred lines, except for the conserved domain. Prokaryotic and eukaryotic expression systems were constructed and expressed, and combined with bioassays, it was demonstrated that the antifeedant activity of BBTI is determined by protein modifications and conserved domains. Through RT-qPCR detection of BBTI and JA regulatory pathway-related genes' temporal expression in different maize inbred lines, we identified the regulatory mechanism of BBTI synthesis under the JA pathway. This study successfully cloned and identified the MeJA-induced anti-feedant activity gene BBTI and conducted functional validation in different maize inbred lines, providing valuable insights into the response mechanism of insect resistance induced by the plant JA pathway. The increased expression of the anti-feedant activity gene BBTI through exogenous MeJA induction may offer a potential new strategy for mediating plant defense against Lepidoptan insects.

Geminiviruses and Food Security: A Molecular Genetics Perspective for Sustainable Agriculture in Africa

The African continent is vulnerable to food insecurity. Increased food costs, job losses, and climate change force Africans to chronic hunger. Biotechnology can be used to mitigate this by using techniques such as CRISPR/Cas9 systems, TALENs, and ZFNs. Biotechnology can utilize geminiviruses to deliver the necessary reagents for precise genome alteration. Additionally, plants infected with geminiviruses can withstand harsher weather conditions such as drought. Therefore, this article discusses geminivirus replication and its use as beneficial plant DNA viruses. It focuses explicitly on genome editing to increase plant resistance by manipulating plants’ salicylic acid and jasmonic acid pathways.

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.

Biocontrol Potential of Bacillus strains against soybean cyst nematode (Heterodera glycines) and for promotion of soybean growth

The soybean cyst nematode (SCN, Heterodera glycines) is the most yield-limiting pathogen in soybeans worldwide. Using chemical pesticides to control this disease is harmful to human and environment. It is urgent to develop environment-friendly nematicides. The aim of this study was to discover novel biocontrol agents on H. glycines control and soybean growth under greenhouse and field conditions Eight Bacillus strains were isolated from soil rhizosphere soils and the stability and efficiency of H. glycines was assessed in greenhouse and field experiments in 2021 and 2022. In particular, the Ba2-6 strain had the highest potential, because it was a biocontrol agent against H. glycines shown to cause 93.85% juvenile mortality. Furthermore, strains Ba 1–7, Ba2-4, and Ba2-6 effectively reduced the number of females and improved the soybean seed number per plant. Based on their morphological, physiological, biochemical and molecular (16 S rRNA) characteristics, the three strains were identified as B. aryabhattai (Ba1-7), B. megatherium (Ba2-4), and B. halotolerans (Ba2-6). The ability of Ba2-6 to induce systemic resistance to H. glycines in soybeans was investigated by the split-root system and real-time quantitative PCR experiments. The results indicated that the Ba2-6 strain induced systemic resistance to suppress the penetration of H. glycines, and enhanced gene expression of PR1, PR3a, PR5, and NPR1-2, involved in the salicylic acid and jasmonic acid pathways. The study suggests that the strains of B. aryabhattai Ba1-7, B. megatherium Ba2-4, and B. halotolerans Ba2-6 can be considered as effective biocontrol agents to control H. glycines. Further, B. halotolerans Ba2-6 not only promotes soybean growth but also enhances resistance to H. glycines by regulating defense-related gene expression and inducing systemic resistance in soybean.

Towards Characterization of Hass Avocado Peel and Pulp Proteome during Postharvest Shelf Life.

In recent years, avocados have gained worldwide popularity as a nutritive food. This trend is causing a rise in the production of this fruit, which is accompanied by several problems associated with monocultural practices. Despite massive economic gains, limited molecular and structural information has been generated about avocado ripening. In fact, limited studies have attempted to unravel the proteome complexity dynamics of avocado fruit. We therefore conducted a comparative proteomics study on avocado peel and pulp during the postharvest shelf life using tandem mass tag synchronous precursor selection triple-stage mass spectrometry. We identified 3161 and 1128 proteins in the peel and pulp, respectively. Peels exhibited major over-accumulation of proteins associated with water deprivation and oxidative stress, along with abscisic acid biosynthesis. Ethylene, jasmonic acid, phenylpropanoid, and flavonoid biosynthesis pathways were activated. Structurally, we observed the accumulation of lignin and a reduction in cuticular thickness, which coincides with the reduction in the levels of long-chain acyl-coenzyme A synthetase and a marginal increase in 10,16-dihydroxyhexadecanoic acid. Our study sheds light on the association of proteome modulation with the structural features of Hass avocado. Its detailed characterization will provide an alternative for better preservation during the postharvest period.

Transcriptomic and coexpression network analyses revealed the regulatory mechanism of Cydia pomonella infestation on the synthesis of phytohormones in walnut husks

The codling moth (Cydia pomonella) has a major effect on the quality and yield of walnut fruit. Plant defences respond to insect infestation by activating hormonal signalling and the flavonoid biosynthetic pathway. However, little is known about the role of walnut husk hormones and flavonoid biosynthesis in response to C. pomonella infestation. The phytohormone content assay revealed that the contents of salicylic acid (SA), abscisic acid (ABA), jasmonic acid (JA), jasmonic acid-isoleucine conjugate (JA-ILE), jasmonic acid-valine (JA-Val) and methyl jasmonate (MeJA) increased after feeding at different time points (0, 12, 24, 36, 48, and 72 h) of walnut husk. RNA-seq analysis of walnut husks following C. pomonella feeding revealed a temporal pattern in differentially expressed genes (DEGs), with the number increasing from 3,988 at 12 h to 5,929 at 72 h postfeeding compared with the control at 0 h postfeeding. Walnut husks exhibited significant upregulation of genes involved in various defence pathways, including flavonoid biosynthesis (PAL, CYP73A, 4CL, CHS, CHI, F3H, ANS, and LAR), SA (PAL), ABA (ZEP and ABA2), and JA (AOS, AOC, OPR, JAZ, and MYC2) pathways. Three gene coexpression networks that had a significant positive association with these hormonal changes were constructed based on the basis of weighted gene coexpression network analysis (WGCNA). We identified several hub transcription factors, including the turquoise module (AIL6, MYB4, PRE6, WRKY71, WRKY31, ERF003, and WRKY75), the green module (bHLH79, PCL1, APRR5, ABI5, and ILR3), and the magenta module (ERF27, bHLH35, bHLH18, TIFY5A, WRKY31, and MYB44). Taken together, these findings provide useful genetic resources for exploring the defence response mediated by phytohormones in walnut husks.

Synergistic interaction between brassinosteroid and jasmonate pathways in rice response to cadmium toxicity

Brassinosteroids (BRs) and jasmonic acid (JA) are known to be involved in regulating plant responses to cadmium (Cd) stress. However, their specific roles and interaction in this process remain unclear. In this study, we discovered that exogenous BR alleviated Cd-mediated growth inhibition of rice seedlings. Enhanced Cd tolerance was also observed in m107, a BR-overproduction mutant. Phenotypic analysis of genetic materials involved in BR signaling confirmed the positive role of BR in regulating rice response to Cd toxicity. OsDLT, a key component in the BR signaling pathway, was found to be crucial for BR-mediated Cd tolerance. Further analysis demonstrated that activation of the BR pathway reduced the accumulation of Cd and reactive oxygen species (ROS) by modulating the expression of genes associated with Cd transport and ROS scavenging. Interestingly, transcriptome analysis indicated that the JA pathway was enriched in OsDLT-regulated differently expressed genes (DEGs). Gene expression and hormone assays showed that BR promoted the expression of JA pathway genes and JA levels in plants. Moreover, BR-induced tolerance was compromised in the JA signaling-deficient mutant osmyc2, suggesting that BR-mediated Cd resistance depends on the activation of the JA signaling pathway. Overall, our study revealed the synergistic interaction between BR and JA pathways in rice response to Cd stress, providing insights into the complex hormonal interplay in plant tolerance to heavy metals.

Unraveling Pinus massoniana's defense mechanisms against Bursaphelenchus xylophilus under aseptic conditions: A transcriptomic analysis.

Pine wilt disease (PWD) is caused by pine wood nematode (PWN, Bursaphelenchus xylophilus) and significantly impacts pine forest ecosystems globally. This study focuses on Pinus massoniana, an important timber and oleoresin resource in China, and is highly susceptible to PWN. However, the defense mechanism of pine trees in response to PWN remains unclear. Addressing the complexities of PWD, influenced by diverse factors like bacteria, fungi, and environment, we established a reciprocal system between PWN and P. massoniana seedlings under aseptic conditions. Utilizing combined second and third-generation sequencing technologies, we identified 3,718 differentially expressed genes post-PWN infection. Transcript analysis highlighted the activation of defense mechanisms via stilbenes, salicylic acid and jasmonic acid pathways, terpene synthesis, and induction of pathogenesis-related proteins and resistance genes, predominantly at 72 hours post-infection. Notably, terpene synthesis pathways, particularly the mevalonate pathway, were crucial in defense, suggesting their significance in P. massoniana's response to PWN. This comprehensive transcriptome profiling offers insights into P. massoniana's intricate defense strategies against PWN under aseptic conditions laid a foundation for future functional analyses of key resistance genes.

The Role of Salicylic, Jasmonic Acid and Ethylene in the Development of the Resistance/Susceptibility of Wheat to the SnTox1-Producing Isolate of the Pathogenic Fungus Stagonospora nodorum (Berk.).

The SnTox1 effector is a virulence factor of the fungal pathogen Stagonospora nodorum (Berk.), which interacts with the host susceptibility gene Snn1 in a gene-for-gene manner and causes necrosis on the leaves of sensitive wheat genotypes. It is known that salicylic acid (SA), jasmonic acid (JA) and ethylene are the key phytohormones involved in plant immunity. To date, effectors of various pathogens have been discovered that can manipulate plant hormonal pathways and even use hormone crosstalk to promote disease development. However, the role of SnTox1 in manipulating hormonal pathways has not been studied in detail. We studied the redox status and the expression of twelve genes of hormonal pathways and two MAPK genes in six bread wheat cultivars sensitive and insensitive to SnTox1 with or without treatment by SA, JA and ethephon (ethylene-releasing agent) during infection with the SnTox1-producing isolate S. nodorum 1SP. The results showed that SnTox1 controls the antagonism between the SA and JA/ethylene signaling pathways. The SA pathway was involved in the development of susceptibility, and the JA/ethylene pathways were involved in the development of wheat plants resistance to the Sn1SP isolate in the presence of a SnTox1-Snn1 interaction. SnTox1 hijacked the SA pathway to suppress catalase activity, increase hydrogen peroxide content and induce necrosis formation; it simultaneously suppresses the JA and ethylene hormonal pathways by SA. To do this, SnTox1 reprogrammed the expression of the MAPK genes TaMRK3 and TaMRK6 and the TF genes TaWRKY13, TaEIN3 and TaWRKY53b. This study provides new data on the role of SnTox1 in manipulating hormonal pathways and on the role of SA, JA and ethylene in the pathosystem wheat S. nodorum.

The phytohormone jasmonic acid is involved in rice resistance to Southern rice black-streaked dwarf virus

Viruses are significant pathogens causing severe plant infections and crop losses globally. The resistance mechanisms of rice to viral diseases, particularly Southern rice black-streaked dwarf virus (SRBSDV), remain poorly understood. In this study, we assessed SRBSDV susceptibility in 20 Xian/indica (XI) and 20 Geng/japonica (GJ) rice varieties. XI-1B accessions in the Xian subgroup displayed higher resistance than GJ accessions. Comparative transcriptome analysis revealed changes in processes like oxido-reductase activity, jasmonic acid (JA) metabolism, and stress response. JA sensitivity assays further linked antiviral defense to the JA pathway. These findings highlight a JA-mediated resistance mechanism in rice and offer insights for breeding SRBSDV-resistant varieties.

A rice amino acid transporter OsMP1 acts as a quantitative trait locus against blast fungus and leaf-blight bacterium.

Amino acid homeostasis is interconnected with the immune network of plants. During plant-pathogen interaction, amino acid transporters (AATs) have been shown to be involved in plant immune responses. However, the molecular mechanism by which how AATs function in this process remains elusive. In this study, we identify OsMP1 that acts as a quantitative trait locus against blast fungus from a joint analysis of GWAS and QTL mapping in rice. Heterogeneous expression of OsMP1 in yeast supports its function in transporting a wide range of amino acids, including Thr, Ser, Phe, His and Glu. OsMP1 could also mediate 15N-Glu efflux and influx in Xenopus oocyte cells. The expression of OsMP1 is dramatically induced by Magnaporthe oryzae in the resistant landrace Heikezijing, while remaining unresponsive in the susceptible landrace Suyunuo. Overexpressing OsMP1 in Suyunuo enhances disease resistance to blast fungus and leaf-blight bacterium without yield penalty. Furthermore, the overexpression of OsMP1 leads to increased accumulation of Thr, Ser, Phe and His in the leaves. And the heightened levels of these amino acids contribute to reduced disease susceptibility, which is associated with upregulated jasmonic acid pathway. Thus, our results elucidate the pivotal role of OsMP1 in disease resistance and provide a potential target for breeding more resistant rice cultivars without compromising yield.