Molecular plant pathology最新文献

Rice is a staple crop feeding over half of the global population, yet it faces severe yield losses due to devastating diseases, including those caused by hemibiotrophic pathogens, such as Magnaporthe oryzae (the causative agent of blast disease) and Xanthomonas oryzae pv. oryzae (the bacterial leaf blight pathogen). While resistance genes are a cornerstone of crop protection, many nucleotide-binding leucine-rich receptor (NLR)-type resistance genes are prone to breakdown and often impose yield penalties. In this study, we report that the cross-species transfer of the maize NAM-ATAF1/2-CUC2 transcription factor ZmNAC2 into rice confers resistance to both blast and bacterial leaf blight diseases without compromising yield. Mechanistically, ZmNAC2 interacts with OsNAC2, a negative regulator of salicylic acid (SA) biosynthesis, and disrupts its association with the APETALA2/ethylene-responsive element binding protein OsEREBP1 in the OsZmNAC2 transgenic rice, thereby quenching repression and promoting SA production. Moreover, ZmNAC2 binds to the cis-regulatory elements within the promoter of the SA biosynthetic gene phenylalanine ammonia lyase 6, transactivating its expression and further enhancing SA accumulation. The resulting elevated SA levels impart broad-spectrum resistance in the transgenic rice against M. oryzae and X. oryzae pv. oryzae. Together, our findings provide a proof of concept for leveraging non-NLR genes from staple food crops to boost disease resistance without incurring yield penalties.

Plant pathogens employ a diverse array of effectors to facilitate host colonisation, including evolutionarily conserved core effectors. In this study, we identified MoPce1, a CAP/PR-1 domain-containing protein widely distributed among fungal species, as a key virulence factor in Magnaporthe oryzae. Among 72 putative core effectors (PCEs), MoPce1 was found to be essential for pathogenicity but dispensable for asexual development. It localises to biotrophic interfacial complex (BIC) in invasive hyphae (IHs) and to the cytoplasm in Nicotiana benthamiana leaves and rice protoplasts. Ectopic expression of a signal peptide-deleted variant of MoPCE1 (MoPCE1^Δsp) in rice compromised blast resistance and suppressed the reactive oxygen species (ROS) burst. Notably, MoPce1 lacks the conserved cysteine residues essential for sterol-binding in the CAP domain, suggesting its potential association with a novel ligand. Further investigation revealed that MoPce1 interacts with rice catalase OsCATC, specifically via the C1 fragment (231-360 aa). Disruption of OsCATC (oscatc) enhanced rice blast resistance and triggered a stronger ROS burst. Collectively, our results indicate that MoPce1 targets OsCATC to disrupt ROS homeostasis and suppress host immunity, thereby facilitating infection.

Taxonomy: Pepino mosaic virus (PepMV); species: Potexvirus pepini; family: Alphaflexiviridae; order: Tymovirales.

Virion and genome properties: PepMV virions are rod-shaped, non-enveloped, and flexuous particles. They encapsidate a monopartite, single-stranded, positive-sense RNA genome of approximately 6.4 kb, that encodes, in the sense orientation, a replicase, three triple gene block proteins, and the coat protein.

Host range: PepMV is widespread and causes a major disease in intensive tomato crops. Natural infections have also been reported in kachuma (also known as cachum or pepino dulce; Solanum muricatum), basil, wild tomato species, and weeds from various families growing near affected tomato crops. Experimentally, PepMV can infect plants of virtually all Solanaceae species.

Diversity: Seven genetic types of PepMV are currently recognised: the original Peruvian (LP), European (EU), American US1, American US2, Chilean (CH2), the new Peruvian (PES), and Europe and the Asia-Pacific region (EAP).

Transmission: PepMV is efficiently transmitted through mechanical means and shows a low rate of seed transmission. Insects, contaminated water, and agricultural tools have also been implicated in viral spread.

Symptomatology: PepMV infections can range from asymptomatic to severe. Common symptoms in tomato plants include leaf blistering, chlorosis, mosaic patterns, and fruit bleaching, flaming, and marbling. Severe cases may exhibit necrosis in leaves, stems, and fruits. Symptom severity depends on the viral isolate, tomato cultivar, timing of infection, and environmental conditions.

Control: No PepMV-resistant tomato varieties are currently available commercially. Therefore, preventive measures are commonly used strategies against PepMV. Cross-protection has proven highly effective and is widely employed for disease management.

This study compares the ability of the cytokinin (CK) trans-zeatin (tZ) and the CK sugar conjugate 6-(3-methoxybenzylamino)purine-9-arabinoside (BAPA) to induce resistance against the bacterial pathogen Pseudomonas syringae in Arabidopsis thaliana. Treatment with either tZ or BAPA significantly reduced bacterial growth after a later infection. This chemically induced resistance (IR) required the CK receptor AHK3, highlighting its critical role in mediating resistance by tZ and BAPA. This is remarkable as these compounds show either high or no affinity for this CK receptor, respectively. Surprisingly, tZ, but not BAPA, induced the expression of CK response genes, including ARR5, suggesting divergent mechanisms of action. Resistance caused by both compounds was abolished in the npr1 mutant, underpinning the functional relevance of the salicylic acid (SA) signalling pathway. Transcriptomic analysis showed that both BAPA and tZ triggered the expression of distinct sets of genes associated with SA and reactive oxygen species (ROS) but not with jasmonic acid (JA) signalling. BAPA and, to a lesser extent, also tZ activated pattern-triggered immunity (PTI) signalling genes, including genes responsible for PTI signal amplification (PREPIP2) and pathogen-associated molecular pattern (PAMP) signalling (PH1, IDL6). This supported the hypothesis that the PTI pathway mediates the protective effect. Similarities and differences of chemically triggered IR by tZ and BAPA, as well as their potential for application, are discussed.

Grapevine, as an important economic crop around the world, has generally poor disease resistance in planting. Vitis vinifera, in particular, show high susceptibility to grey mould (caused by Botrytis cinerea), which leads to a decline in yield and quality. Existing chemical control methods have limitations, including environmental and resistance issues, so breeding disease-resistant varieties is crucial for sustainable agriculture. In this study, we identified a nuclear membrane-localised R2R3-type MYB transcription factor named VlMYB149 whose expression was significantly upregulated following grey mould infection. Overexpression of VlMYB149 in grapevine and Arabidopsis indicated that it significantly enhances resistance to grey mould, characterised by reduced lesion size and inhibited mycelial expansion. VlMYB149 increased the content of copper and increased the activities of antioxidant enzymes such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD). VlMYB149 also directly activated the expression of VlHIPP30, which plays a crucial role in the process of copper transport. Overexpression of VlHIPP30 has been shown to enhance disease resistance by reducing reactive oxygen species (ROS) levels and enhancing copper metabolism. Our findings reveal a novel molecular mechanism model for grapevine resistance to B. cinerea, mediated by the synergistic interaction by copper metabolism and the antioxidant system. This study not only provides crucial genetic resources for breeding disease-resistant crops but also advances our fundamental understanding of plant immunity.

Pathogenic fungi have developed complex and specific infection strategies to invade host tissues successfully. Regulator of G-protein signalling (RGS) proteins exhibit GTPase-accelerating protein activities and play a crucial role in the formation of infection structures in pathogenic fungi. However, specific regulatory mechanisms remain unclear. In the present study, observations of infection structure indicated that the deletion of AaRgs2 resulted in a significant increase in spore germination. Appressorium-like formation rate was compared to that of the wild-type strain on a Gelbond hydrophobic membrane coated with 16-hydroxyhexadecanoic acid or 1,16-hexadecanediol, which are cutin monomers in pear peel. Transcriptome analysis during the appressorium-like formation stage revealed 4124 differentially expressed genes (DEGs) that were annotated in the wild-type strain and the ΔAaRgs2 mutant. KEGG enrichment analysis showed that the cAMP-PKA signalling pathway, MAPK signalling pathway, peroxisome and autophagy pathway were closely associated with appressorium-like formation regulated by AaRgs2. Yeast two-hybrid and bimolecular fluorescence complementation assays demonstrated a specific physical interaction between AaRgs2 and AaGα1, further confirming that AaGα1 interacted with the Pfam domain of adenylate cyclase AC. Our studies provide evidence suggesting that AaRgs2 negatively regulates appressorium-like formation of A. alternata induced by pear cutin monomer via the AaRgs2-AaGα1-AaAC module.

Powdery mildew, caused by Podosphaera aphanis, poses a significant threat to strawberry production, while current chemical controls raise environmental and food safety concerns. In this study, we have identified the key regulatory module, FaMYB63/FvWRKY75-PR10.14, that confers enhanced powdery mildew resistance in transgenic strawberry (Fragaria vesca). FaMYB63, an R2R3-MYB transcription factor, was induced by P. aphanis infection and responsive to the application of defence signalling molecules, including salicylic acid (SA), methyl jasmonate (JA), abscisic acid (ABA), and 1-aminocyclopropane-1-carboxylic acid (ACC). Silencing of FaMYB63 led to reduced SA levels and increased powdery mildew susceptibility, accompanied by suppressed reactive oxygen species (ROS) bursts and down-regulation of PR10.14 expression. Conversely, overexpressing PR10.14 in transgenic lines inhibited P. aphanis spore germination and enhanced ROS accumulation, indicating a dual role in direct pathogen inhibition and hypersensitive response-triggered defence. Yeast one-hybrid, electrophoretic mobility shift assay, β-glucuronidase, and luciferase assays confirmed that FaMYB63 and FvWRKY75 were directly bound to the MYB-binding sites and W-box of the PR10.14 promoter, respectively, and activated its transcription, while WRKY75 negatively regulated the expression of MYB63. PR10.14 exhibited tissue-specific expression, with the highest levels in red-ripening fruits, suggesting a role in developmental-stage-dependent defence. These findings suggest FaMYB63 as an SA-dependent regulator of PR10.14-mediated resistance, bridging hormone signalling and pathogen response. This study provides a molecular target for breeding powdery mildew-resistant strawberry cultivars through genetic engineering approaches, offering an alternative to fungicides for sustainable and environmental disease management in horticultural crops and advances our understanding of MYB- or WRKY-PR10P networks in plant immunity.

This review summarises the current advances and future perspectives on high-temperature resistance in wheat against stripe rust, caused by the airborne fungal pathogen Puccinia striiformis f. sp. tritici (Pst). High-temperature resistance, comprising high-temperature adult-plant (HTAP) and high-temperature all-stage (HTAS) resistance, is critical for durable disease control. HTAP resistance occurs in adult plants at relatively high temperatures, whereas HTAS resistance acts across all growth stages at relatively high temperatures. Genetic mapping has identified numerous HTAP-resistance genes and quantitative trait loci (QTLs) in various chromosomal regions, especially in the B subgenome. Cloned genes, such as Yr18, Yr36 and Yr46, reveal mechanisms involving cell necrosis induction, photosynthesis modulation and nutrient transportation. For HTAS resistance, defence-related factors such as nucleotide-binding site-leucine-rich repeat proteins, transcription factors and receptor-like kinases that mediate resistance via plant-pathogen interactions have been identified; however, research on identifying the genes or QTLs that can be used in breeding programmes is limited. To overcome host defence, Pst secretes effectors that suppress high-temperature resistance by targeting host proteins. Future research should focus on novel gene mining, regulatory network deciphering, effector-host interaction studies and breeding applications via marker-assisted selection and gene editing.

RING-type E3 ubiquitin ligases play crucial roles in plant immunity by ubiquitinating their downstream substrates for degradation. We previously revealed, using CRISR/Cas9-mediated knockout mutant lines, that the RING-H2 E3 ubiquitin ligase OsRFPH2-6, transcriptionally regulated by the NAC transcription factor ONAC083, negatively modulates rice blast resistance. In this study, we further confirmed the negative role of OsRFPH2-6 in rice immunity through overexpression lines and investigated its underlying regulatory mechanism. OsRFPH2-6 possesses E3 ubiquitin ligase activity, which depends on each cysteine residue within its RING domain. OsRFPH2-6 interacts with and ubiquitinates OsNF-YA1, a subunit of nuclear factor Y transcription factor, leading to its degradation. Knockout of OsNF-YA1 attenuates rice blast resistance and weakens chitin-induced immune responses. Transcriptome analysis revealed that OsNF-YA1 regulates a set of defence-associated genes. Notably, some negative immune regulators, like ONAC083, MNAC3 and OsSGR, were upregulated, whereas several positive immune regulators, such as genes encoding for phytoalexin biosynthesis and phenylpropanoid pathway enzymes, hydrolytic enzymes and pathogenesis-related proteins, including OsPAL6, OsATL15, OsCPS4, OsWRKY6, OsPR10a, and chi11, were downregulated in osnf-ya1 mutant plants. These findings suggest that OsNF-YA1 positively regulates rice immunity by modulating the transcription of a set of immune-associated genes. This study extends the previously established ONAC083-OsRFPH2-6 regulatory module in rice immunity by integrating OsNF-YA1 as a downstream substrate of OsRFPH2-6, offering possibilities to improve rice disease resistance through targeted genome editing of the ONAC083-OsRFPH2-6-OsNF-YA1 module.

Negative immune regulator CAD7 is a non-canonical member of the CAD (cinnamyl alcohol dehydrogenase) family in plants. However, little is known on its biochemical functions and underlying mechanisms of immune regulation. Here, we show that Arabidopsis thaliana AtCAD7 harbours substrate-binding residues divergent from lignin-forming CADs (AtCAD4/5), being conserved with bacterial alcohol dehydrogenases EcYahK and EcYjgB. Comparative enzymatic analysis revealed that AtCAD7 exhibits a broad substrate preference for diverse small-molecule aldehydes, including histamine-derived intermediates, being distinct from the canonical lignin-forming AtCAD5. Metabolomic analyses revealed that AtCAD7-overexpression transformants were affected in the biosynthesis and metabolism of amino acids, whereas AtCAD7-silencing lines were activated in the phenylpropanoid pathway and increased in flavonoid accumulation. Histamine was elevated in AtCAD7-overexpression lines and functional validation revealed its promoted effect on plant susceptibility to Phytophthora parasitica. In contrast, phytoalexins scopolin and chlorogenic acid were enriched in AtCAD7-silencing lines, accompanied by upregulated expression of phenylpropanoid pathway-related genes. Functional validation demonstrated that scopolin and chlorogenic acid enhanced plant resistance to P. parasitica. Collectively, our study uncovers that CAD7 functions as a metabolic hub linking small-molecule aldehyde reductase activity to immune suppression, providing a potential novel target for developing crops with enhanced resistance to Phytophthora pathogens.