Physiological and Molecular Plant Pathology最新文献

{"title":"Glutamate metabolism in induced resistance against plant pathogens","authors":"Roohallah Saberi Riseh ,&nbsp;Fariba Fathi ,&nbsp;Masoumeh Vatankhah ,&nbsp;Mozhgan Gholizadeh Vazvani ,&nbsp;Farzaneh Barzegar","doi":"10.1016/j.pmpp.2026.103153","DOIUrl":"10.1016/j.pmpp.2026.103153","url":null,"abstract":"<div><div>Upon pathogen recognition, plants undergo extensive transcriptional reprogramming coupled with a profound reconfiguration of primary metabolism. This metabolic restructuring is not merely a consequence of defense activation but is a critical component of the plant's immune strategy, providing the energy and biochemical precursors required to mount an effective resistance response. This review posits that glutamate (Glu) occupies a central position in this process, functioning as a key metabolic node that transcends its canonical role as a protein building block. We synthesize evidence establishing that Glu serves as a crucial precursor for the biosynthesis of a suite of defense-related compounds, including γ-aminobutyric acid (GABA), proline, glutathione (GSH), and polyamines, each contributing uniquely to antimicrobial activity, redox homeostasis, and signal amplification. Furthermore, we explore the emerging roles of Glu itself as a signaling molecule, primarily through the activation of glutamate receptor-like (GLR) channels that modulate calcium influx and downstream defense gene expression. By integrating recent advances, this article highlights how Glu metabolism is intricately linked to both immediate oxidative burst management and the establishment of systemic immunity, presenting a holistic view of its indispensable function in induced resistance against plant pathogens.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103153"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A hybrid genome assembly reveals key pathogenicity signatures in a virulent Ustilaginoidea virens isolate from India","authors":"Sapna Sharma ,&nbsp;Pooja Parmar ,&nbsp;Mohamad Ayham Shakouka ,&nbsp;Sunil Kumar Sunani ,&nbsp;Najam Waris Zaidi ,&nbsp;Ganesan Prakash ,&nbsp;Ashish Kumar Gupta ,&nbsp;S. Gopala Krishnan ,&nbsp;Bishnu Maya Bashyal","doi":"10.1016/j.pmpp.2026.103150","DOIUrl":"10.1016/j.pmpp.2026.103150","url":null,"abstract":"<div><div><em>Ustilaginoidea virens</em>, responsible for rice false smut, is an emerging pathogen that adversely affects crop yield and grain quality. Despite its growing importance, the molecular basis of pathogenicity in <em>U. virens</em> remains largely unexplored. We report a high-quality whole genome assembly and annotation of a highly virulent isolate, Uv2_4G, using a hybrid sequencing approach combining Nanopore and Illumina platforms. The assembled genome (∼35.9 Mb; 49% GC content, 89 scaffolds) revealed 7444 protein-coding genes. Comparative genome analysis identified genetic variation, including 3,55,173 SNPs, 8,03,524 INDELs, and 7390 SSRs. CAZyme profiling showed enrichment of glycosyl hydrolases (35%), glycosyl transferases (32%), and carbohydrate-binding modules (20%), essential for host colonization. In contrast, the relatively low abundance of auxiliary activities, carbohydrate esterases and polysaccharide lyases implies a limited reliance on extensive cell wall breakdown and lignin degradation, supports the biotrophic or hemibiotrophic lifestyle of <em>U. virens</em>. Additionally, the isolate possessed 6 unique gene clusters enriched in biological processes. Furthermore, 2708 pathogenicity-related genes associated with signal transduction, transcriptional and epigenetic regulation, stress tolerance, iron acquisition, metabolic adaptation, circadian regulation, membrane transport, and host–pathogen interactions were identified. Secretome analysis of the predicted proteome identified 71 putative effectors. Further, qPCR-based validation confirmed high expression of small cysteine rich effectors (SCRE2A and SCRE2B) during early infection stages suggesting SCREs could be a potential effector which can be utilised for disease management strategies under Indian conditions. These findings provide new insights into the molecular basis of <em>U. virens</em> pathogenicity and establish a framework for subsequent functional genomic analyses and improved disease management approaches.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103150"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nigrospora musae causes leaf spot disease on Polygonatum sibiricum in China","authors":"Xijing Li ,&nbsp;Chengke Zhang ,&nbsp;Dengquan Liu ,&nbsp;Zhen Su ,&nbsp;Hualei Wang ,&nbsp;Cheng Li","doi":"10.1016/j.pmpp.2026.103149","DOIUrl":"10.1016/j.pmpp.2026.103149","url":null,"abstract":"<div><div><em>Polygonatum sibiricum</em> Delaroche ex Redouté is an important medicinal plant that is widely used in traditional Chinese medicine owing to its antioxidant, antidiabetic, and anticancer properties. With the expansion of its commercial cultivation, diseases affecting <em>P. sibiricum</em> have increasingly threatened its yield and quality, yet information on their causal agents remains limited. Species of <em>Nigrospora</em> are cosmopolitan plant-pathogenic fungi with a broad range of hosts, and they are commonly associated with leaf spot and blight diseases in economically important crops. In February 2025, a leaf spot disease was widely observed on <em>Polygonatum sibiricum</em> in fields in Huangping County, Guizhou Province, China. Therefore, this study aimed to identify the causal pathogen of this emerging disease. Symptomatic leaves were collected, and the pathogen was characterized using pathogenicity tests, morphological observations, and multi-locus phylogenetic analyses based on internal transcribed spacer (ITS), beta-tubulin (<em>TUB2</em>), and translation elongation factor 1-alpha (<em>TEF1-α</em>) gene sequences. Twenty-one fungal isolates obtained from diseased tissues were identified as <em>N</em>. <em>musae</em>, confirming it as the causal agent. Pathogenicity tests using representative isolates reproduced typical leaf spot symptoms on <em>P. sibiricum</em> leaves, and the pathogen was successfully re-isolated, fulfilling Koch's postulates. This study represents the first report showing that <em>N. musae</em> causes leaf spot disease in <em>P. sibiricum</em> and provides a foundation for future research and management strategies for this economically and medicinally valuable plant.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103149"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386068","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering biochemical basis of root-knot nematode (Meloidogyne incognita) resistance in Solanum torvum introgressed lines in eggplant (Solanum melongena L.)","authors":"Monisha Thangavel,&nbsp;Mohinder Kaur Sidhu,&nbsp;Sukhjeet Kaur,&nbsp;Monika Mahajan,&nbsp;Jasmeen Kaur,&nbsp;Babanjeet","doi":"10.1016/j.pmpp.2026.103148","DOIUrl":"10.1016/j.pmpp.2026.103148","url":null,"abstract":"<div><div>Wild relative-based introgressed germplasm holds immense potential for crop improvement, particularly in conferring resistance to soil-borne pathogens. The present study aimed to identify biochemical correlates associated with resistance to root-knot nematodes (RKN, <em>Meloidogyne incognita</em>) in <em>Solanum torvum</em>-derived introgression lines of eggplant. Nematological and biochemical assessments of leaves and roots under inoculated and mock inoculated conditions across different time intervals revealed a major role of biochemical compounds in imparting resistance. The immune response of <em>S. torvum</em> and the high resistance exhibited by introgressed lines SMST-1-45-11 and SMST-1-26-31, characterized by reduced galling and egg mass formation, were strongly associated with elevated levels of phenols, lignins, total chlorophyll content, PAL (Phenylalanine Ammonia Lyase), TAL (Tyrosine Ammonia Lyase), POD (peroxidase) and CAT (catalase) activity, alongside reduced sugar accumulation. Conversely, the susceptible check variety ‘Punjab Sada Bahar (PSB)’ displayed a higher number of galls and egg masses with increased root sugar content under inoculated conditions. These findings suggested that enhanced phenols, lignin, PAL, TAL, peroxidase and catalase activity, together with reduced sugars, are strongly associated with RKN resistance in eggplant. The contrasting resistant (SMST-1-45-11 and SMST-1-26-31) and highly susceptible (PSB) genotypes provide valuable parental material for developing F₁ crosses and for use in future genetic studies. Furthermore, the identified biochemical responses provide a foundation for molecular investigations into RKN resistance in eggplant.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103148"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386075","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"De novo transcriptome assembly of Piper betle and identification of genes involved in phenylpropanoid metabolism in response to Phytophthora parasitica","authors":"Abhaya Kumar Sahu ,&nbsp;Pratik Priyadarsi Puhan ,&nbsp;Beda Saurav Behera ,&nbsp;Punam Kumari ,&nbsp;Prabhat Kumar ,&nbsp;Bharat Bhusan Patnaik","doi":"10.1016/j.pmpp.2026.103127","DOIUrl":"10.1016/j.pmpp.2026.103127","url":null,"abstract":"<div><div>The phenylpropanoid pathway plays a central role in plant defense by synthesizing lignin polymers that reinforce cell walls and form structural barriers during pathogen invasion. Foot rot disease caused by <em>Phytophthora parasitica</em> severely affects the growth and productivity of betel vine (<em>Piper betle</em> L.), yet the molecular mechanisms underlying host defense are little known. In this study, transcriptomic analysis revealed extensive transcriptional reprogramming in betel vine following <em>P. parasitica</em> infection, with a large number of differentially expressed genes (DEGs) associated with defense-related pathways. Notably, genes linked with phenylpropanoid metabolism were significantly affected and predominantly down-regulated across plant stems and leaves during infection. Consistent with these transcriptional changes, phenylalanine ammonia lyase (PAL) and peroxidase (POD) enzymes linked to phenylpropanoid metabolism exhibited decreased activity, accompanied by lower lignin accumulation and increased vascular disintegration in infected plants. Together, these outcomes demonstrate that <em>P. parasitica</em> reduces phenylpropanoid-mediated defense responses in betel vine, thereby weakening structural barriers and facilitating disease progression. This study provides critical insights into the molecular defense response of betel vine against <em>P. parasitica</em> infection and also offers strategies to develop resistant betel vine plants in the future.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103127"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"RNAseq based comparative gene expression reveals early defense activation and involvement of phenylpropanoid pathway in rice root-knot nematode resistance","authors":"Premakumar ,&nbsp;Divya Singh ,&nbsp;Jyoti Yadav ,&nbsp;Meghraj Chavhan ,&nbsp;Pallavi Mohanapure ,&nbsp;Bidwan Rath ,&nbsp;Alkesh Hada ,&nbsp;Vishal Singh Somvanshi ,&nbsp;S Gopala Krishnan ,&nbsp;KK Vinod ,&nbsp;Prolay K. Bhowmick ,&nbsp;Haritha Bollinedi ,&nbsp;Manoranjan Dash ,&nbsp;Munegowda Manoj Gowda ,&nbsp;Ashok Kumar Singh ,&nbsp;Uma Rao ,&nbsp;Ranjith Kumar Ellur","doi":"10.1016/j.pmpp.2026.103154","DOIUrl":"10.1016/j.pmpp.2026.103154","url":null,"abstract":"<div><div>The rice root-knot nematode (<em>Meloidogyne graminicola</em>, RRKN) is a major constraint to rice cultivation, particulary in direct-seeded systems where most cultivars are susceptible. In contrast, the resistant cultivar Phule Radha exhibited significantly lower nematode penetration and arrested gall development as compared with the susceptible cultivar Pusa Basmati 1121. Transcriptome profiling at 2 days post-inoculation, using both parental lines and resistant and susceptible RIL bulks under infected and uninfected conditions, revealed early activation of defense responses in Phule Radha. Notably, the resistant genotype exhibited higher basal expression of genes involved in the phenylpropanoid pathway, along with upregulation of genes related to secondary metabolite biosynthesis. Several WRKY transcription factors (<em>WRKY62, WRKY70, WRKY2, and WRKY64</em>) were strongly induced and associated with salicylic acid–mediated signaling. Additionally, components of the ethylene signaling pathway, including <em>ETHYLENE INSENSITIVE</em> 3-like 3 transcription factors and ethylene-responsive factors, were enriched. Defense responses also involved enhanced expression of chitinase genes and lignin biosynthesis–related genes, as well as candidate resistance proteins such as <em>Pik</em>-2-like isoform X1. Together, these findings uncover the molecular mechanisms underlying RRKN resistance in Phule Radha and identify promising targets for functional validation and the development of nematode-resistant rice varieties.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103154"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigations on foot rot disease of muskmelon caused by Agroathelia rolfsii – A new record from India","authors":"M.R. Sampathkumar ,&nbsp;S. Mahadevakumar ,&nbsp;V. Basavaraj ,&nbsp;M. Mahesh ,&nbsp;K.R. Sridhar ,&nbsp;K.N. Amruthesh ,&nbsp;N. Lakshmidevi","doi":"10.1016/j.pmpp.2026.103162","DOIUrl":"10.1016/j.pmpp.2026.103162","url":null,"abstract":"<div><div>A significant disease occurrence of foot rot in muskmelon was observed from February to July 2025 in major muskmelon growing regions of the Chamarajanagar district, Karnataka, India. The incidence of the disease ranged between 5% and 23% as recorded across an area of about 10 ha. Initial symptoms appeared as brown sunken lesions at the infected site, followed by the growth of mycelia, yellowing, and quick wilting of the entire plant. Ten fungal isolates were isolated from the infected plants. These isolates were similar in morphology, with white, fluffy aerial mycelia along with many reddish brown sclerotia after 8–10 days on the PDA medium. The ITS region and <em>TEF-1α</em> were amplified from the genomic DNA of two isolates and sequenced. The BLASTn analysis showed a high sequence similarity with <em>Agroathelia rolfsii</em> sequences available in the GenBank database. The phylogenetic analysis based on ITS and <em>TEF-1α</em> further established the identity of the <em>A. rolfsii</em> isolates. Pathogenicity tests exhibited symptom development between 3 and 4 days after inoculation and the pathogen was subsequently re-isolated and identified, thereby fulfilling Koch's postulates. Based on the cultural, morphological, molecular, phylogenetic, and pathogenicity analyses, the isolated pathogen is identified as <em>A</em>. <em>rolfsii</em>, the etiological agent of foot rot in muskmelon. Based on the available scientific literature and databases, there are currently no reports of <em>A. rolfsii</em> causing foot rot disease in muskmelon in India; thus, this study represents the first documented report of muskmelon foot rot caused by <em>A. rolfsii</em> in India.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103162"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386069","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Characterization of streptomycin-induced persister cells in Erwinia pyrifoliae","authors":"Lin He,&nbsp;Jun Myoung Yu","doi":"10.1016/j.pmpp.2026.103168","DOIUrl":"10.1016/j.pmpp.2026.103168","url":null,"abstract":"<div><div>Antibiotic persistence represents a transient physiological state in which a small subpopulation of bacteria survives lethal antibiotic exposure without acquiring genetic resistance. These persister cells are increasingly recognized as a major cause of recurrent infections. <em>Erwinia pyrifoliae</em>, the causal agent of black shoot blight in apple and pear, poses a serious threat to fruit production, yet its ability to persist under antibiotic stress remains poorly understood. In this study, it was demonstrated that <em>E. pyrifoliae</em> forms non-heritable persister cells upon exposure to lethal concentrations of streptomycin. Killing assays revealed a characteristic biphasic survival pattern, while tolerance assays showed that persister cells exhibited markedly enhanced survival under both antibiotic and oxidative stress conditions compared with the normal cell population. Transcriptomic analysis identified a distinct persistence-associated transcriptional program, characterized by the strong induction of toxin–antitoxin systems, global stress-response regulators, membrane stabilization factors, and dormancy-related pathways, accompanied by the repression of growth- and metabolism-related functions. These results establish antibiotic persistence as a survival strategy in <em>E. pyrifoliae</em> under streptomycin stress and provide a mechanistic framework to explain disease recurrence and sporadic black shoot blight outbreaks in orchards. The identified pathways represent potential molecular targets for improving the management of phytopathogenic bacteria under antibiotic pressure.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103168"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calonectria caudovesiculata sp. nov., a new leaf blight pathogen of Eucalyptus distinguished by caudal-fin-shaped vesicles and multilocus phylogenetic analyses","authors":"Sabyasachi Banerjee,&nbsp;Nitika Bansal,&nbsp;Nitika Negi,&nbsp;Shweta Bhimta,&nbsp;Shailesh Pandey","doi":"10.1016/j.pmpp.2026.103139","DOIUrl":"10.1016/j.pmpp.2026.103139","url":null,"abstract":"<div><div>While investigating Calonectria leaf blight (CLB) of <em>Eucalyptus</em> in northern India, fungal isolates were recovered from symptomatic leaves that consistently failed to sporulate on standard synthetic media, even under forced sporulation conditions. Despite this diagnostic recalcitrance, pathogenicity assays revealed that the isolates caused severe CLB symptoms on commercial <em>Eucalyptus</em> clones, highlighting a key limitation of routine culture-based fungal diagnostics. Notably, all diagnostic asexual morph structures were produced exclusively on leaf lesions, including distinctive caudal-fin-shaped vesicles, a morphological character not previously reported within the genus <em>Calonectria</em>. Multilocus phylogenetic analyses resolved these isolates as a well-supported, novel lineage, described and illustrated here as <em>Calonectria caudovesiculata</em>, sister to <em>Calonectria tonkinensis</em>, with pairwise homology index (PHI) test showing no evidence of recombination with closely related taxa. Collectively, these findings demonstrate that reliance on culture-based methods alone can obscure ecologically and economically significant fungal diversity, underscoring the need to integrate host-derived morphology—particularly stable, <em>in planta</em> diagnostic characters—with molecular data for accurate taxonomy, early disease diagnosis, and informed disease management strategies.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103139"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modulation of defense-related biochemical and ultrastructural responses in rice to Bipolaris oryzae under contrasting establishment methods and soil moisture regimes","authors":"Jasima Ali ,&nbsp;Jyoti Jain ,&nbsp;Sandeep Jain ,&nbsp;Pooja Salaria ,&nbsp;Neha Gupta","doi":"10.1016/j.pmpp.2026.103174","DOIUrl":"10.1016/j.pmpp.2026.103174","url":null,"abstract":"<div><div>Brown spot disease, caused by <em>Bipolaris oryzae</em>, is a re-emerging constraint that significantly reduces rice yield and grain quality worldwide. This study aimed to elucidate the integrated biochemical and ultrastructural defense responses of rice cultivar PR 126 to <em>B. oryzae</em> under contrasting crop establishment methods and soil moisture regimes. Rice plants grown under direct-seeded rice (DSR) and puddled transplanted rice (PTR) systems were evaluated at two irrigation levels (15 and 25 kPa soil moisture tension) following pathogen infection. Significant differences in biochemical and anatomical traits were observed between establishment methods and irrigation regimes. Defense-related and antioxidant enzymes were markedly upregulated under combined water (25 kPa) and pathogen stress, with stronger induction in DSR compared with PTR. Accumulation of phenolics, ascorbic acid, lignin, and proline increased under both stresses, whereas malondialdehyde and hydrogen peroxide levels were significantly higher in DSR at 25 kPa, indicating enhanced oxidative stress and lipid peroxidation. Ultrastructural analyses revealed stronger epidermal and surface-based structural defenses in PTR under optimal moisture conditions, whereas DSR showed compromised leaf anatomy and altered vascular organization facilitating pathogen invasion. Water deficit induced adaptive changes in supporting and conducting tissues, reflecting stress-driven structural adjustment. These results demonstrate that establishment method and irrigation regime critically modulate defense responses and anatomical integrity highlighting the importance of integrating appropriate establishment practices with optimized irrigation scheduling to enhance resilience against brown spot.</div></div>","PeriodicalId":20046,"journal":{"name":"Physiological and Molecular Plant Pathology","volume":"143 ","pages":"Article 103174"},"PeriodicalIF":3.3,"publicationDate":"2026-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147386022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}