Plant disease最新文献

{"title":"Fair-Weather Friends: Sequential Coinfection Demonstrates Priority Effects in the Outcome of <i>Parastagonospora nodorum</i> and <i>Pyrenophora tritici-repentis</i> Polymicrobial Foliar Disease of Wheat.","authors":"Leon Lenzo, Evan John, Jason Bradley, Geoff Thomas, Dion Bennett, Kar-Chun Tan","doi":"10.1094/PDIS-11-25-2324-RE","DOIUrl":"10.1094/PDIS-11-25-2324-RE","url":null,"abstract":"<p><p>In plant and animal pathosystems, the host is typically challenged by more than one pathogen simultaneously. Most pathosystem studies involve a single pathogen, but where multiple pathogens have been studied, synergy, antagonism, and priority effects have frequently been detected. <i>Parastagonospora nodorum</i> and <i>Pyrenophora tritici-repentis</i> cause Septoria nodorum blotch and tan spot of wheat, respectively. Field coinfection between these fungal pathogens is widely established, but interaction dynamics remain poorly understood. Using a newly developed digital PCR (dPCR) method, we studied coinfection in naturally infected wheat fields, inoculated field trials, and controlled environment artificial infections. Natural infection revealed that a clear majority of symptomatic infections involved both pathogens, with host leaves resistant to both pathogens showing significantly higher disease and pathogen biomass under coinfection compared with single species infection. Controlled inoculum field experiments showed <i>P</i>. <i>tritici-repentis</i> priority was most similar to natural and controlled mixed infection, suggesting that <i>P</i>. <i>tritici-repentis</i> priority occurs in natural systems. Laboratory experiments showed that consecutive infection where <i>P</i>. <i>tritici-repentis</i> was followed by <i>P</i>. <i>nodorum</i> in a resistant host resulted in a significant increase in disease and biomass for both pathogens. When <i>P</i>. <i>nodorum</i> established on the host first, <i>P</i>. <i>tritici-repentis</i> colonization was highly reduced regardless of host resistance in both controlled field studies and laboratory experiments. To our knowledge, this is the first description of asymmetric priority effects overcoming host resistance in a plant pathosystem. Resistance breeding strategies evaluating single pathogen challenges may inadvertently select for cultivars vulnerable to sequential coinfection, necessitating integrated disease complex approaches for durable resistance development.[Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS11252324RE"},"PeriodicalIF":2.8,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147348051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Volatile Organic Compounds Produced by <i>Bacillus velezensis</i> GX0002980 Inhibit <i>Colletotrichum fructicola</i>: A GC-MS and Transcriptomic Analysis.","authors":"Xiaoying Xie, Ganlin Chen, Jing Wang, Shujing Wu, Mingguo Jiang, Lifang Yang, Yan Zhou","doi":"10.1094/PDIS-01-26-0096-RE","DOIUrl":"https://doi.org/10.1094/PDIS-01-26-0096-RE","url":null,"abstract":"<p><p>One of the most significant diseases affecting mango production is anthracnose, which severely impacts yield and quality. In this study, <i>Bacillus velezensis</i> GX0002980, a strain isolated from the Guangxi Damingshan National Nature Reserve, and its volatile organic compounds (VOCs) exhibited strong antifungal activity against <i>Colletotrichum fructicola</i>, the causal agent of anthracnose. A total of 33 VOCs were identified by GC-MS. Antifungal assays using partitioned Petri dishes revealed seven VOCs with inhibitory activity, among which 2-ethylhexanol showed the greatest effect. Observations utilizing microscopy indicated that <i>C. fructicola</i> exposed to 2-ethylhexanol (2-EH) exhibited swollen, deformed, intertwined, and fractured hyphae with visible perforations. Fluorescent staining further confirmed that 2-EH disrupted the cell wall and cell membrane structure, while also inducing elevated mitochondrial reactive oxygen species (ROS) levels. RNA-seq analysis of <i>C. fructicola</i> exposed to 2-EH revealed multiple differentially expressed genes (DEGs) enriched in metabolic pathways related to the cell wall and membrane, as well as a significant downregulation of genes encoding key enzymes in the TCA cycle and energy metabolism. Collectively, our findings indicate that 2-EH inhibits <i>C. fructicola</i> by disrupting cell wall integrity, damaging the cell membrane and its permeability, suppressing energy metabolism, impairing the mitochondrial respiratory chain, and inducing ROS accumulation. Experiments conducted on harvested mango fruits indicated that 2-EH significantly delayed the development of anthracnose. Our study reveals that 2-EH effectively controls mango anthracnose. We further elucidate the underlying mechanism, showing that both <i>B. velezensis</i> GX0002980 and 2-EH directly inhibit <i>C. fructicola</i>.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS01260096RE"},"PeriodicalIF":2.8,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149113530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Diverse Strains of Aster Yellows Phytoplasma Are Associated with the Potato Leafhopper (<i>Empoasca fabae</i>) in Eastern Canada.","authors":"Ariane Barrot, Joshua Molligan, Abraão Almeida Santos, Nicolas Plante, Edel Pérez-López","doi":"10.1094/PDIS-03-26-0486-SC","DOIUrl":"10.1094/PDIS-03-26-0486-SC","url":null,"abstract":"<p><p>Phytoplasmas are cell wall-less bacteria that are transmitted by phloem-feeding insects. In Canada, insect vectors of this pathogen are leafhoppers (Hemiptera: Cicadellidae), and they can contribute to significant economic losses. As climate change alters the composition and movement of insect communities, migratory species such as the potato leafhopper (<i>Empoasca fabae</i>, Harris 1841), one of the most abundant leafhoppers in Québec affecting berries, may play an emerging role in phytoplasma transmission. Although <i>E</i>. <i>fabae</i> is not currently confirmed to act as a vector, its frequent presence and abundance in fields, along with its potential to acquire phytoplasmas, deserve further investigation. In this study, we tested DNA from <i>E</i>. <i>fabae</i> collected in strawberry fields for the presence of '<i>Candidatus</i> Phytoplasma' using a highly validated nested PCR assay. The amplicons from positive insects were cloned and 46 of those clones were sequenced to identify phytoplasma groups and subgroups. Our findings confirmed the presence of multiple aster yellows (16SrI-related) subgroups in <i>E</i>. <i>fabae</i> based on phylogenetic analysis, restriction fragment length polymorphism profiling, and single-nucleotide polymorphism profiles. However, although phytoplasma was detected in a new generation of leafhoppers reared under controlled conditions in disease-free alfalfa plants, the ability of <i>E</i>. <i>fabae</i> to transmit the pathogen remains unknown. Overall, these findings highlight the importance of monitoring common pests such as <i>E</i>. <i>fabae</i> as early indicators of phytoplasma diversity in Eastern Canadian agricultural systems.[Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS03260486SC"},"PeriodicalIF":2.8,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147819599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"<i>Diaporthe</i> Species Associated with Postharvest Fruit Rot of Kiwifruit in Anhui Province, China.","authors":"Qi Zou, Xinyi Yang, Xiaoli Li, Rui He, Shuai Cao, Yuhang Song, Ke Zhang, Haimei Jin, Lixin Zhang, Min Fu","doi":"10.1094/PDIS-11-25-2195-RE","DOIUrl":"10.1094/PDIS-11-25-2195-RE","url":null,"abstract":"<p><p><i>Diaporthe</i> species are important pathogens, endophytes, and saprophytes on various plants. Although kiwifruit is an important host for this genus, the species occurring on kiwifruit remain largely unresolved. In this study, 75 <i>Diaporthe</i> isolates were isolated from 60 kiwifruit samples suspected of fruit rot disease collected in Anhui Province, China. Phylogenetic analyses based on five loci (ITS, <i>cal</i>, <i>his3</i>, <i>tef1</i>, and <i>tub2</i>) combined with morphology of 34 representative isolates showed that they belong to six <i>Diaporthe</i> species (<i>D. arecae</i>, <i>D. biguttulata</i>, <i>D. eres</i>, <i>D. hongkongensis</i>, <i>D. sojae</i>, and <i>D. unshiuensis</i>), distributed across three sections (Eres, Foeniculina, and Sojae). Of these, <i>D. eres</i> (38.7%), <i>D. arecae</i> (17.3%), and <i>D. hongkongensis</i> (14.7%) were the most prevalent species in Anhui Province. Pathogenicity tests on 'Hongyang' kiwifruit revealed varying aggressiveness among species and isolates, with <i>D. unshiuensis</i> and <i>D. hongkongensis</i> exhibiting strong pathogenicity, while <i>D. sojae</i> showed weaker pathogenicity. Subsequent verification of 18 previously reported species on kiwifruit confirmed 12 as valid species (<i>D. actinidiicola</i>, <i>D. ambigua</i>, <i>D. eres</i>, <i>D. ganjae</i>, <i>D. hongkongensis</i>, <i>D. novem</i>, <i>D. passiflorae</i>, <i>D. psoraleae-pinnatae</i>, <i>D. rudis</i>, <i>D. sojae</i>, <i>D. tulliensis</i>, and <i>D. unshiuensis</i>). This study represents the first report of <i>D. arecae</i>, <i>D. biguttulata</i>, <i>D. hongkongensis</i>, <i>D. sojae</i>, and <i>D. unshiuensis</i> causing fruit rot on kiwifruit and provides timely updates on the taxonomic status of <i>Diaporthe</i> species previously reported on kiwifruit, thereby offering valuable information for the disease control in kiwifruit.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS11252195RE"},"PeriodicalIF":2.8,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147717717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Etiology of Rachis Tip Dieback of Macadamia Flowers in Australia.","authors":"Xiaoxue Xu, Vivian A Rincón-Flórez, Lilia C Carvalhais, Olufemi A Akinsanmi","doi":"10.1094/PDIS-02-26-0303-RE","DOIUrl":"10.1094/PDIS-02-26-0303-RE","url":null,"abstract":"<p><p>Botrytis blight, Cladosporium blight, Pestalotiopsis blight, and Phytophthora blight are distinct diseases of macadamia flowers. Rachis tip dieback (RTD) is part of the symptoms associated with all these flower blights. However, some racemes show flower blight without RTD, while others exhibit RTD but maintain healthy flowers. RTD has also been associated with physiological and environmental stresses. This study investigated the prevalence and etiology of RTD in 20 commercial macadamia orchards in Australia at flowering seasons in 2023 and 2024. From 307 raceme samples with RTD and 54 asymptomatic samples, 20 fungal genera were identified by DNA sequencing. <i>Neopestalotiopsis</i> (27.5%), <i>Epicoccum</i> (20.4%), <i>Diaporthe</i> (19.1%), <i>Cladosporium</i> (7.8%), <i>Alternaria</i> (5.6%), and <i>Fusarium</i> (5.6%) were the most frequently isolated genera from RTD samples. Pathogenicity assays with representative isolates and flower blight pathogens showed that <i>N. maddoxii</i>, <i>N. macadamiae</i>, and <i>E. italicum</i> were the primary pathogens associated with RTD. In addition, established flower blight pathogens were capable of inducing RTD symptoms, and species of <i>Diaporthe</i> and <i>Epicoccum</i> are reported here as novel pathogens of macadamia racemes. The high diversity of fungal species obtained revealed that multiple species can infect the same racemes and co-occur in the same tree expressing RTD symptoms. This study revealed that RTD has a biotic cause and is part of the flower blight disease complex in macadamia. The contributions of RTD to yield losses and a potential tool for predicting flower blight severity to support management decisions are discussed.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS02260303RE"},"PeriodicalIF":2.8,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147675734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transcriptomic Analysis Uncovers Critical Molecular Pathways in Resistant Rice in Response to <i>Magnaporthe oryzae</i> Infection.","authors":"Xiurong Yang, Shuangyong Yan, Zhongchi Cui, Yuejiao Li, Ruixiang Wang, Shuqin Sun, Guangsheng Li, Fei Zhao, Jingping Su, Shengjun Wang","doi":"10.1094/PDIS-07-25-1546-RE","DOIUrl":"https://doi.org/10.1094/PDIS-07-25-1546-RE","url":null,"abstract":"<p><p>Rice blast, caused by <i>Magnaporthe oryzae</i>, severely threatens global rice production. This study deciphers the molecular basis of blast resistance through comparative transcriptomics of resistant (403) and susceptible (402) rice cultivars. Resistant plants exhibited limited symptom development, accompanied by targeted transcriptional reprogramming with only 393 differentially expressed genes (DEGs) versus 1,336 DEGs in susceptible plants. Kyoto Encyclopedia of Genes and Genomics (KEGG) analysis revealed preferential activation of defense-centric pathways in resistant cultivars, including diterpenoid biosynthesis (12 DEGs), phenylpropanoid metabolism (5 upregulated genes: <i>prx15</i>, <i>poxN</i>, <i>OsPAL04</i>, <i>POXgX9</i>, and <i>4CL5</i>), and MAPK signaling. Notably, conserved upregulation of terpenoid/lipid metabolism genes (93 DEGs) and resistant-specific induction of key regulators (LOX-L2 for jasmonic acid [JA] biosynthesis and BOR2/UGD1 for cell wall reinforcement) formed a coordinated defense network. Contrastingly, susceptible plants showed inefficient activation of DNA replication and cell cycle pathways. Transcription factor (TF) dynamics further highlighted this divergence, with resistant plants displaying focused TF regulation (23 DEGs) versus widespread changes in susceptible plants (105 DEGs). Quantitative real-time PCR (qPCR) validation confirmed resistant-specific upregulation of phenylpropanoid (<i>prx128</i>, <i>prx15</i>, <i>OsPAL04</i>, <i>poxN</i>, and <i>POXgX9</i>) and phenylalanine metabolism genes (<i>OsAMI2</i>, <i>TDC1</i>, and <i>OsTDC3</i>), while susceptibility-associated genes (<i>prx27</i> and <i>prx17</i>) were upregulated in susceptible varieties. This study uncovers the diterpenoid biosynthesis pathway as a central hub in rice blast resistance, providing theoretical foundations for improving resistance through genetic engineering or molecular breeding.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS07251546RE"},"PeriodicalIF":2.8,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149113603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of a Novel Powdery Mildew Resistance Gene in a Winter Wheat Cultivar.","authors":"Xiangyang Xu, Genqiao Li, Tezera Wolabu Watira, Christina Cowger, Guihua Bai, Brett F Carver, Ruolin Bian, Amy Bernardo, Yanqi Wu","doi":"10.1094/PDIS-01-26-0240-RE","DOIUrl":"10.1094/PDIS-01-26-0240-RE","url":null,"abstract":"<p><p>Wheat (<i>Triticum aestivum</i>) is an important staple crop that sustains over one-third of the global population. Powdery mildew, an economically important disease caused by <i>Blumeria graminis</i> f. sp. <i>tritici</i> (<i>Bgt</i>), significantly affects wheat production in many wheat-growing regions. Therefore, identification of novel powdery mildew resistance genes that can be easily used in wheat cultivar development is essential for meeting the needs of the increasing global human population. PI 606247 (formerly 'Samara') is a winter wheat cultivar developed in the Czech Republic in 1995 that exhibits resistance to representative U.S. <i>Bgt</i> isolates. An F₇ recombinant inbred line (RIL) population derived from PI 606247 × Jagalene was evaluated for responses to <i>Bgt</i> isolate <i>OKS(14)-B</i>-<i>3</i>-<i>1</i>. Genetic analysis indicated that a single gene, designated <i>PmSA</i>, conditions powdery mildew resistance in PI 606247. Selective genotyping of a subset of RILs identified a set of single nucleotide polymorphisms (SNPs) co-segregating with powdery mildew resistance in the terminal region of chromosome arm 2BL. Linkage analysis using Kompetitive Allele Specific PCR (KASP) markers located <i>PmSA</i> to a 14.43-Mb interval between 686.69 and 701.12 Mb in the Chinese Spring IWGSC RefSeq v2.1 reference sequence. <i>PmSA</i> is a new powdery mildew resistance gene differing from the others in the terminal region of 2BL in genomic location, origin, and responses to a set of <i>Bgt</i> differential isolates. <i>PmSA</i> is valuable for enhancing powdery mildew resistance, and the KASP markers closely linked to <i>PmSA</i> can facilitate its rapid deployment in wheat cultivars via marker-assisted selection.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS01260240RE"},"PeriodicalIF":2.8,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147663103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Identification of <i>Epicoccum nigrum</i> Causing Soybean Leaf Blight in Northeast China and Its Sensitivity to Selected Fungicides.","authors":"Suli Zheng, Yuxuan Liu, Yu Ding, Jinxin Liu, Chunqiu Yang, Xueying Zhao, Zhipeng Ren, Yonggang Li","doi":"10.1094/PDIS-09-25-1924-RE","DOIUrl":"10.1094/PDIS-09-25-1924-RE","url":null,"abstract":"<p><p>Soybean (<i>Glycine max</i> [L.] Merr.) holds significant global economic importance because of its considerable nutritional and commercial value. Since 2022, a leaf blight of unknown etiology has been observed in soybean-growing areas of Nehe City and Hongxinglong Farm in Heilongjiang Province, China. Although the disease has not yet reached epidemic levels, it warrants attention because of its potential to spread under favorable environmental conditions. Initial symptoms on infected leaves appear as small brown spots that gradually expand to form streaks of necrotic tissue delimited by the veins, with a brown necrotic center surrounded by a yellow margin. Through systematic sampling and isolation, 26 fungal isolates with similar morphologies were obtained. Morphological characterization, molecular identification, and phylogenetic analyses were used to identify the pathogen of this new soybean leaf blight as <i>Epicoccum nigrum</i>. This study represents the first report of <i>E. nigrum</i> as a pathogen of soybean in China. Pathogenicity tests showed that most isolates displayed moderate to high virulence on soybeans. In greenhouse spray inoculation assays, <i>E. nigrum</i> isolates infected several legume species but did not cause disease on maize or hyacinth bean under the conditions tested. In vitro sensitivity assays showed that <i>E. nigrum</i> isolates exhibited high sensitivity to pyraclostrobin and azole-tebuconazole, with an EC₅₀ value ≤0.50 μg ml^-1. In pot experiments, both fungicides provided significant disease control, achieving 90.2% control efficacy at 450 μg ml^-1 (pyraclostrobin) and 91.7% at 600 μg ml^-1 (azole-tebuconazole). These results support the use of chemical fungicides as a key strategy for managing soybean leaf blight caused by <i>E. nigrum</i>. Overall, this study clarifies the causal agent of soybean leaf blight, thereby providing a scientific basis for its management in soybean production. Additionally, the identification of effective fungicides provides practical guidance for targeted disease management, which is essential for safeguarding soybean yields and mitigating economic losses associated with this emerging disease. Furthermore, this study also establishes a foundation for future investigations into the pathogenic mechanisms and epidemiological dynamics of <i>E. nigrum</i>.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS09251924RE"},"PeriodicalIF":2.8,"publicationDate":"2026-09-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147717635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Infection Rate Thresholds Reveals Instability in Resistance to Sheath Rot Caused by <i>Sarocladium oryzae</i> in Rice Genotypes.","authors":"Amritpal Mehta, Umer Basu, Sonali Sharma, S K Singh, Amrish Vaid, Bahaderjeet Singh, Lovepreet Singh, Harwinder Singh Buttar, Ashawani K Basandrai, Daisy Basandrai, Shafat Ahmad Ahanger","doi":"10.1094/PDIS-06-26-1203-RE","DOIUrl":"https://doi.org/10.1094/PDIS-06-26-1203-RE","url":null,"abstract":"<p><p>Sheath rot caused by <i>Sarocladium oryzae</i> has emerged as a serious threat to rice production, and host resistance remains the most sustainable management strategy. However, whether moderately resistant genotypes maintain their stability under increasing disease pressure is not well understood. The present study was undertaken to identify resistant genotypes, quantify the effect of infection rate on resistance behavior in moderately resistant genotypes, and develop a binary classification model for predicting stable versus unstable resistance. One hundred three rice genotypes were evaluated under field conditions during the <i>kharif</i> seasons of 2019 and 2020, with disease severity recorded weekly to calculate area under the disease progress curve (AUDPC) and infection rate (<i>r</i>). Residual maximum likelihood (REML) analysis gave significant genotypic variance (σ²g = 120.42) and high heritability (H² = 97.78%). Of the 103 genotypes screened, four (TMRH-2110, UPLRH-179510, RRX-805, and Rasi) were resistant (R), 35 were moderately resistant (MR), 62 were susceptible (S), and two (IIRRH-146 and Pusa Basmati 1121) were highly susceptible (HS). MR genotypes had <i>r</i> like those of S genotypes. Binomial logistic regression identified a critical infection rate threshold (<i>r</i> = 0.073). Above this value, the probability of moving from MR to S exceeded 50%. The model had an area under the ROC (receiver operating characteristic) curve (AUC) of 0.63 (95% CI = 0.551 to 0.710). Sensitivity and specificity were 0.476 and 0.714, respectively. Several MR genotypes had r greater than threshold, were classified as potentially unstable. <i>'r'</i> can signal resistance instability early. This study demonstrates that r may be serve as a quantitative predictor of resistance stability to sheath rot in rice and provides a preliminary threshold-based framework for identifying MR genotypes that are likely to remain stable or unstable under disease pressure. Adding this component to breeding programs improves selection over severity-based methods.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149075268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Water stress and elevated salinity exacerbate Macrophomina root rot and reduce marketable yield in California strawberry.","authors":"Marina Jade Gutierrez, Peter M Henry, Oleg Daugovish, Andre Biscaro, Kyle A Blauer, Shashika Hewavitharana, Gerald J Holmes","doi":"10.1094/PDIS-08-26-1611-RE","DOIUrl":"https://doi.org/10.1094/PDIS-08-26-1611-RE","url":null,"abstract":"<p><p>Macrophomina root rot, caused by the soilborne fungus <i>Macrophomina phaseolina</i>, is a disease responsible for devastating economic losses in California strawberry production. Disease incidence and severity are influenced by plant stress, emphasizing the importance of identifying which abiotic stressors contribute most to disease development. Two field experiments (in 2024 and 2025) were conducted to evaluate the impact of water and salt stress on plant mortality of cultivars Fronteras (moderately susceptible) and Sweet Ann (highly susceptible). Strawberry transplants were inoculated with <i>M. phaseolina</i> and subjected to one of five treatments: grower standard (i.e., low/no stress), water stress, two elevated chloride levels, and high electrical conductivity (EC_W). Plant mortality was assessed weekly, and fruit yield was recorded. Salt-related foliar injuries were evaluated with visual ratings and drone-based aerial imagery. Across both seasons, treatment (<i>P</i> = 0.008 and <i>P</i> = 0.024, respectively) and cultivar (<i>P</i> < 0.0001 and <i>P</i> < 0.0001, respectively) significantly affected plant mortality, with no significant treatment × cultivar interaction (<i>P</i> > 0.05). Water stress in Year 1 and high EC_W stress in Year 2 resulted in significantly greater plant mortality and reduced total fruit yield compared to the grower standard. When comparing cultivars, Sweet Ann had significantly higher average plant mortality than Fronteras across both seasons. Under the study conditions, visual ratings and aerial imagery did not reliably distinguish differences in salt-related injuries among treatments. These results highlight the importance of utilizing soil moisture sensors, low-saline irrigation water, and disease-resistant cultivars to minimize plant mortality caused by <i>M. phaseolina</i>.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2026-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149075320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}