Plant disease最新文献

{"title":"An Efficient Strategy for Developing Fusarium Wilt-Resistant Watermelon Germplasm Using EMS Mutagenesis and Toxin Screening.","authors":"Zhengjing Wu, Xinrong Fu, Qianjin Zhan, Zijing Lin, Weilin Zhu","doi":"10.1094/PDIS-12-24-2713-RE","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2713-RE","url":null,"abstract":"<p><p>Fusarium wilt of watermelon (Citrullus lanatus), caused by Fusarium oxysporum f. sp. niveum, severely threatens watermelon production worldwide. This study, for the first time, explored a rapid and efficient method for creating disease-resistant watermelon germplasm by combining ethyl methanesulfonate (EMS) mutagenesis with crude toxin screening. Watermelon seeds treated with 1% EMS for 18 h achieved a germination rate of 52%, and resistant mutants were successfully identified using 50% crude toxin stock solution. The mutants exhibited enhanced stress tolerance, with significantly higher superoxide dismutase (SOD) and catalase (CAT) activities and lower malondialdehyde (MDA) content compared to susceptible varieties. Artificial fungal inoculation confirmed the resistance of mutant plants, which exhibited a disease index comparable to that of the resistant varieties. This study demonstrated the effectiveness of a practical and innovative strategy combining chemical mutagenesis and toxin screening for developing Fusarium wilt-resistant watermelon germplasm.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576085","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":"First Report of Tomato Sour Rot Caused by <i>Geotrichum candidum</i> in Heilongjiang Province, China.","authors":"Hongting Wang, Liangxu Dong, Wenzhuo Liu, Yong Hao, Han Shen, Chunqing Pan, Dong Liu, Yanju Zhang","doi":"10.1094/PDIS-03-25-0630-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0630-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Tomato sour rot, caused by Geotrichum candidum, is a postharvest disease. It has been detected across major tomato-producing regions in temperate to subtropical zones (e.g., United States, Mediterranean Basin, India), yet the impact in northeastern China remains poorly understood. G. candidum infects various fruits and vegetables, including kiwifruit, strawberry, peaches and so on (Hussain et al., 2016; Lu et al., 2021; Cheng et al., 2021). In September 2023, during the postharvest packing process of tomatoes in Changchan village, Shuangcheng District, Harbin City, Heilongjiang Province, rotten fruits were detected. Asymptomatic tomatoes harvested from the fields developed decay after harvest within two days, resulting in a 9% morbidity rate and 2.5-ton yield loss. Initially, watery spots appeared on the fruits. The skin then ruptured and turned outward, exposing the flesh. The affected area became soft, rotten and producing a sour odor, covered by a white mold layer. Five diseased tomatoes were collected. Tissue pieces (5 × 5 mm) from the margin of lesions were disinfected and cultured on PDA at 28°C. Five isolates were obtained using the single-spore isolation method. Ten uniformly ripened tomatoes were surface-sterilized with 75% ethanol and wound-inoculated via syringe with 30 μL of a 1×10⁶ spores·mL-1 spore suspension for each of 5 isolates. Sterile water was used as the control. Three replicates were conducted, and all samples were incubated at 28°C, 75% RH in humid chambers. After 2 days, 3 isolates showed the same symptoms as the initial, while the control remained healthy. Three same pathogens were re-isolated from the diseased tomatoes and no pathogen was isolated from the control. The diameter of colonies reached 7 cm in 7 days, appearing creamy white, suborbicular, powdery and flat. Microscopy showed the hyphae were colorless and septate. The conidiophores were erect, and the conidia were cylindrical or ellipsoid with rounded ends, single-celled, colorless, and arranged in tandem. Conidia measured 6.80 ± 0.30 μm in length and 5.51 ± 0.59 μm in width (n=30). DNA was extracted from 7-day-old cultures using a modified cetyl trimethyl ammonium bromide method. Internal transcribed spacer (ITS), 18S ribosomal RNA (18S rRNA), and translation elongation factor 1-alpha (TEF1-α) sequences were amplified using primers ITS1/ITS4, NS3/NS8 (White et al., 1990), and EF1-728F/EF1-1567R (Carbone and Kohn, 1999), respectively. The sequences obtained by polymerase chain reaction (PCR) were sequenced and submitted to GenBank. According to BLAST search, the ITS (PQ579186.1), 18S rRNA (PQ579206.1) and TEF1-α (PQ616986.1) sequences showed 99.48%, 98.03%, and 98.31% similarity to G. candidum (PQ836313.1, AB000652.1 and OQ981192.1, respectively), and matched 383 bp/388 bp, 1142 bp/1182 bp and 638 bp/682 bp of each reference sequences, respectively. Phylogenetic analysis by maximum likelihood method generated based on ITS (388 bp), 18S rRNA (1182 bp) and","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576104","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":"First Report of <i>Exserohilum rostratum</i> Causing Leaf Blight on Maize (<i>Zea mays</i> L.) in India.","authors":"Sumit Kumar Aggarwal, Mohammad Ashraf Ahanger, Alla Singh, Mamta Gupta, Sharanappa Ishwarappa Harlapur, Vivek Shinde, N Mallikarjuna, Harmanjot Kaur, Pardeep Kumar, Ramandeep Kaur, Pooja Goyal, Hanuman Sahay Jat","doi":"10.1094/PDIS-04-25-0730-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0730-PDN","url":null,"abstract":"<p><p>Leaf blight disease of maize was observed during a field survey of Karnataka and Maharashtra in 580 and 360 ha areas, respectively, conducted in the Kharif season of 2020 at V3 to V7 growth stages. The symptomatic plants showed grey to brown spindle-shaped spots. Four fungal isolates (Ero_DWD-27, Ero_DWD-20, Ero_Mya-1 and Ero_Rri-1) were obtained. Isolation used standard tissue culture on PDA, followed by single spore purification (Johnston and Booth 1983). Microscopic observations of pure cultures revealed spore characteristics resembling Exserohilum rostratum. The isolation process was repeated on the same symptomatic leaves from the original locations, confirming morphological and cultural similarity to E. rostratum despite typical turcicum leaf blight symptoms. Pathogenicity was confirmed via whole-plant inoculation on susceptible maize, fulfilling Koch's postulates. The characteristic symptoms on leaves first appear as yellowish, water-soaked spots, progressing to spindle-shaped necrotic lesions. Single-spore cultures' morphological and cultural characteristics revealed their resemblance to E. rostratum. Conidia were dark brown, straight to slightly curved (48.28-65.35 x 12.24-15.84 µm), with six to seven septa and a prominent hilum. Conidia developed with six to seven septa, including two terminal dark and thick septa (Lin et al. 2011). The conidiophores were septate, light to dark brown, geniculate, single or in groups of 2-6, and measured about 140-350 x 6-14 µm in size. Colony color varied on PDA after 14 days, from dark grey to greyish white with circular or filamentous growth forms and mostly regular margins. Molecular identification used ITS, β-tubulin, and LSU regions amplified with standard primers (White et al. 1990; Kroon et al. 2004; Fliegerová et al. 2006; Manzar et al. 2022; Anwer et al. 2022). Sequences were deposited in GenBank (NCBI) under accession numbers PQ394595-PQ394596 and PQ408655-PQ408656 (ITS), PQ432870-PQ432871 and PQ438739-PQ438740 (β-tubulin), and PQ300560, PQ373037, PQ373042, and PQ375114 (LSU). BLAST analysis confirmed the high similarity of isolates Ero_DWD-27, Ero_DWD-20, Ero_Mya-1, and Ero_Rri-1 to E. rostratum. A maximum-likelihood phylogenetic tree based on combined ITS, β-tubulin, and LSU sequences corroborated this identification. Based on colony and morphological characters, pathogenicity, and confirmation at the molecular level, the isolated fungal isolates were identified as E. rostratum. Although E. rostratum has been reported to cause the leaf spot on maize in Henan, China (Xie et al. 2022). To our knowledge, this is the first study of E. rostratum causing maize leaf blight in India. The study underscores the need for accurate pathogen identification and management, as maize is India's third major cereal.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576088","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":"First report of <i>Fusarium oxysporum</i> causing wilt on <i>Perilla frutescens</i> in China.","authors":"Shan Zhong, LingYu Wang, Bin Wang, Jian-He Wei, Weiwei Gao, Yong Li","doi":"10.1094/PDIS-03-25-0467-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0467-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Perilla frutescens, commonly known as \"ZI SU\", is an herbaceous plant known for its culinary and medicinal properties and is distributed throughout China (Igarashi and Miyazaki, 2013). In October 2023, wilt symptoms were observed on P. frutescens plants in Shaowu (27.34°N, 117.49°E), Fujian province, China (incidence rate: 30%). The stems first showed discoloration, which transitioned from green to dark brown or black. The leaves drooped and often curled, eventually drying out. Fifteen typical symptomatic stems were randomly selected and samples were taken from the margins of the lesions and cut into 5 × 5-mm pieces. The samples were surface sterilized with 5% sodium hypochlorite solution for 1 min, rinsed with sterile water three times, and dried. Samples were incubated on potato dextrose agar (PDA) medium for 5 d at 25°C in the dark, then transferred using monospore isolation to new PDA plates and incubated for another 5 d at 25°C in the dark. Thirteen of the 20 isolates obtained had similar colony morphology (isolation rate 65%). The front of colonies exhibited a flat, cottony texture. The reverse side of the colonies was pale yellow. Two representative isolates, 1380 and 1383, were cultivated on carnation leaf agar (CLA) medium. Microconidia of the isolates were oval, cylindrical or ovate, and were 5.56 to 15.26 × 2.82 to 4.49 μm (n = 50). Macroconidia had 2 to 5 septa, usually 3 septa, and were straight or slightly curved, 2.6 to 5.47 × 20.8 to 42.4 μm (n = 50). Chlamydospores were roundish, terminal or intercalary. The morphological characteristics were consistent with the description of Fusarium (Leslie and Summerell 2006). DNA was extracted from the two isolates using the cetyltrimethylammonium bromide (CTAB) method. The partial internal transcribed spacer (ITS) region, the translation elongation factor (TEF-1α) and partial RNA polymerase second largest subunit (RPB2), were amplified (GenBank accession numbers for TEF-1α were PV057161 and PV057162, for RBP2 were PV057159 and PV057160, and for ITS were PV639174 and PV639175 for 1380 and 1383, respectively) (Crous et al 2009). When compared with other Fusarium species in GenBank, both isolates exhibited 99.85% (TEF-1α, MN417200), 99.90% (RBP2, AB986568), and 100% (ITS, OR753367) similarity with Fusarium oxysporum. A phylogenetic tree which combined ITS, TEF-1α and RPB2 was constructed using MEGA6 with the maximum likelihood method (Xu et al 2022), and the two isolates clustered with F. oxysporum with 99% bootstrap values. To test pathogenicity, a conidial suspension of 1383 with a concentration of 1 × 106 conidia/mL was sprayed on three stems of one-month-old P. frutescens seedlings. For the control, sterile water was sprayed on two control stems and there were 3 biological replicates. Seedlings were covered with plastic film for 24 h and kept in a culture room at 25°C, and inoculated stems exhibited similar symptoms to those in the field 4 days' post inoculation, while control stems ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576089","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":"First Report of <i>Bipolaris sorokiniana</i> Causing Spot Blotch on Wheat (<i>Triticum aestivum</i> L.) from the Kashmir Valley of Western Himalayas, India.","authors":"Nikita Aggarwal, Mukesh Rathore, Mehnaz Shakeel, Mohammad Anwar Khan, Reyazul Rouf Mir","doi":"10.1094/PDIS-03-25-0697-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-25-0697-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;The Kashmir Valley, in the Pir Panjal range, is bordered by the Himalayas to the east and the Karakoram to the north, creating a unique geographical setting in the Western Himalayas. Its temperate climate with high rainfall, temperature fluctuations, warm summers, and cool winters fosters various wheat diseases. Wheat, a vital cereal crop supporting the livelihoods and food security of Kashmir's population, is significantly impacted by diseases, particularly spot blotch caused by Bipolaris sorokiniana. Although B. sorokiniana has been reported in warmer, humid regions including Bihar, Gujarat, Rajasthan, and Uttar Pradesh (Acharya et al. 2011), its presence in the cooler climate of Kashmir has not been documented. In April 2023 and 2024, spot blotch symptoms were consistently detected in the wheat research fields of SKUAST- Kashmir, with an incidence ranging from 40-50%. Initial symptoms included light brown, oval to elliptical necrotic spots that enlarged, leading to chlorosis and leaf death. To identify the causal pathogen, symptomatic leaf tissue was excised from the diseased-healthy tissue interface, surface disinfected in 1% NaOCl for 1 min, rinsed thrice with sterile water, dried, and plated onto PDA amended with 100 ppm streptomycin sulfate. After five days at 25°C, the putative causal agent was isolated from 90% of symptomatic samples and purified via single hyphal tip technique. The culture initially appeared velvety and olive brown with a loose cottony mass of white mycelium, turning black with profuse sporulation after 8 days. The conidia were dark olivaceous brown and obclavate to cylindrical or broadly ellipsoidal with tapered ends, featuring three to eight distosepta and measuring 50-100 × 10-17.5 µm. Based on symptoms and morphological characteristics described by Manamgoda et al. (2014), the fungus was tentatively identified as B. sorokiniana. For molecular identification, eight representative isolates were amplified and Sanger sequenced using primer pairs for the internal transcribed spacer (ITS) region (ITS1/ITS4) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH) gene (GPD1/GPD2) (White et al. 1990; Berbee et al. 1999). Sequences were deposited in GenBank (ITS:PV162803-PV162810; GAPDH:PV295261-PV295268). BLAST searches of the obtained sequences revealed 98-100% for ITS and 97-100% for GAPDH homology with B. sorokiniana sequences in GenBank, OR575723 (isolate HUBS-54) and OR260701 (isolate LB-22), respectively. To confirm pathogenicity, 4 replicates of 21-day old plants of the susceptible variety Shalimar Wheat-2 were sprayed with a conidial suspension (1 × 10⁵ conidia/ml) and incubated in plastic bags for 24 h in a greenhouse (temperature: ~25±2°C). Control plants were sprayed with sterile water. Inoculated plants developed symptoms similar to those observed in the field within 7 days, while controls remained healthy. The pathogen was reisolated from lesions and confirmed as B. sorokiniana based on morphology and resequ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576087","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":"First Report of Anthracnose on <i>Camellia oleifera</i> Caused by <i>Colletotrichum fioriniae</i> in Hunan, China.","authors":"Hong Liu, Li'ang'xuan Qu, Zhaohui Hu, Jinghao Dai, Yuanye Zhu, He Li, Guo Ying Zhou","doi":"10.1094/PDIS-01-25-0221-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0221-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Camellia oleifera, known as the tea-oil tree, is a multifunctional woody oil crop renowned as the \"Oriental olive\". During 2023-2024, in Jishou City (28°17'N, 109°29'E), Hunan Province, China, 100% of tea-oil tree plants and over 40% of the leaves on each plant exhibited typical anthracnose symptoms. Initially, infected areas displayed yellowish regions. As the disease progressed, brown necrotic lesions with dark brown margin and tiny, dark dots emerged. Diseased leaves were collected, rinsed under running water, and cut into small pieces (5×5 mm) from the edges of the lesions. These pieces were surface-disinfected with 70% ethanol for 30 seconds, followed by 2% NaOCl for 2 minutes, and then rinsed three times with sterile water. The disinfected samples were placed on potato dextrose agar (PDA supplemented with 100 mg/L streptomycin sulphate) and incubated at 28℃ in the dark. After 3 days, mycelia plugs from the infected tissues were transferred to fresh PDA for subculturing. Twenty isolates displaying two distinct morphological types were obtained. One representative strain from each morphology type (designated as LinC-A and LinC-B) was randomly selected for further study. On PDA, LinC-A developed cottony, raised colonies that were initially white on the obverse and yellowish on the reverse. Over time, the colonies turned reddish to deep red at the center, with red pigmentation on the reverse side. LinC-B colonies were initially white to yellowish on the obverse and deep yellow on the reverse, later turning yellowish to deep pink on both sides, producing pink pigmentation. Conidia of both strains were single-celled, hyaline, fusiform with acute ends, and smooth-walled. The average conidial size of LinC-A was 12.9 ± 1.6 × 5.8 ± 1.6 μm (n=100), while that of LinC-B was 15.6 ± 2.2 × 6.4 ± 0.7 μm (n=100). Additionally, brown setae were observed surrounding dark brown acervulus. For molecular identification, the ITS region and four other genes (GAPDH, CHS-1, ACT, and TUB2), were amplified and sequenced. The sequences were deposited in GenBank (ITS: PQ825943, PQ825944; GAPDH: PQ827013, PQ827014; CHS-1: PQ827015, PQ827016; ACT: PQ827017, PQ827018; TUB2: PQ827019, PQ827020). Phylogenetic analysis based on the combined ITS, GAPDH, CHS-1, ACT, and TUB2 sequences confirmed that both LinC-A and LinC-B clustered with C. fioriniae strains, consistent with the homology search results. Therefore, based on morphological and molecular evidence, LinC-A and LinC-B were identified as C. fioriniae. To fulfill Koch's postulates, pathogenicity tests were conducted using conidial suspensions of 1×106 conidia/mL on tea-oil tree plants. A 50 μL aliquot of the suspension conidia was applied on each leaf, while control leaves were inoculated with an equivalent volume of sterile distilled water. Inoculated plants were maintained in humid chambers at 28℃ under a 12-hour light-dark cycle. Six leaves were used for each of the three replicates. After five days, all inocula","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576091","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":"First Report of Leaf Anthracnose on <i>Dendrobium nobile</i> Caused by <i>Colletotrichum citricola</i> in China.","authors":"Youchao Dang, Chaoqin Wang, Ziyi Ren, Jiaqi Gao, Luping Qin, Bo Zhu","doi":"10.1094/PDIS-04-25-0910-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0910-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Dendrobium nobile, a rare orchid in Orchidaceae, is a traditional Chinese medicinal herb known for its diverse biological activities, including anti-tumor, anti-aging, and hypoglycemic effects (Fan et al. 2023). In February 2025, symptoms of leaf anthracnose were observed on D. nobile plants growing in the medicinal plant plantation of Zhejiang Chinese Medical University (30.08°N, 119.88°E), China. The affected area covered approximately 25 m2, with a disease incidence of around 55%. The disease symptoms began at the leaf edges, where light yellow spots first appeared. As the lesions expanded, they turned into irregular brown or black patches. The edges of the infected leaves dried out, forming a large necrotic area with dark brown spots, ultimately leading to defoliation. Six symptomatic leaf samples (5×5 mm) were surface sterilized with 75% ethanol for 30 s, followed by 2.5% NaClO for 1 minute. Afterair-drying, the tissues were placed on potato dextrose agar (PDA) medium and incubated at 28°C for five days. Two fungal isolates, DNLP07 and DNLP08, were obtained using the hyphal-tip isolation method. On PDA, the colonies appeared white and cottony on the surface, with a white reverse side, yellow-brown discoloration, and concentric rings visible on both sides. The conidia were single-celled, aseptate, cylindrical to oval, measuring 21.6-31.1 × 9.5-14.9 μm (average 25.9 × 11.7 μm; n=50). These morphological characteristics were consistent with those of Colletotrichum citricola (Fu et al. 2019). Six gene regions were amplified: internal transcribed spacer (ITS), actin (ACT), calmodulin (CAL), chitin synthase (CHS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and beta-tubulin 2 (TUB2). The following primer sets were used: ITS1/ITS4, ACT-512F/ACT-783R, CL1C/CL2C, CHS-79F/CHS-345R, GDF/GDR, and T1/Bt2b, respectively (Weir et al. 2012). The resulting sequences were submitted to GenBank with the following accession numbers: ITS: PV271806, PV271807; ACT: PV287640, PV287641; CAL: PV287638, PV287639; CHS: PV287642, PV287643; GAPDH: PV287644, PV287645; TUB2: PV287646, PV287647. BLASTn analysis showed that the isolate DNLP08 shared 99% to 100% sequence identity with the C. citricola type strain CBS 134228, including: ITS (KC293576; 468/468 bp), ACT (KC293616; 268/270 bp), CAL (KC293696; 424/425 bp), CHS (KC293792; 278/278 bp), GAPDH (KC293736; 239/239 bp), and TUB2 (KC293656; 487/488 bp). A maximum likelihood phylogenetic tree was constructed using the concatenated sequence dataset in MEGA 11, which showed that both isolates clustered with C. citricola. To confirm pathogenicity, a conidial suspension of isolate DNLP08 (1×106 spores/mL) was sprayed onto three healthy D. nobile plants. Three additional plants were treated with sterile distilled water as controls. All plants were maintained at 28°C with 85% relative humidity and a 12-hour photoperiod. After 12 days, the inoculated plants developed symptoms identical to those observed in the field, w","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576092","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":"First Report of Leaf Spotting Disease Caused by <i>Plectosphaerella alismatis</i> of Alisma (<i>Alisma plantago-aquatica</i> Linn.) in China.","authors":"Wenhui Chen, Yuhong Pu, Qi Zhang, Kejun Chen, Zizhong Tang, Yanger Chen, Cairong Yang, Shu Yuan, Ming Yuan","doi":"10.1094/PDIS-04-25-0914-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0914-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Alisma (&lt;i&gt;Alisma Plantago-Aquatica&lt;/i&gt; Linn.) is a traditional medicinal aquatic plant in China. Since August 2024, a leaf spotting disease of Alisma, with an average incidence of 70% ~ 90% across fields, has been observed in Yucheng District, Ya`an City, Sichuan Province, China (29°98'N and 102°98'E). The round red-brown spots were first observed on the outer leaves, and then the larger spots merged, resulting in leaf yellowing and death, ultimately leading to approximately 35% yield loss. To isolate pathogenic microorganisms, ten symptomatic leaf samples were collected and disinfected with 75% ethanol for 30 s, followed by 0.5% NaClO for 2 min. After rinsing three times with sterile water, the samples were transferred to potato dextrose agar (PDA) medium supplemented with 50 mg L&lt;sup&gt;-1&lt;/sup&gt; streptomycin sulfate, and cultured in the dark at 28°C. After 7 days, the hyphal tips of the emerging colonies were transferred to fresh PDA for purification. The eight isolates obtained were named ZX1 to ZX8. We initially tested the isolates' pathogenicity on detached leaves. 5 mm PDA agar blocks of the isolates were inoculated onto healthy detached leaves, with blank PDA agar as the control. After 7 days, only the leaves inoculated with ZX6 showed spots and yellowing symptoms similar to those observed in the field. The leaves inoculated with other isolates and the control showed no symptoms. Consequently, we further tested the pathogenicity of ZX6 on whole plants. Healthy Alisma seedlings (2-month-old) were inoculated with ZX6 conidial suspension (10&lt;sup&gt;6&lt;/sup&gt; spores/ml) and with clean water as the control. Plants were incubated in a growth chamber (22-28°C, 85% relative humidity, 16 h light and 8 h dark). The pathogenicity test was repeated twice. Typical leaf spot symptoms were observed on the inoculated leaves after 7 days. The pathogens, reisolated from infected leaves, displayed the same morphological traits as the initial isolates ZX6, according to Koch's requirements. This result indicated that ZX6 is the pathogen leading to leaf spotting disease on Alisma. Colonies of ZX6 were initially white and fluffy on PDA, and gradually turned salmon pink, with few aerial hyphae and slimy surfaces. Conidia were smooth, with 0-1 septa, elliptical or ovoid, measuring 12.2 ~ 19.4 × 2.2 ~ 3.4 µm (average 15.5 × 2.7 µm, n=100). These morphological characteristics were similar to &lt;i&gt;Plectosphaerella&lt;/i&gt; spp. (Carlucci et al. 2012; Pitt et al. 2005). For species identification, we extracted mycelium genomic DNA and performed amplification of the internal transcribed spacer (ITS), large subunit of rDNA (LSU), and calmodulin (CaM) genes using primer pairs ITS1/ITS4 (White et al. 1990), LR0R/LR5 (Hopple et al. 1999), and CL1/CL2 (Weir et al. 2012), respectively. In a BLAST search, the ITS, LSU, and CaM sequences showed 99.39% (492 / 495 bp), 100% (850 / 850 bp), and 100% (479 / 479 bp) similarity to &lt;i&gt;Plectosphaerella alismatis&lt;/i&gt; strain CBS 113362 in the N","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576093","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":"Characterization and aggressiveness of <i>Fusarium</i> spp. associated with root and stem rot in <i>Carica papaya</i> in Northeast Brazil.","authors":"Jarlan Lucas Santos Silva, Elisandra Alves Bento, Ana Paula de Moura, Tatianne Raianne Costa Alves, Igor Vinícius Pereira da Silva, Vitória Maria Gomes Souza, Vanuza Maria Avila Filha, Jemerson Willami Silva Ribeiro, Washington Luis da Silva, Márcia Michelle Queiroz Ambrosio","doi":"10.1094/PDIS-02-25-0400-RE","DOIUrl":"https://doi.org/10.1094/PDIS-02-25-0400-RE","url":null,"abstract":"<p><p>In the past five years, papaya farmers in northeastern Brazil have been reporting major losses in fruit production, up to 50% in some years, due to diseases caused by soil-borne pathogens. To diagnose the causal agents of this disease's complex in the region (root and stem rots), we collected samples of root and stem from papaya plants in commercial fields exhibiting yellowing, wilting, and plant collapse. Fifteen Fusarium isolates were obtained from six production areas sampled, and Koch's postulates were carried out to confirm the pathogenicity of these isolates. Five species were identified causing this disease in the region: F. falciforme (FSSC 3+4), F. petroliphilum (FSSC 1), F. pernambucanum (FIESC 17), F. sulawesiense (FIESC 16), and F. delphinoides (FDSC). Among these species, the most aggressive was F. delphinoides, followed by F. pernambucanum, F. falciforme, and F. petroliphilum, and the least aggressive was F. sulawesiense. Our findings will aid the development of strategies to manage these disease complexes to help farmers reduce the damage caused by these pathogens in papaya in Brazil and other papaya production areas in the world.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576086","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":"First Report of <i>Xanthomonas sacchari</i> Causing Bacterial Panicle Blight of Rice in the United States.","authors":"Jobelle Bruno, Inderjit Barphagha, John Ontoy, Felipe Dalla Lana, Jong Hyun Ham","doi":"10.1094/PDIS-04-25-0819-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-25-0819-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Rice (&lt;i&gt;Oryza sativa&lt;/i&gt;) plants showing severe leaf and panicle blight symptoms were observed and collected from four field plots in Louisiana in summer 2023. As the observed symptoms looked like bacterial leaf and panicle blight caused by &lt;i&gt;Pantoea ananatis&lt;/i&gt; (Bruno et al. 2025) or bacterial panicle blight caused by &lt;i&gt;Burkholderia glumae&lt;/i&gt; and &lt;i&gt;B. gladioli&lt;/i&gt; (Nandakumar et al. 2009), we presumptively attempted to isolate one of these bacterial pathogens as the causal agent. Bacteria were isolated from the symptomatic seeds, which were surface sterilized, dehulled and ground in sterile distilled water using a sterile mortar and pestle. The homogenate was spread on the CCNT medium (Kawaradani et al. 2000) and LB agar supplemented with nitrofurantoin (50 µg/ml) and cycloheximide (50 µg/ml). After 72 h incubation at 41⁰C, round, smooth and faint, yellow-colored bacterial colonies appeared on both CCNT and LB agar plates. Unexpectedly, all six bacterial isolates from rice samples were initially identified as &lt;i&gt;Xanthomonas sacchari&lt;/i&gt; based on PCR-amplified 16S rDNA sequences using the primers fD1 (5'-CCGAATTCGTCGACAACAGAGTTTGATCCTGGCTCAG-3')/rD1 (3'-CCCGGGATCCAAGCTTAAGGAGGTGATCCAGCC-5') (Weisburg et al. 1991), regardless of their sampling locations. Whole genome sequencing analyses (NCBI Accession ID: PRJNA1223440) performed through a hybrid sequencing approach using Oxford Nanopore sequencer & Illumina NextSeq2000 system (Plasmidsaurus Inc., California, USA) further confirmed that all six strains belong to &lt;i&gt;X. sacchari&lt;/i&gt;. To satisfy Koch's postulates, each of the six strains LXP-1780, LXP-1783, LXP-1790, LXP-1791, LXP-1792, and LXP-1793 was confirmed for its pathogenicity to rice through two inoculation methods, using one-month-old plants (cv. Kitaake) at tillering stage; 1) pricking the stems with a sterile toothpick touched to the overnight grown bacterial culture on LB agar (~ 5-8 x 10&lt;sup&gt;5&lt;/sup&gt; bacterial cells per tip) and 2) clipping the leaves with scissors dipped in the bacterial suspension containing ~1 × 10&lt;sup&gt;8&lt;/sup&gt; bacterial cells per mL of sterile distilled water. This virulence assay was conducted twice with three replications for each strain, and rice plants inoculated with sterile distilled water were included as the negative control. By twenty-seven days after inoculation (DAI), the inoculated plants developed symptoms on leaves and panicles, which were similar to the symptoms initially observed in the field. Besides blight symptoms and water-soaked lesions in the leaves, the most noticeable symptom observed was the blackening or darkening of the leaf tips, which appeared as dark spots or streaks. In panicles, panicle blight-like symptoms, such as grain discoloration and darkening of rice hulls, were observed. The bacteria were reisolated from each artificially inoculated plant and their identity were validated to be &lt;i&gt;X. sacchari&lt;/i&gt;. To our knowledge, this is the first report of rice disease caused by &lt;","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576090","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}