Plant disease最新文献

{"title":"First report of ergot caused by <i>Claviceps clavispora</i> in switchgrass (<i>Panicum virgatum</i> L.) in Georgia, USA.","authors":"Samikshya Rijal, Morgan Willis, Bikash Ghimire, Suraj Sapkota, Thomas Pendergast, Mitra Mazarei, Gary C Bergstrom, Neal Stewart, Ali M Missaoui, Katrien Devos, Alfredo Martinez-Espinoza, James Buck, Bochra Amina Bahri","doi":"10.1094/PDIS-07-24-1532-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-07-24-1532-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Switchgrass (Panicum virgatum L.) is a North American grass species with biofuel potential. Claviceps spp. is known to infect the florets of various grass species, initially characterized by a sticky honeydew exudate and later as sclerotium replacing the seed in the infected ovary (Tanaka et al 2023). Since 2019, from July to October, switchgrass panicles in Georgia have been observed with honeydew and black sclerotia. The disease was first noted on some of the 285 accessions of the genome-wide association study (GWAS) panels at the University of Georgia's Iron Horse Farm in Watkinsville and Gibbs Farm in Tifton, GA. In Watkinsville, GA, ergot incidence was 5%, 6%, 65% and 54% in 2019, 2020, 2021 and 2022, respectively. Symptomatic panicles with honeydew and sclerotia were collected in 2021 (sample Scl) and 2023 (samples Cla_M and ATH20cl) from Watkinsville, GA. Under microcopy, panicles with honeydew symptoms had mycelium and conidia (9 μm long [range of 5-13 μm] and 4 μm wide [3-5 μm]) consistent with Claviceps spp. (Tooley et al. 2001). Sclerotia were 1.5 mm long (range 1-3 mm). Sclerotia were surface sterilized for 3 minutes in 5% NaOCl, followed by 70% ethanol then rinsed three times in distilled water. Sterilized sclerotia were plated on potato dextrose agar and placed on bench top with a 12-hour day/night cycle at room temperature (22°C) (Singh 1976). After 2 months, the sclerotia produced sterile apothecia. For molecular identification, genomic DNA was extracted from three honeydew samples following the protocol of Doyle and Doyle (1987). The internal transcribed spacer (ITS) region and RNA polymerase second largest subunit (RPB2) gene were amplified using ITS4/ITS5 (White et al. 1990) and 5F2/7CR (Liu et al. 1999) primer sets. The ITS region of ATH20cl, Cla_M, and Scl (GenBank nos. PP546317- PP546319) showed 92.83-97.48% identity to C. clavispora (NR_163506.1). The RPB2 region of ATH20cl, Cla_M, and Scl (GenBank nos. PP573916- PP573918) showed 97.46-97.72% identity to C. clavispora (LT216566.1). The maximum likelihood tree constructed in MEGA-X (Kumar et al. 2018) using concatenated ITS (539 bp) and RPB2 (792 bp) gene sequences from this study and eleven reference sequences from Tanaka et al. (2023), revealed close relatedness of ATH20cl, Cla_M, and Scl to C. clavispora under section Pusillae. The pathogenicity test for samples ATH20cl and Cla_M was conducted in the greenhouse on switchgrass cultivar 'Alamo' grown in injection molded pots containing Sungro professional growing mix. Three replicates plants at reproductive (R3) growth stage were inoculated by immersing panicles in 105 spores/ml suspension for 5 minutes and bagged for 3 days (Tooley et al. 2001). Control plants were immersed in distilled water. Honeydew symptoms and sclerotia appeared within 7- and 90-days post-inoculation, respectively, whereas control plants remained symptom-free. The honeydew collected from the infected Alamo panicles were reconfirmed to produce si","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505822","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>Fusarium</i> and <i>Neocosmospora</i> Species Associated with the Decline of <i>Metasequoia glyptostroboides</i> in China.","authors":"Duanchong Liu, Wenxia Zhao, Jianping Xia, Sanshan Cai, Wen-Xia Huai, Ru-Bin Zhang, Bin Li, Hualan Peng, Shijun Zhang","doi":"10.1094/PDIS-01-24-0201-RE","DOIUrl":"https://doi.org/10.1094/PDIS-01-24-0201-RE","url":null,"abstract":"<p><p>During surveys conducted in 2020, severe symptoms associated with death and decline were observed on >30-year-old <i>Metasequoia glyptostroboides</i> (Chinese redwood) trees in the shelter-forests along Yangtze River in Jingzhou city, Hubei province, China. A previous study showed that <i>Phytophthora acerina</i> was one of the causal agents of the decline of the Chinese redwood. In this study, a total of 147 fungal isolates were obtained from the diseased roots and xylem of trunks of declining <i>M. glyptostroboides</i> trees. Through morphology and multi-locus phylogenetic analysis, these isolates were identified as eight species belonging to the genera <i>Fusarium</i> and <i>Neocosmospora</i> including <i>F. fujikuroi</i>, <i>F. irregulare</i>, <i>F. odoratissimum</i>, <i>F. reticulatum</i>， <i>N. falciformis</i>, <i>N. keratoplastica</i>, <i>N. solani</i>, and <i>N. tonkinensis</i>. Single inoculation and co-inoculation with <i>P. acerina</i> assays of these <i>Fusarium</i> and <i>Neocosmospora</i> species were then performed to test pathogenicity on three-year-old seedlings of <i>M. glyptostroboides</i>. Lesions (i.e., on seedling stems) caused by species of the genera <i>Neocosmopora</i> and <i>Fusarium</i> were smaller than those caused by <i>P. acerina</i>. Co-inoculation of <i>F. fujikuroi</i> and <i>P. acerina</i>, as well as the co-inoculation of <i>F. reticulatum</i> and <i>P. acerina</i> caused larger lesions than inoculations with <i>P. acerina</i> alone. All these species of <i>Fusarium</i> and <i>Neocosmospora</i> were shown to have the potential to be pathogenic to <i>M. glyptostroboides</i>. This study provided evidence that the decline of <i>M. glyptostroboides</i> in Jingzhou is a disease complex.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505814","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>Colletotrichum spaethianum</i> Causing Anthracnose on Jiaotou (<i>Allium chinense</i> G. Don) in China.","authors":"Changyin Fan, Jia En Su, Ruizhu Jin, Jie Zhong, Xiao Gang Li, Yi Chen, Zhijuan Yang","doi":"10.1094/PDIS-06-24-1313-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-06-24-1313-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Jiaotou (Allium chinense G. Don) is a culinary and aromatic herb belonging to the family Amaryllidaceae. It is native to China and cultivated for its culinary uses in many other countries, which also possess high medicinal value in traditional Chinese medicine (Rhetso et al. 2020). In March 2023, a disease resembling anthracnose was detected in the fields of Changde city, Hunan Province, China. The symptoms manifested as yellow to brown necrotic spots located at the tip or middle of the blade. The lesions tended to wrinkle, leading to leaf distortion, thinning, and wilting. This disease has a high incidence rate of approximately 50% in an area of nearly 20 hectares. Ten symptomatic plants were collected for pathogen isolation. The leaf tissues were surface sterilized using 70% ethyl alcohol and 2% sodium hypochlorite, rinsed with sterile distilled water, and then transferred to potato dextrose agar (PDA) and incubated at 26°C in the dark. Ten colonies with similar cultural morphology were selected from the 10 affected plant samples. The fungal strains produced densely aerial mycelium on PDA, displaying off-white to gray-brown coloration. Conidia were hyaline, curved or slightly curved, aseptate, with a rounded apex and truncate base, contained oil globules, and measuring 21.0 to 29.0 × 4.1 to 5.3 μm (n = 50. Appressoria were dark brown, irregular in shape, partially lobed, and measured 6.5 to 15.5 µm long × 5.0 to 10.5 µm wide. Setae were straight, dark brown, with two- to three-septate, 78.5 to 155.4 μm long (n = 50). These morphological characteristics were similar to Colletotrichum spaethianum (Damm et al. 2009). The internal transcribed spacer (ITS) region of rDNA, actin (ACT), chitin synthase (CHS-1) and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes of three representative strains, JT-1, JT-2 and JT-3, were amplified and sequenced as described in Weir et al. (2012). These sequences were 99 to 100% identical to corresponding sequences of C. spaethianum strains (565/569 bp, MN396364.1 for ITS; 565/569 bp, MN433299.1 for ACT; 262/263 bp, MN433298.1 for GAPDH; 272/272 bp, MH020773 for CHS-1, respectively) (Zhong et al. 2020; Liu et al. 2020; Sun et al. 2020). A concatenated phylogenetic tree showed that all three strains were clustered within the C. spaethianum clade. The sequences of isolate JT-1 were deposited in GenBank (accession nos. PP911453, PP911607, PP911605, and PP911606 for ITS, ACT, GAPDH and CHS-1, respectively). For pathogenicity assays, 1-month-old seedings of A. chinense in plots were inoculated by spraying with a conidial suspension (1 × 105 conidia/ml) until runoff. Control plants were sprayed with sterilized water. All the inoculated plants were kept in a greenhouse at 25°C with a 12-h/12-h light/dark cycle. The experiment was conducted twice with three replications each. After 7 days, symptoms similar to those observed in the field developed on leaves of the inoculated plants, whereas the control plants remaine","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505819","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 citrus yellow vein clearing virus (CYVCV) on citrus in Italy.","authors":"Maria Cinque, Maria Minutolo, Ciro Pugliese, Raffaele Vittorio Griffo, Francesco Di Serio, Beatriz Navarro, Daniela Alioto","doi":"10.1094/PDIS-06-24-1208-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-06-24-1208-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;In March 2024, symptoms of vein clearing (Fig. S1) were observed on leaves of six lemon (Citrus limon (L.) Burm. f.) trees grown in a private garden in Palma Campania (Campania region, Italy). Symptoms strongly resembled those of yellow vein clearing disease, caused by Potexvirus citriflavivenae (citrus yellow vein clearing virus, CYVCV), genus Potexvirus, sub-genus Mandarivirus (Loconsole et al., 2012; Cui et al., 2018). CYVCV was reported in Pakistan, India, China, Iran, Turkey, Korea and USA (Abrahamian et al., 2024; Catara et al., 1993; EPPO, 2024; Sun and Yokomi, 2024; Jin et al., 2024). Since 2022, considering the potential impact of this emerging virus, CYVCV has been included in the EPPO alert list and it has not been reported in any European Union (EU) Member State where the virus is not regulated. To ascertain possible infection with CYVCV, leaf samples were collected and tested by reverse transcription polymerase chain reaction (RT-PCR). Total nucleic acids (TNAs) from leaves of the symptomatic lemon and non-symptomatic lemon and sweet orange (Citrus sinensis (L.) Osbeck) trees grown in the same garden, were extracted using the silica-capture extraction method (Foissac et al. 2001). TNAs were tested by RT-PCR using CYVCV specific primers (Table S1) designed by Chen et al., (2014) targeting the coat protein gene. All symptomatic trees and an asymptomatic sweet orange from the same garden tested positive generating an amplicon of the expected size (612 bp). Direct Sanger sequencing of amplicons obtained from two symptomatic lemons and one non-symptomatic sweet orange (An PP842725-PP842727) followed by BLAST search showed 97.9-98.08% sequence identity (query coverage 100%) with CYVCV isolates previously reported from a mandarin (An OQ418501) and a lemon (An OQ418493) in California. In contrast, no amplicons were detected in samples from non-symptomatic lemon trees. Virus identity was confirmed by RT-PCR with different primers (Table S1) targeting the RNA-dependent RNA polymerase gene of CYVCV. Amplicons of the expected size (832 bp) were obtained only from samples previously tested positive to the virus and their sequences determined by Sanger sequence (An PQ284953-PQ284955) showed 97.98-98.11% identity (query coverage 100%) with CYVCV sequence previously reported from a mandarin (An OR251443) in New Delhi. Since CYVCV is transmitted by insects (Önelge et al., 2011a, 2011b, Zhang et al., 2018, 2019), TNAs (Foissac et al., 2001) from Aphis aurantii infesting symptomatic lemons, and of A. spiraecola and Dialeurodes citri infesting symptomatic lemon and non-symptomatic sweet orange trees were assayed by RT-PCR with primer pairs designed by Chen et al., (2014). Three samples of 15 specimens from three different trees were tested for each insect. In contrast to D. citri, which tested negative, an amplicon of 612 bp was detected from A. aurantii and A. spiraecola and Direct sequencing of amplicons (An PP842721-PP842724) confirmed the natu","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505821","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 Alternaria leaf spot caused by <i>Alternaria brassicae</i> on broccoli in North Carolina, United States.","authors":"Ella Hinchliffe, Anthony P Keinath, Inga Meadows","doi":"10.1094/PDIS-04-24-0740-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-24-0740-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;In September 2023, broccoli (Brassica oleracea var. italica) 'Sweet Bunch' plants on an organic farm in Buncombe County, North Carolina (NC), displayed symptoms of Alternaria leaf spot. Disease affected 10 to 20% of leaf area on all (approximately 30) plants. Lesions were dark brown with chlorotic halos, irregular in shape, and ≤3 cm in diameter. Leaf samples were incubated in a humidity chamber for 24 h, and the pathogen was putatively identified as Alternaria brassicae based on conidial morphology (Rimmer et al. 2007; Supplemental Fig. 1). Leaf pieces (2 x 2 mm) spanning lesion edges were surface-disinfested (1% sodium hypochlorite solution) for 1 min, rinsed in sterile distilled water, embedded in potato dextrose agar, and incubated at 22°C with a 12-h photoperiod. A pure culture was obtained by transferring a hyphal tip onto 20% V8 juice agar and incubated as above. After 10 d, colonies consisted of concentric zones of white to brown mycelia with white, aerial mycelia. Within 7 d, conidia measuring 80 to 150 µm long with 0 to 3 longitudinal septa, 6 to 15 transverse septa, and a long beak were observed, and the isolate was putatively identified as A. brassicae (Rimmer et al. 2007). To confirm identification, DNA was extracted from mycelia and subjected to PCR using primers to amplify a portion of the internal transcribed spacer of rDNA (ITS: ITS1/ITS4) (White et al. 1990), the transcription elongation factor-1 (tef1: EF1-728F/EF1-986R) (Carbone and Kohn 1999), and the glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH: gpd1/gpd2) (Berbee et al. 1999). Amplicons were sequenced at Eton Bioscience (Durham, NC) and subjected to BLAST analysis in NCBI GenBank. Sequences matched (99.5 to 100% identity) A. brassicae CBS 116528 accessions KC584185 (ITS), KC584641 (tef1), and KC584102 (GAPDH) (Woudenberg et al. 2013). All sequences were deposited in NCBI GenBank (accessions PP584506, PP584507, PP584508). To confirm pathogenicity on broccoli and kale (B. oleracea var. sabellica), 5-week-old plants of broccoli 'Sweet Bunch', 'Eastern Crown', and 'Green Magic' and kale 'Winterbor', 'Darkibor', and 'Oldenbor' grown in 10-cm-diameter pots were separated by crop type and arranged in four randomized complete blocks by cultivar. Each block contained single-plant replicates of each cultivar that were either inoculated or non-inoculated. Conidia of A. brassicae obtained from 10-d-old cultures (3.5 x 103 conidia/ml) were sprayed onto each inoculated plant until run-off. Non-inoculated plants were sprayed with distilled water. Plants were incubated in a humidity chamber alternated with ambient greenhouse conditions every 48 h for 10 d, with average greenhouse temperatures ranging from 15 to 28°C. The experiment was conducted twice. Dark brown to gray lesions measuring 1 to 3 mm in diameter were observed on leaves of all inoculated plants within 5 d of inoculation (Supplemental Fig. 2), and non-inoculated plants remained healthy. On broccoli plants, lesion","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505820","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":"Host Genetic Resistance in <i>Brassica napus</i>: A Valuable Tool for the Integrated Management of the Fungal Pathogen <i>Leptosphaeria maculans</i>.","authors":"Susan J Sprague, Angela P Van de Wouw, Stephen J Marcroft, Abebayehu G Geffersa, Alexander Idnurm, Luke G Barrett","doi":"10.1094/PDIS-04-24-0756-RE","DOIUrl":"10.1094/PDIS-04-24-0756-RE","url":null,"abstract":"<p><p>Management of plant disease in agro-ecosystems ideally relies on a combination of host genetic resistance, chemical control, and cultural practices. Growers increasingly rely on chemical and genetic options, but their relative benefits in disease control, yield, and economic outcomes are rarely quantified. We explore this relationship for blackleg crown canker disease (caused by <i>Leptosphaeria maculans</i>), a major biotic constraint limiting canola production globally. Data from 20 field trials conducted from 2013 to 2015 in canola-growing regions of Australia were used to assess the effects of host resistance and fungicide treatment on blackleg severity, grain yield, and gross margin. In the absence of fungicide, blackleg disease was 88% lower in the most resistant compared with the most susceptible blackleg resistance category. In the most susceptible resistance category, the most effective fungicide treatment significantly reduced blackleg severity (from 50 to 6%) and increased grain yield (478 kg/ha, 41%) and gross margin (AU$120/ha, 17%). However, the mean benefits of fungicide tended to decrease with increasing levels of genetic resistance, to the point that yield, disease, and gross margin benefits were close to zero in the most resistant cultivars. Overall, these findings suggest that fungicides can reduce blackleg severity, but the benefits of application strongly depend on associated levels of genetic resistance. Canola cultivars with higher genetic resistance reliably reduced blackleg disease and maintained grain yield without the associated cost of fungicide application. The intensification of canola production to meet increasing global demand will require strategies to sustainably manage and protect finite genetic resistance resources to control blackleg disease.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS04240756RE"},"PeriodicalIF":4.4,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141493020","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 and Characterization of <i>Bipolaris secalis</i> and <i>B. setariae</i> Associated with Brown Stripe Disease on <i>Saccharum officinarum</i> in Yunnan, China.","authors":"Jie Li, Xiao-Yan Wang, Rong-Yue Zhang, Hong-Li Shan, Yin-Hu Li, Chang-Mi Wang, Ying-Kun Huang","doi":"10.1094/PDIS-10-24-2166-SC","DOIUrl":"https://doi.org/10.1094/PDIS-10-24-2166-SC","url":null,"abstract":"<p><p>Sugarcane (Saccharum officinarum L.) is the most important sugar crop that belongs to the Poaceae family and is mainly cultivated in tropical and subtropical regions worldwide. Brown stripe disease is a common and serious foliar fungal disease of sugarcane and has become a serious threat to sugarcane production in China. Yunnan Province is the second-largest sugar base in China. From 2022 to 2023, brown stripe-like symptoms from different sugarcane variety were observed in Yunnan. Thirty-nine Bipolaris-like isolates were obtained from symptomatic leaves of different sugarcane varieties and characterized by means of morphological identification combined with multilocus phylogeny comprising internal transcribed spacer rDNA (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and the translation elongation factor-1α (TEF-1α) gene sequence date. The analysis provided strong support for the delineation and identification of two Bipolaris species associated with sugarcane brown stripe, including Bipolaris secalis and B. setariae. Pathogenicity text in potted sugarcane plants confirmed that these two Bipolaris species can cause brown stripe of sugarcane, thus fulfilling Koch's postulates. This study confirmed that B. secalis and B. setariae were the pathogens of brown stripe in Yunnan Province. To the best of our knowledge, this is the first to report B. secalis as causal agents of brown stripe of sugarcane. Collectively, this finding provides a basis for sugarcane brown stripe disease accurate diagnosis and would be helpful to the development of effective management strategies.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505828","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>Alternaria alternata</i> Causing Alternaria Leaf Spot of Black Nightshade in China.","authors":"Zhanjiang Tie, Shaohua Chen, Zhiqiang Zhang, Juanxu Zhan, Guiyuan Zhang, Chaoyang Ma, Shuyi Jia, Sifeng Zhao, Hui Xi","doi":"10.1094/PDIS-03-24-0567-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-03-24-0567-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Black nightshade (Solanum nigrum L.) belongs to Solanaceae family, which is distributed all over China and has become one of the malignant weeds in cotton field in Xinjiang (Zhang et al., 2020; Zhang et al., 2021). During July 2016 to August 2023, leaf spot was observed on black nightshade in Hami and Shihezi city, Xinjiang, China. The spots appeared as brown circular or irregular, with some small black dots surrounded with yellow halos. Twenty five black nightshade plants were collected from a cotton field (100 m2) for pathogen isolation in Shihezi, July 2023. Leaf samples (2×2 mm) from the boundary between diseased tissue and healthy tissue, sterilized in 70% ethanol for 45 s, dipped in 2% NaClO for 30 s, rinsed three times with sterile distilled water, placed on potato dextrose agar (PDA) after dried and cultivated at 25°C in the dark for 4 days. Twenty-five fungal isolates were obtained and purified by using the single-spore isolation method, and all isolates were found to be similar in morphology, appeared as dark brown and produced dark brown pigmentation on PDA. Conidiophores were black brown, 8 to 58 × 10 to 20 μm, with 1 to 5 transverse septa and 0 to 3 longitudinal septa, the results similar to those of Alternaria alternata isolated from buckwheat (Li et al., 2021). To confirm this identification, total genomic DNA of the isolates were extracted by CTAB method (Doyle et al., 1987). The internal transcribed spacer (rDNA-ITS), Alternaria major allergen gene (Alt α1) and glyceraldehyde-3-phosphate dehydrogenase gene (GAPDH) of the A. alternata 26 were amplified using the primers ITS1/ITS4 (Glass et al., 1995), Altα1-F/Altα1-R (Li et al., 2024) and gpd-F/gpd-R (5'-CAACGGCTTCGGTCGCAT- TG-3' / 5'-GCCAAGCAGTTGGTTGTG-3'), respectively. The rDNA-ITS, Altα1 and GAPDH gene sequences were deposited in GenBank (KX904867, PP263361, PP263360), and showed 100% identity (rDNA-ITS: 572 out of 609 bp; Alt α1: 514 out of 516 bp; GAPDH: 619 out of 619 bp) to A. alternata (KU179665; MW522975; MK451977), respectively. The multi-gene phylogenetic tree showed that the representative isolate was grouped with A. alternata and identified as A. alternata. Black nightshade was used for pathogenicity assay. Fifteen plants at 3 to 4-leaf stage were selected and sprayed with the conidial suspension (1.0×106 spores/mL) of A. alternata 26 after wound the underside of leaves (2 mm length) with inoculating needle. Five plants were sprayed with sterilized water as control. After inoculation, placed the plants in a plastic box and covered with plastic wrap to keep 80% relative humidity for 3 days at 25℃ in the greenhouse, then removed the plastic box. Symptoms of leaf spots appeared within 12 - 15 days that were similar to the symptoms observed in the field, and the fungal pathogen that was re-isolated from symptomatic leaves was identical to original pathogen on the basis of morphological and molecular analysis to fulfill Koch's postulates. This experiment was repeate","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505818","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 blight of <i>Avena strigosa</i> caused by <i>Pyrenophora avenicola</i> in Japan.","authors":"Koya Sugawara, Kiyoshi Nishimoto, Naohiro Uwatoko, Takao Tsukiboshi","doi":"10.1094/PDIS-07-24-1574-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-07-24-1574-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Black oat (&lt;i&gt;Avena strigosa&lt;/i&gt; Schreb.) is used as a cereal crop, forage crop or green manure in temperate regions. In Japan, it is mainly cultivated in Hokkaido island and, because of the vigorous initial growth and ability to suppress the proliferation of plant pathogenic nematodes (Uesugi et al. 2018), its use is recently increasing. In November 2021, a leaf spot and blight disease was observed in the grass cultivated in Kitahiroshima city (N43°0, E141°31). At first, blackish brown spindle-shaped or elliptical lesions, about 3 to 5 × 1 to 2 mm were formed on leaves, and they expanded by forming yellowish-brown halos around them, eventually resulting in leaf blight later on (Fig.1), damaging 5-10 % of leaf area, varied by cultivar. The lesions were excised, surface-sterilized, and incubated on water agar under near-UV light. Three single-spore isolates of &lt;i&gt;Pyrenophora&lt;/i&gt;-like fungus were obtained from the lesions and deposited at the NIAS Genebank, Japan (https://www.gene.affrc.go.jp/index_en.php) as MAFF511692, 511693 and 511694. The sequences of ribosomal RNA gene (rDNA) and its internal transcribed spacer (ITS), and the gpd sequences of the isolates were analyzed as described by Marin-Felix et al. 2019. The rDNA-ITS sequences (GenBank accession no. LC769170, LC769171 and LC769172) of the isolates matched with that of the ex-type strain of &lt;i&gt;Pyrenophora avenicola&lt;/i&gt; (MK539972) isolated from &lt;i&gt;Avena&lt;/i&gt; seed. The sequences of the gpd (accession no. LC795722, LC795723 and LC795724) matched well with that of the ex-type strain (MK540180). Conidiophores of the isolates were septate, straight or flexuous, pale brown to olivaceous brown, 81.4 to 125.7 × 4.2 to 6.5 (ave. 106.4×5.7µm, n=50) µm, with hyaline vegetative hyphae (Fig.2). Conidia were slightly verrucose, cylindrical to obclavate, pale brown to olivaceous brown, 42.2 to 78.5 × 9.0 to 13.3 µm (ave. 56.9 ×10.4µm, n =50) and 2 to 7 distoseptate. This description overlap with the original description of &lt;i&gt;P. avenicolai&lt;/i&gt; (Marin-Felix et al. 2019) and the leaf spot pathogen of &lt;i&gt;Avena sativa&lt;/i&gt; reported in China (Chen et al. 2022). The fungus was identified as &lt;i&gt;P. avenicola&lt;/i&gt; on the basis of morphology and molecular phylogenetic analysis. To produce inoculum, the isolate MAFF511692 was grown on V8 juice agar at 25°C under near-UV light for 7 days. Five plants each of cv. 'Soil saver', 'New oats' of &lt;i&gt;A. strigosa&lt;/i&gt; (Kaneko seeds co.) and 'New almighty' of &lt;i&gt;A. sativa&lt;/i&gt; (Snow brand seed co.) were grown in a greenhouse for approximately 14 days and then inoculated by atomizing them with the conidial suspension (10&lt;sup&gt;4&lt;/sup&gt; conidia/ml) at the five-leaf stage. Five plants of each cultivar sprayed with sterilized distilled water served as the control. Inoculated plants were covered with plastic bags for 24 h at 25°C. After 5 days, blackish brown elliptical lesions developed on the leaves of all inoculated plants of both cultivars of &lt;i&gt;A. strigosa&lt;/i&gt; (Fig. 3) and &lt;i&gt;A","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505823","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 ringspot virus infection of Krymsk 86 (<i>Prunus cerasifera</i> × <i>P. persica</i>), a hybrid rootstock, in California.","authors":"Kishorekumar Reddy, Natalia James Ott, Sheridan L Chavira, Andreas Westphal, Mysore R Sudarshana","doi":"10.1094/PDIS-09-24-1894-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-09-24-1894-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;California produces 99% of prunes (Prunus domestica) in the U.S.A., valued at $148 million and accounting for 40% of world prune production. In the last decade, the rootstock Krymsk 86 (K86; P. cerasifera x P. persica) is increasingly used in prune production because of its high vigor, excellent anchorage and graft compatibility with a wide variety of Prunus crops. An estimated &gt;50% of new prune plantings in the Sacramento Valley are on K86. In late spring of 2023, 'Improved French' prune trees in two Northern California counties, grafted on K86 and Lovell (P. persica) rootstocks, were declining with a pale colored canopy. One orchard was ~ 9-years-old and in the other, trees varied from ~ 20 years to newly planted. The percentage of affected trees in one orchard was 3.6% (n=1,824) and 4.6% (n=1,295) in trees on K86 and Lovell, respectively. Symptomatic trees were scattered throughout this orchard, with a higher density of affected trees in the northeast quadrant. Examination of the trunk revealed a necrotic brown line at the graft union, typical of prune brown line (PBL) disease (Mircetich and Hoy, 1981), caused by infection of rootstock by tomato ringspot virus (ToRSV), a member species of Nepovirus lycopersici (family Secoviridae. The virus is vectored by dagger nematodes (Teliz et al. 1967) and its presence was confirmed in one of the orchards. To confirm infection by ToRSV in declining trees, total RNA from leaf samples, feeder roots, and cambial tissue from bark samples from scion and rootstock of one tree each on K86 and Lovell, was obtained using RNeasy Plant Mini kit (www.qiagen.com) and tested by one step reverse transcription-polymerase chain reaction (RT-PCR) assay using primers previously described (Tang et al., 2014). The reaction conditions included RT at 54oC using random hexamers and Superscript III (Thermo Fisher Scientific, USA), followed by a denaturation step at 95°C for 5 min, and 35 amplification cycles of 95°C for 30 s, 55°C for 30 s, and 72°C for 45 sec; and a final extension of 72°C for 5 min. The expected size amplicons (176 bp) were visualized by agarose gel electrophoresis only from RNA obtained from the cambial tissue below the graft union confirming the ToRSV infection in K86 rootstock. Extracts from bark scrapings of the rootstocks of three symptomatic trees also tested positive for ToRSV with immunostrips (www.agdia.com). In subsequent RT-PCR tests, RNA extracts from cambial tissue from 9 of 10 symptomatic trees on K86 tested positive for ToRSV. The amplicons were purified using a gel extraction kit (Qiagen Inc., Valencia, CA), and subjected to Sanger sequencing (Azenta Life Sciences (South Plainfield, NJ, USA). The sequence of the ToRSV isolates 316 (GenBank accession PQ282959) and 318 (GenBank accession PQ2829560 exhibited 99.4% (175/176 base pairs) and 98.9 % (175/177) sequence identity, respectively, with ToRSV isolate Rasp1-2014 segment RNA2 (GenBank accession KM083895). Our results indicate that ToRSV ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142505826","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}