Pub Date : 2024-09-11DOI: 10.1094/pdis-07-24-1540-pdn
Devin Bily,Tashi Gyatso,Aaron Evans
Monstera deliciosa Liebm. (Araceae) is a monocotyledonous plant that is native to tropical forests of southern Mexico to Panama. It is widely grown as an ornamental in the United States because of its easy maintenance and attractive, fenestrate leaves. On May 10th, 2024, at a nursery and garden center in Henrico County, Virginia, four M. deliciosa plants in 3.8 L containers were observed with necrotic spots surrounded by a yellow halo on the leaves (Fig. 1A). Uredinia were present in the center of the lesions with dense, reddish-brown sporulation mostly on the abaxial surface of the leaves (Fig. 1B). Urediniospores with pedicels were golden brown in color, globose, echinulate, with two opposite germ pores, averaging (28) 25.2 x 25 (23) µm (n = 40) in size and a wall thickness of 1.5 to 2 µm (n = 40) (Fig. 1F - K). Telia were not present. The host, symptoms, and urediniospore size was comparable to reports of Pseudocerradoa paullula (Syd. & P. Syd.) M. Ebinghaus & Dianese from South Carolina (22.9 to 27.9 μm), Florida (24 to 31 μm), and Japan (24.8 to 29.3 μm) (Ebinghaus et al. 2022; Sakamoto et al. 2023; Urbina et al. 2023; Yang et al. 2023). Urediniospores from the infected plants were collected with a sterile needle and DNA was extracted using a Qiagen DNeasy PowerLyzer Microbial Kit (Germantown, MD) according to the manufacturer's instructions. PCR and sequencing of the small ribosomal subunit (SSU) and large ribosomal subunit (LSU) gene regions was performed with primer sets NS1/Rust18SR and LRust1R/LR3 (Beenken et al. 2012; Vilgalys and Hester 1990). The resulting 1,630bp and 638 bp sequence fragments of the SSU and LSU loci from strain GS24-AE50 were deposited into the NCBI Genbank database under accessions PQ059898 and PQ059897, respectively. A pairwise alignment of the SSU gene shared 1,363/1,366 (99%) nucleotides with the P. paullula voucher (ON887197) from Florida. A Genbank nBLAST analysis of the LSU gene shared 636/638 (99%), 636/638 (99%), and 592/600 (99%) nucleotides with vouchers from M. deliciosa from South Carolina (OQ746460), Florida (ON887197) and Japan (OK509070) (Sakamoto et al. 20222; Urbina et al. 2023; Yang et al. 2023). Koch's postulates were fulfilled by spraying four, healthy, non-wounded M. deliciosa plants to run-off with a urediniospore suspension (1 x 106 spores/ml distilled water, 20 ml per plant) that was collected from the original infected plants. An additional four, healthy control plants were sprayed with distilled water only. After 6 weeks in a greenhouse at 22 ± 2°C with ≥85% relative humidity under an 8-h photoperiod, uredinia in the center of lesions identical to those on the original symptomatic plants developed on 12 out of 20 leaves from the inoculated plants, while all the leaves from the control plants remained asymptomatic (Fig.1C - E). Urediniospores collected from the inoculated plants were morphologically identical to the urediniospores from the original infected plants with 100% LSU sequence hom
{"title":"First Detection of Pseudocerradoa paullula Causing Aroid Leaf Rust on Swiss Cheese Plant (Monstera deliciosa) in Virginia.","authors":"Devin Bily,Tashi Gyatso,Aaron Evans","doi":"10.1094/pdis-07-24-1540-pdn","DOIUrl":"https://doi.org/10.1094/pdis-07-24-1540-pdn","url":null,"abstract":"Monstera deliciosa Liebm. (Araceae) is a monocotyledonous plant that is native to tropical forests of southern Mexico to Panama. It is widely grown as an ornamental in the United States because of its easy maintenance and attractive, fenestrate leaves. On May 10th, 2024, at a nursery and garden center in Henrico County, Virginia, four M. deliciosa plants in 3.8 L containers were observed with necrotic spots surrounded by a yellow halo on the leaves (Fig. 1A). Uredinia were present in the center of the lesions with dense, reddish-brown sporulation mostly on the abaxial surface of the leaves (Fig. 1B). Urediniospores with pedicels were golden brown in color, globose, echinulate, with two opposite germ pores, averaging (28) 25.2 x 25 (23) µm (n = 40) in size and a wall thickness of 1.5 to 2 µm (n = 40) (Fig. 1F - K). Telia were not present. The host, symptoms, and urediniospore size was comparable to reports of Pseudocerradoa paullula (Syd. & P. Syd.) M. Ebinghaus & Dianese from South Carolina (22.9 to 27.9 μm), Florida (24 to 31 μm), and Japan (24.8 to 29.3 μm) (Ebinghaus et al. 2022; Sakamoto et al. 2023; Urbina et al. 2023; Yang et al. 2023). Urediniospores from the infected plants were collected with a sterile needle and DNA was extracted using a Qiagen DNeasy PowerLyzer Microbial Kit (Germantown, MD) according to the manufacturer's instructions. PCR and sequencing of the small ribosomal subunit (SSU) and large ribosomal subunit (LSU) gene regions was performed with primer sets NS1/Rust18SR and LRust1R/LR3 (Beenken et al. 2012; Vilgalys and Hester 1990). The resulting 1,630bp and 638 bp sequence fragments of the SSU and LSU loci from strain GS24-AE50 were deposited into the NCBI Genbank database under accessions PQ059898 and PQ059897, respectively. A pairwise alignment of the SSU gene shared 1,363/1,366 (99%) nucleotides with the P. paullula voucher (ON887197) from Florida. A Genbank nBLAST analysis of the LSU gene shared 636/638 (99%), 636/638 (99%), and 592/600 (99%) nucleotides with vouchers from M. deliciosa from South Carolina (OQ746460), Florida (ON887197) and Japan (OK509070) (Sakamoto et al. 20222; Urbina et al. 2023; Yang et al. 2023). Koch's postulates were fulfilled by spraying four, healthy, non-wounded M. deliciosa plants to run-off with a urediniospore suspension (1 x 106 spores/ml distilled water, 20 ml per plant) that was collected from the original infected plants. An additional four, healthy control plants were sprayed with distilled water only. After 6 weeks in a greenhouse at 22 ± 2°C with ≥85% relative humidity under an 8-h photoperiod, uredinia in the center of lesions identical to those on the original symptomatic plants developed on 12 out of 20 leaves from the inoculated plants, while all the leaves from the control plants remained asymptomatic (Fig.1C - E). Urediniospores collected from the inoculated plants were morphologically identical to the urediniospores from the original infected plants with 100% LSU sequence hom","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202591","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}
Pub Date : 2024-09-11DOI: 10.1094/pdis-06-24-1212-pdn
Fangqi Chen,Le Wang,Ruifang Jia,Yuanyuan Zhang,Juan Sun,Zhengqiang Chen,Kejian Lin
Metaplexis japonica (Thunb.) Makino, commonly known as rough potato, has a wide distribution in China, Japan, Korea, and adjacent Russia. In China, M. japonica is a traditional herbal medicinal plant, which is also cultivated as a vegetable (Shi et al. 2020; Wei et al. 2019). In July 2023, leaves of M. japonica plants growing near a soybean field in Qingdao, Shandong province, exhibited leaf crinkling, mosaic and distorting symptoms of probable virus infection (Supplementary Figure 1). The disease incidence in a 50 m2 area was approximately 40%. To identify the suspected viral etiological agents, symptomatic leaves from 10 M. japonica plants were collected and pooled to perform small RNA deep sequencing (sRNA-Seq). TransZol Up Total RNA Extraction Kit (TransGen Biotech, Beijing, China) was used to extract total RNA. Small RNA library construction and high-throughput sequencing (HTS) were performed on Illumina NovaSeq platform by Genepioneer (Nanjing, China) (Li et al. 2024). A total of 17,384,311 raw reads were obtained. Redundant reads were removed by cutadapt software (version 1.18) to obtain 11,580,876 clean reads with 18 to 26 nucleotide (nt) sizes. The clean reads were assembled using velvet software (version 1.1.07). A total of forty-six small contigs from 42 to 283 nt were identified, with 85 to 100% nucleotide sequence identities, respectively, to metaplexis yellow mottle-associated virus (MeYMaV, genus Caulimovirus, family Caulimoviridae, accession numbers: NC_077108.1). Finally, 1,355,955 reads (11.71% mapped ratio of total reads, cover 56.7% over the MeYMaV genome) were mapped to the genome of MeYMaV by bwa software (version 0.7.17-r1188). To confirm the sRNA-Seq results, PCR was performed with specific primers MeYMaV-N-F/MeYMaV-N-R (5'-TGGTATCAGAGCCTAGTTAA-3'/5'-GGAGTTGGTAATGTATTACC-3') and MeYMaV-C-F/MeYMaV-C-R (5'-AATGGAACGGCTGTTAGTAT3'/TTAATTTCTAGCCCTTGGCTACTTAC). Both the primer pairs were designed using GenBank accession numbers: NC_077108.1 (Yang et al. 2021) to obtain the N and C terminals genome fragments of 10 MeYMaV plants. Two amplicons approximately in 4000-, and 3900-bp sizes were amplified (Supplementary Figure 2), sequenced (tsingke, Beijing, China) and aligned to obtain 7,742-nt complete MeYMaV genome sequence (Accession no. PP892524). BLASTn analysis revealed 90.16% and 92.18% sequence identity, respectively, with the MeYMaV isolate LM-Cau-A (NC_077108.1) based on complete genome and coat protein sequences, respectively. Previously, cucumber mosaic virus and MeYMaV were reported in M. japonica from Jiangsu and Liaoning provinces in China, respectively (Yang et al. 2018; 2021). To our knowledge, this is the first natural infection report of MeYMaV in M. japonica in Shandong, China. The natural occurrence of MeYMaV is not only affects the quality of M. japonica, but also poses a potential threat to surrounding crops. This study enriches information on the disease distribution of MeYMaV and will be helpful for disease ma
{"title":"First Report of metaplexis yellow mottle-associated virus Infecting Metaplexis japonica (Thunb.) Makino in Shandong, China.","authors":"Fangqi Chen,Le Wang,Ruifang Jia,Yuanyuan Zhang,Juan Sun,Zhengqiang Chen,Kejian Lin","doi":"10.1094/pdis-06-24-1212-pdn","DOIUrl":"https://doi.org/10.1094/pdis-06-24-1212-pdn","url":null,"abstract":"Metaplexis japonica (Thunb.) Makino, commonly known as rough potato, has a wide distribution in China, Japan, Korea, and adjacent Russia. In China, M. japonica is a traditional herbal medicinal plant, which is also cultivated as a vegetable (Shi et al. 2020; Wei et al. 2019). In July 2023, leaves of M. japonica plants growing near a soybean field in Qingdao, Shandong province, exhibited leaf crinkling, mosaic and distorting symptoms of probable virus infection (Supplementary Figure 1). The disease incidence in a 50 m2 area was approximately 40%. To identify the suspected viral etiological agents, symptomatic leaves from 10 M. japonica plants were collected and pooled to perform small RNA deep sequencing (sRNA-Seq). TransZol Up Total RNA Extraction Kit (TransGen Biotech, Beijing, China) was used to extract total RNA. Small RNA library construction and high-throughput sequencing (HTS) were performed on Illumina NovaSeq platform by Genepioneer (Nanjing, China) (Li et al. 2024). A total of 17,384,311 raw reads were obtained. Redundant reads were removed by cutadapt software (version 1.18) to obtain 11,580,876 clean reads with 18 to 26 nucleotide (nt) sizes. The clean reads were assembled using velvet software (version 1.1.07). A total of forty-six small contigs from 42 to 283 nt were identified, with 85 to 100% nucleotide sequence identities, respectively, to metaplexis yellow mottle-associated virus (MeYMaV, genus Caulimovirus, family Caulimoviridae, accession numbers: NC_077108.1). Finally, 1,355,955 reads (11.71% mapped ratio of total reads, cover 56.7% over the MeYMaV genome) were mapped to the genome of MeYMaV by bwa software (version 0.7.17-r1188). To confirm the sRNA-Seq results, PCR was performed with specific primers MeYMaV-N-F/MeYMaV-N-R (5'-TGGTATCAGAGCCTAGTTAA-3'/5'-GGAGTTGGTAATGTATTACC-3') and MeYMaV-C-F/MeYMaV-C-R (5'-AATGGAACGGCTGTTAGTAT3'/TTAATTTCTAGCCCTTGGCTACTTAC). Both the primer pairs were designed using GenBank accession numbers: NC_077108.1 (Yang et al. 2021) to obtain the N and C terminals genome fragments of 10 MeYMaV plants. Two amplicons approximately in 4000-, and 3900-bp sizes were amplified (Supplementary Figure 2), sequenced (tsingke, Beijing, China) and aligned to obtain 7,742-nt complete MeYMaV genome sequence (Accession no. PP892524). BLASTn analysis revealed 90.16% and 92.18% sequence identity, respectively, with the MeYMaV isolate LM-Cau-A (NC_077108.1) based on complete genome and coat protein sequences, respectively. Previously, cucumber mosaic virus and MeYMaV were reported in M. japonica from Jiangsu and Liaoning provinces in China, respectively (Yang et al. 2018; 2021). To our knowledge, this is the first natural infection report of MeYMaV in M. japonica in Shandong, China. The natural occurrence of MeYMaV is not only affects the quality of M. japonica, but also poses a potential threat to surrounding crops. This study enriches information on the disease distribution of MeYMaV and will be helpful for disease ma","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202592","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}
Bacterial blight caused by Pseudomonas syringae pv. glycines (Psg) is a widespread foliar disease. Although four Resistance to Pseudomonas syringae pv. glycinea (Rpg) 1 ~ 4 (Rpg1~4) genes that have been observed to segregate in a Mendelian pattern have been reported to confer resistance to Psg in soybean, the genetic basis of quantitative resistance to bacterial blight in soybean remains unclear. In the present study, the Psg resistance of two soybean association panels consisting of 573 and 213 lines, respectively, were phenotyped in multiple environments in 2014 - 2016. Genome-wide association study (GWAS) were performed using 2 models FarmCPU and BLINK to identify Psg resistance loci. A total of 40 soybean varieties with high level of Psg resistance were identified, and 14 quantitative trait loci (QTLs) were detected on 12 soybean chromosomes. These QTLs were identified for the first time. The majority of the QTLs were only detected in one or the other association panels, while qRPG-18-1 was detected in both association panels for at least one growing season. A total of 46 candidate Psg resistance genes were identified from the qRpg_13_1, qRPG-15-1, and qRPG-18-1 loci based on gene function annotation. In addition, we found the genomic region covering rpg1-b and rpg1-r harbored the synteny with a genomic region on chromosome 15, and identified 16 nucleotide binding site - leucine-rich repeat (NBS-LRR) genes as the candidate Psg resistance genes from the synteny blocks. This study provides new information for dissecting the genetic control of Psg resistance in soybean.
{"title":"Genome-wide association study of bacterial blight resistance in soybean.","authors":"Fangzhou Zhao,Yanan Wang,Wei Cheng,Augustine Antwi-Boasiako,Wenkai Yan,Chunting Zhang,Xuewen Gao,Jiejie Kong,Wusheng Liu,Tuanjie Zhao","doi":"10.1094/pdis-01-24-0162-re","DOIUrl":"https://doi.org/10.1094/pdis-01-24-0162-re","url":null,"abstract":"Bacterial blight caused by Pseudomonas syringae pv. glycines (Psg) is a widespread foliar disease. Although four Resistance to Pseudomonas syringae pv. glycinea (Rpg) 1 ~ 4 (Rpg1~4) genes that have been observed to segregate in a Mendelian pattern have been reported to confer resistance to Psg in soybean, the genetic basis of quantitative resistance to bacterial blight in soybean remains unclear. In the present study, the Psg resistance of two soybean association panels consisting of 573 and 213 lines, respectively, were phenotyped in multiple environments in 2014 - 2016. Genome-wide association study (GWAS) were performed using 2 models FarmCPU and BLINK to identify Psg resistance loci. A total of 40 soybean varieties with high level of Psg resistance were identified, and 14 quantitative trait loci (QTLs) were detected on 12 soybean chromosomes. These QTLs were identified for the first time. The majority of the QTLs were only detected in one or the other association panels, while qRPG-18-1 was detected in both association panels for at least one growing season. A total of 46 candidate Psg resistance genes were identified from the qRpg_13_1, qRPG-15-1, and qRPG-18-1 loci based on gene function annotation. In addition, we found the genomic region covering rpg1-b and rpg1-r harbored the synteny with a genomic region on chromosome 15, and identified 16 nucleotide binding site - leucine-rich repeat (NBS-LRR) genes as the candidate Psg resistance genes from the synteny blocks. This study provides new information for dissecting the genetic control of Psg resistance in soybean.","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202599","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}
Pub Date : 2024-09-10DOI: 10.1094/pdis-06-24-1332-re
Nuraizat Abidin,Ming Pei You,Martin John Barbetti,Roger Anthony Charles Jones
Few recent investigations examine coinfection interactions between fungal and viral plant pathogens. Here, we investigated coinfections between Leptosphaeria maculans and turnip mosaic virus (TuMV) in canola (Brassica napus). Different combinations of L. maculans isolate P11 and resistance breaking isolates L. maculans UWA192 and TuMV 12.1, were inoculated to three cultivars with differing pathogen resistances/susceptibilities. They were inoculated first to entire or half cotyledons 10-12 days after emergence, and second to opposite entire or half cotyledons on the same day (day 0) or 3 or 7 days afterwards. The parameters measured were L. maculans cotyledon disease index (%CDI), and TuMV systemically infected leaf symptom intensity (SI) and virus concentration (VC). Except when both day 0 inoculations were with isolate UWA192, %CDI values were supressed strongly or only weakly when isolates P11 and/or UWA192 were inoculated to plants with L. maculans single gene resistance (SGR) or polygenic resistance, respectively. However, except when isolate P11 was inoculated first and UWA192 second, these values declined after inoculation day 0 when SGR was absent. TuMV infection suppressed %CDI values, although this decrease was usually smaller following day 0 half cotyledon inoculations. When TuMV temperature sensitive extreme resistance was present and both inoculations were with TuMV, SI and VC values diminished greatly. However, the extent of this decrease was reduced when second inoculations were with L. maculans. SI and VC values were also smaller when SGR was present and second inoculations were with L. maculans. When L. maculans resistance was lacking, SI and VC values were smaller when second inoculations to entire cotyledons were with L. maculans rather than TuMV. This also occurred after second half cotyledon inoculations with isolate P11 but not isolate UWA192. Therefore, diverse inter- or intra-pathogen interactions developed depending upon host resistance, isolate combination, cotyledon inoculation approach and second inoculation timing.
{"title":"Inter- and Intra-Pathogen Interactions Emanating from Coinfection with Different Fungal and Viral strains in Canola Cultivars with Differing Host Resistances.","authors":"Nuraizat Abidin,Ming Pei You,Martin John Barbetti,Roger Anthony Charles Jones","doi":"10.1094/pdis-06-24-1332-re","DOIUrl":"https://doi.org/10.1094/pdis-06-24-1332-re","url":null,"abstract":"Few recent investigations examine coinfection interactions between fungal and viral plant pathogens. Here, we investigated coinfections between Leptosphaeria maculans and turnip mosaic virus (TuMV) in canola (Brassica napus). Different combinations of L. maculans isolate P11 and resistance breaking isolates L. maculans UWA192 and TuMV 12.1, were inoculated to three cultivars with differing pathogen resistances/susceptibilities. They were inoculated first to entire or half cotyledons 10-12 days after emergence, and second to opposite entire or half cotyledons on the same day (day 0) or 3 or 7 days afterwards. The parameters measured were L. maculans cotyledon disease index (%CDI), and TuMV systemically infected leaf symptom intensity (SI) and virus concentration (VC). Except when both day 0 inoculations were with isolate UWA192, %CDI values were supressed strongly or only weakly when isolates P11 and/or UWA192 were inoculated to plants with L. maculans single gene resistance (SGR) or polygenic resistance, respectively. However, except when isolate P11 was inoculated first and UWA192 second, these values declined after inoculation day 0 when SGR was absent. TuMV infection suppressed %CDI values, although this decrease was usually smaller following day 0 half cotyledon inoculations. When TuMV temperature sensitive extreme resistance was present and both inoculations were with TuMV, SI and VC values diminished greatly. However, the extent of this decrease was reduced when second inoculations were with L. maculans. SI and VC values were also smaller when SGR was present and second inoculations were with L. maculans. When L. maculans resistance was lacking, SI and VC values were smaller when second inoculations to entire cotyledons were with L. maculans rather than TuMV. This also occurred after second half cotyledon inoculations with isolate P11 but not isolate UWA192. Therefore, diverse inter- or intra-pathogen interactions developed depending upon host resistance, isolate combination, cotyledon inoculation approach and second inoculation timing.","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202601","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}
Rhizoctonia zeae was recently identified as the major Rhizoctonia species in corn and soybean fields in Nebraska and was shown to be pathogenic on corn and soybean seedlings. Fungicide seed treatments commonly used to manage seedling diseases include prothioconazole (demethylation inhibitor), fludioxonil (phenylpyrrole), sedaxane (succinate dehydrogenase inhibitor), and azoxystrobin (quinone outside inhibitor; QoI). To establish the sensitivity of R. zeae to these fungicides, we isolated this pathogen from corn and soybean fields in Nebraska during 2015 to 2017 and estimated the relative effective concentration for 50% inhibition (EC50) of a total of 91 R. zeae isolates from Nebraska and Illinois. Average EC50 for prothioconazole, fludioxonil, sedaxane, and azoxystrobin was 0.219, 0.099, 0.078, and > 100 µgml-1, respectively. In planta assays showed that azoxystrobin did not significantly reduce the disease severity on soybean (P > 0.05). The cytochrome b gene of R. zeae did not harbor any mutation known to confer QoI resistance and had a type-I intron directly after codon 143 suggesting that a G143A mutation is unlikely to evolve in this pathogen. For prothioconazole, fludioxonil, and sedaxane, EC50 of isolates did not differ significantly among years of collection (P > 0.05) and their single discriminatory concentrations were identified as 0.1 µgml-1. This is the first study to establish non-target site resistance of R. zeae to azoxystrobin and the sensitivity of R. zeae to commonly used seed treatment fungicides in Nebraska. This information will help to guide strategies for chemical control of R. zeae and monitor sensitivity shifts in future.
根瘤菌（Rhizoctonia zeae）最近被确定为内布拉斯加州玉米和大豆田中的主要根瘤菌种类，并被证明对玉米和大豆幼苗具有致病性。通常用于防治苗期病害的杀菌剂种子处理剂包括丙硫菌唑（脱甲基化抑制剂）、氟虫腈（苯基吡咯）、噻虫嗪（琥珀酸脱氢酶抑制剂）和唑螨酯（醌外抑制剂；QoI）。为了确定 R. zeae 对这些杀菌剂的敏感性，我们在 2015 年至 2017 年期间从内布拉斯加州的玉米田和大豆田中分离出了这种病原体，并估算了来自内布拉斯加州和伊利诺伊州的共 91 个 R. zeae 分离物的 50%抑制相对有效浓度（EC50）。丙硫菌唑、氟硅唑、苯醚甲环唑和唑菌酰胺的平均 EC50 分别为 0.219、0.099、0.078 和 > 100 µgml-1。植物试验表明，唑啉草酯不能显著降低大豆的病害严重程度（P > 0.05）。R. zeae 的细胞色素 b 基因没有携带任何已知能赋予 QoI 抗性的突变，并且在密码子 143 之后有一个 I 型内含子，这表明 G143A 突变不太可能在这种病原体中发生。对于丙硫菌唑、氟虫腈和噻虫嗪，不同采集年份分离物的 EC50 没有显著差异（P > 0.05），它们的单一鉴别浓度被确定为 0.1 µgml-1。这是首次研究确定 R. zeae 对唑菌酰胺的非靶标抗性以及 R. zeae 对内布拉斯加州常用种子处理杀菌剂的敏感性。这些信息将有助于指导 R. zeae 的化学防治策略，并监测未来的敏感性变化。
{"title":"Fungicide Sensitivity and Non-Target Site Resistance in Rhizoctonia zeae Isolates Collected from Corn and Soybean Fields in Nebraska.","authors":"Nikita Gambhir,Srikanth Kodati,Anthony Oyegoke Adesemoye,Sydney Everhart","doi":"10.1094/pdis-02-24-0352-re","DOIUrl":"https://doi.org/10.1094/pdis-02-24-0352-re","url":null,"abstract":"Rhizoctonia zeae was recently identified as the major Rhizoctonia species in corn and soybean fields in Nebraska and was shown to be pathogenic on corn and soybean seedlings. Fungicide seed treatments commonly used to manage seedling diseases include prothioconazole (demethylation inhibitor), fludioxonil (phenylpyrrole), sedaxane (succinate dehydrogenase inhibitor), and azoxystrobin (quinone outside inhibitor; QoI). To establish the sensitivity of R. zeae to these fungicides, we isolated this pathogen from corn and soybean fields in Nebraska during 2015 to 2017 and estimated the relative effective concentration for 50% inhibition (EC50) of a total of 91 R. zeae isolates from Nebraska and Illinois. Average EC50 for prothioconazole, fludioxonil, sedaxane, and azoxystrobin was 0.219, 0.099, 0.078, and > 100 µgml-1, respectively. In planta assays showed that azoxystrobin did not significantly reduce the disease severity on soybean (P > 0.05). The cytochrome b gene of R. zeae did not harbor any mutation known to confer QoI resistance and had a type-I intron directly after codon 143 suggesting that a G143A mutation is unlikely to evolve in this pathogen. For prothioconazole, fludioxonil, and sedaxane, EC50 of isolates did not differ significantly among years of collection (P > 0.05) and their single discriminatory concentrations were identified as 0.1 µgml-1. This is the first study to establish non-target site resistance of R. zeae to azoxystrobin and the sensitivity of R. zeae to commonly used seed treatment fungicides in Nebraska. This information will help to guide strategies for chemical control of R. zeae and monitor sensitivity shifts in future.","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202597","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}
A unique cyst nematode population (Heterodera spp.) was collected from rice roots in Luoding County, Guangdong Province, China. Morphological and molecular analyses revealed it is significantly different from all previously described cyst nematode species. It is described as Heterodera luodingensis n. sp. and classified in the Cyperi group. H. luodingensis n. sp. is characterized by its lemon-shaped cyst with a prominent terminal vulval cone that is ambifenestrate with abundant bullae and a relatively short vulval slit, 31.3 (24.4 -38.7) μm long. The second-stage juveniles (J2) are characterized by dumbbell shaped labials, three lip annules and a lateral field with three incisures. The J2 stylet is 18.7 (16.9 -19.8) μm long with anterior concave or spherical knobs. The tail is elongate conoid, tapering to a rounded terminus or zig tapering to a rounded terminus that is 54.9 (43.9 - 64.3) μm long with a hyaline region comprising 40.3%-52.5% of the tail. Phylogenetic tree analysis based on rDNA 28S D2D3 and ITS fragments showed that the H. luodingensis n. sp. is unique and clearly separated it from other cyst nematodes. It is most closely related to H. oryzicola, H. fengi, H. elachista, H. oryzae, and H. guangdongensis. H. luodingensis n. sp. can be distinguished from H. oryzicola by its shorter vulval slit and underbridge, from H. elachista by abundant bullae, shorter vulval slit and fenestrate width, from H. oryzae by a shorter vulval slit and underbridge, from H. fengi by a shorter vulval slit, from H. guangdongensis by a longer cyst length and abundant bulla. Based on PCR-RFLP of rDNA-ITS, H. luodingensis n. sp. can be clearly distinguished from H. oryzicola, H. mothi, H. elachista, H. guangdongensis and H. cyperi. A parasitism test from a pure culture derived from a single cyst in greenhouse showed that H. luodingensis n. sp. can successfully complete its life cycle on rice and rice is its type host.
在中国广东省罗定县的水稻根部采集到一个独特的胞囊线虫种群（Heterodera spp.）。形态学和分子分析表明，它与之前描述的所有胞囊线虫物种都有显著不同。将其描述为 Heterodera luodingensis n. sp.H. luodingensis n. sp.的特征是它的柠檬形囊肿有一个突出的顶端外阴锥体，该锥体有丰富的鼓泡，外阴裂缝相对较短，长 31.3 (24.4 -38.7) μm。第二阶段幼体（J2）的特点是唇瓣呈哑铃状，唇部有三个环纹，侧领域有三个切口。J2 的花柱长 18.7（16.9 -19.8）微米，前部凹陷或呈球形。尾部为长圆锥形，逐渐变细至圆形末端，或呈 "之 "字形逐渐变细至圆形末端，长 54.9 (43.9 - 64.3) μm，透明区占尾部的 40.3% - 52.5%。基于 rDNA 28S D2D3 和 ITS 片段的系统发生树分析表明，H. luodingensis n. sp.它与 H. oryzicola、H. fengi、H. elachista、H. oryzae 和 H. guangdongensis 的亲缘关系最为密切。Luodingensis n. sp.与H. oryzicola的区别在于其较短的外阴裂缝和下桥，与H. elachista的区别在于丰富的鼓泡、较短的外阴裂缝和栅栏宽度，与H. oryzae的区别在于较短的外阴裂缝和下桥，与H. fengi的区别在于较短的外阴裂缝，与H. guangdongensis的区别在于较长的包囊长度和丰富的鼓泡。根据 rDNA-ITS 的 PCR-RFLP，H. luodingensis n. sp. 可以与 H. oryzicola、H. mothi、H. elachista、H. guangdongensis 和 H. cyperi 明确区分。温室中单个孢囊纯培养的寄生试验表明，H. luodingensis n. sp.能成功地在水稻上完成其生命周期，水稻是其类型宿主。
{"title":"A New Cyst Nematode, Heterodera luodingensis n. sp. (Nematoda: Heteroderinae) From Rice In China.","authors":"Yanhua Wen,Fuxiang Liu,Haoyang Zhen,WeiMin Ye,Chunhui Ni,Chunling Xu,Deliang Peng","doi":"10.1094/pdis-07-24-1565-re","DOIUrl":"https://doi.org/10.1094/pdis-07-24-1565-re","url":null,"abstract":"A unique cyst nematode population (Heterodera spp.) was collected from rice roots in Luoding County, Guangdong Province, China. Morphological and molecular analyses revealed it is significantly different from all previously described cyst nematode species. It is described as Heterodera luodingensis n. sp. and classified in the Cyperi group. H. luodingensis n. sp. is characterized by its lemon-shaped cyst with a prominent terminal vulval cone that is ambifenestrate with abundant bullae and a relatively short vulval slit, 31.3 (24.4 -38.7) μm long. The second-stage juveniles (J2) are characterized by dumbbell shaped labials, three lip annules and a lateral field with three incisures. The J2 stylet is 18.7 (16.9 -19.8) μm long with anterior concave or spherical knobs. The tail is elongate conoid, tapering to a rounded terminus or zig tapering to a rounded terminus that is 54.9 (43.9 - 64.3) μm long with a hyaline region comprising 40.3%-52.5% of the tail. Phylogenetic tree analysis based on rDNA 28S D2D3 and ITS fragments showed that the H. luodingensis n. sp. is unique and clearly separated it from other cyst nematodes. It is most closely related to H. oryzicola, H. fengi, H. elachista, H. oryzae, and H. guangdongensis. H. luodingensis n. sp. can be distinguished from H. oryzicola by its shorter vulval slit and underbridge, from H. elachista by abundant bullae, shorter vulval slit and fenestrate width, from H. oryzae by a shorter vulval slit and underbridge, from H. fengi by a shorter vulval slit, from H. guangdongensis by a longer cyst length and abundant bulla. Based on PCR-RFLP of rDNA-ITS, H. luodingensis n. sp. can be clearly distinguished from H. oryzicola, H. mothi, H. elachista, H. guangdongensis and H. cyperi. A parasitism test from a pure culture derived from a single cyst in greenhouse showed that H. luodingensis n. sp. can successfully complete its life cycle on rice and rice is its type host.","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202602","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}
Pub Date : 2024-09-10DOI: 10.1094/pdis-08-24-1606-pdn
Oliul Hassan,Hyeon-Yeong Ju,Hyunjoo Ryu,Hyo-Won Choi,Sung Kee Hong
Chili (Capsicum annuum L.) is an economically important crop worldwide, valued for its culinary uses. In South Korea, anthracnose caused by Colletotrichum spp. including C. truncatum, C. gloeosporioides, C. coccodes, C. acutatum, and C. scovillei incurs on substantial economic loss (Kim et al. 2008; Oo and Oh 2020). In August 2022, somewhat different types of symptoms that was not typical on chilli fruits were observed in a field in Yereonggwang (GPS: 35.2579° N, 126.4742° E), South Korea. The disease symptoms appeared as sunken, necrotic lesions with dense black spore masses forming in concentric rings. The estimated disease incidence the 0.2 ha field showing up to 1% of fruits affected. To isolate the pathogen, six symptomatic chilli fruits were collected. Small pieces (5 mm²) were cut from the margins of the lesions, surface-sterilized in 70% ethanol for 30 sec, followed by 1% sodium hypochlorite for 1 minute, and then rinsed three times in sterile distilled water. The tissue pieces were placed on potato dextrose agar (PDA) plates and incubated at 25°C in the dark. After 3 to 5 days, emerging fungal colonies were sub-cultured to obtain pure isolates. A total of five isolates were obtained and initially identified as Colletotrichum spp. based on morphological characteristics. Seven-day old colonies were initially white, turning light orange with age on PDA. Setae (observed on lesion) were dark brown, verruculose and septate. Conidia were cylindrical, hyaline, and measured 14.8 to 19.9 × 4.2 to 6.5 µm (mean 16.7 × 5.6 μm, n = 70) in size; appressoria were brown to dark brown and irregularly shaped. These morphological characteristics of the isolates agree with those reported for the morphology of C. sojae by Damm et al. (2019). To confirm the identity of the isolates, DNA was extracted and specific gene regions were amplified and sequenced using the following primer sets: ITS (ITS1 and ITS4), GAPDH (GDF1 and GDR1), ACT (ACT-512F and ACT-783R), TUB (T1 and Bt2b), HIS3 (CYLH3F and CYLH3R), and CHS-1 (CHS-79F and CHS-345R). The resulting sequences were deposited in the NCBI GenBank with accession numbers (LC830742 to LC830766). Maximum likelihood phylogenetic analysis using combine sequences of ITS, GAPDH, ACT, TUB, HIS3 and CHS-1 in MEGA X confirmed the isolates as C. sojae, marking the first report of this pathogen on chilli in South Korea, previously known to infect soybean. Pathogenicity tests were conducted on wound and nonwounded healthy and mature-green chili fruits (cv. Bicksita) to confirm the pathogenicity of the isolated C. sojae. The fruits were surface-sterilized using 70% ethanol and then rinsed with sterile distilled water. The fruits were wounded using a sterile needle to facilitate infection. A conidial suspension (1x106 conidia/mL) was prepared from 7-day-old PDA cultures. Each fruit was inoculated by placing a 10 µL drop of the conidial suspension onto the wounded and nonwounded sites (4 to 5) of the wound and unwound fruits, res
{"title":"First Report of Chili Anthracnose Caused by Colletotrichum sojae in South Korea.","authors":"Oliul Hassan,Hyeon-Yeong Ju,Hyunjoo Ryu,Hyo-Won Choi,Sung Kee Hong","doi":"10.1094/pdis-08-24-1606-pdn","DOIUrl":"https://doi.org/10.1094/pdis-08-24-1606-pdn","url":null,"abstract":"Chili (Capsicum annuum L.) is an economically important crop worldwide, valued for its culinary uses. In South Korea, anthracnose caused by Colletotrichum spp. including C. truncatum, C. gloeosporioides, C. coccodes, C. acutatum, and C. scovillei incurs on substantial economic loss (Kim et al. 2008; Oo and Oh 2020). In August 2022, somewhat different types of symptoms that was not typical on chilli fruits were observed in a field in Yereonggwang (GPS: 35.2579° N, 126.4742° E), South Korea. The disease symptoms appeared as sunken, necrotic lesions with dense black spore masses forming in concentric rings. The estimated disease incidence the 0.2 ha field showing up to 1% of fruits affected. To isolate the pathogen, six symptomatic chilli fruits were collected. Small pieces (5 mm²) were cut from the margins of the lesions, surface-sterilized in 70% ethanol for 30 sec, followed by 1% sodium hypochlorite for 1 minute, and then rinsed three times in sterile distilled water. The tissue pieces were placed on potato dextrose agar (PDA) plates and incubated at 25°C in the dark. After 3 to 5 days, emerging fungal colonies were sub-cultured to obtain pure isolates. A total of five isolates were obtained and initially identified as Colletotrichum spp. based on morphological characteristics. Seven-day old colonies were initially white, turning light orange with age on PDA. Setae (observed on lesion) were dark brown, verruculose and septate. Conidia were cylindrical, hyaline, and measured 14.8 to 19.9 × 4.2 to 6.5 µm (mean 16.7 × 5.6 μm, n = 70) in size; appressoria were brown to dark brown and irregularly shaped. These morphological characteristics of the isolates agree with those reported for the morphology of C. sojae by Damm et al. (2019). To confirm the identity of the isolates, DNA was extracted and specific gene regions were amplified and sequenced using the following primer sets: ITS (ITS1 and ITS4), GAPDH (GDF1 and GDR1), ACT (ACT-512F and ACT-783R), TUB (T1 and Bt2b), HIS3 (CYLH3F and CYLH3R), and CHS-1 (CHS-79F and CHS-345R). The resulting sequences were deposited in the NCBI GenBank with accession numbers (LC830742 to LC830766). Maximum likelihood phylogenetic analysis using combine sequences of ITS, GAPDH, ACT, TUB, HIS3 and CHS-1 in MEGA X confirmed the isolates as C. sojae, marking the first report of this pathogen on chilli in South Korea, previously known to infect soybean. Pathogenicity tests were conducted on wound and nonwounded healthy and mature-green chili fruits (cv. Bicksita) to confirm the pathogenicity of the isolated C. sojae. The fruits were surface-sterilized using 70% ethanol and then rinsed with sterile distilled water. The fruits were wounded using a sterile needle to facilitate infection. A conidial suspension (1x106 conidia/mL) was prepared from 7-day-old PDA cultures. Each fruit was inoculated by placing a 10 µL drop of the conidial suspension onto the wounded and nonwounded sites (4 to 5) of the wound and unwound fruits, res","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202600","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}
Pub Date : 2024-09-10DOI: 10.1094/pdis-07-24-1414-re
Luis Moll,Esther Badosa,Leonardo De La Fuente,Emilio Montesinos,Marta Planas,Anna Bonaterra,Lidia Feliu
Xylella fastidiosa is a xylem-limited plant pathogenic bacterium that is a menace to the agriculture worldwide threating economically relevant crops such as almond. The pathogen presents a dual lifestyle in the plant xylem, consisting of sessile microbial aggregates and mobile independent cells that move by twitching motility. The latter is essential for the systemic colonization of the host and is mediated through type IV pili. In previous reports, it has been demonstrated that peptides can affect different key processes of X. fastidiosa, but their effect on motility has never been assessed. In the present work, peptides previously identified and newly designed analogs were studied for its effect in vitro on the motility of X. fastidiosa and their protective effect against almond leaf scorch was determined. By assessing the twitching fringe width in colonies and using microfluidic chambers, the inhibitory effect of BP100 on twitching motility was demonstrated. Interestingly, type IV pili of BP100-treated cells were similar in frequency and length, and presented no morphological differences when compared to the non-treated control. The application of BP100 by endotherapy in almond plants inoculated with X. fastidiosa under greenhouse conditions significantly reduced population levels and showed less affected xylem vessels, which correlated with decreased disease symptoms. Therefore, BP100 is a promising candidate to manage almond leaf scorch caused by X. fastidiosa.
{"title":"Mitigation of almond leaf scorch by a peptide that inhibits the motility of Xylella fastidiosa.","authors":"Luis Moll,Esther Badosa,Leonardo De La Fuente,Emilio Montesinos,Marta Planas,Anna Bonaterra,Lidia Feliu","doi":"10.1094/pdis-07-24-1414-re","DOIUrl":"https://doi.org/10.1094/pdis-07-24-1414-re","url":null,"abstract":"Xylella fastidiosa is a xylem-limited plant pathogenic bacterium that is a menace to the agriculture worldwide threating economically relevant crops such as almond. The pathogen presents a dual lifestyle in the plant xylem, consisting of sessile microbial aggregates and mobile independent cells that move by twitching motility. The latter is essential for the systemic colonization of the host and is mediated through type IV pili. In previous reports, it has been demonstrated that peptides can affect different key processes of X. fastidiosa, but their effect on motility has never been assessed. In the present work, peptides previously identified and newly designed analogs were studied for its effect in vitro on the motility of X. fastidiosa and their protective effect against almond leaf scorch was determined. By assessing the twitching fringe width in colonies and using microfluidic chambers, the inhibitory effect of BP100 on twitching motility was demonstrated. Interestingly, type IV pili of BP100-treated cells were similar in frequency and length, and presented no morphological differences when compared to the non-treated control. The application of BP100 by endotherapy in almond plants inoculated with X. fastidiosa under greenhouse conditions significantly reduced population levels and showed less affected xylem vessels, which correlated with decreased disease symptoms. Therefore, BP100 is a promising candidate to manage almond leaf scorch caused by X. fastidiosa.","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202598","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}
Pub Date : 2024-09-10DOI: 10.1094/pdis-07-24-1401-re
Kephas Mphande,Mark L Gleason,Gwyn A Beattie
Cucurbit yellow vine disease (CYVD), which is caused by the gram-negative bacterium Serratia marcescens and transmitted by squash bugs (Anasa tristis DeGeer), is a devastating disease of cucurbit crops that is emerging rapidly in the eastern half of the U.S. The lack of a robust pathogenicity assay for CYVD in the laboratory has hampered functional tests using genomic sequences to investigate the biology of this phytopathogen. In this study we developed and validated a bioassay that yielded consistent and quantifiable CYVD symptoms on squash in the lab. We compared inoculation by wounding with a multipronged floral pin frog to inoculation by injection in which a needle was moved in and out of the stem multiple times in each of multiple piercings to mimic the feeding behavior of squash bugs. We found that inoculation by needle injection of ≥108 CFU/ml of S. marcescens into the stem of squash (Cucurbita pepo) plants at the cotyledon growth stage reproducibly induced CYVD symptoms, whereas injecting 106 or 107 CFU/ml did not. Additionally, we found that S. marcescens induced symptoms on all of the squash cultivars tested, and induced symptoms that have not been previously reported, including stem elongation and leaf cupping. In short, through our injection approach of mimicking the natural process of S. marcescens transmission by squash bug feeding, we obtained robust and quantifiable CYVD symptoms. This laboratory bioassay provides a crucial tool for investigating the biology and pathology of this emerging pathogen and for plant breeding screens aimed at combatting CYVD.
{"title":"A bioassay that yields quantifiable symptoms of cucurbit yellow vine disease caused by Serratia marcescens.","authors":"Kephas Mphande,Mark L Gleason,Gwyn A Beattie","doi":"10.1094/pdis-07-24-1401-re","DOIUrl":"https://doi.org/10.1094/pdis-07-24-1401-re","url":null,"abstract":"Cucurbit yellow vine disease (CYVD), which is caused by the gram-negative bacterium Serratia marcescens and transmitted by squash bugs (Anasa tristis DeGeer), is a devastating disease of cucurbit crops that is emerging rapidly in the eastern half of the U.S. The lack of a robust pathogenicity assay for CYVD in the laboratory has hampered functional tests using genomic sequences to investigate the biology of this phytopathogen. In this study we developed and validated a bioassay that yielded consistent and quantifiable CYVD symptoms on squash in the lab. We compared inoculation by wounding with a multipronged floral pin frog to inoculation by injection in which a needle was moved in and out of the stem multiple times in each of multiple piercings to mimic the feeding behavior of squash bugs. We found that inoculation by needle injection of ≥108 CFU/ml of S. marcescens into the stem of squash (Cucurbita pepo) plants at the cotyledon growth stage reproducibly induced CYVD symptoms, whereas injecting 106 or 107 CFU/ml did not. Additionally, we found that S. marcescens induced symptoms on all of the squash cultivars tested, and induced symptoms that have not been previously reported, including stem elongation and leaf cupping. In short, through our injection approach of mimicking the natural process of S. marcescens transmission by squash bug feeding, we obtained robust and quantifiable CYVD symptoms. This laboratory bioassay provides a crucial tool for investigating the biology and pathology of this emerging pathogen and for plant breeding screens aimed at combatting CYVD.","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142202603","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}
Pub Date : 2024-09-10DOI: 10.1094/pdis-04-24-0904-pdn
Md Nasir Uddin,Ismam Ahmed Protic,Abu Sina Md Tushar,Mehedi Hasan,Plabon Saha,Uday Rana Singha,Ayesha Sultana,Sabera Akter,Mohammad Ali Jinnah,Md Rashidul Islam
Bacterial panicle blight (BPB) is one of the emerging diseases occurring in different Agro-Ecological Zones (AEZ) of Bangladesh and can cause up to 75% yield loss. In Bangladesh, the typical symptoms of BPB include sheath rot, panicle blight, grain spotting, and grain rot in both inbred and hybrid rice varieties, which resemble those reported by Zhou (2019). To confirm, 300 field samples of 20 panicles each with typical BPB symptoms from 20 districts (3 locations each district and 5 fields per location) were collected during mid-November 2022 for the causal pathogen(s) isolation. Nearly 70% of the panicles showed a dark brown chaffy appearance in the fields. For identification of the causal pathogen(s), 1 g of rice grains with typical BPB symptoms was surface sterilized by immersing for 15 seconds in 70% ethanol, 1 min in 3% sodium hypochlorite solution followed by rinsing the grains three times, and soaked in 1 mL sterile distilled water for 10 min (Mirghasempour et al. 2018). During grinding using mortar and pestle, 5 mL water was added (Islam et al. 2023) after which the suspension (20 μL) was then streaked onto the selective medium (S-PG) (Tsushima et al. 1986). Purple color colonies on the S-PG medium were selected and purified as candidate pathogens. For further confirmation, the genomic DNA of the bacterial isolates was extracted and amplified by PCR using 16SF (5'-AGAGTTTGATCCTGGCTCAG-3') and 16SR (5'-GGCTACCTTGTTACGACTT-3') (Nandakumar et al. 2009), and glu-FW (5'-GAAGTGTCGCCGATGGAG-3') and glu-RV (5'-CCTTCACCGACAGCACGCAT-3') primers (Maeda et al. 2006). The PCR products were visualized on 1% agarose gel resulting amplicons of 1494bp for 16S-rDNA and 529bp for gyrB. The PCR results revealed 529bp amplification for gyrB gene in one sample that was collected from a field in Natore (24°21'0.00" N 89°04'59.88" E) district cultivating Swarna (a local rice variety), primarily indicating the causal pathogen is Burkholderia glumae. The PCR products were sequenced using both primers and sequence data was analyzed by the BLAST nucleotide program. The obtained partial sequences of 16S rDNA and gyrB were deposited in Genbank (OR573691 and PP332812 respectively). The homology of 16S rDNA resulted over 98% with B. glumae (OK559611 and ON870618.1) and 100% with B. glumae (PP332812 and KX213523) for gyrB gene. To confirm B. glumae by pathogenicity test, 10 mL (108 UFC/ml) suspension of the representative strains, 0.5 mL was then injected into the panicles and sheaths of Horidhan (a susceptible local variety) in greenhouse condition and a control was inoculated with distilled water (Nandakumar et al. 2009). Typical BPB like symptoms were observed after 3 weeks post inoculation. The pathogen was again confirmed by reisolating from the infected spots as B. glumae to fulfill Koch's postulates. This report confirms the presence of B. glumae causing BPB of rice in Bangladesh. Future research for the investigation of BPB and the evolutionary origins of its cau
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