Pub Date : 2024-11-11DOI: 10.1094/PDIS-08-24-1718-SR
Marcelo I Bustamante, Karina Elfar, Carlos Carachure, Adam Adaskaveg, John N Kabashima, Christopher Shogren, Akif Eskalen, Shannon Colleen Lynch
Pine ghost canker is a recently described disease affecting multiple pine species in urban forests of Southern California. Symptoms include wedged cankers with irregular margins and cryptic discoloration on cross-sections of branches, which can lead to severe dieback and potentially tree death. In this study, we identified and characterized five Neofusicoccum species (N. luteum, N. mediterraneum, N. parvum, N. stellenboschianum, and N. vitifusiforme) as the primary etiological agents of pine ghost canker. These pathogens were consistently isolated from multiple symptomatic pine samples (n = 41) and identified by morphology and phylogenetic analyses using four DNA barcodes (rDNA ITS, tef1, tub2, and rpb2). Pathogenicity was confirmed on healthy branches of 15-year-old Monterey pines, where the five Neofusicoccum species, caused vascular lesions that were not significantly different in length. Secondary fungi (Diaporthe, Diplodia, Neopestalotiopsis, and Pestalotiopsis spp.) were also recovered from symptomatic tissues but did not cause vascular lesions in pathogenicity tests. The optimal temperature for mycelial growth of N. luteum and N. parvum was 30 °C, whereas for N. mediterraneum, N. stellenboschianum and N. vitifusiforme, it was 25 °C. All five species were able to resume growth at room temperature (20 °C) after showing no growth during a 7-day exposure to 5 °C and 40 °C. This study constitutes the first report of N. luteum, N. stellenboschianum, and N. vitifusiforme causing pine ghost canker in California. Environmental factors such as warmer temperatures, irrigation, and pest infestations are discussed as drivers of disease expression in pine trees. Management practices are also proposed.
松树幽灵腐烂病是最近描述的一种影响南加州城市森林中多个松树品种的疾病。症状包括边缘不规则的楔形溃疡和枝条横截面上的隐性变色,可导致严重枯死,甚至可能造成树木死亡。在这项研究中,我们确定并描述了五种 Neofusicoccum(N. luteum、N. mediterraneum、N. parvum、N. stellenboschianum 和 N. vitifusiforme)为松树鬼皮病的主要病原体。从多个有症状的松树样本(n = 41)中持续分离出了这些病原体,并通过形态学和使用四种 DNA 条形码(rDNA ITS、tef1、tub2 和 rpb2)进行的系统发育分析进行了鉴定。在 15 年树龄的蒙特雷松的健康枝条上证实了致病性,五种 Neofusicoccum 引起的维管病变在长度上没有明显差异。次生真菌(Diaporthe、Diplodia、Neopestalotiopsis 和 Pestalotiopsis spp.)也在有症状的组织中被发现,但在致病性试验中没有引起维管病变。N. luteum 和 N. parvum 菌丝生长的最适温度为 30 °C,而 N. mediterraneum、N. stellenboschianum 和 N. vitifusiforme 的最适温度为 25 °C。在 5 °C 和 40 °C 下暴露 7 天后,所有五个物种都能在室温(20 °C )下恢复生长。这项研究是首次报道 N. luteum、N. stellenboschianum 和 N. vitifusiforme 在加利福尼亚州引起松树鬼腐病。研究讨论了温度升高、灌溉和虫害等环境因素对松树病害表现的影响。此外还提出了一些管理措施。
{"title":"Etiology of Pine Ghost Canker in Southern California Urban Forests.","authors":"Marcelo I Bustamante, Karina Elfar, Carlos Carachure, Adam Adaskaveg, John N Kabashima, Christopher Shogren, Akif Eskalen, Shannon Colleen Lynch","doi":"10.1094/PDIS-08-24-1718-SR","DOIUrl":"https://doi.org/10.1094/PDIS-08-24-1718-SR","url":null,"abstract":"<p><p>Pine ghost canker is a recently described disease affecting multiple pine species in urban forests of Southern California. Symptoms include wedged cankers with irregular margins and cryptic discoloration on cross-sections of branches, which can lead to severe dieback and potentially tree death. In this study, we identified and characterized five <i>Neofusicoccum</i> species (<i>N. luteum</i>, <i>N. mediterraneum</i>, <i>N. parvum</i>, <i>N. stellenboschianum</i>, and <i>N. vitifusiforme</i>) as the primary etiological agents of pine ghost canker. These pathogens were consistently isolated from multiple symptomatic pine samples (<i>n</i> = 41) and identified by morphology and phylogenetic analyses using four DNA barcodes (rDNA ITS, <i>tef1</i>, <i>tub2</i>, and <i>rpb2</i>). Pathogenicity was confirmed on healthy branches of 15-year-old Monterey pines, where the five <i>Neofusicoccum</i> species, caused vascular lesions that were not significantly different in length. Secondary fungi (<i>Diaporthe</i>, <i>Diplodia</i>, <i>Neopestalotiopsis</i>, and <i>Pestalotiopsis</i> spp.) were also recovered from symptomatic tissues but did not cause vascular lesions in pathogenicity tests. The optimal temperature for mycelial growth of <i>N. luteum</i> and <i>N. parvum</i> was 30 °C, whereas for <i>N. mediterraneum</i>, <i>N. stellenboschianum</i> and <i>N. vitifusiforme</i>, it was 25 °C. All five species were able to resume growth at room temperature (20 °C) after showing no growth during a 7-day exposure to 5 °C and 40 °C. This study constitutes the first report of <i>N. luteum</i>, <i>N. stellenboschianum</i>, and <i>N. vitifusiforme</i> causing pine ghost canker in California. Environmental factors such as warmer temperatures, irrigation, and pest infestations are discussed as drivers of disease expression in pine trees. Management practices are also proposed.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625745","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}
Rice spikelet rot disease (RSRD) is an emerging threat to rice crops, with sporadic but severe outbreaks in China in recent years. The composition of its pathogenic fungi has not been consistently identified, and chemical control methods remain unclear. This study aims to characterize the pathogen species responsible for RSRD and develop effective control strategies. Regional variations in disease symptoms and pathogen compositions were analyzed, which led to the identification of six novel pathogens, including Fusarium tanahbumbuense, Alternaria gaisen, Curvularia verruculosa, Curvularia brachyspora, Curvularia muehlenbeckiae, and Curvularia hominis. The pathogenic composition of RSRD exhibited considerable variation across different latitudes within China. Specifically, Alternaria spp. predominated in the Heilongjiang and Liaoning Provinces. Whereas Fusarium spp. and Curvularia spp. were more prevalent in the Hainan and Fujian Provinces. In contrast, Fusarium spp. and Alternaria spp. were the dominant pathogens in the Anhui and Jiangsu Provinces. Furthermore, an assessment of the sensitivity of these predominant pathogens to four chemical compounds was conducted, which led to the identification of potential fungicides for effective disease control. This research provides valuable insights into the pathogenic profile of RSRD across different regions and offers strategic recommendations for fungicide-based management of the disease.
{"title":"Pathogen Composition and Fungicide Sensitivity in Rice Spikelet Rot Disease.","authors":"Jiaqi Chen, Xiping Cao, Xiaolong Fu, Mingguo Zhou, Changjun Chen, Xiu-Shi Song","doi":"10.1094/PDIS-09-24-1807-RE","DOIUrl":"https://doi.org/10.1094/PDIS-09-24-1807-RE","url":null,"abstract":"<p><p>Rice spikelet rot disease (RSRD) is an emerging threat to rice crops, with sporadic but severe outbreaks in China in recent years. The composition of its pathogenic fungi has not been consistently identified, and chemical control methods remain unclear. This study aims to characterize the pathogen species responsible for RSRD and develop effective control strategies. Regional variations in disease symptoms and pathogen compositions were analyzed, which led to the identification of six novel pathogens, including Fusarium tanahbumbuense, Alternaria gaisen, Curvularia verruculosa, Curvularia brachyspora, Curvularia muehlenbeckiae, and Curvularia hominis. The pathogenic composition of RSRD exhibited considerable variation across different latitudes within China. Specifically, Alternaria spp. predominated in the Heilongjiang and Liaoning Provinces. Whereas Fusarium spp. and Curvularia spp. were more prevalent in the Hainan and Fujian Provinces. In contrast, Fusarium spp. and Alternaria spp. were the dominant pathogens in the Anhui and Jiangsu Provinces. Furthermore, an assessment of the sensitivity of these predominant pathogens to four chemical compounds was conducted, which led to the identification of potential fungicides for effective disease control. This research provides valuable insights into the pathogenic profile of RSRD across different regions and offers strategic recommendations for fungicide-based management of the disease.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625751","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 : 2024-11-11DOI: 10.1094/PDIS-12-23-2655-PDN
Elizabeth Peña, Ursula Steinfort, Belén Concha, Inés Marlene Rosales
Ficus benjamina, commonly known as ficus or weeping fig, is an ornamental tree from Southeast Asia in the Moraceae family. It is an evergreen species grown as an interior plant worldwide, prized for its glossy green leaves, gray stem, and multiple branches. F. benjamina can be pruned and kept as a small shrub when grown indoors, with most commercially available cultivars in the ornamental industry derived from sports and propagated cuttings (Chen et al., 2010). In October 2022, symptoms indicative of alfalfa mosaic virus (AMV) infection, such as intense bright yellow spots, mottling and chlorosis were observed in leaves of F. benjamina growing in office environments in Santiago, Chile (supplementary Fig.1). Seven symptomatic and three asymptomatic plants were sampled and traced back to the same plant nursery, and only leaf tissue samples from the symptomatic plants tested positive for the presence of the AMV using enzyme-linked immunosorbent assay (ELISA) (Agdia Inc., Elkhart, IN). These results were verified using reverse transcription (RT)-PCR with specific primers AMV-F and AMV-R, targeting a region of the AMV CP gene (Xu and Nie, 2006). AMV was detected in all symptomatic leaf samples, producing 351-bp amplicons in the RT-PCR assay for all samples that were positive to AMV by ELISA. No amplification product was observed when seronegative samples or non-template control was used as templates in the RT-PCR assays. Three RT-PCR amplicons were directly sequenced in both directions. BLAST analysis of these sequences showed 100% nucleotide sequence identity to an AMV isolate previously reported (GenBank Accession No. KX458469), confirming the detection of AMV in F. benjamina. This pathogen causes disease in several species, including ornamentals plant such as Viburnum tinus L. (Peña et al., 2011), peony (Belardi and Rubies, 2003), phlox (Holcomb et al., 2006), and weeds such as Cayratia japonica (Thunb.) Gagnep, Justicia procumbens L. and Veronica persica Poir. (Gao et al., 2020). F. benjamina is among the most popular ornamental indoor plants in Chile, so nurseries should ensure AMV-free plants to restrict disease incidence and prevent the spread of this virus. However, Chile lacks specific regulations for ornamental nurseries, making adherence to pest and disease recommendations voluntary, and only imported plant material requires a sanitary certificate.
{"title":"First detection of alfalfa mosaic virus in <i>Ficus benjamina</i> in Chile.","authors":"Elizabeth Peña, Ursula Steinfort, Belén Concha, Inés Marlene Rosales","doi":"10.1094/PDIS-12-23-2655-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-12-23-2655-PDN","url":null,"abstract":"<p><p>Ficus benjamina, commonly known as ficus or weeping fig, is an ornamental tree from Southeast Asia in the Moraceae family. It is an evergreen species grown as an interior plant worldwide, prized for its glossy green leaves, gray stem, and multiple branches. F. benjamina can be pruned and kept as a small shrub when grown indoors, with most commercially available cultivars in the ornamental industry derived from sports and propagated cuttings (Chen et al., 2010). In October 2022, symptoms indicative of alfalfa mosaic virus (AMV) infection, such as intense bright yellow spots, mottling and chlorosis were observed in leaves of F. benjamina growing in office environments in Santiago, Chile (supplementary Fig.1). Seven symptomatic and three asymptomatic plants were sampled and traced back to the same plant nursery, and only leaf tissue samples from the symptomatic plants tested positive for the presence of the AMV using enzyme-linked immunosorbent assay (ELISA) (Agdia Inc., Elkhart, IN). These results were verified using reverse transcription (RT)-PCR with specific primers AMV-F and AMV-R, targeting a region of the AMV CP gene (Xu and Nie, 2006). AMV was detected in all symptomatic leaf samples, producing 351-bp amplicons in the RT-PCR assay for all samples that were positive to AMV by ELISA. No amplification product was observed when seronegative samples or non-template control was used as templates in the RT-PCR assays. Three RT-PCR amplicons were directly sequenced in both directions. BLAST analysis of these sequences showed 100% nucleotide sequence identity to an AMV isolate previously reported (GenBank Accession No. KX458469), confirming the detection of AMV in F. benjamina. This pathogen causes disease in several species, including ornamentals plant such as Viburnum tinus L. (Peña et al., 2011), peony (Belardi and Rubies, 2003), phlox (Holcomb et al., 2006), and weeds such as Cayratia japonica (Thunb.) Gagnep, Justicia procumbens L. and Veronica persica Poir. (Gao et al., 2020). F. benjamina is among the most popular ornamental indoor plants in Chile, so nurseries should ensure AMV-free plants to restrict disease incidence and prevent the spread of this virus. However, Chile lacks specific regulations for ornamental nurseries, making adherence to pest and disease recommendations voluntary, and only imported plant material requires a sanitary certificate.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625746","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}
Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is the most devastating fungal disease affecting wheat in China, particularly in the northwestern (Qinghai, Gansu, and Ningxia) and southwestern (Sichuan, Yunnan, and Guizhou) oversummering regions. In this study, 302 isolates collected from these six provinces were analyzed using virulence testing and single-nucleotide polymorphism (SNP) markers. Virulence testing on 19 Chinese differentials identified 38 previously reported and 49 novel races. CYR34 was the most prevalent race in both the northwestern and southwestern oversummering regions, with frequencies of 24.00% and 21.05%, respectively. In the northwestern oversummering region, the prevalence of CYR32 (10.70%) and G22-14 (10.67%) was nearly identical, whereas in the southwestern oversummering region, CYR32 (13.20%) and G22-14 (9.87%) exhibited significant differences. Additionally, 112 races were identified using 18 Yr single-gene differentials, although none of the isolates showed virulence to either Yr5 or Yr15. The virulence diversity of Pst populations was greater in the southwestern than in the northwestern oversummering region, as indicated by the differential sets. Further molecular analysis with 20 pairs of polymorphic KASP-SNP markers confirmed that the southwestern Pst population exhibited higher genetic diversity than the northwestern population. Both virulence phenotypes and genotype data demonstrated that the Pst population was more diverse in the southwestern oversummering region, despite presence of the exchange of Pst sources between regions. In addition, mutant isolates indicating resistance to tiadimefon fungicide were detected in both regions. This study provides a systematic comparison of Pst populations in the northwestern and southwestern oversummering regions based on virulence phenotyping and SNP marker genotyping, and the findings are crucial for the integrated management of wheat stripe rust in these regions and across the country.
{"title":"Virulence and Diversity of <i>Puccinia striiformis</i> f. sp. <i>tritici</i> Populations in Northwestern and Southwestern Oversummering Regions of China.","authors":"Jie Wang, Xinyun Liu, Mengjie Ma, Yongjin Jin, Liyao Fu, Mingju Li, Lili Huang, Zhensheng Kang, Gangming Zhan","doi":"10.1094/PDIS-09-24-1901-RE","DOIUrl":"https://doi.org/10.1094/PDIS-09-24-1901-RE","url":null,"abstract":"<p><p>Stripe rust, caused by <i>Puccinia striiformis</i> f. sp. <i>tritici</i> (<i>Pst</i>), is the most devastating fungal disease affecting wheat in China, particularly in the northwestern (Qinghai, Gansu, and Ningxia) and southwestern (Sichuan, Yunnan, and Guizhou) oversummering regions. In this study, 302 isolates collected from these six provinces were analyzed using virulence testing and single-nucleotide polymorphism (SNP) markers. Virulence testing on 19 Chinese differentials identified 38 previously reported and 49 novel races. CYR34 was the most prevalent race in both the northwestern and southwestern oversummering regions, with frequencies of 24.00% and 21.05%, respectively. In the northwestern oversummering region, the prevalence of CYR32 (10.70%) and G22-14 (10.67%) was nearly identical, whereas in the southwestern oversummering region, CYR32 (13.20%) and G22-14 (9.87%) exhibited significant differences. Additionally, 112 races were identified using 18 <i>Yr</i> single-gene differentials, although none of the isolates showed virulence to either <i>Yr5</i> or <i>Yr15</i>. The virulence diversity of <i>Pst</i> populations was greater in the southwestern than in the northwestern oversummering region, as indicated by the differential sets. Further molecular analysis with 20 pairs of polymorphic KASP-SNP markers confirmed that the southwestern <i>Pst</i> population exhibited higher genetic diversity than the northwestern population. Both virulence phenotypes and genotype data demonstrated that the <i>Pst</i> population was more diverse in the southwestern oversummering region, despite presence of the exchange of <i>Pst</i> sources between regions. In addition, mutant isolates indicating resistance to tiadimefon fungicide were detected in both regions. This study provides a systematic comparison of <i>Pst</i> populations in the northwestern and southwestern oversummering regions based on virulence phenotyping and SNP marker genotyping, and the findings are crucial for the integrated management of wheat stripe rust in these regions and across the country.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625755","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 : 2024-11-11DOI: 10.1094/PDIS-04-24-0876-RE
John Bickel, Madeline Grace Henrickson, Alyssa K Betts
Corn (Zea mays L.) is the top grain crop by hectares grown in Delaware (DE). Increased pre- and post-emergence damping-off in corn caused by Pythium species have been observed in recent seasons. To date, no characterization studies have been performed to understand Pythium species diversity in DE. Symptomatic corn seedlings were collected from 33 fields across DE in 2019 and 2020. Isolates were obtained from infected root tissues and identified by molecular sequencing. In total, 14 species were recovered: P. aristosporum, P. arrhenomanes, P. attrantheridium, P. catenulatum, P. dissotocum, P. graminicola, P. inflatum, P. irregulare, P. oligandrum, P. periplocum, P.spinosum, P. sylvaticum, P. tardicrescens, and P. torulosum. The dominant species recovered was P. graminicola, accounting for 66% of the isolates. Five species were screened for fungicide sensitivity to calculate the EC50 of mefenoxam, ethaboxam, and picarbutrazox which are the most commonly used active ingredients to manage species of Pythium in corn seed treatment packages. All species tested were sensitive to mefenoxam and picarbutrazox. For ethaboxam, P. torulosum was the only species with an EC50 value > 10 µg ml 1. Ten species were screened for fungicide sensitivity to mefenoxam, ethaboxam, or picarbutrazox at 18, 21, and 25ºC. As temperatures increased, percent inhibition was reduced in 40, 70, and 80% of the species screened for sensitivity to ethaboxam, picarbutrazox, and mefenoxam, respectively. Nine of these species were screened for isolate aggressiveness in greenhouse panels to examine impact on emergence, shoot height, shoot weight, and root weight. While all species were recovered from inoculated roots, P. arrhenomanes, P. attrantheridium, P. spinosum, and P. sylvaticum had the greatest root weight reduction.
{"title":"Characterization of the species of <i>Pythium</i> associated with corn seedlings in Delaware.","authors":"John Bickel, Madeline Grace Henrickson, Alyssa K Betts","doi":"10.1094/PDIS-04-24-0876-RE","DOIUrl":"https://doi.org/10.1094/PDIS-04-24-0876-RE","url":null,"abstract":"<p><p>Corn (Zea mays L.) is the top grain crop by hectares grown in Delaware (DE). Increased pre- and post-emergence damping-off in corn caused by Pythium species have been observed in recent seasons. To date, no characterization studies have been performed to understand Pythium species diversity in DE. Symptomatic corn seedlings were collected from 33 fields across DE in 2019 and 2020. Isolates were obtained from infected root tissues and identified by molecular sequencing. In total, 14 species were recovered: P. aristosporum, P. arrhenomanes, P. attrantheridium, P. catenulatum, P. dissotocum, P. graminicola, P. inflatum, P. irregulare, P. oligandrum, P. periplocum, P.spinosum, P. sylvaticum, P. tardicrescens, and P. torulosum. The dominant species recovered was P. graminicola, accounting for 66% of the isolates. Five species were screened for fungicide sensitivity to calculate the EC50 of mefenoxam, ethaboxam, and picarbutrazox which are the most commonly used active ingredients to manage species of Pythium in corn seed treatment packages. All species tested were sensitive to mefenoxam and picarbutrazox. For ethaboxam, P. torulosum was the only species with an EC50 value > 10 µg ml 1. Ten species were screened for fungicide sensitivity to mefenoxam, ethaboxam, or picarbutrazox at 18, 21, and 25ºC. As temperatures increased, percent inhibition was reduced in 40, 70, and 80% of the species screened for sensitivity to ethaboxam, picarbutrazox, and mefenoxam, respectively. Nine of these species were screened for isolate aggressiveness in greenhouse panels to examine impact on emergence, shoot height, shoot weight, and root weight. While all species were recovered from inoculated roots, P. arrhenomanes, P. attrantheridium, P. spinosum, and P. sylvaticum had the greatest root weight reduction.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625823","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 : 2024-11-11DOI: 10.1094/PDIS-05-24-0960-PDN
Flávia Fernandes Ribeiro Miranda, Marcio Akio Ootani, Raynne Barbosa Santos Rabelo, Eliane Regina Archangelo, Jonahtan Chaves Melo, Raimundo Wagner de Souza Aguiar, Eugenio Eduardo Oliveira, Gil R Santos
Elephant grass, Cenchrus purpureus, exhibits high efficiency in sequesting atmospheric CO2 during photosynthesis, leading to significant biomass production. As a C4 plant, it holds immense potential for alternative biodiesel production and serves as fresh feed for cattle (Negawo et al. 2018). Field observations in commercial pastures planted with elephant grass, located in the Brazilian cerrado, revealed necrotic leaf spots with a brownish center and a yellowish halo, reaching a severity of 30 to 50% between 2022 and 2023 in Palmas (10°24'08"S 48°21'45" W) and Gurupi (11°46'21"S 49°02'08" W), municipalities located in the state of Tocantins, Brazil. In both years, the field incidence of the disease on young and mature leaves approached 100% during the rainy season. Affected leaves were collected, packed in a thermal box, and taken to the phytopathology laboratory. The 198 leaves were sanitised in 1% hypochlorite for 30 seconds and washed thrice in sterile water. Upon sanitisation, leaf tissues were cut and cultured on potato dextrose agar (PDA) medium and incubated in a controlled chamber (BOD) at 28°C with a 12-hour photoperiod. Colonies exhibited a greyish colour with whitish edges, and the top plate was brownish, growing to a diameter of 5 cm over seven days. The colonies obtained from monosporic cultures formed curved conidia, predominantly with three septa, of a brownish colour, with lengths ranging from (7 µm to 14 µm and widths from 5 µm to 7 µm. (N=-50, Fig 1) (Yasanthika et al. 2023). The UFTCC01 isolate's DNA was extracted using the extraction kit (PROMEGA ®), amplified for genes (ITS, Gapdh and Tefα1), sequenced (OR345316.1, OR344427.1 and OR344428.1) and compared in BLASTn at Gen Bank deposited sequences. Phylogenetic analysis using the parsimony method in MEGA X identified the isolate as Curvularia chiangmaiensis, showing 99.5% identity with reference sequences (MN215651.1, MN264085.1, and MN263942.1). Concatenated region comparison revealed 94% similarity to sequences (OP564987.1 and MF490814.1) in the phylogenetic tree, confirming the species. The pathogenicity test used 60 seedlings of 50-day-old elephant grass, 30 of which were inoculated with a spore suspension (3.0 × 106 spores/mL) and 30 with sterile water. The solutions were sprayed twice. Only plants inoculated with the spore suspension exhibited symptoms akin to those observed in the field. Then, the fungus was reisolated from the lesions and Koch's postulates were confirmed twice.Previous studies have documented the C. chiangmaiensis pathogenicity in other grasses, such as maise in Thailand (Marin et al. 2017). Our studies constitute the first report of C. chiangmaiensis causing leaf spots on elephant grass in the Brazil.
{"title":"First report of <i>Curvularia chiangmaiensis</i> causing leaf spot in elephant grass in Brazil.","authors":"Flávia Fernandes Ribeiro Miranda, Marcio Akio Ootani, Raynne Barbosa Santos Rabelo, Eliane Regina Archangelo, Jonahtan Chaves Melo, Raimundo Wagner de Souza Aguiar, Eugenio Eduardo Oliveira, Gil R Santos","doi":"10.1094/PDIS-05-24-0960-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-05-24-0960-PDN","url":null,"abstract":"<p><p>Elephant grass, Cenchrus purpureus, exhibits high efficiency in sequesting atmospheric CO2 during photosynthesis, leading to significant biomass production. As a C4 plant, it holds immense potential for alternative biodiesel production and serves as fresh feed for cattle (Negawo et al. 2018). Field observations in commercial pastures planted with elephant grass, located in the Brazilian cerrado, revealed necrotic leaf spots with a brownish center and a yellowish halo, reaching a severity of 30 to 50% between 2022 and 2023 in Palmas (10°24'08\"S 48°21'45\" W) and Gurupi (11°46'21\"S 49°02'08\" W), municipalities located in the state of Tocantins, Brazil. In both years, the field incidence of the disease on young and mature leaves approached 100% during the rainy season. Affected leaves were collected, packed in a thermal box, and taken to the phytopathology laboratory. The 198 leaves were sanitised in 1% hypochlorite for 30 seconds and washed thrice in sterile water. Upon sanitisation, leaf tissues were cut and cultured on potato dextrose agar (PDA) medium and incubated in a controlled chamber (BOD) at 28°C with a 12-hour photoperiod. Colonies exhibited a greyish colour with whitish edges, and the top plate was brownish, growing to a diameter of 5 cm over seven days. The colonies obtained from monosporic cultures formed curved conidia, predominantly with three septa, of a brownish colour, with lengths ranging from (7 µm to 14 µm and widths from 5 µm to 7 µm. (N=-50, Fig 1) (Yasanthika et al. 2023). The UFTCC01 isolate's DNA was extracted using the extraction kit (PROMEGA ®), amplified for genes (ITS, Gapdh and Tefα1), sequenced (OR345316.1, OR344427.1 and OR344428.1) and compared in BLASTn at Gen Bank deposited sequences. Phylogenetic analysis using the parsimony method in MEGA X identified the isolate as Curvularia chiangmaiensis, showing 99.5% identity with reference sequences (MN215651.1, MN264085.1, and MN263942.1). Concatenated region comparison revealed 94% similarity to sequences (OP564987.1 and MF490814.1) in the phylogenetic tree, confirming the species. The pathogenicity test used 60 seedlings of 50-day-old elephant grass, 30 of which were inoculated with a spore suspension (3.0 × 106 spores/mL) and 30 with sterile water. The solutions were sprayed twice. Only plants inoculated with the spore suspension exhibited symptoms akin to those observed in the field. Then, the fungus was reisolated from the lesions and Koch's postulates were confirmed twice.Previous studies have documented the C. chiangmaiensis pathogenicity in other grasses, such as maise in Thailand (Marin et al. 2017). Our studies constitute the first report of C. chiangmaiensis causing leaf spots on elephant grass in the Brazil.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625748","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 : 2024-11-11DOI: 10.1094/PDIS-09-24-1883-PDN
Xinjie Zhan, Zhuoqiu Qiu, Qi Huang, Shuangshuang Qin, Zhanjiang Zhang, Shugen Wei, Ni Jiang, Lisha Song
<p><p>Spatholobus suberectus Dunn is an important Chinese medicinal plant, which is the only officially recognized authentic source of the Chinese herbal medicine Spatholobi caulis in the China Pharmacopeia (Qin et al. 2024). In November 2023, a serious leaf disease was observed in the S. suberectus planting base in Nanning city (108.22E, 22.51N), Guangxi, China, with an incidence rate of 80%. Initially the symptoms appeared in the diseased leaves tips and was irregular in shape. The necrosis displayed discoloration of the gray color with a deep brown margin and this gradually expanded through into the lamina. To isolate the causal agent, 10 symptomatic leaves were collected and small segments (5×5 mm) of infected tissues were cut, and then they were surface sterilized (30s in 75% EtOH, 2 min in 2.5% NaOCl, and rinsed three times in sterilized distilled water), placed on potato dextrose agar (PDA) and incubated at 28℃ for 5 days. The hyphal tips were transferred to PDA to obtain pure cultures. 36 isolates were obtained, 23 of them had similar morphology, which were isolated from all the symptomatic leaves and were considered pathogens, and named YY-3-S. After 7 d, the colonies were white, fluffy, with white aerial mycelium. Sporulation was induced using pine needle medium (Su et al. 2012). After 30 days, the globose pycnidia developed, which were superficial to semi-immersed on the pine needle medium, and they appeared to be orange to black in color, with pale yellow conidial droplets. The alpha conidia spores were 3.53 to 6.85×1.75 to 3.70 μm (n = 50). They were unicellular, hyaline, aseptate and ellipsoidal to fusiform. These morphological features were consistent with Diaporthe sp (Sun et al. 2021). For further molecular identification, isolate YY-3-S underwent sequencing of the internal transcribed spacer (ITS), beta-tubulin (TUB2), and translation elongation factor 1-alpha (TEF1) sections (Huang et al. 2021). Obtained sequences of ITS, TUB2 and TEF1 (Genebank accessions nos. PP838571, PP865050 and PP865051) displayed a 99% similarity to Diaporthe tulliensis (Genebank accessions nos. OP163562, KR936132, OR662168, respectively). Phylogenetic analysis was based on a combination of ITS, TUB2 and TEF1 sequence data using MEGA 11 software to construct a phylogenetic tree with Neighbor-Joining. In the phylogenetic tree, the combined sequences attributed YY-3-S to D. tulliensis. The pathogenicity test was conducted on 1-year-old S. suberectus seedlings. We sprayed the mixed suspension of spores and mycelia on the unwounded leaves, while control seedlings received sterile water. 3 leaves per plant and 5 plants per treatment were selected for assessment. All seedings were placed in pots in a moist chamber at 28°C and 90% humidity. After 5 d, browning was observed on all the inoculated leaves tips. 14 d after inoculation, necrotic lesions expanded outward and their symptoms like those in the field, while control plants remained healthy. D. tulliensis w
{"title":"First Report in China of Leaf Blight on <i>Spatholobus suberectus</i> Dunn Caused by <i>Diaporthe tulliensis</i>.","authors":"Xinjie Zhan, Zhuoqiu Qiu, Qi Huang, Shuangshuang Qin, Zhanjiang Zhang, Shugen Wei, Ni Jiang, Lisha Song","doi":"10.1094/PDIS-09-24-1883-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-09-24-1883-PDN","url":null,"abstract":"<p><p>Spatholobus suberectus Dunn is an important Chinese medicinal plant, which is the only officially recognized authentic source of the Chinese herbal medicine Spatholobi caulis in the China Pharmacopeia (Qin et al. 2024). In November 2023, a serious leaf disease was observed in the S. suberectus planting base in Nanning city (108.22E, 22.51N), Guangxi, China, with an incidence rate of 80%. Initially the symptoms appeared in the diseased leaves tips and was irregular in shape. The necrosis displayed discoloration of the gray color with a deep brown margin and this gradually expanded through into the lamina. To isolate the causal agent, 10 symptomatic leaves were collected and small segments (5×5 mm) of infected tissues were cut, and then they were surface sterilized (30s in 75% EtOH, 2 min in 2.5% NaOCl, and rinsed three times in sterilized distilled water), placed on potato dextrose agar (PDA) and incubated at 28℃ for 5 days. The hyphal tips were transferred to PDA to obtain pure cultures. 36 isolates were obtained, 23 of them had similar morphology, which were isolated from all the symptomatic leaves and were considered pathogens, and named YY-3-S. After 7 d, the colonies were white, fluffy, with white aerial mycelium. Sporulation was induced using pine needle medium (Su et al. 2012). After 30 days, the globose pycnidia developed, which were superficial to semi-immersed on the pine needle medium, and they appeared to be orange to black in color, with pale yellow conidial droplets. The alpha conidia spores were 3.53 to 6.85×1.75 to 3.70 μm (n = 50). They were unicellular, hyaline, aseptate and ellipsoidal to fusiform. These morphological features were consistent with Diaporthe sp (Sun et al. 2021). For further molecular identification, isolate YY-3-S underwent sequencing of the internal transcribed spacer (ITS), beta-tubulin (TUB2), and translation elongation factor 1-alpha (TEF1) sections (Huang et al. 2021). Obtained sequences of ITS, TUB2 and TEF1 (Genebank accessions nos. PP838571, PP865050 and PP865051) displayed a 99% similarity to Diaporthe tulliensis (Genebank accessions nos. OP163562, KR936132, OR662168, respectively). Phylogenetic analysis was based on a combination of ITS, TUB2 and TEF1 sequence data using MEGA 11 software to construct a phylogenetic tree with Neighbor-Joining. In the phylogenetic tree, the combined sequences attributed YY-3-S to D. tulliensis. The pathogenicity test was conducted on 1-year-old S. suberectus seedlings. We sprayed the mixed suspension of spores and mycelia on the unwounded leaves, while control seedlings received sterile water. 3 leaves per plant and 5 plants per treatment were selected for assessment. All seedings were placed in pots in a moist chamber at 28°C and 90% humidity. After 5 d, browning was observed on all the inoculated leaves tips. 14 d after inoculation, necrotic lesions expanded outward and their symptoms like those in the field, while control plants remained healthy. D. tulliensis w","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625747","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 : 2024-11-11DOI: 10.1094/PDIS-08-24-1759-PDN
Estefania Peña-Zuñiga, Noelia Barriga-Medina, Dario Ramirez-Villacis, Madelein Miranda-Guerrero, Corné Pieterse, Jos M Raaijmakers, Antonio Leon-Reyes
<p><p>Potato (Solanum tuberosum) is grown in Ecuador's Andean region at altitudes from 2,200 to 3,600 m.a.s.l., and the most commercially significant cultivar is Superchola, which constitutes 60% of total production, covering around 11,000 hectares (MAG, s.f. 2022). From November 2022 to January 2023, dark, water-soaked lesions progressing upwards from the base of the stems were observed on Superchola potato plants in Cañar, Ecuador (2°23'56.4''S 78°59'13.2''W). Approximately 20 plants in a hectare showed symptoms. Symptomatic stems from five plants were collected, surface-disinfected with 2% sodium hypochlorite, followed by 70% ethanol, and thoroughly rinsed with sterile distilled water. Plant tissue sections (1 cm²) were homogenized in 10 mM MgCl₂, serially diluted, and plated on Tryptic Soy Agar (TSA). After 48 hours of incubation at 28°C, creamy-white, yellowish, and white round colonies appeared. Streak plating was performed, yielding 14 purified bacterial isolates named M1 to M14. For the pathogenicity tests, each purified isolate was inoculated into healthy potato tubers and stem pieces (5 cm) using the prick inoculation method described by Ma et al. (2018) with modifications. Surface-sterilized tubers and stems were wounded using autoclaved toothpicks, into which 5µl of a bacterial suspension, carrying ~1 x 106 CFU/ml of bacteria per strain, was deposited into a 5 mm deep wound. Three independent replicates were conducted. Only one isolate, designated as M3, presented maceration on potato tubers, and dark, watered-soaked lesions appeared on the stem 48 h post-inoculation with strain. Other bacterial isolates showed no symptoms in either stems or tubers. Pathogenicity tests were confirmed on healthy, 4-week-old potato plants grown in a 50% perlite and 50% peat moss substrate. Inoculations were done using two methods: (1) toothpick piercing, where 5 µl of saline solution containing ~1 x 106 CFU/ml of bacteria was applied to a wound approximately 5mm deep (Ma et al. 2018), and (2) immersion of the plant foliage in a bacterial suspension of 1x 108 CFU/ml in saline solution for 10 min Controls used bacteria-free toothpicks (wounded) and sterile 10 mM MgCl₂ solution (unwounded). Plants were enclosed in plastic containers to maintain high humidity and grown at 15/25°C (day/night) with a 12 h photoperiod. Five days post-inoculation, blackleg symptoms were observed in the stems of the infected area, which turned black and rotten (wounded and unwounded). In all cases, negative controls remained symptomless. To complete Koch's postulates, bacteria were reisolated from symptomatic potato stems and showed the same morphology. To identify the isolate M3, whole genome sequencing using Oxford Nanopore technology was performed. Three marker genes were extracted, and a 5,734-bp sequence was concatenated from dnaX (2073 bp), recA (1,074bp), and leuS (2,583bp) (GenBank accession nos. PQ177849, PQ177847 and PQ177848, respectively). The concatenated sequences
{"title":"First report of <i>Pectobacterium peruviense</i> as the causal pathogen of blackleg and soft rot in <i>Solanum tuberosum</i> cv. Superchola in Cañar, Ecuador.","authors":"Estefania Peña-Zuñiga, Noelia Barriga-Medina, Dario Ramirez-Villacis, Madelein Miranda-Guerrero, Corné Pieterse, Jos M Raaijmakers, Antonio Leon-Reyes","doi":"10.1094/PDIS-08-24-1759-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-08-24-1759-PDN","url":null,"abstract":"<p><p>Potato (Solanum tuberosum) is grown in Ecuador's Andean region at altitudes from 2,200 to 3,600 m.a.s.l., and the most commercially significant cultivar is Superchola, which constitutes 60% of total production, covering around 11,000 hectares (MAG, s.f. 2022). From November 2022 to January 2023, dark, water-soaked lesions progressing upwards from the base of the stems were observed on Superchola potato plants in Cañar, Ecuador (2°23'56.4''S 78°59'13.2''W). Approximately 20 plants in a hectare showed symptoms. Symptomatic stems from five plants were collected, surface-disinfected with 2% sodium hypochlorite, followed by 70% ethanol, and thoroughly rinsed with sterile distilled water. Plant tissue sections (1 cm²) were homogenized in 10 mM MgCl₂, serially diluted, and plated on Tryptic Soy Agar (TSA). After 48 hours of incubation at 28°C, creamy-white, yellowish, and white round colonies appeared. Streak plating was performed, yielding 14 purified bacterial isolates named M1 to M14. For the pathogenicity tests, each purified isolate was inoculated into healthy potato tubers and stem pieces (5 cm) using the prick inoculation method described by Ma et al. (2018) with modifications. Surface-sterilized tubers and stems were wounded using autoclaved toothpicks, into which 5µl of a bacterial suspension, carrying ~1 x 106 CFU/ml of bacteria per strain, was deposited into a 5 mm deep wound. Three independent replicates were conducted. Only one isolate, designated as M3, presented maceration on potato tubers, and dark, watered-soaked lesions appeared on the stem 48 h post-inoculation with strain. Other bacterial isolates showed no symptoms in either stems or tubers. Pathogenicity tests were confirmed on healthy, 4-week-old potato plants grown in a 50% perlite and 50% peat moss substrate. Inoculations were done using two methods: (1) toothpick piercing, where 5 µl of saline solution containing ~1 x 106 CFU/ml of bacteria was applied to a wound approximately 5mm deep (Ma et al. 2018), and (2) immersion of the plant foliage in a bacterial suspension of 1x 108 CFU/ml in saline solution for 10 min Controls used bacteria-free toothpicks (wounded) and sterile 10 mM MgCl₂ solution (unwounded). Plants were enclosed in plastic containers to maintain high humidity and grown at 15/25°C (day/night) with a 12 h photoperiod. Five days post-inoculation, blackleg symptoms were observed in the stems of the infected area, which turned black and rotten (wounded and unwounded). In all cases, negative controls remained symptomless. To complete Koch's postulates, bacteria were reisolated from symptomatic potato stems and showed the same morphology. To identify the isolate M3, whole genome sequencing using Oxford Nanopore technology was performed. Three marker genes were extracted, and a 5,734-bp sequence was concatenated from dnaX (2073 bp), recA (1,074bp), and leuS (2,583bp) (GenBank accession nos. PQ177849, PQ177847 and PQ177848, respectively). The concatenated sequences ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625831","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 : 2024-11-11DOI: 10.1094/PDIS-08-24-1639-PDN
Sangmin Bak, Daeun Kim, Hyewon Jeong, Minki Kim, Ilkwon Yeon, Seunghan Kim, Seungbin Baek, Su-Heon Lee, Wonkwon Jung
<p><p>Burdock (<i>Arctium lappa</i>) is a fiber-rich root vegetable widely used in Asian cuisine with many health benefits. In July 2023, two burdock leaf samples showing viral symptoms, such as yellowing and interveinal chlorosis, were collected from a field in Daegu, South Korea, with an incidence rate of about 10%. The samples were pooled, ground with liquid nitrogen, and total RNA was extracted using a Maxwell® 16 LEV Plant RNA Kit (Promega, Madison, USA). A cDNA library was constructed using TruSeq Standard Total RNA with Ribo-Zero (Illumina, San Diego, USA) and sequenced on an Illumina NovaSeq 6000 (BIOTO, Daejeon, Korea) with 100 bp paired-end reads. Of the approximately 84 million reads generated, about 61 million clean reads were identified using Trimmomatic 0.39 with default parameters. Subsequently, Trinity 2.13.0 was used for <i>de novo</i> assembly, resulting in 179,910 contigs, which, when annotated as previously described (Bak et al., 2024), revealed the presence of tomato spotted wilt virus (TSWV) and pepper chlorosis-associated virus (PepCaV). Three PepCaV-related contigs, representing a near-complete genome, were submitted to NCBI GenBank (PP502423-PP502425). BLASTn analysis showed 95.21% (7275/7641 bp), 95.89% (1680/1752 bp), and 96.18% (1461/1519 bp) identities with the L, M, and S segments of the PepCaV isolate Higashitsuno_2021 (LC719619-LC719621), respectively. RT-PCR was performed to confirm the presence of viruses using specific primers for PepCaV (5'-CACCTTGATTATAGACATGACAG/GTTCTCAAATCTTCCCAATCG-3') targeting the coat protein region, and TSWV (5'-GCAACAACTTGCAAGAAGATG/CATGACCTTCAGAAGGCTTG-3'; Kim et al., 2021). Initial results showed both samples were positive for TSWV, and one was positive for PepCaV. Additionally, 26 symptomatic and 8 asymptomatic samples were collected from the same field. PepCaV was positive in 3 samples, TSWV in 12, and TSWV+PepCaV in 11 by RT-PCR. All asymptomatic samples were negative. Leaves infected with PepCaV, whether solely or co-infected with TSWV, initially exhibited interveinal chlorosis and vein contraction on one side of the main vein (Fig. S1). In plants infected with PepCaV alone, these symptoms were mild or less noticeable in the initial phases. The majority of PepCaV-infected samples were co-infected with TSWV, during which symptoms appeared more severe. Following this, an amplicon, derived from the sample that initially tested positive for PepCaV in the first RT-PCR was cloned using the All in OneTM Cloning Kit (BioFact, Daejeon, Korea) and sequenced by Bionner (Daejeon, Korea). The resulting sequence, submitted to NCBI GenBank (PP928956), demonstrated 96.87% (805/831 bp) identity with the PepCaV isolate Higashitsuno_2021 (LC719600). Moreover, sap inoculation was performed on <i>A. lappa</i>, <i>Nicotiana benthamiana</i>, <i>N. clevelandii</i>, <i>N. debneyi</i>, <i>N. rustica</i>, <i>N. tabacum</i>, <i>Chenopodium amaranticolor</i>, and <i>C. quinoa</i>, but no transmission was ide
{"title":"First Report of Pepper Chlorosis-Associated Virus in Burdock (<i>Arctium lappa</i>) in Korea.","authors":"Sangmin Bak, Daeun Kim, Hyewon Jeong, Minki Kim, Ilkwon Yeon, Seunghan Kim, Seungbin Baek, Su-Heon Lee, Wonkwon Jung","doi":"10.1094/PDIS-08-24-1639-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-08-24-1639-PDN","url":null,"abstract":"<p><p>Burdock (<i>Arctium lappa</i>) is a fiber-rich root vegetable widely used in Asian cuisine with many health benefits. In July 2023, two burdock leaf samples showing viral symptoms, such as yellowing and interveinal chlorosis, were collected from a field in Daegu, South Korea, with an incidence rate of about 10%. The samples were pooled, ground with liquid nitrogen, and total RNA was extracted using a Maxwell® 16 LEV Plant RNA Kit (Promega, Madison, USA). A cDNA library was constructed using TruSeq Standard Total RNA with Ribo-Zero (Illumina, San Diego, USA) and sequenced on an Illumina NovaSeq 6000 (BIOTO, Daejeon, Korea) with 100 bp paired-end reads. Of the approximately 84 million reads generated, about 61 million clean reads were identified using Trimmomatic 0.39 with default parameters. Subsequently, Trinity 2.13.0 was used for <i>de novo</i> assembly, resulting in 179,910 contigs, which, when annotated as previously described (Bak et al., 2024), revealed the presence of tomato spotted wilt virus (TSWV) and pepper chlorosis-associated virus (PepCaV). Three PepCaV-related contigs, representing a near-complete genome, were submitted to NCBI GenBank (PP502423-PP502425). BLASTn analysis showed 95.21% (7275/7641 bp), 95.89% (1680/1752 bp), and 96.18% (1461/1519 bp) identities with the L, M, and S segments of the PepCaV isolate Higashitsuno_2021 (LC719619-LC719621), respectively. RT-PCR was performed to confirm the presence of viruses using specific primers for PepCaV (5'-CACCTTGATTATAGACATGACAG/GTTCTCAAATCTTCCCAATCG-3') targeting the coat protein region, and TSWV (5'-GCAACAACTTGCAAGAAGATG/CATGACCTTCAGAAGGCTTG-3'; Kim et al., 2021). Initial results showed both samples were positive for TSWV, and one was positive for PepCaV. Additionally, 26 symptomatic and 8 asymptomatic samples were collected from the same field. PepCaV was positive in 3 samples, TSWV in 12, and TSWV+PepCaV in 11 by RT-PCR. All asymptomatic samples were negative. Leaves infected with PepCaV, whether solely or co-infected with TSWV, initially exhibited interveinal chlorosis and vein contraction on one side of the main vein (Fig. S1). In plants infected with PepCaV alone, these symptoms were mild or less noticeable in the initial phases. The majority of PepCaV-infected samples were co-infected with TSWV, during which symptoms appeared more severe. Following this, an amplicon, derived from the sample that initially tested positive for PepCaV in the first RT-PCR was cloned using the All in OneTM Cloning Kit (BioFact, Daejeon, Korea) and sequenced by Bionner (Daejeon, Korea). The resulting sequence, submitted to NCBI GenBank (PP928956), demonstrated 96.87% (805/831 bp) identity with the PepCaV isolate Higashitsuno_2021 (LC719600). Moreover, sap inoculation was performed on <i>A. lappa</i>, <i>Nicotiana benthamiana</i>, <i>N. clevelandii</i>, <i>N. debneyi</i>, <i>N. rustica</i>, <i>N. tabacum</i>, <i>Chenopodium amaranticolor</i>, and <i>C. quinoa</i>, but no transmission was ide","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625838","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}
<p><p>Syrian rue (Peganum harmala L) belongs to the family Zygophyllaceae and is mainly distributed in arid and semi-arid areas of Xinjiang, Gansu, Ningxia, Qinghai, and Inner Mongolia in China. It serves as a pioneer species in soil and water conservation, as well as in reclamation of wastelands, playing a crucial role in soil preservation and stabilization against sand encroachment. In 2023, a disease resembling root rot and wilt affected the quality and yield of Syrian rue in Xilingol (122.67°N, 42.78°E), Inner Mongolia, China. Symptoms ranged from yellowing to wilting, accompanied by darkening of the xylem in the roots. This disease was observed in approximately 50% of Syrian rue plants in desertification-prone grassland. A total number of 45 symptomatic root samples were collected from Syrian rue plants to isolate the pahogen. Small pieces of diseased tissue were surface sterilized with 75% alcohol for five seconds, rinsed twice with sterilized water, dried, and then placed on water agar and incubated for 72 h at 25℃ in darkness. A total of 45 isolates were obtained, showing identical morphology and sequences of the internal transcribed spacer region (ITS), translation elongation factor 1-alpha (EF1-α) and RNA polymerase II second largest subunit (RPB2) genes. Therefore, the isolate LTP-5 was used as the representative for further study. On potato dextrose agar (PDA), fungal colonies of LTP-5 exhibited yellow to light brown colore with white aerial mycelia and irregular growth after 7 days of incubation at 25℃. Conidia and chlamydospre development were observed in carboxymethylcellulose sodium medium. Chlamydospores were abundant, terminal or intergrown between hyphae, rough brown walls of 5.9 to 19.82 μm in diameter (n = 75) were observed in the culture. Macroconidia had 5 to 7 septa, thick in the middle and thin at both ends, measured 28.17 to 62.81 μm in length and 1.50 to 4.19 μm in width (n = 128). Microconidia were absent. The morphological characteristics were consistent with the descriptions of Fusarium equiseti (Nelson et al., 1983). The pathogen was further confirmed to be F. equiseti by sequence analysis of the ITS, EF1-α and RPB2 genes amplified using polymerase chain reaction (PCR) with the primers ITS4/ITS5 (White et al., 1990), EF-1/EF-2 (O'Donnell et al., 1998), and RPB2-5F2 /fRPB2-7cR (Zhen et al., 2017). The sequences showed 100% similarity to the F. equiseti strain in the NCBI GenBank with accession numbers MH054914.1, KJ396323.1, and KT213286.1 for ITS, EF1-α, and RPB2, respectively. The sequences of PCR products were submitted to GenBank with accession numbers PP814863.1 (ITS), PP831628.1 (EF1-α) and PP826937.1 (RPB2). Pathogenicity tests were conducted through a pot assay. Five Syrian rue seedlings were inoculated by immersing plant roots in a suspension of 1×107 spores/mL for 30 min and transplanting to pots containing autoclaved soil. Control plants were immersed in sterile water. The inoculated plants showed yellow a
{"title":"First Report of Root Rot Caused by <i>Fusarium equiseti</i> on Syrian rue (<i>Peganum harmala</i>) in China.","authors":"Ruifang Jia, Jianfeng Yang, Jianjun Hao, Shengze Wang, Jie Wu, Kejian Lin, Zhengqiang Chen, Yuanyuan Zhang","doi":"10.1094/PDIS-06-24-1297-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-06-24-1297-PDN","url":null,"abstract":"<p><p>Syrian rue (Peganum harmala L) belongs to the family Zygophyllaceae and is mainly distributed in arid and semi-arid areas of Xinjiang, Gansu, Ningxia, Qinghai, and Inner Mongolia in China. It serves as a pioneer species in soil and water conservation, as well as in reclamation of wastelands, playing a crucial role in soil preservation and stabilization against sand encroachment. In 2023, a disease resembling root rot and wilt affected the quality and yield of Syrian rue in Xilingol (122.67°N, 42.78°E), Inner Mongolia, China. Symptoms ranged from yellowing to wilting, accompanied by darkening of the xylem in the roots. This disease was observed in approximately 50% of Syrian rue plants in desertification-prone grassland. A total number of 45 symptomatic root samples were collected from Syrian rue plants to isolate the pahogen. Small pieces of diseased tissue were surface sterilized with 75% alcohol for five seconds, rinsed twice with sterilized water, dried, and then placed on water agar and incubated for 72 h at 25℃ in darkness. A total of 45 isolates were obtained, showing identical morphology and sequences of the internal transcribed spacer region (ITS), translation elongation factor 1-alpha (EF1-α) and RNA polymerase II second largest subunit (RPB2) genes. Therefore, the isolate LTP-5 was used as the representative for further study. On potato dextrose agar (PDA), fungal colonies of LTP-5 exhibited yellow to light brown colore with white aerial mycelia and irregular growth after 7 days of incubation at 25℃. Conidia and chlamydospre development were observed in carboxymethylcellulose sodium medium. Chlamydospores were abundant, terminal or intergrown between hyphae, rough brown walls of 5.9 to 19.82 μm in diameter (n = 75) were observed in the culture. Macroconidia had 5 to 7 septa, thick in the middle and thin at both ends, measured 28.17 to 62.81 μm in length and 1.50 to 4.19 μm in width (n = 128). Microconidia were absent. The morphological characteristics were consistent with the descriptions of Fusarium equiseti (Nelson et al., 1983). The pathogen was further confirmed to be F. equiseti by sequence analysis of the ITS, EF1-α and RPB2 genes amplified using polymerase chain reaction (PCR) with the primers ITS4/ITS5 (White et al., 1990), EF-1/EF-2 (O'Donnell et al., 1998), and RPB2-5F2 /fRPB2-7cR (Zhen et al., 2017). The sequences showed 100% similarity to the F. equiseti strain in the NCBI GenBank with accession numbers MH054914.1, KJ396323.1, and KT213286.1 for ITS, EF1-α, and RPB2, respectively. The sequences of PCR products were submitted to GenBank with accession numbers PP814863.1 (ITS), PP831628.1 (EF1-α) and PP826937.1 (RPB2). Pathogenicity tests were conducted through a pot assay. Five Syrian rue seedlings were inoculated by immersing plant roots in a suspension of 1×107 spores/mL for 30 min and transplanting to pots containing autoclaved soil. Control plants were immersed in sterile water. The inoculated plants showed yellow a","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2024-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142625750","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}