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First report of genotypes of citrus tristeza virus breaking resistance in sweet orange and clementine in Spain.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-05 DOI: 10.1094/PDIS-11-24-2496-PDN
Ana Belén Ruiz-García, Antonio Olmos
<p><p>Citrus tristeza virus (CTV) classified as Closterovirus tristezae within the genus Closterovirus, family Closteroviridae is broadly distributed in the major citrus-growing regions. CTV has eight main strains (genotypes or phylogenetic groups): T36, T30, T3, T68, VT, RB, HA16-5, and S1, that can induce different symptoms (Sun et al., 2024) with RB isolates being the only variants able to infect and spread within Poncirus trifoliata (Yokomi et al., 2017). In Spain, most isolates belong to the biologically mild T30 strain. Citriculture relies on CTV-resistant P. trifoliata rootstock and its hybrids to prevent virus-induced graft incompatibility. Only rarely, severe VT isolates inducing stem pitting on sweet orange have been reported (Moreno et al., 2008). From February to June 2023, citrus orchards in 4 areas in the Valencian Community were surveyed for monitoring circulanting strains. Five plants (3 sweet orange and 2 clementine trees) showing symptoms of tristeza disease and decline, grafted onto the resistant rootstock Carrizo citrange (Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.) were individually analyzed by high-throughput sequencing (HTS): sweet orange trees 137.4 in Moncada, 141.4 and 141.5 in Sagunto and clementine trees 142.13 in Nules and 152.7 in Burriana. Five leaves showing vein chlorosis and leaf cupping were pooled and analyzed per tree. Total RNA purified from leaf tissue was sequenced in a Novaseq 6000 platform using TrueSeq Illumina methodology with ribo-depletion. Bioinformatic analysis by CLC Genomics Workbench 10.1.1, according to Ruiz-García et al. (2019), allowed the recovery of 13 near full-length CTV genomes from different strains. Interestingly, 3 isolates belonged to the RB strain, 5 to the VT strain and 5 to the T30 strain. Sweet orange trees exhibited co-infections with CTV isolates from different strains: VT and T30 (OQ714508 and PQ576736) in 137.4; RB, VT and T30 (PQ538530, PQ576743 and PQ576742) in 141.4; and RB, VT and T30 (OQ848758, PQ576738 and PQ576737) in 141.5. In clementine trees CTV co-infections were also observed: RB, VT and T30 (PQ538529, PQ576740 and PQ576739) in 142.13; and VT and T30 (PQ576741 and PQ576744) in 152.7. BLASTn analysis showed that the RB isolates PQ538530 and OQ848758 belong to RB2 group, with the highest nucleotide identity of 99.63% (19198/19269 nt) and 99.62% (19197/19270 nt), respectively, to the isolate B390-5 (KU883265); whereas RB isolate PQ538529 belongs to RB1 group, with the highest nucleotide identity of 99.1% (19082/19255 nt) to the isolate B301 (JF957196). Supplementary Table 1 shows data from the HTS analysis, including additional viruses and viroids detected for which no association with the symptoms was established. The presence of the RB isolates found by HTS was confirmed by RT-PCR analysis and Sanger sequencing, using CTV-RB specific primers previously reported (Cook et al., 2016). In a survey of 147 citrus trees with tristeza symptoms across 7 orchar
{"title":"First report of genotypes of citrus tristeza virus breaking resistance in sweet orange and clementine in Spain.","authors":"Ana Belén Ruiz-García, Antonio Olmos","doi":"10.1094/PDIS-11-24-2496-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2496-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Citrus tristeza virus (CTV) classified as Closterovirus tristezae within the genus Closterovirus, family Closteroviridae is broadly distributed in the major citrus-growing regions. CTV has eight main strains (genotypes or phylogenetic groups): T36, T30, T3, T68, VT, RB, HA16-5, and S1, that can induce different symptoms (Sun et al., 2024) with RB isolates being the only variants able to infect and spread within Poncirus trifoliata (Yokomi et al., 2017). In Spain, most isolates belong to the biologically mild T30 strain. Citriculture relies on CTV-resistant P. trifoliata rootstock and its hybrids to prevent virus-induced graft incompatibility. Only rarely, severe VT isolates inducing stem pitting on sweet orange have been reported (Moreno et al., 2008). From February to June 2023, citrus orchards in 4 areas in the Valencian Community were surveyed for monitoring circulanting strains. Five plants (3 sweet orange and 2 clementine trees) showing symptoms of tristeza disease and decline, grafted onto the resistant rootstock Carrizo citrange (Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.) were individually analyzed by high-throughput sequencing (HTS): sweet orange trees 137.4 in Moncada, 141.4 and 141.5 in Sagunto and clementine trees 142.13 in Nules and 152.7 in Burriana. Five leaves showing vein chlorosis and leaf cupping were pooled and analyzed per tree. Total RNA purified from leaf tissue was sequenced in a Novaseq 6000 platform using TrueSeq Illumina methodology with ribo-depletion. Bioinformatic analysis by CLC Genomics Workbench 10.1.1, according to Ruiz-García et al. (2019), allowed the recovery of 13 near full-length CTV genomes from different strains. Interestingly, 3 isolates belonged to the RB strain, 5 to the VT strain and 5 to the T30 strain. Sweet orange trees exhibited co-infections with CTV isolates from different strains: VT and T30 (OQ714508 and PQ576736) in 137.4; RB, VT and T30 (PQ538530, PQ576743 and PQ576742) in 141.4; and RB, VT and T30 (OQ848758, PQ576738 and PQ576737) in 141.5. In clementine trees CTV co-infections were also observed: RB, VT and T30 (PQ538529, PQ576740 and PQ576739) in 142.13; and VT and T30 (PQ576741 and PQ576744) in 152.7. BLASTn analysis showed that the RB isolates PQ538530 and OQ848758 belong to RB2 group, with the highest nucleotide identity of 99.63% (19198/19269 nt) and 99.62% (19197/19270 nt), respectively, to the isolate B390-5 (KU883265); whereas RB isolate PQ538529 belongs to RB1 group, with the highest nucleotide identity of 99.1% (19082/19255 nt) to the isolate B301 (JF957196). Supplementary Table 1 shows data from the HTS analysis, including additional viruses and viroids detected for which no association with the symptoms was established. The presence of the RB isolates found by HTS was confirmed by RT-PCR analysis and Sanger sequencing, using CTV-RB specific primers previously reported (Cook et al., 2016). In a survey of 147 citrus trees with tristeza symptoms across 7 orchar","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256333","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}
引用次数: 0
Septoria lamiicola Causing Leaf Spot on Lamium purpureum in Korea.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-05 DOI: 10.1094/PDIS-12-24-2711-PDN
Joon-Ho Choi, Bora Nam, Seong-Jin Lee, Young-Joon Choi, Hyeon-Dong Shin
<p><p>Lamium purpureum L. (purple dead-nettle), an annual herbaceous plant in the family Lamiaceae, is native to Europe and western Asia. It has become invasive in eastern Asia, including Korea and North America. Due to its rapid growth and tolerance of disturbed soils, it invades croplands and natural ecosystems, reducing crop yields (Mock et al. 2009). It also serves as an overwintering host for cucumber mosaic virus (Tomlinson et al. 1970). Leaf spots on purple dead-nettle were first observed in April 2022 in Gimje (35°43'10"N, 127°00'42"E) and in April 2023 in Jangsu (35°36'16"N, 127°22'43"E), Korea, with a disease incidence of 20-30% among surveyed plants. Symptoms were distinct, angular, pale brown to brown, and bordered by leaf veins. Numerous blackish conidiomata with cirriform conidial horns were visible on the spots. Conidiomata were numerous, scattered, pycnidial, amphigenous but abundantly epigenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, 60 to 110 µm in diameter, with ostioles measuring 28 to 56 µm in diameter. Conidiogenous cells lining the inner wall layer were hyaline and ampulliform. Conidia were filiform, straight or slightly curved, 32 to 48 × 2 to 3 µm, hyaline, 2 to 5-septate, but often 3-septate. Morphological descriptions were consistent with Septoria lamiicola Sacc. (Verkley et al. 2013). For monoconidial isolation, a conidial horn was collected, placed in a 1.5 ml tube containing sterile water, and streaked onto the surface of 2% water agar (WA). After four days, a hyphal tip was transferred to fresh potato dextrose agar (PDA). Colonies incubated for two weeks at 25°C on PDA were measured 10 to 15 mm in diameter, with a white to greyish at the center and a dark grey to black at the margin. Voucher specimens were deposited at the Korea University Herbarium (KUS-F32758 and F33612), and a representative culture was deposited at the Korea Agricultural Culture Collection (Acc. No. KACC 410468). Nucleotide sequences of the internal transcribed spacer (ITS), 28S rDNA (LSU), β-tubulin (TUB2), translation elongation factor 1-α (EF), actin (ACT), and RNA polymerase II second largest subunit (RPB2) genes were determined (Verkley et al. 2013) and deposited in GenBank (Accession Nos: PQ061283, PQ106849, PQ120989, PQ120981, PQ120994, and PQ120985). BLASTn search of the sequences showed 100% identity with the reference sequences of Septoria lamiicola CBS 102328 for ITS (KF251441.1), LSU (KF251945.1), ACT (KF253745.1), and RPB2 (KF252438.1). The TUB2 sequences showed 99.7% similarity (1/311 nucleotides different) with KF252913.1, and the EF sequences showed 96.0% similarity (13/368 different) with KF253389.1. In a phylogenetic tree reconstructed using the multi-loci sequences, the Korean isolate formed a well-supported group with reference isolates of S. lamiicola (Verkley et al. 2013). Pathogenicity was tested twice by spraying a conidial suspension (1×104 conidia/mL) harvested from a
{"title":"<i>Septoria lamiicola</i> Causing Leaf Spot on <i>Lamium purpureum</i> in Korea.","authors":"Joon-Ho Choi, Bora Nam, Seong-Jin Lee, Young-Joon Choi, Hyeon-Dong Shin","doi":"10.1094/PDIS-12-24-2711-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-12-24-2711-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Lamium purpureum L. (purple dead-nettle), an annual herbaceous plant in the family Lamiaceae, is native to Europe and western Asia. It has become invasive in eastern Asia, including Korea and North America. Due to its rapid growth and tolerance of disturbed soils, it invades croplands and natural ecosystems, reducing crop yields (Mock et al. 2009). It also serves as an overwintering host for cucumber mosaic virus (Tomlinson et al. 1970). Leaf spots on purple dead-nettle were first observed in April 2022 in Gimje (35°43'10\"N, 127°00'42\"E) and in April 2023 in Jangsu (35°36'16\"N, 127°22'43\"E), Korea, with a disease incidence of 20-30% among surveyed plants. Symptoms were distinct, angular, pale brown to brown, and bordered by leaf veins. Numerous blackish conidiomata with cirriform conidial horns were visible on the spots. Conidiomata were numerous, scattered, pycnidial, amphigenous but abundantly epigenous, scattered, dark brown to rusty brown, globose, embedded in host tissue or partly erumpent, 60 to 110 µm in diameter, with ostioles measuring 28 to 56 µm in diameter. Conidiogenous cells lining the inner wall layer were hyaline and ampulliform. Conidia were filiform, straight or slightly curved, 32 to 48 × 2 to 3 µm, hyaline, 2 to 5-septate, but often 3-septate. Morphological descriptions were consistent with Septoria lamiicola Sacc. (Verkley et al. 2013). For monoconidial isolation, a conidial horn was collected, placed in a 1.5 ml tube containing sterile water, and streaked onto the surface of 2% water agar (WA). After four days, a hyphal tip was transferred to fresh potato dextrose agar (PDA). Colonies incubated for two weeks at 25°C on PDA were measured 10 to 15 mm in diameter, with a white to greyish at the center and a dark grey to black at the margin. Voucher specimens were deposited at the Korea University Herbarium (KUS-F32758 and F33612), and a representative culture was deposited at the Korea Agricultural Culture Collection (Acc. No. KACC 410468). Nucleotide sequences of the internal transcribed spacer (ITS), 28S rDNA (LSU), β-tubulin (TUB2), translation elongation factor 1-α (EF), actin (ACT), and RNA polymerase II second largest subunit (RPB2) genes were determined (Verkley et al. 2013) and deposited in GenBank (Accession Nos: PQ061283, PQ106849, PQ120989, PQ120981, PQ120994, and PQ120985). BLASTn search of the sequences showed 100% identity with the reference sequences of Septoria lamiicola CBS 102328 for ITS (KF251441.1), LSU (KF251945.1), ACT (KF253745.1), and RPB2 (KF252438.1). The TUB2 sequences showed 99.7% similarity (1/311 nucleotides different) with KF252913.1, and the EF sequences showed 96.0% similarity (13/368 different) with KF253389.1. In a phylogenetic tree reconstructed using the multi-loci sequences, the Korean isolate formed a well-supported group with reference isolates of S. lamiicola (Verkley et al. 2013). Pathogenicity was tested twice by spraying a conidial suspension (1×104 conidia/mL) harvested from a ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256285","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}
引用次数: 0
Identification of Wheat Stripe Rust Inoculum Sources and Dispersal Routes Responsible for Initial Rust Establishment in Southern Henan of China. 确定中国河南南部小麦条锈病初发的接种源和传播途径。
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-05 DOI: 10.1094/PDIS-02-24-0362-RE
Aolin Wang, Shiqin Cao, Hong Peng, Ru Jiang, Meihui Zhang, Xiao Nie, Fei Xu, Liang Huang, Zhenyu Sun, Xiaoping Hu, Wei Liu, Jieru Fan, Yilin Zhou, Xiangming Xu

Wheat stripe rust (yellow rust), caused by Puccinia striiformis f. sp. tritici (Pst), is an important airborne disease worldwide. Pst inoculum strength in southern Henan in winter or early spring is important for spring epidemics in the main autumn-sown wheat-growing regions of China. However, there is limited knowledge about the source and time of initial infection on winter wheat in southern Henan. The first occurrence of wheat stripe rust in southern Henan was recorded annually from 2011 to 2022, from which we used the backward trajectory approach to infer the likely source of Pst inoculum responsible for the initial disease occurrence. The results suggested that the Pst inoculum responsible for initial rust established in the winter in southern Henan originated from the Gansu Pst oversummering area in China, whereas it originated from the adjacent winter Pst sporulation regions in southern Shaanxi and northwestern Hubei if Pst symptoms were first observed in early spring in southern Henan. Another possible Pst source is southern Hubei where Pst can also sporulate in the winter. Thus, early Pst development in winter in the main wheat production region in China (Henan) is likely to be caused by Pst inoculum spread from the oversummering inocula or Pst epidemics in autumn seedlings in Gansu.

由 Puccinia striiformis f. sp. tritici(Pst)引起的小麦条锈病(黄锈病)是世界上一种重要的气传病害。河南南部冬季或早春的 Pst 接种体强度对中国主要秋播小麦种植区的春季流行非常重要。然而,人们对河南南部冬小麦的初次侵染源和侵染时间了解有限。2011-2022年期间,豫南地区每年都有小麦条锈病初发记录,据此我们采用后向轨迹法推断了导致病害初发的Pst接种体的可能来源。结果表明,造成河南南部冬季锈病初发的 Pst 接种体来源于中国甘肃 Pst 过夏区,而如果河南南部在早春首次观察到 Pst 症状,则来源于邻近的陕西南部和湖北西北部冬季 Pst 孢子产区。另一个可能的 Pst 来源地是湖北南部,那里的 Pst 也能在冬季产生孢子。因此,中国(河南)小麦主产区冬季早发的 Pst 很可能是由过夏接种的 Pst 接种体传播或甘肃秋苗 Pst 流行造成的。
{"title":"Identification of Wheat Stripe Rust Inoculum Sources and Dispersal Routes Responsible for Initial Rust Establishment in Southern Henan of China.","authors":"Aolin Wang, Shiqin Cao, Hong Peng, Ru Jiang, Meihui Zhang, Xiao Nie, Fei Xu, Liang Huang, Zhenyu Sun, Xiaoping Hu, Wei Liu, Jieru Fan, Yilin Zhou, Xiangming Xu","doi":"10.1094/PDIS-02-24-0362-RE","DOIUrl":"10.1094/PDIS-02-24-0362-RE","url":null,"abstract":"<p><p>Wheat stripe rust (yellow rust), caused by <i>Puccinia striiformis</i> f. sp. <i>tritici</i> (<i>Pst</i>), is an important airborne disease worldwide. <i>Pst</i> inoculum strength in southern Henan in winter or early spring is important for spring epidemics in the main autumn-sown wheat-growing regions of China. However, there is limited knowledge about the source and time of initial infection on winter wheat in southern Henan. The first occurrence of wheat stripe rust in southern Henan was recorded annually from 2011 to 2022, from which we used the backward trajectory approach to infer the likely source of <i>Pst</i> inoculum responsible for the initial disease occurrence. The results suggested that the <i>Pst</i> inoculum responsible for initial rust established in the winter in southern Henan originated from the Gansu <i>Pst</i> oversummering area in China, whereas it originated from the adjacent winter <i>Pst</i> sporulation regions in southern Shaanxi and northwestern Hubei if <i>Pst</i> symptoms were first observed in early spring in southern Henan. Another possible <i>Pst</i> source is southern Hubei where <i>Pst</i> can also sporulate in the winter. Thus, early <i>Pst</i> development in winter in the main wheat production region in China (Henan) is likely to be caused by <i>Pst</i> inoculum spread from the oversummering inocula or <i>Pst</i> epidemics in autumn seedlings in Gansu.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":"PDIS02240362RE"},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142293155","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}
引用次数: 0
First Report of Lasiodiplodia theobromae Causing Wilt and Fruit Rot of Pepper in Hainan Province, China.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-05 DOI: 10.1094/PDIS-10-24-2161-PDN
Lizhu Tang, Wentao Huang, Jiaqi Wang, Shaopeng Huang, Yu Liu, Maofu Li, Shun Feng
<p><p>Ornamental pepper (Capsicum annuum L.) is an economically important plant with extensive genetic diversity (Zhang et al. 2020). In September 2022, symptoms of wilt and fruit rot were identified in approximately 0.02 hectares of an ornamental pepper plantation in Haikou, Hainan Province, China (110°32' E, 20°06' N). Disease severity reached 85%, with an incidence rate of 90%. Symptoms started as black foliar spots that expanded into large lesions, spreading to fruits and stems, causing wilting (Fig. S1). Samples from symptomatic leaves, fruits, and stems of 27 plants were surface-sterilized with 75% ethanol for 30 s, rinsed five times with sterile water, air-dried, plated on potato dextrose agar (PDA), and incubated at 28°C for 5 to 6 days. To obtain pure fungal cultures, initial isolates were subcultured onto fresh PDA. Among the 27 fungal cultures, 11 isolates from leaves and fruits consistently formed gray to olivaceous colonies. Isolate LJY224 initially produced grayish-white, fluffy mycelia with radiating aerial hyphae. Over time, the colony became grayish-black and produced black, nearly spherical pycnidia. The conidia were oval, initially transparent, and single-celled. Mature conidia were dark brown, septate, with longitudinal striations, averaging 11.55 ± 0.75 µm in width and 24.93 ± 1.50 µm in length (n=35) (Fig. S2), indicating Lasiodiplodia spp. Genomic DNA was extracted using a fungal DNA extraction kit (OMEGA BIO-TEK, GZ Feiyang Biotech Co., Ltd., Guangzhou, China). Molecular identification involved sequencing the rRNA internal transcribed spacer (ITS) region and genes encoding β-tubulin (TUB) and translation elongation factor 1-α (TEF1) with primers ITS1/ITS4, Bt2a/Bt2b, and EF1-983F/EF1-2218R, respectively (White et al. 1990; Rosado et al. 2016; Rehner and Buckley 2005). BLASTn searches with the obtained ITS, TUB, and TEF1 sequences (GenBank accessions OQ612711, OR039814, OR039813) revealed 98% to 100% identity with Lasiodiplodia theobromae reference sequences from the NCBI database (OR018404, KR260830, MN461169), matching 541/548, 446/446, and 947/955 base pairs, respectively. A phylogenetic tree was constructed using concatenated multi-locus sequence analysis (MLSA) of ITS, TUB, and TEF1 (Fig. S3). To fulfill Koch's postulates, healthy 3-month-old ornamental pepper plants were inoculated by spraying the entire plant with a conidial suspension (50 ml, 107 conidia/L) of LJY224, using sterile water as a negative control. Each treatment included three replicates. Plants were maintained at 25°C, 75% humidity, under a 12-h light/dark cycle, and monitored daily. After 14 days, inoculated plants developed black foliar spots that expanded into large lesions, spreading to fruits and stems, and causing wilting, consistent with initial symptoms, while control plants remained healthy (Fig. S4). The re-isolated pathogen showed identical morphology to the original strain. In contrast, no fungi were isolated or recovered from the plants in
{"title":"First Report of <i>Lasiodiplodia theobromae</i> Causing Wilt and Fruit Rot of Pepper in Hainan Province, China.","authors":"Lizhu Tang, Wentao Huang, Jiaqi Wang, Shaopeng Huang, Yu Liu, Maofu Li, Shun Feng","doi":"10.1094/PDIS-10-24-2161-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-10-24-2161-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Ornamental pepper (Capsicum annuum L.) is an economically important plant with extensive genetic diversity (Zhang et al. 2020). In September 2022, symptoms of wilt and fruit rot were identified in approximately 0.02 hectares of an ornamental pepper plantation in Haikou, Hainan Province, China (110°32' E, 20°06' N). Disease severity reached 85%, with an incidence rate of 90%. Symptoms started as black foliar spots that expanded into large lesions, spreading to fruits and stems, causing wilting (Fig. S1). Samples from symptomatic leaves, fruits, and stems of 27 plants were surface-sterilized with 75% ethanol for 30 s, rinsed five times with sterile water, air-dried, plated on potato dextrose agar (PDA), and incubated at 28°C for 5 to 6 days. To obtain pure fungal cultures, initial isolates were subcultured onto fresh PDA. Among the 27 fungal cultures, 11 isolates from leaves and fruits consistently formed gray to olivaceous colonies. Isolate LJY224 initially produced grayish-white, fluffy mycelia with radiating aerial hyphae. Over time, the colony became grayish-black and produced black, nearly spherical pycnidia. The conidia were oval, initially transparent, and single-celled. Mature conidia were dark brown, septate, with longitudinal striations, averaging 11.55 ± 0.75 µm in width and 24.93 ± 1.50 µm in length (n=35) (Fig. S2), indicating Lasiodiplodia spp. Genomic DNA was extracted using a fungal DNA extraction kit (OMEGA BIO-TEK, GZ Feiyang Biotech Co., Ltd., Guangzhou, China). Molecular identification involved sequencing the rRNA internal transcribed spacer (ITS) region and genes encoding β-tubulin (TUB) and translation elongation factor 1-α (TEF1) with primers ITS1/ITS4, Bt2a/Bt2b, and EF1-983F/EF1-2218R, respectively (White et al. 1990; Rosado et al. 2016; Rehner and Buckley 2005). BLASTn searches with the obtained ITS, TUB, and TEF1 sequences (GenBank accessions OQ612711, OR039814, OR039813) revealed 98% to 100% identity with Lasiodiplodia theobromae reference sequences from the NCBI database (OR018404, KR260830, MN461169), matching 541/548, 446/446, and 947/955 base pairs, respectively. A phylogenetic tree was constructed using concatenated multi-locus sequence analysis (MLSA) of ITS, TUB, and TEF1 (Fig. S3). To fulfill Koch's postulates, healthy 3-month-old ornamental pepper plants were inoculated by spraying the entire plant with a conidial suspension (50 ml, 107 conidia/L) of LJY224, using sterile water as a negative control. Each treatment included three replicates. Plants were maintained at 25°C, 75% humidity, under a 12-h light/dark cycle, and monitored daily. After 14 days, inoculated plants developed black foliar spots that expanded into large lesions, spreading to fruits and stems, and causing wilting, consistent with initial symptoms, while control plants remained healthy (Fig. S4). The re-isolated pathogen showed identical morphology to the original strain. In contrast, no fungi were isolated or recovered from the plants in","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256331","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}
引用次数: 0
First report of Fusarium proliferatum causing rhizome rot on Polygonatum cyrtonema in China.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-05 DOI: 10.1094/PDIS-11-24-2310-PDN
Shan Zhong, Jian-Jun Qi, Rong Wang, Bin Wang, Jian-He Wei, Wan-Long Ding, Jing Yu, Yong Li
<p><p>Polygonatum cyrtonema Hua (Asparagaceae) is a perennial herb widely distributed in China (Chen et al. 2021). The rhizome has antioxidant, anti-inflammatory, and immunomodulatory properties and is traditionally used to treat dizziness, diabetes, and asthma (Lu et al. 2023; Pang et al. 2022). About 3000 P. cyrtonema plants were planted in five fields at the Institute of Medicinal Plant Development (40.04°N, 116.28°E), Beijing, China, where rhizome rot was observed from June to October 2023, with an incidence rate of about 10%. Most cases occurred in low-lying, waterlogged fields. Initially, infected plants had no obvious aboveground symptoms but had brown spots on their rhizomes. In severe cases, plants exhibited aboveground withering and brown rot in rhizomes. A fungus was isolated from symptomatic plants (isolation rate 73%), and single spores were used to grow pure colonies on potato-dextrose-agar (PDA) and incubated for 5 d at 25°C in the dark. Eleven isolates with the same morphology were obtained. The upper surface of the colonies was white, with cottony mycelium and a light purple center. The lower surface of the colonies was hazel in the center. Two representative isolates, C76 and C78, were cultivated on carnation leaf agar medium. Microconidia of the isolates were aseptate, oval, elliptic or clavate, and their dimensions were 4.9 to 12.1 × 1.5 to 4.5 μm (n = 50). Macroconidia were long, slender and thin, rod-shaped or slightly curved, with one to five septa, and their dimensions were 15.3 to 44.9 × 2.7 to 4.5 μm (n = 50). The isolates were classified as Fusarium based on morphology (Leslie and Summerell 2006). To determine the species identity, we sequenced the translation elongation factor (TEF-1α) and partial RNA polymerase second largest subunit (RPB2) of two isolates (i.e., C76 and C78, GenBank access numbers: TEF-1α, PQ550044, PQ285402; RBP2, PQ550045, PQ285403, respectively) (Crous et al 2009) and compared them to other Fusarium species found at Fusarium-ID and GenBank databases. Both isolates exhibited 99.84% (TEF-1α, MT305203) and 100% (RBP2, LT841252) similarity with Fusarium proliferatum. The phylogenetic tree was constructed by combining TEF-1α, and RBP2 using MEGA6, and the two isolates clustered with F. proliferatum. To demonstrate pathogenicity, 2 mL of conidial suspension (1 × 106 conidia/mL) of the isolate of F. proliferatum designed C76 were dropped on the surface of four rhizomes without wounding. For the control, sterile water was applied on two control rhizomes. All treatments were repeated three times. Seedlings were grown at 25°C in moist soil. After 7 d, inoculated roots exhibited similar symptoms to those in the field, while control roots showed no symptoms. The same isolate was reisolated from diseased roots and was identified based on morphological characteristics, fulfilling Koch's postulates. Based on morphology and molecular biology, the isolates were identified as F. proliferatum, a ubiquitous pathogen
{"title":"First report of <i>Fusarium proliferatum</i> causing rhizome rot on <i>Polygonatum cyrtonema</i> in China.","authors":"Shan Zhong, Jian-Jun Qi, Rong Wang, Bin Wang, Jian-He Wei, Wan-Long Ding, Jing Yu, Yong Li","doi":"10.1094/PDIS-11-24-2310-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-11-24-2310-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Polygonatum cyrtonema Hua (Asparagaceae) is a perennial herb widely distributed in China (Chen et al. 2021). The rhizome has antioxidant, anti-inflammatory, and immunomodulatory properties and is traditionally used to treat dizziness, diabetes, and asthma (Lu et al. 2023; Pang et al. 2022). About 3000 P. cyrtonema plants were planted in five fields at the Institute of Medicinal Plant Development (40.04°N, 116.28°E), Beijing, China, where rhizome rot was observed from June to October 2023, with an incidence rate of about 10%. Most cases occurred in low-lying, waterlogged fields. Initially, infected plants had no obvious aboveground symptoms but had brown spots on their rhizomes. In severe cases, plants exhibited aboveground withering and brown rot in rhizomes. A fungus was isolated from symptomatic plants (isolation rate 73%), and single spores were used to grow pure colonies on potato-dextrose-agar (PDA) and incubated for 5 d at 25°C in the dark. Eleven isolates with the same morphology were obtained. The upper surface of the colonies was white, with cottony mycelium and a light purple center. The lower surface of the colonies was hazel in the center. Two representative isolates, C76 and C78, were cultivated on carnation leaf agar medium. Microconidia of the isolates were aseptate, oval, elliptic or clavate, and their dimensions were 4.9 to 12.1 × 1.5 to 4.5 μm (n = 50). Macroconidia were long, slender and thin, rod-shaped or slightly curved, with one to five septa, and their dimensions were 15.3 to 44.9 × 2.7 to 4.5 μm (n = 50). The isolates were classified as Fusarium based on morphology (Leslie and Summerell 2006). To determine the species identity, we sequenced the translation elongation factor (TEF-1α) and partial RNA polymerase second largest subunit (RPB2) of two isolates (i.e., C76 and C78, GenBank access numbers: TEF-1α, PQ550044, PQ285402; RBP2, PQ550045, PQ285403, respectively) (Crous et al 2009) and compared them to other Fusarium species found at Fusarium-ID and GenBank databases. Both isolates exhibited 99.84% (TEF-1α, MT305203) and 100% (RBP2, LT841252) similarity with Fusarium proliferatum. The phylogenetic tree was constructed by combining TEF-1α, and RBP2 using MEGA6, and the two isolates clustered with F. proliferatum. To demonstrate pathogenicity, 2 mL of conidial suspension (1 × 106 conidia/mL) of the isolate of F. proliferatum designed C76 were dropped on the surface of four rhizomes without wounding. For the control, sterile water was applied on two control rhizomes. All treatments were repeated three times. Seedlings were grown at 25°C in moist soil. After 7 d, inoculated roots exhibited similar symptoms to those in the field, while control roots showed no symptoms. The same isolate was reisolated from diseased roots and was identified based on morphological characteristics, fulfilling Koch's postulates. Based on morphology and molecular biology, the isolates were identified as F. proliferatum, a ubiquitous pathogen ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143256325","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}
引用次数: 0
Host range and molecular characterization of the four races of Fusarium oxysporum f. sp. lactucae.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-04 DOI: 10.1094/PDIS-07-24-1505-RE
Muhammad Waqas, Giovanna Gilardi, Vladimiro Guarnaccia, Davide Spadaro

Vascular wilt of lettuce is caused by strains of the Fusarium oxysporum species complex. According to their biological activity, these strains are members of the forma specialis lactucae (FOL). The aim of this study was to characterize strains of Fusarium oxysporum isolated from lettuce in Italy and other countries, belonging to the four currently known races. Strains were analyzed based on pathogenicity on different hosts and a combined phylogenetic analysis of rpb2, tef-1α, cmdA and tub2 genes. For uncharacterized strains, the race was determined through pathogenicity test with a set of differential lettuce cultivars for races 1 and 4. To assess the host range, pathogenicity tests were performed on five species: lettuce (Lactuca sativa), lamb's lettuce (Valerianella locusta), spinach (Spinacia oleracea), wild rocket (Diplotaxis tenuifolia) and cultivated rocket (Eruca sativa). Most FOL strains were pathogenic on lettuce with different levels of disease severity; in particular, FOL races 3 and 4 showed the highest level of virulence on lettuce. FOL races 3 and 4 were pathogenic both on lettuce and lamb's lettuce, whereas races 1 and 2 only on lettuce. Furthermore, this study identified the first occurrence of FOL race 4 in Italy to 2016, as the strain FOL 1/16 was assigned to race 4. Results of multigene phylogenetic analysis showed that FOL races 1 and 4 cluster with the species F. curvatum, strains of race 2 with F. curvatum and F. odoratissimum and strains of race 3 with F. cugenangense. Phylogenetically, race 4 is very close to race 1, but it showed more similarities to race 3 for host range and virulence. This study shows for the first time a broader host range for the races 3 and 4 of FOL. The results demonstrate that phylogenetic analysis permits the separation of some races of FOL, but phylogenetic classification alone is insufficient for conclusive separation of races, therefore it should be accompanied by biological assays based on pathogenicity.

{"title":"Host range and molecular characterization of the four races of <i>Fusarium oxysporum</i> f. sp. <i>lactucae</i>.","authors":"Muhammad Waqas, Giovanna Gilardi, Vladimiro Guarnaccia, Davide Spadaro","doi":"10.1094/PDIS-07-24-1505-RE","DOIUrl":"https://doi.org/10.1094/PDIS-07-24-1505-RE","url":null,"abstract":"<p><p>Vascular wilt of lettuce is caused by strains of the Fusarium oxysporum species complex. According to their biological activity, these strains are members of the forma specialis lactucae (FOL). The aim of this study was to characterize strains of Fusarium oxysporum isolated from lettuce in Italy and other countries, belonging to the four currently known races. Strains were analyzed based on pathogenicity on different hosts and a combined phylogenetic analysis of rpb2, tef-1α, cmdA and tub2 genes. For uncharacterized strains, the race was determined through pathogenicity test with a set of differential lettuce cultivars for races 1 and 4. To assess the host range, pathogenicity tests were performed on five species: lettuce (Lactuca sativa), lamb's lettuce (Valerianella locusta), spinach (Spinacia oleracea), wild rocket (Diplotaxis tenuifolia) and cultivated rocket (Eruca sativa). Most FOL strains were pathogenic on lettuce with different levels of disease severity; in particular, FOL races 3 and 4 showed the highest level of virulence on lettuce. FOL races 3 and 4 were pathogenic both on lettuce and lamb's lettuce, whereas races 1 and 2 only on lettuce. Furthermore, this study identified the first occurrence of FOL race 4 in Italy to 2016, as the strain FOL 1/16 was assigned to race 4. Results of multigene phylogenetic analysis showed that FOL races 1 and 4 cluster with the species F. curvatum, strains of race 2 with F. curvatum and F. odoratissimum and strains of race 3 with F. cugenangense. Phylogenetically, race 4 is very close to race 1, but it showed more similarities to race 3 for host range and virulence. This study shows for the first time a broader host range for the races 3 and 4 of FOL. The results demonstrate that phylogenetic analysis permits the separation of some races of FOL, but phylogenetic classification alone is insufficient for conclusive separation of races, therefore it should be accompanied by biological assays based on pathogenicity.</p>","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143190175","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}
引用次数: 0
First report of Needle Cast of Cathaya argyrophylla caused by Neofusicoccum parvum in China.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-04 DOI: 10.1094/PDIS-04-24-0920-PDN
Hongjin Wei, JiaoJiao Lei, Cun Yu, Xuewen Wang, Run Luo, Mingyue Ou, Xiao-Li Wei
<p><p>Cathaya argyrophylla Chun et Kuang is a first-grade protected tree in China with significant conservation value. In June 2022, needle cast was observed in approximately 27 to 34% of C. argyrophylla (n=200, covering about 1 ha) at Dashahe National Nature Reserve (28.89° N, 107.6° E) in Daozhen County, Guizhou, China. Initial symptoms were small red lesions (3 to 5 mm in diameter) on needles. Over time, these lesions expanded, turned necrotic, and led to needle cast. In addition, the diseased needles exhibit brown spots surrounded by a yellowish discoloured area measuring 0.5 mm2. The disease is most severe in young trees, with over 60% of the needles displaying discoloration in 15% of young trees (n=100). Forty infected conifer tissues were randomly selected, surface sterilized, and incubated on PDA in the dark at 26°C for 5d. Among the 40 samples, 39 exhibited fungi with similar morphology. Single-spore isolation method was used to obtain pure cultures for 9 isolates. The isolates were morphologically identical. On PDA medium, colonies were white with abundant aerial mycelium. After 14 days of growth under light, the colonies became greyish black with septate mycelium. Conidia were hyaline, thin-walled, smooth-surfaced, and ranged from ellipsoid to ovoid in shape, measuring 6.5 to 15.2 ×2.0 to 3.1 μm (n=50). Based on these morphological characteristics, the isolates were identified as belonging to Neofusicoccum spp. (Pavlic et al., 2009). For molecular identification, genomic DNA was extracted from 3 selected isolates. The internal transcribed spacer (ITS) region was amplified using primers ITS1/ITS4 (White et al., 1990). In addition, chitin synthase 1 (CS1) was amplified using primers CT-WK3-S/CT-WK3-A (Zimoch et al., 2003). The ITS (OR710949) and CS1 (OR714767) sequences of isolate JY1-1 were deposited in GenBank, exhibiting a homology of 99% to 100% (537/538, 191/192) with N. parvum MUCC211 (accession numbers EU301017 and EU339495). The reconstructed phylogenetic tree further substantiated the genetic relationship between isolate JY1-1 and N. parvum. Consequently, the isolate associated with needle cast on C. argyrophylla was identified as N. parvum. Isolates JY1-1, JY1-2, and JY1-3 were used to confirm Koch's postulates. The needles of 15 healthy 2-year-old C. argyrophylla saplings were inoculated with a conidial suspension of N. parvum (2.0 × 105 conidia/mL). As a control, the needles of C. argyrophylla saplings were treated with sterile water (n=10). The needles were covered with Ziplock bags, and maintained at humidity levels exceeding 90%. All treatments were placed in a greenhouse at 26℃. After 7 days of inoculation, the needles exhibited a change in color, with reddish-brown symptoms observed on day 30 (disease rate=100%). Furthermore, the lesion expanded, and needles were shed after 4 months. No symptoms were observed in the control group. Pathogens reisolated from all diseased plants exhibited morphological and ITS sequence iden
{"title":"First report of Needle Cast of <i>Cathaya argyrophylla</i> caused by <i>Neofusicoccum parvum</i> in China.","authors":"Hongjin Wei, JiaoJiao Lei, Cun Yu, Xuewen Wang, Run Luo, Mingyue Ou, Xiao-Li Wei","doi":"10.1094/PDIS-04-24-0920-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-04-24-0920-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Cathaya argyrophylla Chun et Kuang is a first-grade protected tree in China with significant conservation value. In June 2022, needle cast was observed in approximately 27 to 34% of C. argyrophylla (n=200, covering about 1 ha) at Dashahe National Nature Reserve (28.89° N, 107.6° E) in Daozhen County, Guizhou, China. Initial symptoms were small red lesions (3 to 5 mm in diameter) on needles. Over time, these lesions expanded, turned necrotic, and led to needle cast. In addition, the diseased needles exhibit brown spots surrounded by a yellowish discoloured area measuring 0.5 mm2. The disease is most severe in young trees, with over 60% of the needles displaying discoloration in 15% of young trees (n=100). Forty infected conifer tissues were randomly selected, surface sterilized, and incubated on PDA in the dark at 26°C for 5d. Among the 40 samples, 39 exhibited fungi with similar morphology. Single-spore isolation method was used to obtain pure cultures for 9 isolates. The isolates were morphologically identical. On PDA medium, colonies were white with abundant aerial mycelium. After 14 days of growth under light, the colonies became greyish black with septate mycelium. Conidia were hyaline, thin-walled, smooth-surfaced, and ranged from ellipsoid to ovoid in shape, measuring 6.5 to 15.2 ×2.0 to 3.1 μm (n=50). Based on these morphological characteristics, the isolates were identified as belonging to Neofusicoccum spp. (Pavlic et al., 2009). For molecular identification, genomic DNA was extracted from 3 selected isolates. The internal transcribed spacer (ITS) region was amplified using primers ITS1/ITS4 (White et al., 1990). In addition, chitin synthase 1 (CS1) was amplified using primers CT-WK3-S/CT-WK3-A (Zimoch et al., 2003). The ITS (OR710949) and CS1 (OR714767) sequences of isolate JY1-1 were deposited in GenBank, exhibiting a homology of 99% to 100% (537/538, 191/192) with N. parvum MUCC211 (accession numbers EU301017 and EU339495). The reconstructed phylogenetic tree further substantiated the genetic relationship between isolate JY1-1 and N. parvum. Consequently, the isolate associated with needle cast on C. argyrophylla was identified as N. parvum. Isolates JY1-1, JY1-2, and JY1-3 were used to confirm Koch's postulates. The needles of 15 healthy 2-year-old C. argyrophylla saplings were inoculated with a conidial suspension of N. parvum (2.0 × 105 conidia/mL). As a control, the needles of C. argyrophylla saplings were treated with sterile water (n=10). The needles were covered with Ziplock bags, and maintained at humidity levels exceeding 90%. All treatments were placed in a greenhouse at 26℃. After 7 days of inoculation, the needles exhibited a change in color, with reddish-brown symptoms observed on day 30 (disease rate=100%). Furthermore, the lesion expanded, and needles were shed after 4 months. No symptoms were observed in the control group. Pathogens reisolated from all diseased plants exhibited morphological and ITS sequence iden","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143190170","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}
引用次数: 0
First report of Curtobacterium flaccumfaciens pv. flaccumfaciens the causal agent of bacterial wilt disease in bean plants (Phaseolus vulgaris) in The Netherlands.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-04 DOI: 10.1094/PDIS-01-25-0172-PDN
Rita Volkers, Bo van Doorn, Jeroen van de Bilt, Peggy Gorkink-Smits, Manon Teunissen, Nathalie Blom, Marco Landman, Aron A L A M van Duijnhoven, Tijs van den Bosch, Michiel Pel, Robert Vreeburg, Tom Raaymakers, Maria Bergsma-Vlami
<p><p>Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), a European quarantine organism, is the causal agent of bacterial wilt in several members of the Fabaceae family (Osdaghi et al., 2020). Recently, several Cff findings have been reported on the European continent (Tarakanov et al., 2022; EPPO 2022; EPPO 2024). In August 2024, following the Cff finding in an imported common bean seed lot, asymptomatic common bean plants were sampled from three fields in the Netherlands, ranging from approximately 0.5 to 4.8 ha in size, where the crop was cultivated for human consumption. Each sample consisted of 200 pieces of stem of 2-4 cm long. After short surface sterilization in 70% EtOH the pieces were crushed in a Stomacher bag and incubated in 50 mL 0.05 M phosphate buffer with 0.02% Tween 20 at 100 rpm at room temperature for 30 minutes. For bacteria isolation, 20 µL of the plant extract was plated onto YPG medium (5 g/L yeast extract, 10 g/L peptone, 5.5 g/L glucose, 15 g/L agar) and modified King's B medium (38 g/L Pseudomonas agar F, 10 g/L sucrose, 100 mg/L cycloheximide) by dilution plating. After incubation at 28 °C for 4 days, one typical colony (shiny, slimy, cream-colored) per sample was selected from the modified King's B medium for purification. For preliminary identification MALDI-TOF MS analysis was performed (Bruker, Germany) comparing the spectra of the three purified isolates with in-house made reference spectra of several C. flaccumfaciens (Cf) strains. The DNA of isolates that were identified as Cf was isolated by thermal lysis and used for identification at the pathovar level using the conventional PCR by Tegli et al. (2002). The genomes of these isolates, generated using Illumina sequencing (accession numbers JBKYKM000000000, JBKYKN000000000 and JBKYKO000000000) share between 96.0-97.3% average nucleotide identity (ANI) with the Cf type strain CFBP 3418 confirming they fall within the species boundary. Recently, yellow-pigmented Cf strains showed higher than 94 % ANI among themselves and with CFBP 3418 but below 94% ANI with members of the pink-/orange-/red-pigmented strains (Osdaghi et al., 2024). A pathogenicity test on Phaseolus vulgaris var. Ferrari plants, performed according to EPPO (2011), confirmed the virulence of these isolates. Per isolate, 7-8 out of 10 plants showed typical Cff symptoms at 7 dpi, including wilting and interveinal chlorotic areas in the leaves, similar to the positive control plants. Negative control plants remained asymptomatic. The isolates were successfully re-isolated from the inoculated plants and identified as Cff using the above mentioned methods. The diagnostic procedure followed justifies the classification of the three Cf isolates as Cff. This is the first confirmed report of Cff on common bean in the Netherlands. Eradication measures have been imposed on the fields from which plants tested positive, including destruction of the crop and crop remains, hygiene measures, and prohibition to
{"title":"First report of <i>Curtobacterium flaccumfaciens</i> pv. <i>flaccumfaciens</i> the causal agent of bacterial wilt disease in bean plants (<i>Phaseolus vulgaris</i>) in The Netherlands.","authors":"Rita Volkers, Bo van Doorn, Jeroen van de Bilt, Peggy Gorkink-Smits, Manon Teunissen, Nathalie Blom, Marco Landman, Aron A L A M van Duijnhoven, Tijs van den Bosch, Michiel Pel, Robert Vreeburg, Tom Raaymakers, Maria Bergsma-Vlami","doi":"10.1094/PDIS-01-25-0172-PDN","DOIUrl":"https://doi.org/10.1094/PDIS-01-25-0172-PDN","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Curtobacterium flaccumfaciens pv. flaccumfaciens (Cff), a European quarantine organism, is the causal agent of bacterial wilt in several members of the Fabaceae family (Osdaghi et al., 2020). Recently, several Cff findings have been reported on the European continent (Tarakanov et al., 2022; EPPO 2022; EPPO 2024). In August 2024, following the Cff finding in an imported common bean seed lot, asymptomatic common bean plants were sampled from three fields in the Netherlands, ranging from approximately 0.5 to 4.8 ha in size, where the crop was cultivated for human consumption. Each sample consisted of 200 pieces of stem of 2-4 cm long. After short surface sterilization in 70% EtOH the pieces were crushed in a Stomacher bag and incubated in 50 mL 0.05 M phosphate buffer with 0.02% Tween 20 at 100 rpm at room temperature for 30 minutes. For bacteria isolation, 20 µL of the plant extract was plated onto YPG medium (5 g/L yeast extract, 10 g/L peptone, 5.5 g/L glucose, 15 g/L agar) and modified King's B medium (38 g/L Pseudomonas agar F, 10 g/L sucrose, 100 mg/L cycloheximide) by dilution plating. After incubation at 28 °C for 4 days, one typical colony (shiny, slimy, cream-colored) per sample was selected from the modified King's B medium for purification. For preliminary identification MALDI-TOF MS analysis was performed (Bruker, Germany) comparing the spectra of the three purified isolates with in-house made reference spectra of several C. flaccumfaciens (Cf) strains. The DNA of isolates that were identified as Cf was isolated by thermal lysis and used for identification at the pathovar level using the conventional PCR by Tegli et al. (2002). The genomes of these isolates, generated using Illumina sequencing (accession numbers JBKYKM000000000, JBKYKN000000000 and JBKYKO000000000) share between 96.0-97.3% average nucleotide identity (ANI) with the Cf type strain CFBP 3418 confirming they fall within the species boundary. Recently, yellow-pigmented Cf strains showed higher than 94 % ANI among themselves and with CFBP 3418 but below 94% ANI with members of the pink-/orange-/red-pigmented strains (Osdaghi et al., 2024). A pathogenicity test on Phaseolus vulgaris var. Ferrari plants, performed according to EPPO (2011), confirmed the virulence of these isolates. Per isolate, 7-8 out of 10 plants showed typical Cff symptoms at 7 dpi, including wilting and interveinal chlorotic areas in the leaves, similar to the positive control plants. Negative control plants remained asymptomatic. The isolates were successfully re-isolated from the inoculated plants and identified as Cff using the above mentioned methods. The diagnostic procedure followed justifies the classification of the three Cf isolates as Cff. This is the first confirmed report of Cff on common bean in the Netherlands. Eradication measures have been imposed on the fields from which plants tested positive, including destruction of the crop and crop remains, hygiene measures, and prohibition to ","PeriodicalId":20063,"journal":{"name":"Plant disease","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143190095","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}
引用次数: 0
Ecofriendly Control Strategies Against Clavibacter michiganensis, the Causal Agent of Bacterial Canker of Tomato.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-04 DOI: 10.1094/PDIS-09-24-1931-FE
Nasim Sedighian, Anaelle Guineheux, Jan Van der Wolf, Eric Déziel

Bacterial canker of tomato, caused by the pathogenic Gram-positive bacterium Clavibacter michiganensis, represents a serious threat to tomato growers worldwide. Diverse approaches have been reported to control this infectious and aggressive bacterium. Current control strategy mostly relies on the application of copper-based products, and to some extent mancozeb and streptomycin, which are leading to growing concerns about resistance promotion, phytotoxicity effect and environmental pollution. In this paper, we present a comprehensive overview on ecofriendly management strategies to control this phytopathogen. New technologies, including the application of biological and non-biological inducers integrated with conventional preventive measures, represent a new approach in plant protection to develop a sustainable strategy to fight this devastating disease.

由致病性革兰氏阳性细菌 Clavibacter michiganensis 引起的番茄细菌性腐烂病对全球番茄种植者构成严重威胁。据报道,控制这种传染性和侵袭性细菌的方法多种多样。目前的控制策略主要依赖于铜基产品的应用,在一定程度上也依赖于锰锌和链霉素,但这些产品的抗药性增强、植物毒性效应和环境污染问题日益受到关注。本文全面概述了控制这种植物病原体的生态友好型管理策略。新技术(包括生物和非生物诱导剂的应用)与传统的预防措施相结合,代表了植物保护领域的一种新方法,可为防治这种毁灭性病害制定可持续的战略。
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引用次数: 0
Field Assessment of Turkish fir (Abies bornmuelleriana) Resistance to Five Root-Rotting Phytophthora Species.
IF 4.4 2区 农林科学 Q1 PLANT SCIENCES Pub Date : 2025-02-04 DOI: 10.1094/PDIS-08-24-1679-RE
Katie McKeever, Jeremy Johnson, Gary Chastagner

Turkish fir (Abies bornmuelleriana) has been evaluated as a Phytophthora Root Rot (PRR)-resistant alternative to other PRR-susceptible Abies Christmas tree species. Though Turkish fir survival under heavy PRR disease pressure exceeds that of other host species, previous research has suggested that there may be variability in resistance owing to pedigree, ambient environment, and Phytophthora species. To assess differences in PRR survival in the field, 36 open-pollinated families of Turkish fir were challenged with a mixture of five species of Phytophthora under conditions conducive for disease. Seedlings were grown from seed that was gathered during a provenance collection effort from three provinces in Turkey. At the collection locations in each province, mother trees were located along an altitudinal gradient. The goals for this study included determining Turkish fir resistance in comparison to susceptible fir spp., evaluating phenotype among Turkish fir families, assessing if differences in phenotypes could be attributable to source location or elevation, determining if source province or elevation influenced mortality, and comparing recovery of the five Phytophthora spp. used as inoculum. Turkish fir was demonstrated to be more resistant than noble fir (A. procera) or Fraser fir (A. fraseri) under the experimental conditions. Among the 36 Turkish fir families, six families had a significantly lower probability of PRR mortality compared to all other families; half of these families were from the Karabük province. Similarly, the Karabük province had the lowest overall mortality when family mortality proportions were totaled and compared among provinces. Evaluation of mortality among families from higher elevation sites within a province showed reduced mortality in comparison to mid and lower elevation sites, with variation among seed sources from different provinces. Among the five species of Phytophthora bulked for inoculum, P. cryptogea was the predominant species recovered from dead seedlings in both years. Results suggest that Turkish fir may be a viable PRR-resistant option for utilization in the Christmas tree industry despite some variability in phenotype among family.

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引用次数: 0
期刊
Plant disease
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