First of Alternaria dauci Causing Leaf Spot on Lentil (Lablab purpureus) in China

HomePlant DiseaseAhead of PrintFirst of Alternaria dauci Causing Leaf Spot on Lentil (Lablab purpureus) in China PreviousNext DISEASE NOTE OPENOpen Access licenseFirst of Alternaria dauci Causing Leaf Spot on Lentil (Lablab purpureus) in ChinaMing-Yan Luo and Yu-Lan JiangMing-Yan Luohttps://orcid.org/0000-0002-3433-0126Department of Plant Pathology, College of Agriculture, Guizhou University, Guiyang 550025, Guizhou, China and Yu-Lan Jiang†Corresponding author: Y.-L. Jiang; E-mail Address: [email protected]Department of Plant Pathology, College of Agriculture, Guizhou University, Guiyang 550025, Guizhou, ChinaAffiliationsAuthors and Affiliations Ming-Yan Luo Yu-Lan Jiang † Department of Plant Pathology, College of Agriculture, Guizhou University, Guiyang 550025, Guizhou, China Published Online:1 Oct 2025https://doi.org/10.1094/PDIS-01-25-0171-PDNAboutSectionsView articlePDFSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations Share on View article Lablab purpureus, commonly known as lentil, is a legume cultivated globally for its both nutritional and medicinal values. In July 2021, a leaf spot disease was detected on lentil variety "Zhaibubai" in a 10-hectare field in Qingzhen (26°58′14″N, 106°50′23″E; 1,050 m), Guizhou Province, China. An investigation of 100 lentil plants showed a disease incidence rate of 80%. The symptoms appeared as brown, nearly circular spots on the leaves, with slightly darker margins. In advanced stages, the lesions expanded and coalesced, resulting in irregularly shaped patterns. To identify the pathogen, 5 × 5-mm tissue segments were excised from the margins of leaf spots on 10 symptomatic leaves, sterilized with 3% sodium hypochlorite for 60 s, followed by 75% ethanol for 30 s, rinsed two times with sterile distilled water, dried on sterile filter paper, and incubated on potato dextrose agar (PDA) at 28°C for 2 days. Thirteen consistent isolates were acquired in total. The colonies were gray on PDA. The conidia were dark brown, 3 to 11 septate, and 25.0 to 95.0 × 12.5 to 30.0 μm (n = 50), with long beaks. Morphological characteristics were consistent with Alternaria dauci (Woudenberg et al. 2014). In addition, the rDNA internal transcribed spacer (ITS), small subunit (SSU) (White et al. 1990), large subunit (LSU) (Vilgalys and Hester 1990), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) (Carbone and Kohn 1999), RNA polymerase second largest subunit (RPB2) (Liu et al. 1999), and translation elongation factor 1-alpha (TEF1) (Berbee et al. 1999) loci were amplified and sequenced. The BLASTn results revealed that the sequences of a randomly selected strain (GUCC19-5298-1) showed high homologies with A. dauci. Specifically, ITS (PQ650767), SSU (PQ65076), LSU (PQ650774), GAPDH (PQ660508), RPB2 (PQ66551), and TEF1 (PQ660510) showed 99, 100, 100, 99, 98, and 96% identities, respectively, with those of A. dauci CBS 117097. The phylogenetic analysis of the six sequences revealed that 13 strains were grouped within the A. dauci clade. The 13 strains were confirmed as A. dauci based on their morphological features and multigene phylogenetic analysis. Pathogenicity tests were operated three times by spraying conidial suspension (1 × 105 conidia/ml) of the 13 strains onto 26 healthy 1-month-old lentil variety "Zhaibubai" seedlings, with two seedlings per strain. Two additional plants were treated with sterile water as controls. All plants were kept moist under plastic bags and incubated in a greenhouse at 28°C under a 12-h dark/light cycle. Ten days after inoculation, leaf spots resembling those observed in the field developed on the inoculated plants, while the control plants remained asymptomatic. A. dauci was successfully reisolated from the infected tissues of inoculated lentil plants and reconfirmed by morphological analysis and sequencing of the ITS, LSU, SSU, RPB2, GAPDH, and TEF1 loci. A. dauci has been reported to cause leaf spots on Lactuca sativa, Daucus carota, and Coriandrum sativum (Bessadat et al. 2019; Koike et al. 2017). To the best of our knowledge, this finding is the first report of leaf spot disease on lentil caused by A. dauci globally, providing a valuable foundation for later researchers to accurately diagnose this disease and develop effective prevention and control strategies. The author(s) declare no conflict of interest.References:Berbee, M. L., et al. 1999. Mycologia 91:964. https://doi.org/10.1080/00275514.1999.12061106 CrossrefWeb of ScienceGoogle ScholarBessadat, N., et al. 2019. Plant Dis. 103:2471. https://doi.org/10.1094/PDIS-03-19-0582-PDN LinkWeb of ScienceGoogle ScholarCarbone, I., and Kohn, L. M. 1999. Mycologia 91:553. https://doi.org/10.2307/3761358 CrossrefWeb of ScienceGoogle ScholarKoike, S. T., et al. 2017. Plant Health Prog. 18:136. https://doi.org/10.1094/PHP-12-16-0074-RS LinkWeb of ScienceGoogle ScholarLiu, Y. J., et al. 1999. Mol. Biol. 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All rights reserved, including those for text and data mining, AI training, and similar technologies.FundingGuizhou Provincial Basic Research Program (Natural Science)Grant/Award Number: [2023] Key 005KeywordsAlternaria dauciLablab purpureusleaf spotThe author(s) declare no conflict of interest.PDF download