First Report of Pythium myriotylum Associated with Peanut Pod Rot in China

HomePlant DiseaseVol. 103, No. 7First Report of Pythium myriotylum Associated with Peanut Pod Rot in China PreviousNext DISEASE NOTESFirst Report of Pythium myriotylum Associated with Peanut Pod Rot in ChinaJ. Yu, M. Xu, C. Liang, X. Zhang, Z. Guo, J. Wu, X. Li, Y. Chi, and S. WanJ. YuShandong Peanut Research Institute, Qingdao, Shandong, China, M. XuShandong Peanut Research Institute, Qingdao, Shandong, China, C. Lianghttp://orcid.org/0000-0002-0139-8140Qingdao Agricultural University, Qingdao, Shandong, China, X. ZhangShandong Peanut Research Institute, Qingdao, Shandong, China, Z. GuoShandong Peanut Research Institute, Qingdao, Shandong, China, J. WuShandong Peanut Research Institute, Qingdao, Shandong, China, X. LiBiotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan, Shandong, China, Y. Chi†Corresponding authors: Y. Chi; E-mail Address: [email protected] and S. Wan; E-mail Address: [email protected]http://orcid.org/0000-0002-5263-3032Shandong Peanut Research Institute, Qingdao, Shandong, China, and S. Wan†Corresponding authors: Y. Chi; E-mail Address: [email protected] and S. Wan; E-mail Address: [email protected]Shandong Academy of Agricultural Sciences/Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan, Shandong, ChinaAffiliationsAuthors and Affiliations J. Yu1 M. Xu1 C. Liang2 X. Zhang1 Z. Guo1 J. Wu1 X. Li3 Y. Chi1 † S. Wan4 † 1Shandong Peanut Research Institute, Qingdao, Shandong, China 2Qingdao Agricultural University, Qingdao, Shandong, China 3Biotechnology Research Center, Shandong Academy of Agricultural Sciences, Jinan, Shandong, China 4Shandong Academy of Agricultural Sciences/Shandong Provincial Key Laboratory of Crop Genetic Improvement, Ecology and Physiology, Jinan, Shandong, China Published Online:16 May 2019https://doi.org/10.1094/PDIS-02-19-0321-PDNAboutSectionsSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat Peanut (Arachis hypogaea) is a globally important crop for food and oil extraction. In the past year, rot-like symptoms were observed on peanut pods in Shandong and Henan provinces, the main peanut-producing areas. Brown to black lesions were seen primarily on infected pods and kernels. From August to November 2018, samples of pods were collected from 10 peanut-producing areas in five provinces. Pieces of pod-rot-symptomatic tissue (5 mm2) were cut from the pods, surface sterilized with 0.5% NaClO, rinsed with sterile water, dried on a paper towel, and then plated on 2.5% vegetable (V8) juice medium. The plates were incubated at 25°C for 2 to 3 days in the dark. White fungal colonies with nonseptate mycelia grew from the tissue pieces. Single-hyphal-tip cultures were placed on corn meal agar (CMA) containing rifampicin (50 mg/liter), phenamacril (5 mg/liter), ampicillin (50 mg/liter), and pentachloronitrobenzene (50 mg/liter) (Chen et al. 2017). Seven isolates with similar morphological characteristics were obtained. The isolates were identified as Pythium spp. based on growth pattern and sporangial and oogonial structures (Van der Plaats-Niterink 1981). The colony of isolate PRI180062 on CMA was white with sparse hyphae. Primary hyphae were 6.64 ± 0.89 μm wide; appressoria were clavate, usually formed in clusters, often up to 60 μm in long. Sporangia were terminal or intercalary, filamentous, with undifferentiated and inflated lobulate elements of variable length and 7 to 17 μm wide. Oogonia were globose, terminal or intercalary, 23 to 32 μm in diameter. Antheridia, three to six per oogonium, stalks branched, with 10 more or less loosely enveloping the oogonium, diclinous, occasionally monoclinous, antheridial cells clavate or crook-neck, mostly 8 to 30 × 4 to 8 μm. Oospores aplerotic, colorless or yellowish, and 17 to 25 μm in diameter. The wall was up to 1.1 to 1.9 μm thick. DNA of each representative isolate was extracted, and the internal transcribed spacer (ITS1-5.8S-ITS2) regions of rDNA were amplified and sequenced with primers ITS1 and ITS4 (Seliger 1990). ITS sequences of the isolates, deposited in GenBank (accession nos. MK377157 to MK377164) shared 99 to 100% similarity with Pythium myriotylum isolates in GenBank (accession nos. KJ162354, HQ237488, and KX671106, respectively). The COI gene was amplified with the primers OomCoxI-Levlo (CYTCHGGRTGWCCRAAAAACCAAA) and OomCoxI-Levup (TCAWCWMGATGGCTTTTTTCAAC) (Robideau et al. 2011). COI gene sequences of the isolates, deposited in GenBank (accession nos. MK510842 to MK510848), shared 99 to 100% similarity with P. myriotylum isolates in GenBank (accession nos. KF761209, HQ708640, and KF761197, respectively). Phylogenetic analysis was done by neighbor joining analysis based on ITS + COI sequences. The isolates were identified as P. myriotylum based on molecular analysis and morphological characteristics. Pathogenicity of one representative isolate (PRI180062) was tested on peanut under greenhouse conditions (30°C in the day and 25°C at night, 60% relative humidity). Ten 2-month-old peanut seedlings (cv. Zhonghua No. 12) grown in 22-cm pots (sterilized field soil) were inoculated with PRI180062 by placing 10 Pythium-infested oat seeds around the roots. Ten noninoculated peanut seedlings were used as the control. One month after inoculation, the pods were harvested and washed before disease assessments were done. All seedlings inoculated with PRI180062 showed pod rot symptoms similar to those observed in the field. P. myriotylum were reisolated from the symptomatic pods and its identity confirmed by morphological characteristics and molecular analysis. No pod rot symptoms were seen on the control peanuts. The experiment was repeated three times. P. myriotylum is associated with peanut pod rot in the United States (Wheeler et al. 2005). To our knowledge, this is the first report of P. myriotylum causing peanut pod rot in China. The occurrence of pod rot caused by P. myriotylum in a region where peanut is production is economically important is of concern, and disease management programs for peanut pod rot need to be initiated.The author(s) declare no conflict of interest.References:Chen, J.-J., et al. 2017. Phytotaxa 309:135. https://doi.org/10.11646/phytotaxa.309.2.4 Crossref, ISI, Google ScholarRobideau, G. P., et al. 2011. Mol. Ecol. Resour. 11:1002. https://doi.org/10.1111/j.1755-0998.2011.03041.x Crossref, ISI, Google ScholarSeliger, H. 1990. Trends Biotechnol. 8:335. https://doi.org/10.1016/0167-7799(90)90215-J Crossref, Google ScholarVan der Plaats-Niterink, A. J. 1981. Stud. Mycol.: 21. Google ScholarWheeler, T. A., et al. 2005. Peanut Sci. 32:9. https://doi.org/10.3146/0095-3679(2005)32[9:PSAWPR]2.0.CO;2 Crossref, Google ScholarJ. Yu and M. Xu contributed equally to the paper. Y. Chi and S. Wan contributed equally to the paper.Funding: Funding was provided by National Key Scientific and Technological Project (grant no. 2018YFD0201007), Natural Science Foundation of Shandong Province of China (grant no. ZR2018LC015), and Qingdao Civil Science and Technology Project (grant no. 17-3-3-70-nsh).The author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 103, No. 7 July 2019SubscribeISSN:0191-2917e-ISSN:1943-7692 DownloadCaptionApple cultivar Joya Cripps Red lesions caused by Colletotrichum fructicola (Nodet et al.). Photo credit: P. Nodet. Symptoms of Lotus powdery mildew caused by Erysiphe takamatsui (Zhou et al.). Photo credit: C. Liang. Symptoms of tar spot (Phyllachora maydis) on maize leaves (Dalla Lana et al.). Photo credit: F. Dalla Lana. Metrics Article History Issue Date: 20 Jun 2019Published: 16 May 2019First Look: 18 Mar 2019Accepted: 13 Mar 2019 Pages: 1794-1794 Information© 2019 The American Phytopathological SocietyFundingNational Key Scientific and Technological ProjectGrant/Award Number: 2018YFD0201007Natural Science Foundation of Shandong Province of ChinaGrant/Award Number: ZR2018LC015Qingdao Civil Science and Technology ProjectGrant/Award Number: 17-3-3-70-nshKeywordsoomycetesArachis hypogaeaPythium myriotylumpathogen detectionThe author(s) declare no conflict of interest.Cited byFirst Report of Root Rot Caused by Pythium myriotylum on Sesame in ChinaMin Jia, Yunxia Ni, Xintao Liu, Hui Zhao, Xinbei Zhao, Bipo He, Chunyan Zhang, and Hongyan Liu24 July 2023 | Plant Disease, Vol. 107, No. 8Cloning and Functional Characterization of a Pericarp Abundant Expression Promoter (AhGLP17-1P) From Peanut (Arachis hypogaea L.)20 January 2022 | Frontiers in Genetics, Vol. 12Pythium myriotylum (brown rot of groundnut)CABI Compendium, Vol. CABI CompendiumFirst Report of Root Rot on Mungbean Caused by Pythium myriotylum in ChinaQiang Yan, Qinxue Zhang, Pei Ding, Xingxing Yuan, Ranran Wu, Jingbin Chen, Chenchen Xue, and Xin Chen13 November 2020 | Plant Disease, Vol. 105, No. 1