First Report of Onion ( Allium cepa ) Bulb Rot Caused by Pantoea agglomerans in China
2021; American Phytopathological Society; Volume: 106; Issue: 3 Linguagem: Inglês
10.1094/pdis-07-21-1393-pdn
ISSN1943-7692
AutoresJinfeng Zhang, Jianglai Wang, Jinxiu Ma, Lu Liu, Tong Shen, Yongqiang Tian,
Tópico(s)Plant-Microbe Interactions and Immunity
ResumoHomePlant DiseaseVol. 106, No. 3First Report of Onion (Allium cepa) Bulb Rot Caused by Pantoea agglomerans in China PreviousNext DISEASE NOTE OPENOpen Access licenseFirst Report of Onion (Allium cepa) Bulb Rot Caused by Pantoea agglomerans in ChinaJinfeng Zhang, Jianglai Wang, Jinxiu Ma, Lu Liu, Tong Shen, and Yongqiang TianJinfeng ZhangSchool of Biological and Pharmaceutical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China, Jianglai WangSchool of Biological and Pharmaceutical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China, Jinxiu MaSchool of Biological and Pharmaceutical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China, Lu LiuSchool of Biological and Pharmaceutical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China, Tong ShenResearch Institute, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China, and Yongqiang Tian†Corresponding author: Y. Tian; E-mail Address: tian2918@163.comhttps://orcid.org/0000-0003-1361-7838School of Biological and Pharmaceutical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China AffiliationsAuthors and Affiliations Jinfeng Zhang1 Jianglai Wang1 Jinxiu Ma1 Lu Liu1 Tong Shen2 Yongqiang Tian1 † 1School of Biological and Pharmaceutical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China 2Research Institute, Lanzhou Jiaotong University, Lanzhou 730070, Gansu, China Published Online:16 Feb 2022https://doi.org/10.1094/PDIS-07-21-1393-PDNAboutSectionsView articlePDFSupplemental ToolsAdd to favoritesDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InRedditEmailWechat View articleOnion (Allium cepa L.) is one of the most cultivated vegetables throughout the world. With an average annual production quantity of 18 million kilograms over a recent 21 years, China is the world's biggest onion producer (Hanci 2018). Among them, onion is mainly cultivated in the provinces of Gansu, Shandong, Yunnan, Jiangsu, Zhejiang, and Henan. A survey in Gansu Province in the last several years showed that the incidence of onion bulb rot was 30 to 80%. In April 2020, bulbs appeared water-soaked, and then rot symptoms were observed during storage in Lanzhou City, Gansu Province, China. The initial symptoms of bulb rot disease were yellowish brown color and production of an abundant exudate in the inner bulb scales when cut. Gradually, symptomatic bulbs became soft, watery, and decayed. In severe infections, the onions showed total rot of the bulb. Therefore, we sampled some diseased onions and isolated pathogenic bacteria from the junction of lesions along with healthy parts on Luria-Bertani (LB) medium. Three representative single colonies were obtained on LB medium, and the culture characteristics were raised elevation, mucoid texture, round, and smooth with entire margin; the brown at the beginning and turned yellow later; and scanning electron microscopy observations showed that these isolates were short rod-shaped. The physiological and biochemical determination revealed that the isolates were positive for yellow pigment, Voges–Proskauer test, growth at 37°C, nitrate reduction, catalase, glucose, sucrose, D (–)-salicin, starch hydrolysis, motility, and pellicle. They were negative for indole production, methyl red, lactose, gelatin liquefaction, glycerol, and gram staining (Gavini et al. 1989; Nabrdalik et al. 2018). Based on these morphological, physiological, and biochemical characteristics, three isolates were initially identified as Pantoea agglomerans (Guo et al. 2020). A representative isolate, L1, was selected to extract DNA, and the conserved sequences of the pathogen gene were sequenced according to 23S ribosomal RNA (23S rRNA), DNA gyrase subunit B (gyrB), and elongation factor G (fusA) (She et al. 2021) housekeeping gene. The sequence alignment of the 23S rRNA gene (P. agglomerans, MZ314289, 930 bp) showed that the homology between the strain L1 and P. agglomerans (CP016889) with similarity of 99.54%, and based on the sequence alignment of gyrB (P. agglomerans, MZ337547, 1,189 bp) and fusA (P. agglomerans, MZ350961, 1,037 bp) genes, the similarity with P. agglomerans (FJ617386 and MG845872) was 100%. A phylogenetic analysis based on the 23S, gyrB, and fusA housekeeping gene sequences was performed by using the neighbor-joining methods in MEGA 7.0 under the p-distance (Kumar et al. 2016), which included P. agglomerans strains AR1a, TH81, L15, and ASB05, P. eucalypti strain LMG 24197, P. dispersa strains BJQ0007 and DSM 32899, P. ananatis strains LMG 20103 and AJ13355, and P. vagans strains C9-1, LMG24199, and PV989. The phylogenetic distribution generated five primary phylogroups, and strain L1 formed a clade with the other four P. agglomerans strains. Thus, the strain L1 was identified as P. agglomerans. To satisfy Koch's postulates, 10 onions were divided into two groups, five in each group, and needle puncture wounded on the surface of each onion. In the experimental group, 400-μl bacterial suspensions were injected with a sterile syringe, and the other five onions were injected with the same amount of sterile distilled water as the negative control. Inoculated onions were incubated in the greenhouse incubator (28°C, humidity >80%). After 4 days of incubation, all onions inoculated with strain L1 appeared water-soaked and displayed rot symptoms, and no symptoms were observed in the negative control. Subsequently, pathogens were reisolated from inoculated bulbs and identified as P. agglomerans according to molecular identification described above. To the best of our knowledge, this is the first report of bulb rot disease of stored onion caused by P. agglomerans in China.The author(s) declare no conflict of interest.References:Gavini, F., et al. 1989. Int. J. Syst. Bacteriol. 39:337. https://doi.org/10.1099/00207713-39-3-337 Crossref, Google ScholarGuo, M., et al. 2020. Plant Dis. 104:277. https://doi.org/10.1094/PDIS-04-19-0746-PDN Link, Google ScholarHanci, F. 2018. J. Agric. Vet. Sci. 11:17. https://doi.org/10.9790/2380-1109011727 Google ScholarKumar, S., et al. 2016. Mol. Biol. Evol. 33:1870. https://doi.org/10.1093/molbev/msw054 Crossref, ISI, Google ScholarNabrdalik, M., et al. 2018. Ecol. Chem. Eng. S 25:331. https://doi.org/10.1515/eces-2018-0023 ISI, Google ScholarShe, X., et al. 2021. Crop Protection 139:105385. https://doi.org/10.1016/j.cropro.2020.105385 Crossref, Google ScholarFunding: Funding was provided by National Natural Science Foundation of China (NFSC No. 21967015); Gansu Province science and technology key research and development project (20YF3FA038); Gansu Jiayuguan city science and technology major project (20-04).The author(s) declare no conflict of interest.DetailsFiguresLiterature CitedRelated Vol. 106, No. 3 March 2022SubscribeISSN:0191-2917e-ISSN:1943-7692 Download Metrics Downloaded 625 times Article History Issue Date: 30 Mar 2022Published: 16 Feb 2022First Look: 15 Sep 2021Accepted: 14 Sep 2021 Page: 1057 Information© 2022 The American Phytopathological SocietyFundingNational Natural Science Foundation of ChinaGrant/Award Number: 21967015Gansu Province science and technology key research and development projectGrant/Award Number: 20YF3FA038Gansu Jiayuguan city science and technology major projectGrant/Award Number: 20-04Keywordsvegetablesyield loss and economic impactsonionPantoea agglomeransbulb rotThe author(s) declare no conflict of interest.PDF download
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