广西甜瓜细菌性果斑病病原鉴定及16S rDNA序列分析

Identification of pathogen causing melon bacterial fruit blotch in Guangxi and analysis of its 16S rDNA sequence

【目的】对广西区内疑似甜瓜细菌性果斑病的病原菌进行分离鉴定,明确引起该病害的病原菌,为甜瓜细菌性果斑病的抗病育种及综合防治提供理论依据。【方法】分别采集南宁市和贺州市疑似甜瓜细菌性果斑病的病叶(编号:WM0922)和病果(编号:XD0611)样品,对样品进行分离纯化,并通过测定分离菌株的致病性、观察菌落形态和培养性状、测定其生理生化性状及比对分析16S rDNA序列,对供试病原菌进行鉴定。【结果】从编号WM0922的病叶上分离得到5株菌株,经致病性测定有3株菌株(WM0922-2、WM0922-3和WM0922-4)具有致病性;从编号XD0611的病果上分离得到8株菌株,经致病性测定有4株菌株(XD0611-5、XD0611-6、XD0611-7和XD0611-8)具有致病性;择优选取具有代表性的菌株WM0922-3和XD061 1-7进行后续试验,发现二者均可侵染葫芦子叶,革兰氏反应均为阴性,培养性状及生理生化测定结果一致,对比分析16S rDNA基因序列,与Acidororax citrulli的相似性均在99%以上。【结论】引起甜瓜细菌性果斑病的病原菌为燕麦嗜酸菌西瓜亚种(A.avenae subsp.citrulli)。

【Objective】In order to provide a basis for disease-resistant breeding and integrated management of bacterial fruit blotch,suspected pathogen causing melon bacterial fruit blotch was isolated and identified.【Method】Suspected leaves and fruits samples were collected from Nanning（No.WM0922） and Hezhou（No.XDO611）,and pathogen was isolated and purified from samples,then identified based on pathogenicity test,colony morphology and cultivate characteristics,physiological and biochemical characteristics and 16 S rDNA sequence analysis.【Result】 Results showed that,five germs were isolated from suspected leaves（No.WM0922）,and three of which（No.WM0922-2,WM0922-3,WM0922-4）were pathogenic.Eight germs were isolated from suspected fruits（No.XDO611）,four of which（No.XDO611-5,XD0611-6、XD0611-7,XD0611-8） were pathogenic.Two representative germs WM0922-3 and XD0611-7 were selected for follow-up test,and the test result showed that they could infect gourd leaves,and were identified as Gram-negative bacterium,with same culture characters,physiology and biochemistry,and their 16 S rDNA sequences shared more than 99%similarily with that of Acidororax citrulli.【Conclusion】The pathogen causing melon bacterial fruit blotch is identified as A.avenae subsp.citrulli.