Abstract:

To identify the pathogenic agent of a newly bacterial wilt disease in kiwifruit， which found in Shihou village， Jiaocheng district， Ningde city， Fujian province in recent years， the bacterial strains were isolated and purified by the dilution separation method. The pathogenicity of the isolated strains was tested by inoculating on stems and roots of kiwifruit seedlings， and its taxonomic status were identified by Koch’s postulates， bacteria biological and biochemical characteristics， biolog test， PCR verification with the specific primer， evolutionary type was determined by multiplex PCR， analysis of 16S rDNA and endoglucanase gene （egl） sequences. The results showed that 9 strains were isolated and purified from the vascular tissues of the infected stems. Followed Kock’s postulates， the 9 strains could produce the similar symptoms on the inoculated kiwifruit seedlings， and the similar bacterial strains were also re-isolated. The colony morphology of the isolates was irregular， flat， spreading around， and could not produce viscous substances in NA medium， the colony color was dark red， producing reddish-brown pigment diffused into the medium and poor fluidity in TTC medium， while the colony was milky whitish in YDC medium. According to all kinds of analysis， the 9 isolates were identified as Ralstonia pseudosolanacearum， belonging to biovar Ⅲ， phylotype Ⅰ （Asia group）， sequevar 14. This was the first report of a disease caused by R.pseudosolanacearum on kiwifruit （Actinidia chinensis Planch）. Above results provided a theoretical basis for the accurate and effective prevention and control of kiwifruit bacterial wilt.

Key words: kiwi, bacterial blight wilt, pathogen identification, physiological and biochemical determination, Ralstonia pseudosolanacearum, 16S rDNA

摘要：

为明确近年来在福建省宁德市蕉城区石后乡猕猴桃苗圃新发生的一种细菌性病害病的原菌，并进一步探讨其发生流行规律，采用稀释分离法对采集病株进行病原菌的分离和纯化，对获得的细菌菌株进行致病性测定，通过柯赫氏法则验证、常规的细菌生物学特性、生理生化反应、Biolog 鉴定、16S rDNA和内切葡聚糖酶基因（egl）序列分析对病原菌进行分类鉴定。结果表明，从发病猕猴桃病株上获得9株细菌菌株，将其接种在健康的猕猴桃植株后，其发病症状与田间自然发病症状基本一致，且从接种后病株的茎秆和根部又重新分离到与原菌落形态相同的细菌。柯赫氏法则证实这9株细菌菌株为猕猴桃细菌性枯萎病的致病菌。这9株菌株在NA培养基上的菌落形态一致，均呈不规则型、扁平，并逐渐向四周扩散，不产生粘稠状物质，不会使培养基变色；在TTC培养基上，菌落颜色呈暗红色，产生可扩散至培养基中的红褐色色素，其流动性较差；在YDC培养基上，菌落呈乳白色。经综合分析，这9株细菌菌株均被鉴定为假茄科雷尔氏菌（Ralstonia pseudosolanacearum），生化型Ⅲ和演化型Ⅰ（亚洲组），序列变种14。这是首例青枯菌侵染猕猴桃的报道。以上研究结果为制定猕猴桃细菌性枯萎病精准有效的综合防控提供了理论依据。

关键词: 猕猴桃, 细菌性枯萎病, 病原菌鉴定, 生理生化测定, 假茄科雷尔氏菌, 16S rDNA