木麻黄青枯病菌的分离及强致病菌株的筛选

Isolation of Pathogen of Casuarina Bacterial Wilt and Screening of High Pathogenic Strains

[目的]筛选出强致病菌株用于木麻黄抗病育种研究工作。[方法]在广东沿海木麻黄青枯病发病区采集病根,开展病原菌两种不同分离方法的比较研究,对分离出的31个病株进行16s rRNA测序鉴定及致病性测定。[结果]采用稀释分离法及根系溢出法在TTC培养基上共分离出了31个病原菌株,根系溢出法操作简便,杂菌含量低,分离率在60%左右,可作为常规稀释分离法的补充。31个菌株进行分子鉴定,只有22个菌株扩增出了特异性条带,经测序比对确定这22个菌株为青枯菌。青枯菌株致病性测定结果显示菌株致病性在无性系间、菌株间及菌株与无性系间的交互作用均具有极显著差异(P<0.01),不同接种方法间菌株致病性相关系数值较小,介于0.496 6~0.731 0之间,即室内水培接种与小苗盆栽接种不存在密切的直线相关关系。[结论]综合选择在不同无性系及不同接种方法中均具有较强致病性的GL-2、H、M、TC-1、F、Q菌株作为下一步木麻黄种质资源抗性鉴定及抗病育种研究试验菌株。

[ Objective] To screen high pathogenic strains for studies on germplasm resources resistance identifica- tion and resistance breeding of Casuarina. [ Method ] The Casuarina roots were collected from heavily infected are- as in western Guangdong Province. Two methods, dilution isolation and root overflow, were used in strains isola- tion. Ralstonia solanacearum strains were identified by 16S rRNA sequencing and the pathogenicity of these strains were measured. [ Result ] 31 strains were isolated. The method of root overflow is simple to operate and the isola- tion rate was about 60%, thus was supplementary to regular dilution method. Only 22 strains were amplified from the 31 strains by using 16S rRNA sequencing, and the amplified strains were identified as R. solanacearum. The re- suits of pathogenicity measurement showed that the pathogenicity of different strains was significantly different （p 〈 0.01 ）, and the correlation coefficients between two different inoculation approaches （water planting and potting） were significant but relatively low （0. 496 6 - O. 731 0 ） , suggesting that the two approaches were independent.[ Conclusion] Six strains were selected tbr next-step study.