一株内蒙古自治区武川县马铃薯黑胫病菌的分离鉴定及全基因组分析

Isolation and whole genome analysis of a pathogenic bacterial strain causingpotato blackleg in Wuchuan County, Inner Mongolia Autonomous Region

为明确内蒙古自治区武川县马铃薯黑胫病的病原种类及其致病机制,从当地表现黑胫病的马铃薯植株上分离病原菌,利用薯块接种法和盆栽接种法验证其致病性,利用形态学特征结合分子生物学技术对致病菌株进行鉴定,采用Pacbio SequelⅡ三代测序技术测定致病菌株的全基因组序列并对其致病机制进行分析。结果表示:分离获得1株菌株TDHJ7,该菌株能引起马铃薯典型黑胫病症状,经形态学特征、16S rRNA序列分析以及全基因组比较最终将其鉴定为黑腐果胶杆菌Pectobacterium atrosepticum,该菌株的全基因组大小为4997951 bp,有4623个编码序列。致病菌株基因注释结果显示,菌株TDHJ7中共有245个基因参与致病过程,其中参与果胶酶、纤维素酶和蛋白酶合成的基因分别有22、19和12个,参与Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅵ型分泌系统的基因有171个,参与编码毒素的基因有21个,表明菌株TDHJ7可能主要通过产生果胶酶、纤维素酶和蛋白酶等细胞壁降解酶,Ⅰ、Ⅱ、Ⅲ、Ⅳ和Ⅵ型分泌系统参与毒素类物质的转运,同时产生毒素类物质来引起植物发病。

In order to clarify the pathogenic species responsible for blackleg disease in Wuchuan County,Inner Mongolia Autonomous Region,and uncover the pathogenic mechanism,potato plants showing typical blackleg symptoms were collected from this region.Bacteria were isolated from these symptomatic samples,and their pathogenicity was assessed using tuber and plant inoculation methods.The pathogenic bacterial isolate was identified with morphological characters,16S rRNA sequence analysis,and comparative complete genome sequence analysis.The complete genome sequence of pathogenic strain was determined by the Pacbio Sequel II,and then the potential pathogenic mechanisms was predicted.Results showed that one pathogenic isolate,named TDHJ7,was isolated from symptomatic plants,and it was identified as Pectobacterium atrosepticum based on morphological characteristics,16S rRNA analysis,and comparative complete genome sequencing.The whole genomic sequence of P.atrosepticum TDHJ7 was 4997951 bp,containing 4623 coding sequences.Pathogenic annotation of strain TDHJ7 showed that 245 genes were involved in the pathogenic process,among them,22,19,and 12 genes were involved in the synthesis of pectinase,cellulase,and protease,respectively 171 genes were involved in type I,II,III,IV,and VI secretion systems,and 21 genes were involved in annotating toxin.The results suggest that the potential pathogenicity mechanisms of the strain TDHJ7 included cell wall-degrading enzymes(such as pectinase,cellulase and protease),secretion systems(including types I,II,III,IV and VI)and toxic compounds.