广东省马铃薯块茎软腐病病原菌鉴定

为明确广东省惠州市马铃薯块茎软腐病的病原菌,采用常规病组织分离法获得4株菌株,通过生理生化特征和分子生物学特性对其进行鉴定,并测定了该病原菌对20个马铃薯品种的致病力。结果显示,该病原菌为革兰氏阳性菌,在LB平板上菌落有透明和不透明2种形态;除葡萄糖发酵阳性、对链霉素和青霉素具有抗性等特征不同外,BP-hd-1、BP-hd-2、BP-hd-3和BP-hd-4菌株与短小芽胞杆菌Bacillus pumilus菌株的其它生理生化特征均相同。系统进化分析结果表明,4株菌株的16S rDNA序列分别与短小芽胞杆菌AI-Khrj18(KY123871)、ML270(KC692158)、NCTC10337(LT906438)和ARD21(KX023236)的相似性为100.0%;4株菌株的gyrB基因序列均与短小芽胞杆菌AUEC29菌株(HM585095)的gyrB基因相似性最高,为99.7%～99.8%。生理生化特征及分子生物学鉴定结果表明,引起广东省马铃薯块茎软腐病的病原菌为短小芽胞杆菌。致病力测定结果显示,接种菌株BP-1后20个马铃薯品种的发病率均为100.0%,表明该病原菌对马铃薯有强致病力。

Identification of the pathogen causing potato tuber soft rot in Guangdong Province

In order to confirm the pathogen of potato tuber soft rot in Huizhou City, Guangdong Province, four isolates of the pathogen were isolated with diseased tissue isolation method. Four isolates were identified with physiological and biochemical characteristics and molecular biological identification. Twenty potato varieties were used for pathogenicity test of the pathogen. The results showed that the pathogen was a gram-positive bacterium and possessed transparent colonies and opaque colonies on LB plates. The physiological and biochemical characteristics of BP-hd-1, BP-hd-2, BP-hd-3 and BP-hd-4 same as those of Bacillus pumilus except for glucose fermentation positive reaction, streptomycin resistance and penicillin resistance. The results of phylogenetic analysis showed that 16S rDNA gene sequences of the four isolates were highly similar to those of B. pumilus AI-Khrj18 (KY123871), ML270 (KC692158), NCTC10337 (LT906438) and ARD21 (KX023236), with an identity of 100.0%, respectively. The gyrB gene sequences of the four isolates were highly similar to that of B. pumilus AUEC29 (HM585095), with an identity of 99.7%-99.8%. The pathogen of potato soft rot was identified as B. pumilus based on physiological and biochemical characteristics and molecular biological identification. The results of the pathogenicity tests showed that the disease incidence of 20 potato varieties artificially inoculated by BP-1 were 100.0%, indicating that the pathogen was highly pathogenic to potato.