瓠瓜果斑病症状及其病原菌的鉴定

为有效防控瓠瓜果斑病，自浙江省象山县田间采集具有典型果斑病症状的瓠瓜样本，对其进行病原菌分离、形态观察、致病性测定及分子生物学鉴定，并利用特异性引物PL1/PL2 PCR扩增和基质辅助激光解吸电离飞行时间质谱（matrix assisted laser desorption ionization time-of-flight massspectrometry，MALDI-TOF-MS）技术对其病原菌进行亚群鉴定。结果表明：瓠瓜果斑病田间典型症状是发病叶片和果实上病斑由水渍状小斑点逐渐发展为伴有黄色晕圈的褐色不规则病斑，果实腐烂、有臭味。通过菌体形态和培养特性观察、PCR鉴定、16S rDNA序列分析和7个看家基因的系统发育分析将其病原菌鉴定为西瓜噬酸菌Acidovorax citrulli。从瓠瓜上分离的菌株均属于西瓜噬酸菌亚群I，从西瓜上分离的菌株均属于西瓜噬酸菌亚群II。

Symptoms of fruit blotch in bottle gourd and identification of its pathogen

Aiming to effectively prevent and control fruit blotch of bottle gourd (Lagenaria siceraria), samples of bottle gourd with typical symptoms of fruit blotch were collected from fields in Xiangshan County, Zhejiang Province, pathogen was isolated from these samples, and then morphological observation, pathogenicity test and molecular biological identification were carried out. The group of pathogens were also identified via PCR amplification with specific primers PL1/PL2 and matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF-MS) technology. The results showed that the typical symptoms of the disease included spots on the infected leaves and fruits, which gradually developed from small water-like spots into brown irregular spots with yellow halos, and caused the fruit to rot and smell bad. Bacterial morphology, culture characteristics, PCR identification, 16S rDNA sequencing and phylogenetic analysis based on seven housekeeping genes confirmed that the pathogen was Acidovorax citrulli. All the strains isolated from bottle gourd were A. citrulli group I while those from watermelon belonged to A. citrulli group II.