杏树梨火疫病在中国首次发生

First report of pear fire blight on apricot caused by Erwinia amylovora in China

2020年6月,在新疆伊犁州巩留县杏树上观察到一种疑似梨火疫病症状的新病害,对症状组织分离物进行菌落形态特征观察、烟草过敏性反应、致病性测定、PCR检测和16S rDNA序列分析。试验结果表明,分离菌株在NA培养基上菌落特征为圆形,边缘整齐,乳白色至奶油色,隆起,有粘性,表面光滑且有光泽,接种于幼嫩杏树叶片后病菌沿叶脉向四周扩散侵染,叶柄处有菌脓;可引发烟草过敏性反应,PCR检测为梨火疫病菌阳性,16S rDNA序列与梨火疫病菌(Erwinia amylovora)序列相似性为100%。根据上述检测结果,将杏树分离物鉴定为梨火疫病菌,这是梨火疫病在中国杏树上的首次发生报道。

In June 2020,a new disease suspected to have the symptoms of pear fire blight was observed on apricot trees in Gongliu County,Yili Kazak Autonomous Prefecture,Xinjiang Uygur Autonomous Region.Colony morphological characteristic,tobacco anaphylaxis,pathogenicity,PCR detection and 16S r DNA sequence analysis were performed on symptomatic tissue isolates.The results showed that the colonies of the isolated strains on NA medium were round,with neat edges,milky white to cream color,raised,sticky,smooth and glossy surface.After inoculation of young apricot leaves,the bacteria infested along the veins of leaves and spread around,and there was fungus pus at the petioles.It could cause allergic reaction in tobacco,and the PCR test was positive for E.amylovora.The 16S rDNA sequence similarity with E.amylovora was 100%.On the basis of the above results,the apricot isolate was identified as E.amylovora,which was the first reported occurrence of E.amylovora on apricot tree in China.