冬季储藏甜瓜黑斑病病原菌的分离与鉴定

[目的]对二氧化氯消毒低温冷库中储藏甜瓜黑斑病原菌进行分离与鉴定.[方法]采用回接感染进行致病性测定.4株真菌中发现XJU8能使甜瓜产生黑斑,对其形态特征、生理生化特性、26 S rDNA D1/D2区碱基序列、全细胞脂肪酸等进行分析.[结果]形态特征观察以及生理生化特性的测定结果表明,菌株XJU8 与链格孢属有很大的相似性;26S rDNA D1/D2区序列序列进行碱基序列分析比对表明,与交链格孢Alternaria alternata IFM53800具有99;的序列同源性;系统进化树也表明XJU8和已知的交链格孢(A. alternata)聚类在同一分支上;全细胞脂肪酸分析结果显示XJU8的主要脂肪酸组分为C18∶2 CIS 9,12/18∶0a(52.83;),C16∶0 (19.19;) 和Sum In Feature 8 (16.41;),与链格孢属的脂肪酸特性相同,并与链格孢属中其它种具有51.8;的相同脂肪酸成分.[结论]置菌株XJU8属于链格孢属交链格孢菌的新变种,该菌种被命名为Alternaria alternata XJU8,菌株保藏于中国典型培养物保藏中心,保藏编号为:CCTCC AF 207029.

Isolation and Identification of Black spot Pathogens from Winter Storage Melon

[Objective]This research was conducted to isolate and identify black spot pathogens from decayed tissue of melons stored under the cold storage condition with chlorine dioxide disinfection.[Method]The melons with four strains were identified and found that only the isolate XJU8 can cause black spot symptom in melons during cold storage processing.Morphological,physiological,and biochemical characteristics of Strain XJU8 were identified by 26S rDNA D1/D2 gene sequences and cell fatty acid compositions were analyzed.[Result]The morphological,physiological and biochemical characteristics of isolate XJU8 were closely similar to the reference strain Alternaria.Comparative 26S rDNA D1/D2 gene sequences analysis showed that strain XJU8 was closely related to A.alternata IFM53880 with sequence homology of 99%;phylogenetic dendrogram showed that strain XJU8 formed a coherent cluster with members of the genus Alternaria.The cell fatty acid compositions analysis showed that the major cellular fatty acids were C18:2 CIS 9,12/18:0a (52.83%),C16:0 (19.19%) and Sum In Feature 8 (16.41%),and shares 51.8% the same cellular fatty acid compositions with other members in Alternaria sp.[Conclusion]On the basis of above results,the strain XJU8 was classified as a variation species with A.alternata,was named as A.alternata XJU8 and was deposited in China Center for Type Culture Collection (N0.CCTCC AF 207029).