大白菜褐腐病（茎基腐病）的病原菌鉴定

2011年在北京、河北、江苏等地的部分大白菜种植区，当地俗称的大白菜“茎基腐病”普遍严重发生，实际调查后共采集到大白菜“茎基腐病”病样12份，分离获得12个真菌分离物，经形态学鉴定，分离到的菌株均为立枯丝核菌Rhizoctonia solani；采用真菌通用引物ITS1/ITS4对病原菌rDNA-ITS进行PCR扩增，并将测序结果在GenBank中进行同源性比对分析，分子生物学鉴定结果与形态学鉴定结果一致。将分离到的菌株分别回接健康的大白菜植株，植株表现出与田间相似的发病症状，重新进行病原菌的分离，得到相同的病原物。基于形态学、分子生物学鉴定和致病性试验最终确定北京、河北、江苏等地大白菜 “茎基腐病” 病原菌为立枯丝核菌Rhizoctonia solani，大白菜“茎基腐病”与大白菜褐腐病、大白菜立枯病属同病异名。

Pathogen Identification of Chinese Cabbage Brown Rot(Base Stem Rot)

In 2011，the disease known as‘base stem rot’of Chinese cabbage〔Brassica campestris L. ssp. pekinensis（Lour）Olsson〕was prevalent in Beijing，Hebei and Jiangsu Provinces．12 fungi isolates were collected from rotten stem of Chinese cabbage．The morphological identification show the isolated bacteria strain is Rhizoctonia solani．PCR of rDNA-ITS was propagated by general primer ITS1/ITS4 and the sequencing result was compared and analyzed in GenBank．The results of molecular identification and morphological identification were the same．Then the isolated bacteria strains were inoculated to the healthy Chinese cabbage stems．The symptoms resembled the ones originally observed in the fields．Finally，the pathogen’s identity was confirmed by re-isolation from lesions of infected plants．Based on the tests of morphological characteristics，pathogenicity and molecular biology，the pathogens of Chinese cabbage‘base stem rot’found in Beijing，Hebei and Jiangsu Provinces were the same as brown rot，Rhizoctonia solani．etc.