马铃薯早疫病病原菌鉴定及其对不同药剂的敏感性

Identification of the pathogens of potato early blight and their sensitivity to different fungicides

为了明确马铃薯早疫病病原菌及其对不同药剂的敏感性,2009～2011年从河北省5个县采集180个早疫病样,以常规方法进行分离与纯化。根据病原菌的形态特征和致病性,结合其rDNA-ITS区域的序列分析对病原菌进行鉴定,并采用菌丝生长速率法测定病原菌对不同药剂的敏感性。结果分离到两种菌(A、B),分离比例为4:6。致病性测定证实分离菌A和B均为马铃薯早疫病病原菌。经形态学鉴定,初步认定A为茄链格孢(Alternaria solani),B为链格孢(Alternaria alternata)。采用通用引物ITS1/ITS4对病原菌A和B的rDNA-ITS序列区扩增并测序,通过与GenBank数据库比对,A与A.so-lani同源性为98%,B与A.alternata的同源性达100%。两种病原菌对咯菌腈、吡唑醚菌酯、啶酰菌胺、苯醚甲环唑等药剂的敏感性差异极显著,而对异菌脲的敏感性差异不显著。因此,将河北省马铃薯早疫病菌鉴定为茄链格孢(A.solani)和链格孢(A.alternata),二者对同一药剂的敏感性不同。

To clarify the pathogens of potato early blight and their sensitivity to different fungicides, 180 sampies of potato early blight were collected from 5 counties of Hebei Province during 2009 -2011, and then isolated and purified by conventional method. Through morphological characteristics, pathogenicity test along with sequence analysis of the internal transcribed spacer region of the ribosomal DNA （ ITS ）, two kinds of fungi were identified （A, B）, with a ratio of 4：6. The sensitivity of the pathogens to different fungicides was also determined by mycelial growth rate test. Through further pathogenicity test it was demonstrated that A and B were the pathogen causing potato early blight. The preliminary morphological identification showed that A and B were Alternaria solani and Alternaria alternata, respectively. ITS sequences of A and B were amplified with universal primers of ITS1/ITS4, and compared with the GenBank database using BLAST analysis. The results showed that the nucleotide homogeneity between A and A. solani, B and A. alternata was 98% and 100%, respectively. Highly significant differences existed in the sensitivity of two pathogens to four fungicides, fludioxonil, boscalid, pyraclostrobin and difenoconazole, and no difference in the sensitivity to iprodione. Therefore, it confirmed that the pathogens of potato early blight in Hebei were A. solani and A. alternate, and their sensitivity to the same fungicide was different.