甘肃定西地区马铃薯线虫病病原的分离鉴定
Identification of the pathogenic nematodes from potatoes in Dingxi of Gansu Province

为明确甘肃省定西市马铃薯线虫病的病原种群分类地位，采用形态学结合分子生物学的方法对该地区马铃薯上的4个线虫群体进行了鉴定，观察和测量其形态特征值，基于rDNA-ITS序列以UPGMA法构建线虫群体的系统发育树，并按照柯赫氏法则进行了致病性测定。结果表明，4个线虫群体在形态学上与马铃薯腐烂茎线虫Ditylenchus destructor一致，但群体DX27与群体DX11、DX16、DX19雌虫的体长、体长/食道长、体长/尾长值存在极显著差异。利用通用引物TW81/AB28扩增rDNA-ITS序列均获得长度为915 bp的片段；序列比对分析表明，群体DX27与其它3个群体相比在ITS1区的第96～255 bp片段内有25个碱基的差异；系统发育树显示，群体DX27与C型群体聚为1支，群体DX11、DX16、DX19与B型群体聚为1支。根据形态学特征及rDNA-ITS序列分析结果确定该病原线虫为马铃薯腐烂茎线虫，其中群体DX27属于C型，群体DX11、DX16、DX19属于B型。
In order to clarify the pathogenic nematodes in Dingxi of Gansu Province, four nematode populations isolated from potatoes were identified based on morphological and molecular methods. The morphological characteristics were observed and measured; UPGMA method was used to draw the phylogenetic tree of nematode populations based on rDNA-ITS sequence, and the pathogenicity was tested according to Koch's rule. The results showed that the morphological features of the four populations were consistent with Ditylenchus destructor, and the body length, total body length/oesophageal length and total body length/tail length of the female were significantly different at P<0.01 level between the population DX27 and other three populations. The amplified products of rDNA-ITS by using the universal primers TW81/AB28 were 915 bp in length. The sequence analysis showed that there were differences of 25 bases between DX27 and other three populations in no. 96-255 bases of ITS1 region. Phylogenetic tree showed that the population DX27 was clustered to the haplotype C, and the populations of DX11, DX16 and DX19 were clustered to the haplotype B. Based on morphological characteristics and rDNA-ITS sequence analysis, the pathogenic nematodes were identified as D. destructor, and the population DX27 belonged to haplotype C and populations of DX11, DX16 and DX19 belonged to haplotype B.