榆中县黄瓜根结线虫鉴定及根系定殖效果测定

为了明确甘肃榆中县温室大棚黄瓜根结线虫种类及根际定殖情况，采用形态和分子生物学鉴定其种类，并室内测定和显微观察其在根际定殖效果。结果表明，甘肃榆中县黄瓜根结线虫不同虫态形态、大小和雌虫会阴花纹特征等均具有典型南方根结线虫(Meloidogyne incognita)形态特征。基于线粒体COI基因序列比对和构建系统发育树，鉴定发现榆中县黄瓜根结线虫线粒体COI基因序列与已报道的南方根结线虫台湾株系(KU517167)聚为一类，其相似性为99.75%;根结线虫多序列特异位点鉴定发现其与南方根结线虫孟加拉国株系(MN196556)和南方根结线虫印度株系(MN728697)聚为一类，相似性分别为100%和96.91%。经致病性测定发现，待接种根结线虫2龄幼虫30 d后其能够侵染黄瓜根系并形成大量根结，经染色发现黄瓜幼苗根系组织内寄生大量线形蠕虫、雌虫和卵囊，且镜检观察发现其形态与田间采集后分离的线虫形态一致。综上可知，引起甘肃省榆中县黄瓜根结线虫病的病原为南方根结线虫。

Identification of Cucumber Root-knot Nematodes in Yuzhong County and Determination of Its Root Colonization

In order to clarify the species of cucumber root-knot nematode in the greenhouses of Yuzhong county in Gansu province, the species was identified by morphology and molecular biology, and its colonization efficiency in rhizosphere was determined and observed by microscope. The results showed that the cucumber root knot nematodes in Yuzhong county of Gansu had the typical morphological characteristics of Meloidogyne incognita according to the nematodes morphology, size and female perineal pattern. The sequence of mitochondrial COI gene of cucumber root-knot nematode from Yuzhong county was identified as one group with Taiwan strain of M.incognita (KU517167), and the similarity was 99.75% according to the alignment of mitochondrial COI gene sequence and phylogenetic tree construction. The multiple pair of specific sites sequence was clustered with the sequence of Bangladesh strain of M.incognita (MN196556) and Indian strain of M.incognita (MN728697), and the similarity was 100% and 96.91%, respectively. The pathogenicity test found that the cucumbers root was infected and formed a large number of root knots at 30 days after inoculation with the juveniles at the second stages of cucumber root-knot nematodes. A large number of linear worms, females and egg masses were parasitized on the tissues of roots after staining. Microscopic observation showed that the morphology of re-isolated nematodes was consistent with the nematodes that collected from the field. Thus, the cucumber root-knot nematodes in Yuzhong county of Gansu province was identified as M.incognita according to the morphological and molecular characteristics.