番石榴根部短尾短体线虫的鉴定

Identification of Pratylenchus brachyurus from the Root of Guava

从福建省漳州市云霄县的番石榴变黑腐烂的根组织内分离和鉴定了短尾短体线虫（Pratylenchusbrachyurtts）。根据光学显微镜和扫描电镜对该线虫进行形态特征观察及形态测量的结果．其鉴别特征为：唇环2个，唇盘椭圆形；唇片6个，包括2个侧唇片和4个近圆形亚中唇片．侧器孔窄圆形、位于唇盘两侧：口针长15．3～19．9μm，1：3针基部球圆形；单卵巢直伸，受精囊不明显，后阴子宫囊长度略小于阴门处体宽，阴门位于虫体长度的83％～86％；尾宽圆锥形，腹面环纹16～21条。末端光滑、宽圆。对该线虫rDNA—ITS和28SrDNA—D2D3区进行扩增、测序与比对分析，其序列大小分别为730bp和779～780bp，与已登录的短尾短体线虫相应序列的相似度分别为89％．93％和97％。99％．D2D3序列比ITS序列更适于Pbrachyur123分子鉴定。根据对病根组织内线虫的分离和染色观察．证实了短尾短体线虫能侵染番石榴根系并引起根表皮产生褐色斑痕和变黑腐烂等症状．这是首次在中国的番石榴上发现该线虫。

Pratylenchus brachyurus was isolated from the brown necrotic roots of Guava （Psidium guajava）in Xunxiao, Zhangzhou, Fujian Province. By applying light microscope and scanning electronic microscope, the nematode＇s diagnostic characters are as follows： 2 lips annule, labial disc oblong and surrounded by 6 lips including 2 lateral lips and 4 subrounded submedial lips; amphidial apertures narrow oval, closely abutting both sides of lip disc; stylet 15.3-19.9 μm, basal knobs round; ovary straight, spermatheca inconspicuous, post uterine sac slightly shorter than width at vulva, vulva situated at 83% -86% of body length; tail broadly conoid with ventral annules 16-21, tip smooth and broadly rounded. The rDNA-ITS and 28S rDNA-D2D3 of the nematode were amplified and analyzed, the sequences were 730 bp and 779-780 bp respectively and their similarity with the corresponding sequences of P. brachyurus in Genbank were 89%-93% and 97-99% respectively. Using D2D3 was more suitable than using ITS in the molecular identification of P. brachyurus. The results of isolation and staining of the nematodes within the diseased root tissues confirmed that the damaged Guava＇s roots were infected by P. brachyurus inducing black rotten roots and brown lesions on the root cortex. It was the first report in China that P. brachyurus was isolated in the root of Guava.