三种稻飞虱体内类酵母共生菌18S rDNA和 ITS 5.8S rDNA序列克隆及进化分析

为研究水稻3种主要害虫灰飞虱Laodelphax striatellus、 褐飞虱Nilaparvata lugens和白背飞虱Sogatella furcifera体内类酵母共生菌（yeast-like symbiotes, YLS）的种属地位及与寄主的进化关系， 测定了其体内YLS的18S rDNA及ITS-5.8S rDNA的全长序列。基于3种稻飞虱体内YLS的18S rDNA序列比对表明， 褐飞虱YLS和白背飞虱YLS的一致性比其与灰飞虱YLS的高（褐飞虱YLS和白背飞虱YLS为98.91%， 灰飞虱YLS和褐飞虱YLS为95.74%， 灰飞虱YLS和白背飞虱YLS为96.02%）， 而基于ITS-5.8S rDNA序列比对， 灰飞虱YLS和白背飞虱YLS的一致性比其与褐飞虱YLS的要高（白背飞虱YLS和灰飞虱YLS为99.57%， 灰飞虱YLS和褐飞虱YLS为91.91%， 白背飞虱YLS和褐飞虱YLS为90.46%）。基于真菌18S rDNA和ITS-5.8S rDNA的系统发育树均表明， 3种稻飞虱体内YLS与其他已知真菌进化关系较远。本研究证实了昆虫真菌类共生菌与寄主形成了长期的进化关系， 从而形成了不同于已知真菌的分类地位。

Phylogenetic position of yeast-like symbiotes from three rice planthoppers(Homoptera:Delphacidae) based on 18S rDNA and ITS-5.8S rDNA sequences

In order to study the species status of yeast-like symbiotes(YLS) from three rice planthoppers(Laodelphax striatellus,Nilaparvata lugens and Sogatella furcifera) and the evolutionary relationship of YLS with insect hosts,the complete sequences of 18S rDNA and ITS-5.8S rDNA of YLS from the three planthoppers were determined.Sequence identity comparison of YLS from rice planthoppers was conducted based on 18S rDNA and ITS-5.8S rDNA sequences.The results showed that YLS of N.lugens has a higher identity to that of S.furcifera(98.91%) than to that of L.striatellus(95.74%) according to 18S rDNA sequences,but YLS of L.striatellus has a higher identity to that of S.furcifera(99.57%) than that to N.lugens(91.91%) according to the ITS-5.8S rDNA sequences.Phylogenetic analysis based on both 18S rDNA and ITS-5.8S rDNA showed that YLS from three rice planthoppers has no obvious identity to other known fungi.The results suggest that insect YLS have a close evolutionary relationship with hosts and form a taxonomic group different from other fungi.