关键词：
矩镰荚苜蓿;ITS2序列;二级结构;分子鉴定
摘 要：
为准确鉴定矩镰荚苜蓿(Medicago archiducis-nicolai)及其近缘种花苜蓿(M.ruthenica)、阔荚苜蓿(M.platycarpos)和毛荚苜蓿(M.edgeworthii),利用DNA条形码技术对4个物种的ITS2序列进行注释、比对、检验,计算种内种间遗传距离,邻接法(neighbor-joining,NJ)构建系统发育树,通过RNAfold web server预测4个近缘种的ITS2二级结构.结果显示,矩镰荚苜蓿及其近缘种的ITS2序列长度为220~221 bp,稳定性好;种间遗传距离(0.004 55~0.022 73)明显大于种内遗传距离(均为0),存在明显的"Barcoding Gap"区域;NJ系统发育树显示,毛荚苜蓿聚为一支,矩镰荚苜蓿、花苜蓿和阔荚苜蓿聚为另一支,然后矩镰荚苜蓿与阔荚苜蓿又各自形成单系;在二级结构中,矩镰荚苜蓿与阔荚苜蓿、毛荚苜蓿存在明显差异,但与花苜蓿极为相似,难以区分.分析表明:除花苜蓿外,以ITS2序列作为条形码并辅以二级结构,可以达到对矩镰荚苜蓿、阔荚苜蓿和毛荚苜蓿准确、快速鉴定的目的.
译 名：
Molecular Identification of Medicago archiducis-nicolai and Its Related Species Based on ITS2 Sequence and Its Secondary Structure
关键词：
Medicago archiducis-nicolai%ITS2 sequence%Secondary structure%Molecular identifica-tion
摘 要：
In order to accurately identify Medicago archiducis-nicolai and its relative species,M.ru-thenica,M.platycarpos and M.edgeworthii,the ITS2 sequences of four species were annotated,com-pared and examined by DNA barcoding,and the genetic distances of intra-and inter-species were calcu-lated,the neighbor-joining phylogenetic tree was constructed,the ITS2 secondary structures of four re-lated species were predicted by RNA fold web server.The results showed that the length of ITS2 se-quence of four species was between 220-221 bp and showed good stability.The genetic distance of inter-species(0.004 55-0.022 73)was significantly larger than that of the intra-species(0),and there was an obvious barcoding gap region.The NJ phylogenetic tree showed that M.edgeworthii clustered into one branch,and Medicago archiducis-nicolai,M.ruthenica and M.platycarpos clus-tered into another branch,then Medicago archiducis-nicolai and M.platycarpos formed monophylet-ic,respectively.The ITS2 secondary structure of Medicago archiducis-nicolai was obviously different from that of M.platycarpos and M.edgeworthii,but it was very similar to that of M.ruthenica,and difficult to distinguish.The analysis showed that ITS2 sequence as a barcode and supplemented with secondary structure can be accurately and rapidly used for the identification of M.archiducis-nicolai,M.platycarpos and M.edgeworthii exception for M.ruthenica.
