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目的研究菟丝子rDNA-ITS序列特征。方法分别采用PCR产物直接测序法和克隆测序法,对菟丝子属7个种rDNA的ITS区(包括ITS-1,5.8S rDNA和ITS-2)进行序列测定。结果菟丝子属植物ITS序列总长度约为612 bp,GC含量分别为:ITS-1区53%~63%,5.8S rDNA 48%~55%,ITS-2区46%~56%;苜蓿菟丝子种内的3个地理种发现了3个变异位点。用NJ法构建系统发育树显示:含日本菟丝子Cuscuta.japonica的分支处于系统树靠近基部位置,与之亲缘关系较近的依次为中国菟丝子C.chinensis和杯花菟丝子C.cupulata;余下5个种的分支中田野菟丝子C.campestris和五角菟丝子C.pentagona合为一支,南方菟丝子C.australis和苜蓿菟丝子C.approximata合为一支。结论NJ法建立的发育树与形态学分类基本相符,为菟丝子属植物分类鉴定提供了重要的分子依据。
Objective To study the characteristics of rDNA-ITS sequence of Cuscuta chinensis. Methods The ITS regions (including ITS-1, 5.8S rDNA and ITS-2) of seven kinds of rDNA from Cuscuta genus were sequenced by direct sequencing of PCR products and cloning and sequencing. Results The total length of the ITS sequences of the genus Cuscuta was about 612 bp. The GC content was 53%-63% in the ITS-1 region, 48%-55% in the 5.8S rDNA region, and 46%-56% in the ITS-2 region. The three geographical species within the site found three mutation sites. The phylogenetic tree constructed by NJ method showed that the branch containing Cuscuta.japonica of Cuscuta chinensis was located near the base of the phylogenetic tree, and the closest relatives were C.chinensis and C. cupulata, and the remaining 5 species. The branches of C. campestris and C. pentagona were combined into one, and C. austalis and C. approximata were combined into one. Conclusion The development tree established by NJ method is basically consistent with the morphological classification, which provides an important molecular basis for the classification and identification of Cuscuta species.