荔枝nrDNA ITS序列多态性分析

Polymorphism in the nrDNA ITS of Litchi chinesis

为了解荔枝nrDNA ITS序列多态性,对荔枝4个品种的nrDNA ITS序列进行克隆测序,分析其序列特征、核苷酸多态性、遗传距离、5.8S保守基序、二级结构最小自由能、系统发育树及rRNA二级结构等。结果表明,荔枝nrDNA ITS序列在品种间、品种内均存在多态性,同时包含假基因序列,表明其ITS序列逃离了致同进化。分子方差分析(AMOVA)显示,荔枝nrDNA ITS序列遗传变异主要来源于品种内。自然杂交可能是荔枝ITS序列产生多态性的主要原因。

In order to realize the polymorphism in the nrDNA ITS of Litchi chinesis,the nrDNA ITS se‑quences of four litchi varieties were cloned and sequenced to analyze the sequence characteristics,nucle‑otide polymorphism,genetic distance,5.8S conservative motif,minimum free energy of secondary struc‑ture,phylogenetic tree and secondary structure of rRNA.The results showed that there was diversity of nrDNA ITS sequences between or within litchi varieties,and pseudogenes exist in the nrDNA ITS cop‑ies,suggesting an incomplete concerted evolution of ITS region.Analysis of molecular variance(AMO‑VA)showed that the genetic variation of nrDNA ITS sequence in Litchi chinesis mainly occurred within the varieties.Natural hybridization may be the main cause of ITS polymorphism in Litchi chinesis.