摘要
藜科植物Grayia spinosa是美国西部地区的特有种,多生长在干旱盐碱地,具有重要的生态价值。该研究测定了采自美国西部犹他州G.spinosa的nrDNA ITS序列,与Gen Bank中已提交的G.spinosa的所有ITS序列以及G.spinosa的四个近缘种作为外类群进行比较,分析了美国西部不同地区G.spinosa ITS序列的一级结构与其RNA二级结构的变异规律。结果表明:所有G.spinosa样品的nrDNA ITS序列长度在611~623 bp之间,GC含量在60.35%~61.0%之间,序列间共存在22个变异位点,5个为简约信息位点。各样品间的遗传距离在0.001 8~0.008 9之间,不同样品间的遗传距离与地理距离的相关性不显著。邻接法构建的系统发育树显示所有G.spinosa聚为一大支,与外类群形成明显分支。此外,利用RNAfold在线软件预测了G.spinosa ITS序列的RNA二级结构,将8个G.spinosa样品的RNA二级结构根据构型差异大体上分为四类,分别记为type A,B,C和D四类,主要变异出现在ITS1和ITS2区。所不同的是在G.spinosa ITS的一级结构分析中GSNE1与GSWA8体现出更近的亲缘关系,但二者的RNA二级结构差异明显,同时GSNE2、GSUT3、GSUT4、GSCA5、GSCA6、GSCO7在ITS序列一级结构分析中也体现出较近的亲缘关系,但是他们的RNA二级结构差异明显。这可能与ITS序列的RNA二级结构在进化中体现出更大的保守性有关。
Grayia spinosa,a species endemic to the Western United States,is mainly distributed in arid and saline areas and has important ecological value. ITS sequence of G. spinosa collected from Utah State of the United States was sequenced,and aligned with other sequences from Gen Bank of this species by Blast. The relationship among G. spinosa from the West United States were analyzed based on ITS sequences and four related species of Grayia were selected as outgroup. ITS sequence variation of G. spinosa and its RNA secondary structure was analyzed in different regions of the United States. The results showed that the length of ITS sequences ranged from 611 bp to 623 bp and the GC contents was 60.35%-61.0%. There were 22 variants sites and five parsimony informative sites in the ITS sequences of G. spinosa from different regions in the United States. Genetic distance ranged from 0.001 8 to 0.008 9 between samples,the correlation was not significant between genetic distances and geographical distances of different samples. The phylogenetic tree constructed by Neighbor-joining method indicated that all samples of G. spinosa were clustered together,forming a distinct branch with the outer group. In addition,the RNA secondary structure of G. spinosa ITS sequence was predicted by RNA fold online software. The RNA secondary structure of G. spinosa samples were roughly divided into four types according to the configuration differences,which were named type A,B,C and D. Unlike the primary structure analysis of G. spinosa ITS sequences,RNA secondary structure did not reflect the more related phylogenetic relationships between GSNE1 and GSWA8. GSUT3,GSUT4,GSCA5,GSCA6 and GSCO7 indicated closer phylogenetic relationships in the primary structure analysis of ITS sequences,but their RNA secondary structures were significantly different,which was related to the higher conservation of RNA secondary structure.
作者
成彩霞
苏雪
高婷
周璇
CHENG Caixia;SU Xue;GAO Ting;ZHOU Xuan(College of Life Sciences,Northwest Normal University,Lanzhou 730070,Chin)
出处
《广西植物》
CAS
CSCD
北大核心
2018年第5期617-625,共9页
Guihaia
基金
国家自然科学基金(31260054)~~
