新疆野苹果叶绿体DNA变异与遗传进化分析

Chloroplast DNA Variation and Genetic Evolution of Malus sieversii(Ledeb.)M.Roem.

利用4对叶绿体DNA引物对来源于新疆巩留、霍城和新源3个地区的242份新疆野苹果种质资源的4个非编码区trnH-psbA、trnS-trnG spacer+intron、trnT-5′trnL和5′trnL-trnF进行了扩增,基于4个叶绿体基因间区的序列变异,从母系遗传的角度评价了遗传变异和不同居群的遗传进化关系。结果表明:4个叶绿体DNA非编码区经测序、拼接、比对和合并之后的片段长度为3812 bp,共有171个多态性变异位点,其中包含6个单一突变位点、16个简约信息位点和149个插入-缺失位点。在242份新疆野苹果种质中,trnH-psbA、trnS-trnG spacer+intron、trnT-5′trnL和5′trnL-trnF区域的变异位点的数量分别为68个、25个、77个和1个,单倍型数量分别为36个、6个、6个和2个,合并之后的叶绿体DNA片段的单倍型为52个。核苷酸多样性和单倍型多样性最高的区域均为trnH-psbA(Hd=0.773,Pi=0.01982),最低的为5′trnL-trnF(Hd=0.025,Pi=0.00002)。242份新疆野苹果种质4个叶绿体DNA区域合并后的遗传多样性较高(Hd=0.806,Pi=0.00291)。Tajima′s D检验中,4个cpDNA区域合并后片段在P<0.05水平上显著,4个cpDNA区域整体不遵循中性进化模型,自然选择的压力是新疆野苹果遗传进化的主要动力。新疆野苹果的遗传变异主要存在于居群内部,新疆巩留和新源居群间的遗传距离较近,与霍城居群间遗传距离相对较远,居群间的遗传分化与地理距离相关。3个地区的新疆野苹果各自经历着遗传分化但又存在频繁的基因交流,有向新疆新源的新疆野苹果演化的趋势。

Four non-coding region,trnH-psbA、trnS-trnG spacer+intron、trnT-5′trnL and 5′trnL-trnF of 242 germplasm accessions of Malus sieversii(Ledeb.)M.Roem.from 3 sources of Gongliu,Huocheng and Xinyuan of Xinjiang Uygur Autonomous Region of China were amplified by four primers.Based on the genetic variation of the four chloroplast intergenic regions,the genetic variation and evolution of Malus sieversii(Ledeb.)M.Roem.populations were explored from the perspective of maternal inheritance.The results showed that the length of the four non-coding regions of chloroplast DNA was 3812 bp after sequencing,splicing,alignment and merging,and 171 variable sites were detected,including 6 singleton variable sites,16 parsimony informative sites and 149 insertion-deletion gaps.Among the 242 accessions of Malus sieversii(Ledeb.)M.Roem.the number of variable sites of the regions trnH-psbA,trnS-trnG spacer+intron,trnT-5′trnL and 5′trnL-trnF were 68,25,77 and 1.The number of haplotypes for the four regions were 36,6,6 and 2,and after the four regions merged the haplotypes of chloroplast DNA fragments were 52.The region with the highest nucleotide and haplotype diversity was trnH-psbA(Hd=0.773,Pi=0.01982),and the nucleotide and haplotype diversity of 5′trnL-trnF was the lowest(Hd=0.025,Pi=0.00002).The cpDNA diversity of Malus sieversii(Ledeb.)M.Roem.with the four chloroplast DNA regions merged was high(Hd=0.806,Pi=0.00291).Tajima′s test showed that all the Tajima′s D values are statistically significant at P<0.05,indicating that the overall variation of the four chloroplast regions had not followed the neutral theory of molecular evolution,and the pressure of natural selection is the main driving force of genetic evolution of Malus sieversii(Ledeb.)M.Roem.The genetic variation of Malus sieversii(Ledeb.)M.Roem.mainly existed within populations.The distance between populations from Gongliu and Xinyuan of Xinjiang was closer than that between populations from Huocheng and Gongliu or from Huocheng and Xinyuan of Xinjiang.The genetic differentiation correlated with the geographical distances.Malus sieversii(Ledeb.)M.Roem.from the 3 sources were experiencing genetic differentiation,but also having frequent gene exchanges among different populations,and had a tendency to evolve to Xinyuan population in Xinjiang.