中国新疆野苹果(Malus sieversii(Ldb.)Roem.)种群地理分布格局及其遗传关系研究

Geographic distribution pattern and genetic relationship of Malus sieversii(Ldb.) Roem.in China

利用SSR(简单重复序列)标记技术,对新疆野苹果的5个主要地理居群(128份材料)进行了种内亲缘关系分析。结果表明:(1)5个居群中巩留居群遗传多样性最丰富;(2)群体的AMO-VA分子方差分析得出野苹果居群遗传多样性有92%来自于居群内,8%来自于居群间,说明遗传多样性主要分布在居群内;(3)5个居群遗传距离与基因流呈极显著负相关,与地理距离呈显著正相关,说明野苹果地理分布格局是决定其遗传关系的主要因素;(4)5个居群间的基因流结果推断野苹果种群在历史上曾发生过迁移,根据种群遗传关系以及地理分布格局推断野苹果在冰期后迁移方向从中亚平原由西向东,由南向北迁移,从而形成现代的地理分布。

Malus sieversii(Ldb.)Roem.in Xinjiang is the source of apple cultivars in China and it has important significance for selection and improvement of cultivars.But recently the distribution area decreased gradually.In order to protect the resources we used 16 microsatellite markers to analyze intraspecific relationship for 128 samples of 5 populations of Malus sieversii(Ldb.)Roem.We used PopGene 1.32 and GenAlEx6 softwares to get genetic parameters and NTSYSpc software to do cluster analysis and principal component analysis.The results show 9 high reproducibility and specificity SSR primer pairs get 41 observed number of alleles(Na) and the average number of alleles is 4.555 6,the average effective number of alleles(Ne) is 2.723 4,the Ne/Na is 61.61%;Shannon's Information Indexes(I) are between 0.151 3(CH01F09) and 1.551 9(CH02B03b),and the average is 1.019 1;Nei's gene diversity(He) indexes are between 0.067 3(CH01F09) and 0.762 5(CH02B03b),and the average is 0.543 8.Shannon's Information Indexes(I) of 5 populations are between 0.903 8 and 1.043 9,and the average is 0.965 0;Nei's gene diversity(He) indexes of 5 populations are between 0.501 1 and 0.554 3,and the average is 0.531 5.Based on their above two exponents,5 populations' magnitudes were ordered as follows: Gongliu's>Xinyuan's >Huocheng's > Emin's > Tuoli's,meaning that Gongliu's population has the highest genetic diversity.So we speculated Gongliu's population is a morden diversity center of Malus sieversii.The gene differentiation coefficient of the total population is 0.029,Nm is 8.482,it means there are some genetic differentiation and gene flows.The analysis of its molecular variance(AMOVA) shows that in the total genetic diversity,the percentage of genetic diversity among the populations is 8% and that within populations is 92%.The genetic diversity distributes within one population.Mantel test shows that there is a negative correlation between gene flow and genetic distance(r=-0.882(P<0.001)),and there is a positive correlation between genetic distances and geographic distance(r=0.642(P<0.05)).It shows that geographical distribution pattern of Malus sieversii is the main factor to determine the genetic relationship.Combined with the population genetic relation and geographical distribution pattern,we infer that after glacial period Malus sieversii was migrated from the west to the east and from the south to the north alone the following three ways;Gongliu and Xinyuan;Daxigou and Guozigou;Tuoli and Emin.Due to the natural genetic isolation formed by the Tianshan Mountains and the glaciers,there were some genetic divergences between the populations of Malus sieversii.However this conclusion needs to be proved further.Xinyuan population is closed to Tuoli and Emin populations in respect of genetic relationship because their longitude geographic distances are closed.Some issues have need of more careful study in the future.