山西省榛属植物居群的SSR遗传多样性研究

利用9对SSR引物对山西省平榛(Corylus heterophylla Fisch)和毛榛(C.mandshurica Maxim.et Rupr.)野生居群、欧榛(C.avellana L.)和平欧杂种榛(C.heterophylla Fisch.×C.avellana L.)的人工栽培居群,共205个样本进行PCR扩增,共扩增出172个等位基因。每个位点的等位基因数为5~18个,平均等位基因数为12.5个。居群观测杂合度(Ho)和预期杂合度(He)的变化范围分别为0.395~0.665和0.778~0.906,表明榛属植物遗传多样性较高,其中平欧杂种榛的遗传多样性最高(He=0.867,I=2.271),毛榛遗传多样性最低(He=0.825,I=2.006)。不同物种居群间遗传分化系数FST=0.106,平均基因流Nm=2.609,表明居群间的遗传分化水平较低。各居群在大多数位点上偏离Hardy-Weinberg平衡,主要原因是人工选择或近交所致。分子方差分析(AMOVA)表明,遗传变异主要发生在物种居群内。NJ聚类结果显示毛榛和平榛多数个体聚在各自居群内,平欧杂种榛和欧榛个体交互混合组成一小支后再与平榛聚在一起,表明平欧杂种榛与欧榛、平榛的亲缘关系较近,而毛榛与其它3种榛属植物的亲缘关系较远。本研究还分析讨论了山西省榛属植物居群具有较高遗传多样性的原因,并提出了野生榛子的保护利用策略。

Genetic Diversity of Hazel Populations in Shanxi Province Based on SSR Markers

Hazel,an endemic tree widely distributed in northern China,has great value for hazel breeding and natural forest ecosystems. The genetic diversity of the natural distribution species Corylus heterophylla Fisch, Corylus mandshurica Maxim. et Rupr. and cultivated species Corylus avellana L. and Corylus heterophylla Fisch.× Corylus avellana L. were investigated using nine SSR primer pairs,with a total of 172 alleles scored in 205 samples and the number of alleles per locus ranging from 5 to 18 （average 12.5）. Observed heterozygosity （Ho） and expected heterozygosity （He） ranged from 0.395-0.665 and 0.778-0.906,respectively,indicating that the genetic diversity of hazel was high,with C. heterophylla Fisch.× C. avellana L. the highest （He=0.867,I=2.271） and C. mandshurica Maxim. et Rupr. the lowest （He=0.825,I=2.006）. The different populations had lower genetic differentiation （FST=0.106）,strong gene flow （Nm=2.609）,and the most locus deviation from the Hardy-Weinberg equilibrium,mainly caused by artificial selection or inbreeding. The AMOVA analysis revealed low genetic differentiation among populations. NJ clustering results showed that the majority units congregated in their own population group,C. heterophylla Fisch.× C. avellana L. and C. avellana L. were mixed together,and then clustered with C. heterophylla Fisch,indicating that the genetic relationship between C. heterophylla Fisch.× C. avellana L. and C. avellana L. and C. heterophylla Fisch was close,but distant with C. mandshurica Maxim. et Rupr. Based on these results,the possible formation of genetic diversity and low genetic differentiation were discussed,and further strategies and suggestions for utilization and conservation of these resources proposed.