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 (F_ST＝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.