Abstract:

In order to further understand the genetic diversity and variation of F₁ population in intra-specific and inter-specific hybrids of chestnut,and the influence of genetic effects and configuration of different parents on F₁ generation,the genome DNA of 235 F₁ hybrids and their parents were amplified by PCR and analyzed by capillary electrophoresis with 32 pairs of SSR markers,and then the genetic parameters,molecular variance,UPGMA clustering and PCA analysis for the statistical data were performed. Two hundred and seventy-eight polymorphic loci were amplified by 32 pairs of primers in the 235 progenies;and the average number of alleles was 8.69;the average value of Shannon’s diversity index (I),genetic diversity index(H_s)and gene flow(N_m)were 1.3707,0.6574 and 1.5951,respectively;the genetic differentiation coefficient(F_st)showed that 85.18% of the variation of F₁ generation existed in the cross combination. Shannon’s diversity index of different combinations ranged from 0.8816 to 1.1317,indicating that there were abundant genetic diversity in their offspring,and the genetic diversity level of those offspring were affected by the genetic effect of different parents and the configuration of parents. The results of molecular variance analysis showed that the genetic variation of F₁ hybrid population mainly came from the combination(78.06%),which was consistent with the result of genetic differentiation coefficient. The genetic distance and UPGMA clustering of different hybrid combinations showed that C3 and C5,which had the same parents,had the closest genetic distance and got together first,followed by the combination with the same female parent or the same male parent,got together respectively. The PCA scatter plot of hybrid progenies further verified the result of cluster analysis of hybrid combination. Most progenies of the same hybrid combination or the combinations with relatively close genetic distance could gather together. At the same time,there was cross overlap phenomenon in different combinations,which indicated that there was more extensive gene exchange among them,and the phenomenon of offspring separation was obvious.

Key words: Castanea mollissima, C. henryi, hybrid, SSR marker, genetic diversity