Studies On The Heterosis Of Liriodendron By SSR Markers

It has been proved that an obvious heterosis occurred in interspecific hybrid of Liriodendron, while its genetic basis has not been clear yet. In this paper, the relationship between heterozygosity of hybrids, the genetic distance among mating parents and the heterosis was analyzed by SSR markers based on the evaluation on the genetic variation of seedling growth and the heterosis of 12 interspecific hybrid combinations, and their parental half-sibs. The main results are as follows:According to the analysis of variance, significant variations of growth was found among both combinations and individuals within combination. Relatively large difference of heterosis among hybrid combinations was found by comparing the seedling growth of hybrids and their parental half-sibs. Not all the hybrids showed heterosis, there were 9 hybrid combinations showed positive heterosis and 3 hybrid combinations showed negative heterosis.Based on the analysis of the genetic distance among parents and the heterozygosity of their F₁ populations, relatively large genetic variations among parents was found, the average genetic distance was 0.529, with variation range of 0.539～0.839. The expected heterozygosity and the observed heterozygosity of all 12 hybrid combinations were relatively large, the range of the expected heterozygosity is 0.415～0.56 ,and the observed heterozygosity is 0.539～0.839.According to results of correlation analysis between the genetic distances among mating parents and the F₁ heterosis, and between the F₁ heterozygosity and the F₁ heterosis, significant correlations were not found, indicating that parental genetic distance and F₁ heterozygosity probably were not the main causes of heterosis in Liriodendron.