Abstract:

In this paper, the genetic effects on the reproductive fitness of Liriodendron were analyzed based on a 8×8 complete-diallel crossing, in which 4 adult L. chinense and 4 adult L.tulipifera were randomly chosen as mating parents. The seed germination ratio for each mating combination was used as an index to evaluate male/female reproductive fitness for its corresponding mating parents. The genetic effects on reproductive fitness, in terms of maternal effect, paternal effect, their interaction effect, general combining ability and specific combining ability, were further dissected. Meanwhile, in order to explore the relationship between the genetic distances (GD) of mating parents and their cross-compatibilities, 11 SSR loci were amplified in 8 mating parents to estimate GD for each parent pair. The results are as follows: the reproductive fitness of Liriodendron was mostly dominated by mother tree, whereas the paternal effect could be ignored. There existed a reasonable difference in the combining ability of reproductive fitness among 8 parents, with more for female reproduction than for male reproduction. The special combining ability of reproductive fitness in intraspecies mating was much bigger than that of interspecific crossing. Although the relationship between parent pair's GD and their cross-compatibility was not significant,there was a trend that the cross-compatibility increased as parent pair's GD augmented in intraspecific mating; while a reverse trend appeared in interspecific mating. These results above would provide valuable knowledge for parent pair selection in hybrid seed orchard and the utilization of heterosis in Liriodendron.

Key words: Liriodendron, reproductive fitness, genetic effect, genetic distance, cross-compatibility