The Genetic Analysis Of Offsprings From Various Mating Types And Inbreding Depression In Liriodendron

Outcrossing species is prone to inbreeding depression. Liriodendron is endangered species and the existing population size is small, the ability to reproduce of natural populations of Liriodendron may be affected by inbreeding depression, it is significant to understand endangered mechanism ,hybrid breeding, management of seed orchard of Liriodendron which developed genetic studies of inbred offspring.In this paper, plumpness and germination rate of seed,seedling growth ,the genetic diversity, percentage of homozygous loci of different mating types in Liriodendron were studied and compared which is to analysis the extent of recession of Inbred offspring , the main results were as follows:Significant variations of plumpness and germination rate of seeds existed among different female parents, mating types, mating combinations within types. Plumpness and germination rate of seeds are all maximum in intra-species progenies , Plumpness of seeds exceeded plumpness of inter- species progenies,backcross progenies,self-cross progenies 33.30%,89.02%,612%. Emergence of seeds exceeded plumpness of inter- species progenies,backcross progenies,self-cross progenies 90.56%,119%,362%. Variation trend of plumpness and emergence is consistent: intra-species progenies> inter- species progenies > backcross progenies >self-cross progenies.In height and GLD traits, significant variations of growth at seedling stage existed among mating types, mating combinations within types, the two traits are all maximum in inter-species progenies , GLD exceeded GLD of self-cross progenies,backcross progenies, intra- species progenies 7.98%,19.73%,91.30%. height exceeded height of self-cross progenies ,backcross progenies, intra- species progenies 9.59%,36.70%,47.45%. Variation trend of height and GLD traits is consistent: inter- species progenies > self-cross progenies > backcross progenies > intra-species progenies.The progenies of 27 mating combinations in Liriodendron were analyzed by using 12 polymorphic primers. Observed heterozygosity and shannon index are all maximum in inter- species progenies,Observed heterozygosity exceeded Observed heterozygosity of backcross progenies, intra-species progenies ,self-cross progenies 17.99%,27.75%,269%; shannon index exceeded shannon index of backcross progenies, intra-species progenies ,self-cross progenies 5.22%,13.34%,19.77%, Variation trend of genetic diversity: inter- species progenies > backcross progenies > intra-species progenies >self-cross progenies.Percentage of homozygous loci is maximum in self-cross progenies ,it exceeded percentage of homozygous loci of intra-species progenies,backcross progenies,inter- species progenies 104%,137%,273%,Variation trend of percentage of homozygous loci : self-cross progenies > intra-species progenies >backcross progenies >inter- species progenies. Gene heterozygosity of Liriodendron and Liriodendron tulipifera parents is respectively 42.72%,47.62%.To conclude,the plumpness and germination rate of seeds,genetic diversity,percentage of homozygous loci are all lower than intra-species and inter- species progenies in varying degrees, but recession of seedling growth is not significant.