Phenotypic And Genetic Analysis Of Ornamental Traits In Hybrids Of Lagerstroemia Indica And L.speciosa

Lagerstroemia,a member of Lythraceae family,is widely used in landscape as a flowering shrub,due to its long-lasting summer bloom and rich color.A combination of L.indica and L speciosa would appear to have great potential for increasing flower size and improving pest resistance together with cold hardiness in crape mytles.The variations for traits and fertility were studied in five crosses between L.speciosa and L.indica ’Dynamite’,’Sacramento’ and ’Purple Velvet’.Some SSR markers correlated with phenotypic traits were also obtained in this study.The main results were as follows.(1)Quantitative traits showed marked variations in hybrid progenies,the coefficient of variation was 9.06%-57.60%.The coefficient of variations in plant height,plant width,panicle length and panicle width were higher than in leaf length,leaf width,flowet diameter,claw length.The traits in progenies showed a continuous distribution,fitted well with normal distribution curve.The PCA results of populations were similar,the first and second components were panicle factor and leaf factor,the third and fourth factor were flower factor.Most traits in F1 generation were below the parents mean value,and showed a hybrid weakness.Correlation analysis showed a significant positive correlation existed between characters,such as plant height,plant width,branch length,branch width,panicle length,panicle width,and flower number,while a significant negative correlation exsited between GSA of primary branch,GSA of secondary branch,plant height and plantwidth.(2)The progenies of L.speciosa and L.indica were found to be highly sterile,with abnormal developed anthers and no open-pollinated seed pods,with exceptions of PD-22,PD-57,PD-69.The pollen germination rate of parents were all above 70%,while 0%in sterile progenies and 24.00%-55.28%in fertile progenies.The stigma receptivity of parents were higher than progenies.Eleven quantative traits in sterile progenies were all intermediate between the parents,and had only purple flowers(Red Purple N80B),while the fertile progenies showed smaller leaves and panicles than ’Purple Velvet’ and a different color(Red Purple 64C).According to phenotypic data,the parents L.indica,L.speciosa,fertile progenies and sterile progenies were clustered into 4 groups,which indicated a significant variation between the fertile and sterile progenies.(3)Initial testing of 450 primer pairs were conducted in L speciosaxL.indica ’Sacramento’(DS)population,which resulted in 19 polymorphic loci.Of these,9 SSR markers were found to be significant correlated with plant height,leaf size,flower size,panicle size and some other traits.These loci explained a small proportion of the phenotypic variance,ranging from3.46%-16.02%.Phenotypic variation and genetic laws of ornamental traits in hybrids of L.speciosaand L.Indica were discussed in this study.The results in this study and the SSR markers developed would provide more experiences for marker-assisted selection in Lagerstroemia.