Development Of Microsatellite Markers Of Lagerstroemia And Molecular Markers Of Dwarf Trait

Crape mytle (Lagerstroemia indica L.) is a member of the Lythraceae family, and has been cultivated as an important woody plant in summer, due to their long-lasting mid summer bloom and rich color. Dwarf cultivars with small leaves and shorter internodes have been bred using the traditional cross-breeding. However, there is a lack of in-depth study of the inheritence of dwarf traits for Lagerstroemia. In this study, microsatellite markers developed with biotin-streptavidin capture method were used in analyzing the genetic diversity of the crape myrtle germplasm resources. And also we initially explored the inheritence of dwarf traits using F1segeregation population. The conclusions are as followed:(1) Using SSR-enriched libraries, one hundred and fifty-five positive clones were successful-ly sequenced, among which64clones contained microsatellites (SSRs). These fragments contain74SSRs and54sequences with long enough sequences (>20bp) on the upper and lower side of the repeats were suitable for primer designing. Of these, twenty pairs of primers were successfully amplified and eleven (55%) of them were found to be polymorphic by testing in ten Lgerstroemia cltivars. All loci could cross-amplify in related species.(2) Using41SSR markers to genotype43L. indica cultivars and five other species of Lagerstroemia, the results showed that317alleles were generated with a mean of7.7317alleles per locus. The mean polymorphism information content (PIC) value was0.5881with a range from0.8507to0.209. The Shannon index was0.5061(SSR21)-2.2835(SSR3) and the mean value was1.3525. The Nei’s index varied from0.2159(SSR21) to0.8687(SSR3). The observed heterozygosity ranged from0.0851(SSR21) to0.7917(SSR3) and expected heterozygosity ranged from0.2183 (SSR21) to0.8798(SSR6) with an average of0.5492. The mean F-statistics (FIs,, FIT and FST) were0.1548,0.2041, and0.0583, respectively, indicating a low level genetic variation among groups.Genetic distance among48materials ranged from0.1585to0.9125with an average of0.5972. Clustering analysis based on genetic distance divided the48genotypes into four distinct groups which contained some subpopulations. The results corresponded with their genetic backgrounds and geographic regions. Ten core primers were futher selected from41polymorphic primer pairs and able to identify the35cultivars obviously. And with the SSR data,35figerprint pattern maps of varities were drawn and a database of digital fingerprints was built.(3) F1population was derived from interspeicific cross between Lagerstroemia fauriei (female parent) and Lagerstroemia indica’pocomoke’(male parent). The plant type was divided into dwarf and normal types according to the plant height. Genetic analysis and chi-square test showed that dwarf type in Lagerstroemia likely controlled by an complete dominance major gene as well as polygene. The gene bulk of dwarf and normal plant type in F1population was constructed by using bulked segregant analysis (BSA) method.28AFLP primers and41SSR primers were used to screen dwarf habit related molecular markers. A AFLP marker M53E39-92linked to dwarf gene were screened, the validity of this AFLP maker was verified by replicate tests and testing individual plant in F1population, the maker was23.33cM far from the loci controlling dwarf trait.