Genetic variation and relationships of Lagerstroemia indica cultivars

Lagerstroemia indica cultivars is famous ornamental plants with large pyramidal racemes, long flower duration, diverse colors and cultivars. It has been cultivated for nearly 1600 years and it is essential for investigating the germplasm and assessing genetic variation would assist international cultivar identification and breeding programs. In this study, 20 common Lagerstroemia indica cultivars from different varietal groups and flower morphologies, and multiple wild relatives species were investigate the maternal donor of Lagerstroemia indica cultivars and to discover the genetic variation and relationships among cultivars based on the plastome and nrDNA sequences. There were 47 SNPs and 24 indels were identified in the 20 L. indica cultivars, while 25 SNPs in the nrDNA. Phylogenetic analysis based on the plastome sequences showed all the cultivars formed a clade with the species of L. indica, indicating the L. indica was the maternal donor of the cultivars. Population structure and PCA analyses supported two clades of the cultivars and exhibited significant genetic difference according to the plastome dataset. The nrDNA supported there were divided three clades and most of the cultivars had at least two genetic backgrounds and had with higher gene flow. Our results suggested that the plastome and nrDNA sequence can be used as the molecular markers for assessing the genetic variation and relationships of cultivars.