Spatial structure of microsatellite variability within and among populations of wild radish Raphanus sativus L. var. hortensis Backer f. raphanistroides Makino (Brassicaceae) in Japan

摘要

Genetic variability and its spatial structure within and among Japanese populations of wild radish Raphanus sativus L. var. hortensis Backer f. raphanistroides Makino were surveyed at regional ( T = 0.577) and local ( H _T = 0.604) samples. Local populations and subpopulations showed heterozygote deficiency as expressed by average inbreeding coefficient values of 0.206 and 0.179, respectively. The level of genetic differentiation among populations was low, with fixation index values of 0.048 and 0.034 for regional and local scales, respectively. Nonetheless, analysis of molecular variance showed significant genetic differentiation among populations/subpopulations. Spatial genetic analysis indicated a positive correlation between pairwise values of spatial distance and genetic differentiation both at regional and local levels. These results suggest that the wild radish populations surveyed are genetically structured and each population retains a unique genetic composition. Genetic heterogeneity among local populations provides the opportunity to obtain genetic resources with various useful traits by extensive exploration of different populations.