The extent of natural cross-pollination in wild soybean (Glycine soja)

To evaluate the extent of natural cross-pollination in wild soybean (Glycine soja Sieb, and Zucc,), we analyzed the genetic structure of four populations along the Omono River in Akita Prefecture, Japan, by examining allozyme variation, In addition, observations of flower visitors were made in the field, Although it was thought previously that G. soja is autogamous, as is cultivated soybean (G. max), we obtained higher within-population genetic variation (H-S = 0.315) and lower genetic divergence among populations (G(ST) = 0.087) than would be expected for a selfing plant species, Furthermore, the mean multilocus outcrossing rate (t(m)) estimate was 13%, ranging from 9.3-19% among the four populations, These values are much higher than the outcrossing rate previously reported for both G, soja and G. max, This higher outcrossing rate was supported by observations of frequent visits by honeybees and carpenter bees to flowers.