Abstract: 【Objective】 There are numbers of germplasm accessions of soybean, including both cultivated soybean (Glycine max (L.) Merr.) and wild soybean (Glycine soja Sieb. et Zucc.), available in China where the former were domesticated from the latter. It is a basic work to characterize the genetic variability and evolutionary peculiarity of the soybean germplasm in breeding for isoflavone contents. 【Method】 The 895 accessions, including 580 landraces, 106 released cultivars, 209 wild materials from various ecological regions in China with 88 released cultivars from abroad as reference, a total of 983 accessions were tested for their 12 isofavone contents by using rapid high performance liquid chromatography technique. 【Result】 A large variation in total isoflavone (TISF) and its components both in cultivated and wild soybeans in China was observed. The ranges of TISF in wild accessions, landraces and released cultivars were 927.29-7 932.94, 259.38-7 725.45 and 489.67-5 968.90 μg?g-1, with their averages of 2 994.51 μg?g-1, 3 241.33 μg?g-1, and 2 704.83 μg?g-1, respectively. In average, with the long term artificial selection, the total genistin group content (TG, especially 6’-O-malonylgenistin) and total glycitin group content (TGL, especially 6’-O-acetyl- and 6’-O- malonylglycitin) increased, while the total daidzin group content (TD, especially 6’-O-acetyldaidzin) decreased obviously, which led TISF in released cultivars lower than that in wild soybean. There existed also great variabibility of isoflavone contents in wild and cultivated soybeans within each eco-region as was that in the whole country. The TISF of cultivated soybeans was negatively correlated both with longitude (r =-0.264) and latitude (r=-0.380) at P＜0.01 significance level, while no such correlation was found in wild soybeans, which indicated that the differential directions of artificial selection acted on the cultivated soybeans among geographic regions caused the correlation between genotypes and geographic sites in the cultivated soybean different from that of the wild soybeans. From the 983 accessions, elite ones, such as ZYD3621 (TISF 7 932.94 μg?g-1), N3188 (TISF 7 725.45 μg?g-1), N20793 (TGL 5 122.21 μg?g-1), etc. were screened out for isflavone breeding. 【Conclusion】 The evolutionary peculiarity of isoflavone content and its components from the wild species to cultivated landrace and to the released cultivars of soybean in China elucidated that the average of TISF, TG and TGL of G. max was higher than that of G. soja, while the average of TD of G. max was lower than that of G. soja. There existed great variation in total isoflavone and its components both in the whole country and in each eco-region in both wild and cultivated soybeans. Elite germplasm accessions with high isoflavone components in G. soja and G. max were screened out for breeding purposes.

Key words: cultivated soybean (Glycine max (L.) Merr.), wild soybean (Glycine soja Sieb. et Zucc.), germplasm, isoflavone component, genetic variation, evolutionary peculiarity