Establishment of a Core Collection for the Chinese annual wild soybean (Glycine Soja)

With more than 6000 accessions collected from across China, the Chinese National Crop Gene Bank (CNCGB) holds the largest collection of annual wild soybean (Glycine Soja) germplasm in the world. To facilitate the management and utilization of these germplasm collections, it is important to establish a Core Collection. This study compares five sampling strategies, namely random, constant, proportional, logarithmic and genetic diversity-based, to establish a Core Collection for the annual wild soybean germplasm. Among the strategies evaluated, the genetic diversity-based was found to be the simplest and most efficient. Using hierarchical classification and cluster analysis, in the genetic diversity diversity-based strategy, 652 accessions, accounting for 10.65% of the total 6172 accessions, were selected out to represent the total accessions. The established Core Collection has the following features: (i) the 21 descriptors observed in the entire collection were compared by the Core Collection, all 18 quality characters of entire collection were preserved by core collection, and coincidence rate of average was 98.4%; (ii) the variant of 13 descriptors of the two collections was very similar, with the coincidence index being 0.96; (iii) the coincidence rate of genetic diversity between the two collections was 81.38% DNA alleles; (iv) the geographic distribution pattern of core collection was the same as the entire collection; (v) molecular marker analysis by 20 SSR primer pairs on 299 accessions showed that the Core Collection covered 83.64% of the entire collection. It thus is concluded that the established Core Collection is representative and will be a valuable entry point for better evaluation and more efficient utilization of the genetic resources available in the annual wild soybean germplasm bank.