Genetic Diversity and Core Collection of Alien Pisum sativum L. Germplasm

China is the second producer of pea (Pisum sativum L.) in the world with a collection of 5,000 accessions, of which approximately 20% are introduced from 70 foreign countries. To evaluate genetic diversity of the introduced pea germplasm and construct its core collection, 731 pea accessions originating from 67 countries of various continents were analyzed using 21 simple sequence repeat (SSR) primer pairs. One hundred and nine polymorphic bands were amplified in all accessions with an average of 5.19 alleles per primer pair. The polymorphic alleles were not uniformly distributed among accessions from different continents, and the number of effective alleles and Shannon's information index (I) varied among origin-based groups of alien pea resources. The I values were much different among origin-based groups according to pairwise comparison. The Asia group possessed the highest level of genetic diversity (I = 1.1753), followed by the Europe (I = 1.1387), USSR (I = 1.0285), America (I = 1.0196), Africa (I = 0.9254), and Oceania (I = 0.8608) groups. Using Structure Ver2.2 and POPGEN1.32 software, the 731 accessions were classified into 3 types of structure populations and 4 cluster subgroups in 2 cluster groups, respectively. The 2 category systems were mutually explained well, and the genetic diversity correlated with geographic distribution of the alien pea resources. Based on structure population, the core collection of alien pea resources was constructed with 48 accessions (6.57%) to cover 84.4% of the total allelic variations.