Genetic Diversity Analysis and Core Collection Construction of the Actinidia chinensis Complex (Kiwifruit) Based on SSR Markers

Kiwifruit belonging to the Actinidiaceae family is a perennial, dioecious vine called &lsquo:the king of fruits&rsquo: due to its considerably nutritious and sweet characteristics. A. chinensis complex, including two main groups, A. chinensis var. chinensis and A. chinensis var. deliciosa, is a major component of Actinidia due to their huge economic value and the high degree of development and utilization. Wild resources are widely distributed in China, but are under serious threat due to extreme environments and destroyed habitats. Thus, it is of great significance for the conservation of kiwifruit resources and the sustainable development of the kiwifruit industry to evaluate the genetic diversity of existing genetic resources and to systematically construct a core collection of the A. chinensis complex. In this study, 40 high polymorphism microsatellites markers were used to investigate all accessions from the A. chinensis complex. A total of 888 alleles were marked with 22.2 alleles in each locus. The expected heterozygosity was 0.846, the observed heterozygosity was 0.622, the polymorphism information content was 0.835, and the Shannon information index was 2.369. Among these loci, the observed heterozygosity of 38 loci was lower than expected. The inbreeding coefficient was 0.257, which indicates that frequent hybridization occurred between close relatives. Analyses of molecular variance showed that genetic variations mainly came from the population. Finally, a core collection containing 93 accessions was constructed. The bank not only perfectly represented the genetic diversity of the original population, but also had excellent potential for development and utilization. Our research provides a crucial reference for the future conservation, germplasm identification, and genetic breeding of kiwifruit.