Genetic diversity analysis of avocado germplasm resources based on SRAP molecular markers

【Objective】 The genetic diversity of avocado germplasm resources was analyzed based on SRAP molecular markers, which provided a theoretical basis for the breeding and innovative utilization of new varieties of avocado germplasm resources.【Method】 Using 50 avocado germplasm as materials, 184 pairs of SRAP primer combinations with clear amplification bands and good polymorphism were selected. The genetic diversity index of avocado germplasm was calculated by PopGene 1.32 based on the amplification results. The genetic similarity coefficient was calculated by UPGMA(unweighted group average method) of NTSYS 2.1, and cluster analysis was carried out.【Result】 A total of 17 primer pairs with clear amplification and good polymorphism were selected from 184 pairsof SRAP primer combinations. A total of 322 bands were amplified by PCR from 50 tested avocado germplasm materials by the 17 primer pairs, of which 206 were polymorphic, with an average of 12.12 amplified by each primer, and the polymorphism rate was 63.75%. The observed allele number(N_a) of 50 avocado germplasm materials was 1.0844-1.4034, with an average of 1.2493, effective number of alleles(N_e) was 1.0067-1.6028, with an average of 1.3390. Nei's genetic diversity index(H) was 0.0642-0.1466, with an average of 0.1439, Shannon's information index(I) was 0.0634-0.1759, with an average of 0.1308. Daling 2 and avocado germplasm 4 had the highest genetic consistency(0.9237), the highest genetic similarity coefficient(0.92), and the lowest genetic distance(0.1365), indicating that Daling 2 and avocado germplasm 4 had the closest genetic relationship. The genetic consistency between avocado germplasm 5 and Fuerte was the minimum(0.3765), and the genetic distance between them was the largest(0.8253), indicating that the genetic relationship between avocado germplasm 5 and Fuerte was the farthest. At the genetic similarity coefficient of 0.48, 50 avocado germplasm were divided into four groups.Avocado germplasm from Baisha, Hainan was concentrated in group Ⅲ, and avocado germplasm from Danzhou, Hainan, Zhanjiang, Guangdong and Nanning, Guangxi were distributed in groups I, Ⅱ and IV, indicating that avocado germplasm from Danzhou, Hainan, Zhanjiang, Guangdong and Nanning, Guangxi were rich in genetic diversity.【Conclusion】 The genetic diversity of avocado germplasms from Danzhou, Hainan, Zhanjiang, Guangdong and Nanning, Guangxi are more abundant than that from Baisha, which provided a theoretical basis for innovation in parents selection and breeding.