Genetic diversity of wild male kiwifruit (Actinidia eriantha Benth.) germplasms based on SSR and morphological markers

Abstract: 【Objective】Kiwifruit (Actinidia Lindl.) has gotten a short history of domestication since the early 20 th century when its seeds were introduced into New Zealand. It is wildly distributed throughout the most area of East Asia. The center for the origin of kiwifruit has been considered to be the mountains of the Southwestern China. Jiangxi province is one of the distribution areas of the kiwifruit. Actinidia eriantha Benth. is recognized as a valuable species for commercial kiwifruit improvement for high content of ascorbic acid as well as being used in traditional Chinese medicine. Molecular studies have been proved to be efficient ways for the survey of fruit germplasms. The objective of this study was toassess male A. eriantha genetic diversity and to determine the differences among 68 germplasms grown in Jiangxi province by examining both morphological and molecular characteristics.【Methods】We conducted a simple sequence repeat (SSR) -based analysis of 68 germplasms from 7 regions of Jiangxi province. We also conducted morphological trait association analysis with 10 important floral phenotypic characteristics and 87 SSR loci. The morphological traits were recorded based on the Guidelines for the conduct of tests for distinctness, uniformity, and stability: kiwifruit (Actinidia L.). 50 SSR pairs of primers even distributed on the genetic linkage map of A. chinensis were used to initially assess the polymorphism. Of the 50 pairs of primers tested, 15 pairs successfully amplified polymorphic fragments. The phenotypic variables were analyzed using software SPSS. SSR analysis was carried out using fifteen pairs of primers. NTSYSpc2.1 was used for estimating the level of genetic diversity according to the SSR data. The polymorphism information content (PIC) and the Shannon's information index for each SSR were calculated for measuring the informativeness of the markers. The relationship between the Euclidean distances measured using phenotypic variables and the distances measured using SSR markers was measured by software NTSYSpc2.1. Cluster analysis was performed by means of UPGMA (unweighted pair-group method using arithmetic average) clustering procedure, using the NTSYS-PC package.【Results】High levels of genetic diversity existed among the individuals of the wild male A. eriantha Benth.. There were significant differences in genetic variation from the average variation coefficient of 29.19%, including the main color of petal (the color of the main color inside of the petal, the other color and distribution of the other colors inside of the petal) , color of flament (white to deep pink) , the number of flowers per inflorescence (2-10) , corolla diameter (23.86-46.23 cm) , length of flower stem (5.50-18.67 cm) , stamen number (85.33-424.67) , pollen quantity (800-17 333) and pollen viability (22.10%-94.74%) . The variation coefficient of pollen quantity was the highest (53.41%) , while the variation coefficient of corolla diameter was the lowest (15.47%) . Two groups could be distinguished by truncating the dendrogram at GS value of 1.49. The major group (denoted group A) consists of 66 individuals and could be separated into two subgroups: the first one is composed of 50 genotypes, including the accessions collected from MGS (22) , MA (11) , JGS (7) , YH (4) , XX (1) , LS (5) , the another is composed of 16 genotypes, including the accessions collected from LS (4) , XX (3) , JGS (3) , MA (4) , MGS (1) , HYS (1) . While two individuals coming from the LS formed another group. The distinct phenotypic features of the two accessions, including their great pollen quantity, more stamen, and big corolla made them to be classified into a separate group. The investigation revealed significant allelic richness in the selected landrace accessions, with a mean of 5.67 SSR alleles per locus and high polymorphism information content (PIC) value of 46.48%. The mean number of Shannon's information index was 1.04. It could be divided into three groups according to the cluster analysis. To ascertain the degree of correspondence between the genetic distances based on phenotypic data and molecular (SSR) data, the distance matrices were constructed and compared using the Mantel's test. The analysis revealed a positive and significant correlation between the two matrices, with r =-0.79, p < 0.05.【Conclusion】It is important to couple phenotypic analysis with genetic diversity for germplasm conservation in genebank collections. Wild male A. eriantha may also be regarded as a source of genetic material for plant improvement.