Evaluation of Grapevine Germplasm Resources Based on Phenotypic Traits and SSR Markers

To clarify the genetic background and biological characteristics of grape germplasm resources and provide theoretical support for germplasm innovation and new-variety breeding, we conducted systematic morphological identification and SSR molecular-marker analysis on 38 core grape germplasms (29 fresh-eating cultivars, 1 local cultivar, and 8 wild germplasms) from the National Southeast Mountainous Crop Germplasm Repository (Jiangxi·Yichun) and other regions. For morphological identification, 14 quantitative traits and 5 descriptive traits of leaves, floral organs and fruits were determined in strict accordance with the NY/T 2932-2016 Descriptors for Grape Germplasm Resources. For SSR molecular-marker analysis, eight pairs of internationally universal core primers were used for PCR amplification and fluorescence detection referring to the NY/T 3640-2020 Identification of Grape Cultivars Using SSR Markers, and genetic diversity analysis was conducted on 11 local and wild grape germplasms. The results revealed abundant phenotypic diversity among the tested germplasms: the functional leaves of cultivars were predominantly pentagonal and cuneate, while those of wild germplasms were mostly reniform and cordate, with 3–5 lobes for most germplasms; all germplasms were hermaphroditic, except for two wild accessions with unisexual flowers. Significant variations were observed in fruit traits, with the coefficient of variation (CV) of cluster weight and berry weight reaching 67.64% and 50.53%, respectively. The genetic plasticity of weight-related traits was much higher than that of shape- and length-related traits, and the average Shannon–Wiener index (H′) of 19 morphological traits was 3.47, indicating a high level of overall phenotypic diversity. SSR analysis showed that the eight primer pairs amplified a total of 42 genotypes (5.25 per primer pair on average). The population had a mean observed number of alleles (Na) of 5.28, a mean effective number of alleles (Ne) of 7.25, and a mean polymorphism information content (PIC) of 0.74, demonstrating rich genetic diversity and high polymorphism of the tested loci. Cluster analysis divided the 11 local germplasms into four groups, which clearly reflected the genetic relationships among them, and genetic admixture was found in some germplasms due to unclear introduction traceability. In this study, fresh-eating grape cultivars suitable for the climatic conditions of Jiangxi Province were screened, the utilization value of local germplasm resources was clarified, and a two-dimensional evaluation system based on phenotypic traits and SSR molecular markers was constructed. The findings provide basic data and a scientific basis for the precise evaluation, elite gene mining, and new-variety breeding of grape germplasm resources in Jiangxi Province.