Abstract: To elucidate the genetic diversity and phylogenetic relationships of tea germplasm resources in the Huaihua region and enhance the efficiency of local tea resource development and utilization, this study focused on 72 tea germplasm resources collected and preliminarily screened from the Huaihua area. Through systematic agronomic trait observation and screening, combined with whole-genome sequencing for single nucleotide polymorphism (SNP) detection, an in-depth analysis was conducted on their population genetic structure, identity-by-descent (IBD), and genetic relationships. The results show that the 72 tea resources primarily consisted of large-leaf varieties (39 accessions) and medium-leaf varieties (31 accessions). Among them, 41 accessions had an amino acid content exceeding 5%, three exhibited a phenol-ammonia ratio above 10, and 61 had a ratio below 8. Correlation analysis reveals that bud length was significantly correlated with caffeine content (γ=0.862 8) and water extract (γ=0.871 8). Genomic analysis indicates that the 72 resources could be classified into two pure lineages and one admixed group. Specifically, the Zhongfang and Hongjiang groups clustered together, while the Jingzhou and Yuanling groups formed separate clusters. Using CoreHunter, 56 core germplasm resources were selected. This study provided an important theoretical foundation and material basis for the breeding of specialty Jietan tea cultivars and the innovative utilization of unique tea resources.

Key words: tea plant, Jietan tea, whole-genome sequencing, SNP, genetic structure, core germplasm