7个茶树全基因组SSR位点的鉴定与特征分析

测序技术的进步有力促进了基因组学的研究进展。近年来，已有7个茶树参考基因组相继发表，但不同基因组间SSR的数量和特征尚不清楚。通过对7个茶树全基因组SSR位点的鉴定和比较分析发现，茶树中二核苷酸重复单元SSR最多，其次是三核苷酸重复单元，所有品种Ⅰ类SSR均含量均低于Ⅱ类SSR。品种间SSR数量在391 815至595 417之间变化，全基因组SSR密度则从131.94 Mb^-1到207.66 Mb^-1不等，不同染色体间存在明显差异。与基因组二核苷酸重复最多不同，CDS区SSR密度更低，且以三核苷酸重复单元为主。二核苷酸和三核苷酸重复最多的类型分别为AG/CT和AAT/TTA。同时发现，不同品种基因组间存在丰富的多态性SSR位点。对这些特征的揭示和多态性SSR的鉴定，将为茶树遗传图谱构建、遗传多样性分析和重要性状的遗传机制解析奠定基础并提供支撑。

Identification and characteristic analysis of SSR loci in seven tea plant genomes (Camellia sinensis)

Advances in sequencing technology have strongly promoted the research progress of genomics. In recent years, seven tea plant genomes have been published one after another, but the number and characteristics of SSRs (simples sequence repeats) between different genomes still keep unclear. In this study, through the identification and comparative analysis of seven tea plant genome-wide SSR sites, it was found that the dinucleotide repeating unit SSR was the most in tea plants, followed by the trinucleotide repeating unit. The content of class I SSR in all varieties was lower than that of II. Similar to SSR, the number of SSRs between varieties varied from 391 815 to 595 417, and the SSR density of the whole genome varied from 131.94 Mb^-1 to 207.66 Mb^-1, with obvious differences between different chromosomes. Unlike genomic dinucleotide repeats, the SSR density was lower in the CDS region and was dominated by trinucleotide repeat units. The most repetitive types of dinucleotide and trinucleotide were AG/CT and AAT/TTA, respectively. At the same time, it was found that there were abundant polymorphic SSR loci among the genomes of different varieties. The revealed characteristics and the identification of polymorphic SSRs will lay a foundation and provide some supports for the construction of tea tree genetic map, genetic diversity analysis and genetic mechanism analysis of important traits.