Journal of Tea Science Research, 2024, Vol.14, No.2, 79-91 http://hortherbpublisher.com/index.php/jtsr 87 insights are crucial for understanding the genetic basis of flavor characteristics and other desirable traits in tea plants. Figure 3 Signatures of artificial selection and evidence of parallel domestication in CSA and CSS (Adopted from Zhang et al., 2021a) Image caption: a: The roadmap of parallel domestication in CSA and CSS. During early domestication, CSA mainly involved genes related to glucoside transport, photomorphogenesis, and plant height, while CSS involved chemicals for defense against insects. In the improvement process, CSA focused on the metabolism of alkaloids and aromatic compounds, while CSS mainly concentrated on genes related to cold stress and photomorphogenesis and plant height; b: Selective sweep signals identified based on XP-EHH (cross-population extended haplotype homozygosity). These signals indicate multiple selected gene regions in CSA and CSS; c: Artificial selection signals of the XDH gene (xanthine dehydrogenase-oxidase); d: Artificial selection signals of the CM gene (chorismate mutase), involved in the biosynthesis of aromatic amino acids. During early domestication of CSA varieties, the CM gene shows significant artificial selection signals; e: Strong artificial selection signals of the F3’5’Hgene in catechin biosynthesis, showing high FST scores and significantly low Tajima’s D values in CSS landraces; f: Artificial selection signals of BAS1 and DWF4 genes related to plant height. The reduced plant height in cultivated CSA and CSS varieties is mainly associated with the selection of these genes; g: RNA-seq expression analysis results of artificially selected genes in different tissues, further supporting the potential functions of these genes in various tissues. The results reveal parallel evolutionary pathways during the domestication of CSA and CSS, and through the selection of these genes, tea plant varieties have been improved and adapted (Adapted from Zhang et al., 2021a) In the study on genomic selection for black tea, the best prediction models were identified for various quality traits, such as catechin, astringency, brightness, briskness, and color. The use of putative QTLs, annotated proteins, and KEGG pathways in the prediction models showed robustness and usefulness in predicting phenotypes (Koech et al., 2019). This approach opens up new avenues for future applications of genomic selection in tea breeding, potentially accelerating the development of high-quality tea cultivars. Overall, the advances in high-quality sequencing and annotation of tea genomes have provided a wealth of genetic and molecular information. These studies not only enhance our understanding of the genetic basis of important traits in tea plants but also provide a reference for developing improved tea varieties through genomic selection and gene editing technologies.
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