Journal of Tea Science Research, 2024, Vol.14, No.6, 322-334 http://hortherbpublisher.com/index.php/jtsr 330 6.3 Aroma gene variations in special tea varieties like Kudingcha Specialty teas, like Kudingcha, are known for their unique or even strong flavors that are often different from traditional tea (Camellia sinensis) varieties. Multi-omics studies have shown that these special flavors are closely associated with the presence of specific alleles and variant sites in the aroma synthesis pathway (Chen et al., 2023a). For example, specific combinations of TPS, LOX, and phenylpropanoid pathway genes and their regulatory elements together form rare or highly enriched aroma components in these teas (Gao et al., 2023). With the qRT-PCR, transgenic studies, and correlation analysis between gene expression and metabolite accumulation, researchers have functionally validated candidate regulatory genes in these special teas (Gu et al., 2023; Wei et al., 2024). In Kudingcha and other specialty teas, the expression of specific TPS and MYB genes is associated with the accumulation of unique terpenes and phenyl compounds. Metabolome-wide association studies (mGWAS) further confirmed the direct association between the occurrence and abundance of these aroma components and genetic variation (Wei et al., 2024). 7 Implications for Tea Breeding and Aroma Improvement 7.1 Molecular breeding strategies for improved aroma Aroma is one of the core elements of tea quality. Modern breeding pays more and more attention to this indicator, not only pursuing high concentration, but also stability. The breeding goals include not only increasing the content of monoterpenes, sesquiterpenes, lactones and other ingredients, but also expanding the aroma types, such as floral, fruity, and milky aromas, and ensuring that these aromas can be stably expressed under different origins and processing methods (Zeng et al., 2020). At the same time, aroma traits are also expected to be compatible with agronomic traits such as stress resistance and high yield to meet market and planting needs (Wang et al., 2021; Gao et al., 2023; Fu et al., 2024). Molecular marker-assisted selection (MAS) has become an important means to improve the aroma of tea trees. With the help of high-density genetic maps and QTL positioning, researchers have identified multiple key sites related to volatile terpenes (Parmar et al., 2022; Chen et al., 2023a; b; Gu et al., 2023). For example, in the F1 population, QTL regions related to monoterpene and sesquiterpene content were located, and candidate genes that can be used for breeding were screened (Chen et al., 2023a). In addition, the developed SSR and SNP markers closely related to aroma genes and regulatory elements make it possible to screen for high-aroma materials at the seedling stage (Chen et al., 2023b; Parmar et al., 2022). MAS combined with multi-omics data (Li et al., 2022) further improved breeding efficiency and helped to cultivate high-quality and high-aroma new varieties. 7.2 Potential of genetic engineering in aroma improvement Gene editing technology, especially CRISPR/Cas9, provides a direct and efficient tool for improving the aroma of tea. By precisely editing synthases such as TPS and LOX, or key transcription factors such as MYB and bHLH, the production of specific aroma substances can be greatly improved, and even new aromas can be created (Yue et al., 2025). For example, targeted editing of transcription factors that regulate linalool synthesis may produce varieties with more prominent floral or fruity aromas (Yue et al., 2025). The application of gene editing in tea trees is still in the exploratory stage, but there is already mature experience in other crops, and the relevant transformation system is also being continuously optimized, laying the foundation for subsequent applications in tea trees (Zhang et al., 2021). Transgenic and synthetic biology methods also have potential. By introducing exogenous genes or overexpressing endogenous genes, such as β-glucosidase and methyltransferase, the efficiency of tea aroma release during processing can be improved (Deng et al., 2017; Wang et al., 2024). Furthermore, synthetic biology platforms can even construct entire aroma metabolism pathways to cultivate new varieties with more complex and customizable aromas. However, if these technologies are to be truly promoted, they still have to face practical problems such as regulatory review, ecological safety, and consumer acceptance (Zhang et al., 2021).
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