Tree Genetics and Molecular Breeding 2025, Vol.15, No.3, 89-97 http://genbreedpublisher.com/index.php/tgmb 91 addition, the use of hydrocyanamide in tea oil tea can make it flower earlier. This effect is related to hormones, MAPK pathway, oxygen metabolism, etc. in the plant (Lin et al., 2022). 3.3 Environmental stressors and their impact on flowering When the environment is not ideal, such as drought, high salt content or reduced soil nutrients, the flowering time of tea will also be affected. These pressures can alter the flowering process by regulating photoperiod and hormone signaling pathways (Lee et al., 2023). Under difficult conditions, plants may flower earlier or later to increase the success rate of reproduction (Cho et al., 2017). These environmental signals and photoperiodic control mechanisms are interconnected, and genes like FT act as the “bridge” in the middle, simultaneously participating in responding to stress and controlling flowering (Riboni et al., 2014). In addition, environmental stress may also indirectly affect the expression of genes related to flowering by altering glucose metabolism, reactive oxygen species levels, etc. within plants (Liu et al., 2017; Cho et al., 2018; Lin et al., 2022). 4 Identification of Flowering Time Genes in Tea 4.1 Genome and transcriptome resources for gene discovery In recent years, genomic information and a large amount of transcriptome data of the tea (Camellia sinensis) have laid the foundation for identifying the genes that control the flowering time. By conducting transcriptome sequencing on tea plants of different varieties and at different developmental stages, researchers identified a total of 92 core genes related to flower development, covering the entire process from flower bud formation to full flower opening (Xu et al., 2022). Meanwhile, through genomic alignment, they also identified 401 and 356 genes related to flowering respectively from small-leaf and large-leaf tea plants, all of which are candidates for subsequent functional studies (Liu et al., 2020a). 4.2 Homology-based identification using model species Researchers also identified multiple homologous genes in tea plants by leveraging known flowering genes in model plants such as Arabidopsis thaliana and rice. For instance, CsFLC1 in tea plants belongs to the MADS-box gene family. It is very similar to FLC in Arabidopsis thaliana. Experimental results show that it can affect the flowering time of tea plants and is also related to the dormancy of buds in winter (Figure 1) (Liu et al., 2022). In addition, CsWRKY7 is also very similar to AtWRKY7 and AtWRKY15 of Arabidopsis thaliana. Overexpression of it will cause delayed flowering of plants and reduce the expression of key genes such as FT, AP1 and LFY at the same time (Chen et al., 2019). The regulatory modules miR156 and SPL also have similar functions in tea plants. For example, Csn-miR156d can regulate FT, AP1, FUL and SOC1 by targeting CsSPL1, thereby delaying the flowering time. Figure 1 Expression patterns of CsFLC1 (Adopted from Liu et al., 2022) Image caption: (A) Expression of CsFLC1 in axillary or flower buds of tea plant throughout the year. (B) Different tissue expression of CsFLC in tea plant. (C) Various parts of flowers of tea plant. (D) Expression patterns of CsFLC1 in different parts of flowers in tea plant. (E) GUS staining of pCsFLC1::GUS transgenic Arabidopsis thaliana (Adopted from Liu et al., 2022)
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