Abstract
Albinism in shoots of tea plants is a common phenotypic expression which gives the tea infusion a pleasant umami taste. A novel natural albino mutant tea germplasm containing high amino acids content was found and named as ‘Huabai 1’. ‘Huabai 1’ has white jade tender shoots under low temperature and turns green with increased temperature. In order to understand the molecular mechanism of color change in leaf of ‘Huabai 1’, transcriptome analysis was performed to identify albino-associated differentially expressed genes (DEGs). A total of 483 DEGs were identified from white shoots of ‘Huabai 1’ compared to its green shoots. There were 15 DEGs identified to be involved in phenylpropanoid biosynthesis, which account for the majority of characterized DEGs. The metabolites related to phenylpropanoid biosynthesis revealed similar expression pattern of DEGs. Furthermore, metabolic pathways such as ubiquonone, tyrosine, and flavonoid biosynthesis associated with phenylpropanoid biosynthesis could also contribute to the color change in ‘Huabai 1’ tender shoots. Protein–protein interaction analysis revealed a hub protein NEDD8 (CSA009575) which interacted with many regulated genes in spliceosome, nitrogen metabolism, phenylpropanoid biosynthesis, and other pathways. In conclusion, the findings in this study indicate that the color change of ‘Huabai 1’ tender shoots is a combined effect of phenylpropanoid biosynthesis pathway and other metabolic pathways including flavonoid biosynthesis in tea plants. Chlorophyll biosynthesis-related genes LHCII and SGR may also play some roles in color change of ‘Huabai 1’.
Highlights
Leaf albinism is a common phenomenon which usually occurs in green plants as a result of chlorophyll deficiency[1,2,3]
Carotenoid compounds have been found to be involved in leaf color formation[9], and suppression of phytoene desaturase gene resulted in leaf albinism in tobacco[10]
471 genes were exclusively annotated with 182, 331, 170, 203, differentially expressed genes (DEGs) and metabolites on phenylpropanoid biosynthesis The expression of the genes involved in phenylpropanoid biosynthesis of white tender shoots showed significant higher levels than that of green shoots, especially for the genes related to deoxygenation and hydrogenation reduction reactions
Summary
Leaf albinism is a common phenomenon which usually occurs in green plants as a result of chlorophyll deficiency[1,2,3]. In tea plants (Camellia sinensis), albinism is of great importance since it produces beneficial metabolites such as. Plant leaf albinism is influenced by various biochemical and environmental factors; its molecular mechanisms remain unclear. Carotenoid compounds have been found to be involved in leaf color formation[9], and suppression of phytoene desaturase gene resulted in leaf albinism in tobacco[10]. A number of studies have been conducted to uncover the different molecular mechanisms of leaf albinism in different albino tea cultivars. The significant changes in metabolites involved in carbon fixation, phenylpropanoid and flavonoid biosynthesis
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