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| Tea (Camellia sinensis L.) is a commercially important crop that is valued for its secondary metabolites. Light can influence the accumulation of phenylpropanoids (including catechins, anthocyanins, and lignins) in the seedlings of tea plants. To investigate the molecular mechanism by which light influences phenylpropanoid metabolism, we established light-induced suppression subtractive hybridization (SSH) cDNA libraries of tea callus. A total of 191 clones from the forward (light-induced) SSH library and 74 clones from the reverse (darkness control) library were selected, sequenced, and analyzed in this study. BlastX analysis of the tea callus light-induced cDNA library showed that the subtractive expressed sequence tags (ESTs) were classified into 12 putative cellular functions, in which the ‘photomorphogenesis’, ‘stress defense’, ‘signal transduction’, and ‘phenylpropanoid and secondary metabolism’ categories contained 5, 17, 13, and 9 ESTs, respectively. The bioinformatic sequence analysis of the SSH library, associated with morphological comparison, secondary metabolites analysis, and representative genes expression analysis, implied that: (1) light could inhibit the growth, and promote the differentiation, of the tea callus; (2) light might be effective for activation of the biosynthesis of phenylpropanoids, e.g. analysis and identification of catechins implied that light irradiation could activate epicatechin and epigallocatechin biosynthesis; and (3) light, as a signal or a stress condition, may regulate photomorphogenesis and phenylpropanoid synthesis mediated by the cAMP and Ca2+ signal pathway in tea callus. The SSH library established in this study represents a valuable resource for future research aimed at improving economically important secondary metabolic characteristics in the tea plant. |
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| Keywords:gene expression;light inducement;phenylpropanoid biosynthesis;SSH cDNA library;tea |
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