Isolation and dynamic expression of four genes involving in shikimic acid pathway in Camellia sinensis 'Baicha 1' during periodic albinism.

ABSTRACT

Flavonoids are the main flavor components and functional ingredients in tea, and the shikimic acid pathway is considered as one of the most important pathways in flavonoid biosynthesis, but little was known about the function of regulatory genes in the metabolism phenolic compounds in tea plant (Camellia sinensis), especially related genes in shikimic acid pathway. The dynamic changes of catechin (predominant flavonoid) contents were analyzed in this study, and four genes (CsPPT, CsDAHPS, CsSDH and CsCS) involving in shikimic acid pathway in C. sinensis albino cultivar 'Baicha 1' were cloned and characterized. The full-length cDNA sequences of these genes were obtained using reverse transcription-PCR and rapid amplification of cDNA ends. At the albinistic stage, the amounts of all catechins decreased to the lowest levels, when epigallocatechin gallate was the highest, whereas gallocatechin-3-O-gallate the lowest. Gene expression patterns analyzed by qRT-PCR showed that CsPPT and CsDAHPS were highly expressed in flowers and buds, while CsSDH and CsCS showed high expression levels in buds and leaves. It was also found that the transcript abundance of shikimic acid biosynthetic genes followed a tightly regulated biphasic pattern, and was affected by albinism. The transcript levels of CsPPT and CsDAHPS were decreased at albinistic stage followed elevated expression, whereas CsSDH and CsCS were increased only at re-greening stage. Taken together, these findings suggested that these four genes in C. sinensis may play different roles in shikimic acid biosynthesis and these genes may have divergent functions.