Molecular identification and characterization of a serine carboxypeptidase-like gene associated with abiotic stress in tea plant, Camellia sinensis (L.)

Abstract

Tea (Camellia sinensis L.) contains secondary metabolites including polyphenolic proanthocyanidins (PAs) and their precursors. The SCPL (serine carboxypeptidase-like) proteins are a group of acyltransferase enzymes that modify plant natural products. We isolated CsSCPL, which encodes a SCPL protein, from oolong tea. Sequence alignment analyses showed that CsSCPL is a serine carboxypeptidase with high homology to other SCPLs, including those in persimmon, grape, woodland strawberry, and sweet orange. Quantitative RT-PCR analyses revealed that the highest transcript levels of CsSCPL were in young leaves of tea seedlings and buds of mature plants. CsSCPL transcription increased in response to heat but decreased in response to cold, high salinity, and drought. The degree of epigallocatechin galloylation increased after heat treatment and the degree of epicatechin galloylation decreased after cold treatment. In field-grown tea plants, the highest transcript levels of CsSCPL were in summer. Together, these results show that CsSCPL transcripts accumulate in one-tip-two-leaf tissues of oolong tea plants during the hottest parts of the growing season, and in response to abiotic stress. The degree of catechin galloylation was positively correlated with CsSCPL transcript levels after heat or cold treatments. Our results will be useful for further research on the functions of SCPLs in plants.