PJB-2017-843
LOW LIGHT INDUCE EXPRESSION PATTER OF TIA PATHWAY GENES IN CATHARANTHUS ROSEUS SEEDLINGS
YING LIU
Abstract
Catharanthus roseus (C.roseus) is a rich source of alkaloids of antineoplastic drugs. Dimeric alkaloide such as vinblastine (VBL) are produced by the biochemical coupling of smaller indole alkaloids such as vindoline (VIN) and catharanthine (CAT). High demand and low yield of these alkaloids in the plant has led to explore the alternative means for their production. In this study, the plastic film was used to provide low light condition (18.25 W m-2), the natural light was as control (92.98 W m-2).The effects of low light (LL) on plant photosynthetic pigments, indole alkaloids metabolism and gene expression in C.roseus leaves were investigated. The results shown, the content of chlorophyll and carotenoid was comparatively lower than control at 3rd days (P<0.05), the ratio of chlorophyll a/b and car/chl was not significantly lower than control, and the changes in photosynthetic pigments reflected plant adaptation to LL. The contents of VIN and CAT in leaves increased slightly under low light, and peaked on 15th day (0.57 g mg-1 ± 0.0456) and on 30 th day (0.73 g mg-1 ± 0.0304) respectively, but VBL content decreased compared with control under LL, indicating that biosynthesis of smaller indole alkaloids were promoted under LL. LL-induced increases in TIA transcript levels for 5 genes occurred in the following order, deacetylvindoline 4-O-acetyl transferase (Dat), tryptophan decarboxylase (Tdc), desacetoxyvindoline 4-hydroxylase (D4h), strictosidine synthase (Str), geraniol 10-hydroxylase (G10h), the results suggested that variations in the timing of LL induced increases in transcript levels might be related to complex interactions.
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