桂花OfLCYB提高转基因烟草类胡萝卜素含量和低温胁迫的抗性OA北大核心

Lycopene β-cyclase(LCYB)is a key enzyme that catalyzed lycopene in carotenoid biosynthesis pathway.Osmanthus fragrans is mainly distributed in the south of China.O.fragrans,which bloom in late autumn and winter will show a phenomenon of deepening color when faced with low temperatures.In this study,it was found that the petal color of O.fragrans became darker,the carotenoid content increased significantly,and the expression of key synthetic gene OfLCYB was up-regulated by relatively low temperature treatment.To study the mechanism of OfLCYB accumulation and response to carotenoids,in this study,OfLCYB gene(GenBank No.PP438593)was cloned from O.fragrans petals,and overexpression vector was constructed to transform tobacco(Nicotiana tabacum).The results showed that,overexpression of OfLCYB could promote the accumulation of carotenoids in the leaves of transgenic tobacco,and promote the expression of related genes involved in carotenoid biosynthesis pathway.After low temperature treatment(4℃),tobacco leaves with OfLCYB overexpression showed better low temperature tolerance compared with control plants.Under low temperature treatment,relative electrolyte leakage(REL)and malondialdehyde(MDA)contents in leaves of transgenic plants were significantly lower than those of control plants.The activity of Superoxide dismutase(SOD),peroxidase(POD),catalase(CAT)and proline content were significantly increased.In addition,compared with control plants,the expression levels of 2 cold response transcription factors NtDREB1(dehydration responsive element binding 1)and NtDREB3,and 2 cold induction genes NtERD10A(early responsive to dehydration 10A)and NtERD10B in transgenic tobacco leaves were up-regulated.According to the results,it was speculated that OfLCYB might enhance plant low temperature tolerance by promoting carotenoid synthesis.This study provides an reference for improving cold tolerance of O.fragrans and expanding its cultivation area.