光照强度对南方红豆杉紫杉醇含量及相关酶基因表达的影响

摘要

[目的]研究光照强度对南方红豆杉中紫杉醇和10-脱乙酰基巴卡丁Ⅲ(10-deacetylbaccatin Ⅲ,10-DABⅢ)含量变化,探讨其可能的环境适应机制.[方法]通过高效液相色谱法(high performance liquid chromatography,HPLC)测定不同遮光率(50％、70％和90％)分别遮光30、60、90d后紫杉醇和10-DABⅢ含量;通过PCR法测定相关酶基因表达量.[结果]光照强度能够影响紫杉醇的积累.遮光0～90d,空白组紫杉醇和I0-DABⅢ含量呈下降趋势,各遮光组呈先升后降的趋势,但差异无统计学意义(P＞0.05).其中50％和70％遮光组明显高于空白组及90％遮光组(P＜0.01).此外,光照对紫杉二烯5α-羟基化酶(taxane 5α-hydroxylase,TH5α)、紫杉烷7β-羟基化酶(taxane 7β-hydroxylase,7β)和紫杉烷14β-羟基化酶(taxane 14β-hydroxylase,140H)基因表达也存在明显影响,70％遮光组TH5α基因表达量随遮光时间延长而增加,140H基因则下降(P＜0.01).[结论]本研究初步得到光照因素可以影响南方红豆杉次生代谢产物的合成及相关酶基因的表达,适当的遮光(70％遮光)可以提高紫杉醇的含量,且遮光3月内紫杉醇含量稳定.%[Objective] The changes of paclitaxel and 10-deacetylbaccatin Ⅲ(10-DABⅢ) in Taxus chinensis var.Mairei were studied,and the possible environmental adaptation mechanism was discussed.[Methods] The contents of paclitaxel and 10-DABⅢ were measured by high performance liquid chromatography(HPLC) at different shading rates(50％,70％ and 90％) for 30,60 and 90d respectively.The expression of related enzyme gene was determined by quantitative real-time PCR.[Result] Light intensity can affect the accumulation of paclitaxel.The content of paclitaxel and 10-DABⅢ in the blank group decreased at 0 to 90d,and the shading group increased firstly and then decreased,but there was difference(P＞0.05).50％ and 70％ of the shading group were significantly higher than the blank group and 90％ shading group(P＜0.01).In addition,the expression of 5α-hydroxylase(TH5α),taxane 7β-hydroxylase(7β) and taxane 14β-hydroxylase(14OH) gene were also significantly affected by irradiation.Compared with the blank group,the expression of 7β and 14OH genes was negatively correlated with shading time at 70％ shading,while the trend of 50％ and 90％ shading was not obvious and it was presumed that 7β and 14OH gene in the taxane synthesis process for the competitive relationship.[Conclusion] In this study,the preliminary results showed that light factors could affect the synthesis of secondary metabolites and the expression of related enzyme genes.Appropriate shading(70％ shading) could increase the content of paclitaxel and paclitaxel content was stable shading in 3 months.