光质调控雨生红球藻虾青素合成及油脂积累的效应

Effects of light quality on astaxanthin synthesis and lipid accumulation of Haematococcus pluvialis

为阐明光质对雨生红球藻(Haematococcus pluvialis)虾青素合成和油脂积累的调控效应,本文分析了4种不同光质(白光、红光、蓝光和绿光)对雨生红球藻色素组成、光合作用、总脂含量及脂肪酸组成的影响。结果表明,蓝光处理的藻细胞虾青素含量、虾青素含量/总叶绿素含量比值及总脂含量均高于其他3种光质处理,但实际光化学效率(YⅡ)、最大光化学效率(Fv/Fm)、光化学淬灭系数(qP)和相对电子传递速率(rET)均低于其他3种光质处理,说明蓝光可能在促进虾青素积累的同时会抑制雨生红球藻的光合作用。实时荧光定量PCR检测结果显示,与白光对照相比,蓝光持续上调参与虾青素合成的β-胡萝卜素酮化酶基因(bkt)和八氢番茄红素合成酶基因(psy)的表达,红光处理能诱导参与油体合成的钙蛋白基因(caleosin)在培养4和6 d后高水平表达。根据以上结果推测蓝光下总脂含量的增加可能与其促进虾青素的积累紧密相关,而红光下总脂含量的增加可能与其促进油体合成直接相关。本研究为进一步深入研究不同光质对虾青素和油脂合成的调控机制提供新思路,并为雨生红球藻虾青素工厂化优质高效生产的光环境调控提供理论依据。

In order to clarify the regulatory effect of light quality on astaxanthin synthesis and lipid accumulation of Haematococcus pluvialis,this study was conducted to analyze the effect of light quality (white,red,blue and green lights) on pigment composition,photosynthesis,total lipid content and fatty acid composition.The results show that blue light enhanced astaxanthin content,ratio of astaxanthin content to total chlorophyll content and total lipid content of H.pluvialis,which are significantly higher than those in algal cells treated by white,red and green lights.However,blue light inhibited actual photochemical efficiency(YⅡ),maximum photochemical efficiency (Fv/Fm),photochemical quenching coefficient (qP) and relative electron transfer rate (rET),indicating that blue light accelerated astaxanthin accumulation,accompanied by suppressing photosynthetic activity of H.pluvialis.Quantitative real-time PCR detection showed that blue light treatment induced up-regulation of the astaxanthin synthesis genes,β-carotene ketolase gene(bkt) and phytoene synthase gene (psy),compared to the control of white light treatment.After cultivation for 4 or 6 days,the red light treatment up-regulated the expression of caleosin gene,which was involved in oil body formation.These results suggest that the enhancement of total lipid content induced by blue light may be closely related to the promotion of astaxanthin accumulation,whereas the increased total lipid content induced by red light may be directly related to the oil body synthesis.This study sheds new insights into further study of regulation mechanism of astaxanthin and lipid synthesis under different light quality conditions,and provides a theoretical basis for light environment regulation of astaxanthin production in H.pluvialis.