光合作用抑制剂DCMU对三角褐指藻岩藻黄素含量和叶绿素荧光特征及关键基因表达的影响

为了阐明岩藻黄素生物合成与光合作用之间的关系,研究不同浓度光合作用抑制剂二氯苯基二甲脲(DCMU)对三角褐指藻细胞密度、岩藻黄素含量、叶绿素含量、叶绿素荧光特征和相关关键基因表达的影响。结果表明,不同浓度DCMU均抑制细胞生长,使三角褐指藻内岩藻黄素含量降低,叶绿素含量增加;当DCMU浓度为1 mg·L^-1时,三角褐指藻内岩藻黄素含量最少,较CK减少了26.98%,而叶绿素含量最高(3.16 mg·g^-1)。随着DCMU浓度的增加,电子传递的抑制作用增强,实际光化学量子效率Y(Ⅱ)]、 rETR、相对电子传递速率(NPQ)、光化学淬灭系数(qP)和快速光曲线初始斜率(α)均明显降低,DCMU为1 mg·L^-1时出现电子完全阻断的现象。定量PCR分析结果表明,岩藻黄素合成通路关键基因pds、lcyb的表达水平与岩藻黄素含量变化趋势一致。相关性分析表明,岩藻黄素含量与Y(Ⅱ)、qP和α之间存在显著正相关(P<0.05),说明三角褐指藻岩藻黄素的生物合成不仅与岩藻黄素合成关键基因的表达有关,还与光合作用有关。本研究为进一步探明三角褐指藻岩藻黄素合成的生理生化和分子机理提供了参考。

Effects of the Photosynthesis Inhibitor DCMU on Fucoxanthin Content,Chlorophyll Fluorescence Characteristics and Key Genes of Phaeodactylum tricornutum

In order to clarify the relationship between fucoxanthin biosynthesis and photosynthesis, the effects of different concentrations of the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) on cell density, fucoxanthin content, chlorophyll content, chlorophyll fluorescence characteristics, and expression of related key genes of Phaeodactylum tricornutum were studied. The results showed that different concentrations of DCMU inhibited cell growth, reduced fucoxanthin content in Phaeodactylum tricornutum, and increased chlorophyll content. When the concentration of DCMU was 1 mg·L^-1, the content of fucoxanthin in Phaeodactylum tricornutum was the lowest, which was 26.98% lower than that of CK, and the chlorophyll content was the highest (3.16 mg·g^-1). With the concentration of DCMU increases, the inhibition of electron transfer increases, and the chlorophyll fluorescence parameters Y(Ⅱ), rETR, NPQ, qP, and α were all significantly reduced. At 1 mg·L^-1, electrons were even completely blocked. The results of quantitative PCR analysis showed that the expression level of key genes pds、lcyb in the fucoxanthin synthesis pathway showed the same trend as the fucoxanthin content trend. Correlation analysis showed that there was a significant positive correlation between the fucoxanthin content and Y(Ⅱ), qP and α(P<0.05), indicating that the biosynthesis of fucoxanthin from Phaeodactylum tricornutum is not only related to the expression of key genes for fucoxanthin synthesis, but also to photosynthesis. This study provides a reference for further investigation of the physiological, biochemical, and molecular mechanisms of fucoxanthin accumulation in Phaeodactylum tricornutum.