坛紫菜色素突变体色素基因的表达定量分析

Quantitative analysis of pigment gene expression in pigment mutants of Porphyra haitanensis

以野生型和6种不同色泽的坛紫菜色素突变体为材料,通过实时荧光定量PCR技术分析了4种主要色素基因(Cpeα、Cpcα、Apcβ、Chl.a)在不同色泽突变体不同生长期(初期、盛期、末期)的相对表达水平。结果表明在不同色泽不同生长期的坛紫菜色素突变体中,各色素基因表达水平由高到低均为Apcβ>Cpcα>Chl.a>Cpeα,且Cpeα基因的表达水平最不稳定,会随着生长过程发生显著变化,而Cpcα、Apcβ和Chl.a基因表达水平则相对稳定;此外,对色素突变体和野生型藻体中色素基因表达水平和相应色素蛋白含量的线性相关回归分析结果表明二者间没有相关性,即各色素基因的表达水平与藻体最终显示的颜色无关,由此推测坛紫菜色素突变的可能机制是色素蛋白合成过程中一些相关调控基因突变所致。

Phycoerythrin （PE）, phycocyanin （PC）, allophycocyanin （APC）, and chlorophyll a（Chl.a） are the four major photosynthetic pigments of Porphyra haitanensis. Their contents and ratio determine the blade color of Porphyra. In this study, the relative expressed levels of four pigment genes （Cpeα, Cpcα, Apcβ, and Chl.a） in different growth phases （early phase, bloom phase, and final phase） were determined using quantitative real-time PCR （qPCR） in one wild line and six pigment mutant lines of P. haitanensis. In all the lines, the relative expression levels of the four pigment genes were in the sequence： Apcβ〉Cpcα〉 Chl.a〉Cpeα. The expressed level of Cpeα varied significantly in the different phases in all the lines; how-ever, the expressions of Cpcα, Apcβ, and Chl.a were stable in all phases in all lines. Furthermore, liner correlation and regression analysis indicated that the expression levels of the pigment genes had no relation to the pigment protein contents in any of the lines. In other words, the expression levels of the four pigment genes had no relation to the differences in blade color among the Porphyra lines. Based on these results, we speculate that the pigment mutation of P. haitanensis was induced by mutations in genes that affect the synthesis of the pigment proteins.