拟南芥 QUA1基因在光信号途径中的表达与功能分析

摘要

Plants not only use light as an energy source for photosynthesis, but also have to monitor the light quality and quantity input to execute appropriate physiological and developmental responses, such as cell differentia-tion, structural and functional changes, as well as the formation of tissues and organs. The process is referred to as photomorphogenesis. Arabidopsis QUA1 (QUASIMODO1), which functions in pectin synthesis, is identified as a member of glycosyltransferases. Previously, the hypocotyl elongation of the qua1-1 mutant was shown to be inhibited under dark conditions. In this study, we used the qua1-1/cry1 and qua1-1/phyB double mutants as the materials to study the function of the QUA1 gene in light signal transduction. The results showed that QUA1 not only participated in hypocotyl elongation under dark conditions, but also in blue light, red light and far red light conditions. In qua1-1 mutant seedlings, both the cell length of hypocotyl and the light-regulated gene expression were affected. Compared with cry1 and phyB mutants, qua1-1/cry1 and qua1-1/phyB double mutants had the shorter hypocotyl. Light-regulated gene expression was also affected in the double mutants. These data indicated that QUA1 might participate in the light signal transduction regulated by CRY1 and PHYB. Hence, the QUA1 gene may play multiple roles in light signal transduction by regulating the cell elongation and light-regulated gene expression.%光信号在植物生长发育过程中具有非常重要的作用。不同的光信号通过调节植物下游基因的表达，进而影响细胞分化、结构和功能的改变，以及组织和器官的形成，参与植物光形态建成。QUA1(QUASIMODO1)是拟南芥糖基转移酶家族中的一个成员，参与植物细胞壁中果胶的合成。本文以拟南芥 qua1-1/cry1以及qua1-1/phyB 双突变体为材料，对 QUA1基因在光信号途径中的功能进行了分析。结果显示，qua1-1突变体在暗、蓝光、红光以及远红外光培养条件下下胚轴的伸长均受到抑制，QUA1基因的表达同样受到光信号的调节，而且突变体中多种光信号调节基因的表达也受到了影响。通过对 qua1-1突变体下胚轴的观察发现，突变体下胚轴表皮细胞长度明显变短。与 cry1以及 phyB 突变体相比，qua1-1/cry1和 qua1-1/phyB 双突变体下胚轴长度明显变短，而且双突变体中光信号调节基因的表达也有明显变化，表明 QUA1可能参与了 CRY1以及 PHYB介导的蓝光及红光信号传导。以上结果表明 QUA1影响了下胚轴细胞的伸长以及光信号调节基因的表达，并参与调控多种光信号传导途径。