Leu W M, Cao X L, Wilson T J, Snustad D P, Chua N H
Laboratory of Plant Molecular Biology, Rockefeller University, New York, New York 10021-6399, USA.
Plant Cell. 1995 Dec;7(12):2187-96. doi: 10.1105/tpc.7.12.2187.
Arabidopsis contains six alpha-tubulin and nine beta-tubulin genes that are expressed in a tissue-specific and developmentally regulated manner. We analyzed the effects of light on tubulin mRNA abundance in Arabidopsis seedlings using RNA gel blot hybridizations and gene-specific probes. Transcript levels of all 15 tubulin genes were decreased by continuous white light, although to different degrees. Detailed analysis was performed with the beta-tubulin TUB1 gene. The transcript level of TUB1 was high in etiolated seedlings and decreased to approximately 20% of the dark mRNA level after 2 to 6 hr of white light treatment. We showed that this downregulation requires high-irradiance light treatment and that multiple photoreceptors are involved. In particular, using phytochrome mutants and narrow wave band light, we demonstrated that both the phytochrome A (phyA)-mediated far-red light high-irradiance response and the phytochrome B (phyB)-mediated red light high-irradiance response are involved in the downregulation of TUB1 expression by white light. Histochemical analysis of transgenic plants expressing a TUB1-beta-glucuronidase chimeric transgene indicated that the downregulation observed only in hypocotyls and not in roots is controlled transcriptionally.
拟南芥含有六个α-微管蛋白基因和九个β-微管蛋白基因，这些基因以组织特异性和发育调控的方式表达。我们使用RNA凝胶印迹杂交和基因特异性探针分析了光对拟南芥幼苗中微管蛋白mRNA丰度的影响。尽管程度不同，但连续白光使所有15个微管蛋白基因的转录水平均下降。我们对β-微管蛋白TUB1基因进行了详细分析。TUB1的转录水平在黄化幼苗中较高，在白光处理2至6小时后降至黑暗中mRNA水平的约20%。我们表明这种下调需要高辐照度光处理，并且涉及多种光感受器。特别是，使用光敏色素突变体和窄波段光，我们证明了光敏色素A（phyA）介导的远红光高辐照度反应和光敏色素B（phyB）介导的红光高辐照度反应都参与了白光对TUB1表达的下调。对表达TUB1-β-葡萄糖醛酸酶嵌合转基因的转基因植物进行的组织化学分析表明，仅在下胚轴而非根中观察到的下调是由转录控制的。
