Department of Plant Biology and Ecology, College of Life Sciences, Nankai University and Tianjin Key Laboratory of Protein Sciences, Tianjin 300071, China.
Institute of Biochemistry and Biology, Plant Physiology, University of Potsdam, D-14476 Potsdam-Golm, Germany.
Int J Mol Sci. 2021 Jan 4;22(1):437. doi: 10.3390/ijms22010437.
Plant membrane sterol composition has been reported to affect growth and gravitropism via polar auxin transport and auxin signaling. However, as to whether sterols influence auxin biosynthesis has received little attention. Here, by using the sterol biosynthesis mutant () and sterol application, we reveal that cycloeucalenol, a CPI1 substrate, and sitosterol, an end-product of sterol biosynthesis, antagonistically affect auxin biosynthesis. The short root phenotype of was associated with a markedly enhanced auxin response in the root tip. Both were neither suppressed by mutations in polar auxin transport (PAT) proteins nor by treatment with a PAT inhibitor and responded to an auxin signaling inhibitor. However, expression of several auxin biosynthesis genes () was upregulated in Functionally, mutation reduced the auxin response in and partially rescued its short root phenotype. In support of this genetic evidence, application of cycloeucalenol upregulated expression of the auxin responsive reporter (β-glucuronidase) and of several auxin biosynthesis genes, while sitosterol repressed their expression. Hence, our combined genetic, pharmacological, and sterol application studies reveal a hitherto unexplored sterol-dependent modulation of auxin biosynthesis during Arabidopsis root elongation.
植物膜甾醇组成已被报道通过极性生长素运输和生长素信号影响生长和向重力性。然而，固醇是否影响生长素生物合成还很少受到关注。在这里，我们通过使用固醇生物合成突变体 () 和固醇应用，揭示了环羊毛甾醇，CPI1 的底物，和谷甾醇，固醇生物合成的终产物，拮抗地影响生长素生物合成。突变体的短根表型与根尖生长素反应显著增强有关。这两者都不会被极性生长素运输 (PAT) 蛋白的突变或 PAT 抑制剂的处理所抑制，并且对生长素信号抑制剂有反应。然而，几种生长素生物合成基因 () 的表达在中上调。功能上，突变减少了在中的生长素反应，并部分挽救了其短根表型。支持这一遗传证据，环羊毛甾醇的应用上调了生长素响应报告基因 (β-葡萄糖醛酸酶) 和几种生长素生物合成基因的表达，而谷甾醇则抑制了它们的表达。因此，我们的遗传、药理学和固醇应用研究的综合结果揭示了一个迄今未知的在拟南芥根伸长过程中固醇依赖性调节生长素生物合成的机制。
