Functional analysis of the role of the Arabidopsis NAC transcription factor JUNGBRUNNEN1 (JUB1) in GA and BR signalling

激素在调节植物生长、发育和防御反应中起着至关重要的作用。植物激素的生物合成途径已在很大程度上阐明，然而，激素水平的调节机制仍然知之甚少。我们的小组研究转录因子（TF）的功能，特别是那些调节植物生长和胁迫反应。分析的TF之一是JUNGBRUNNEN 1（JUB 1），一种NAC转录因子。JUB 1在拟南芥中的过表达强烈地延长了寿命，并部分地通过抑制细胞H2 O2水平来赋予对各种非生物胁迫的耐受性。除了延长的寿命，JUB 1过表达子还表现出GA（赤霉酸）和BR（油菜素类固醇）生物合成和感知突变体的典型表型。实验证据表明，JUB 1通过直接转录抑制GA和BR生物合成基因在植物生长和胁迫反应的调节中起着核心作用。因此，该项目的目标是解开JUB 1控制GA和BR生物合成/信号通路的分子机制。这些发现也将为更好地了解JUB 1在调节植物生长中的功能铺平道路。

Hormones play crucial roles in regulating plant growth, development and defence responses. The biosynthetic pathways for plant hormones have been largely elucidated; however, the mechanisms by which hormone levels are regulated are still poorly understood. Our group studies the function of transcription factors (TFs), particularly those regulating plant growth and stress responses. One of the TFs analysed is JUNGBRUNNEN1 (JUB1), a NAC transcription factor. Overexpression of JUB1 in Arabidopsis thaliana strongly extends longevity and confers tolerance to various abiotic stresses in part by dampening the cellular H2O2 level. Beside the extended life span, JUB1 overexpressors show typical phenotypes of GA (gibberellic acid)- and BR (brassinosteroid)-biosynthesis and perception mutants. Experimental evidence suggests that JUB1 plays a central role in the regulation of plant growth and stress responses through direct transcriptional repression of both, GA and BR biosynthesis genes. The goal of the project therefore is to unravel the molecular mechanisms by which JUB1 controls GA and BR biosynthesis/signalling pathways. The discoveries will also pave the way for a better understanding of the functions of JUB1 in regulating plant growth.