Zhou Xin, Zhang Zhong-Lin, Park Jeongmoo, Tyler Ludmila, Yusuke Jikumaru, Qiu Kai, Nam Edward A, Lumba Shelley, Desveaux Darrell, McCourt Peter, Kamiya Yuji, Sun Tai-Ping
Department of Biology, Duke University, Durham, North Carolina 27705 (X.Z., Z.-L.Z., L.T., J.P., E.A.N., T.-p.S.); RIKEN Plant Science Center, Yokohama, Kanagawa 230-0045, Japan (J.Y., Y.K.); Department of Cell and Systems Biology, University of Toronto, Ontario M5S 3B2, Canada (S.L., D.D., P.M.); Centre for the Analysis of Genome Evolution and Function, University of Toronto, Ontario M5S 3B2, Canada (D.D.); andState Key Laboratory of Genetic Engineering and Fudan Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China (K.Q.).
Department of Biology, Duke University, Durham, North Carolina 27705 (X.Z., Z.-L.Z., L.T., J.P., E.A.N., T.-p.S.); RIKEN Plant Science Center, Yokohama, Kanagawa 230-0045, Japan (J.Y., Y.K.); Department of Cell and Systems Biology, University of Toronto, Ontario M5S 3B2, Canada (S.L., D.D., P.M.); Centre for the Analysis of Genome Evolution and Function, University of Toronto, Ontario M5S 3B2, Canada (D.D.); andState Key Laboratory of Genetic Engineering and Fudan Institute of Plant Biology, School of Life Sciences, Fudan University, Shanghai 200433, China (K.Q.)
Plant Physiol. 2016 Aug;171(4):2760-70. doi: 10.1104/pp.16.00154. Epub 2016 Jun 2.
The phytohormone gibberellin (GA) plays a key role in promoting stem elongation in plants. Previous studies show that GA activates its signaling pathway by inducing rapid degradation of DELLA proteins, GA signaling repressors. Using an activation-tagging screen in a reduced-GA mutant ga1-6 background, we identified AtERF11 to be a novel positive regulator of both GA biosynthesis and GA signaling for internode elongation. Overexpression of AtERF11 partially rescued the dwarf phenotype of ga1-6 AtERF11 is a member of the ERF (ETHYLENE RESPONSE FACTOR) subfamily VIII-B-1a of ERF/AP2 transcription factors in Arabidopsis (Arabidopsis thaliana). Overexpression of AtERF11 resulted in elevated bioactive GA levels by up-regulating expression of GA3ox1 and GA20ox genes. Hypocotyl elongation assays further showed that overexpression of AtERF11 conferred elevated GA response, whereas loss-of-function erf11 and erf11 erf4 mutants displayed reduced GA response. In addition, yeast two-hybrid, coimmunoprecipitation, and transient expression assays showed that AtERF11 enhances GA signaling by antagonizing the function of DELLA proteins via direct protein-protein interaction. Interestingly, AtERF11 overexpression also caused a reduction in the levels of another phytohormone ethylene in the growing stem, consistent with recent finding showing that AtERF11 represses transcription of ethylene biosynthesis ACS genes. The effect of AtERF11 on promoting GA biosynthesis gene expression is likely via its repressive function on ethylene biosynthesis. These results suggest that AtERF11 plays a dual role in promoting internode elongation by inhibiting ethylene biosynthesis and activating GA biosynthesis and signaling pathways.
植物激素赤霉素（GA）在促进植物茎伸长方面起着关键作用。先前的研究表明，GA通过诱导DELLA蛋白（GA信号转导抑制因子）的快速降解来激活其信号通路。利用在GA含量降低的突变体ga1 - 6背景下的激活标签筛选，我们鉴定出AtERF11是节间伸长过程中GA生物合成和GA信号转导的新型正调控因子。AtERF11的过表达部分挽救了ga1 - 6的矮化表型。AtERF11是拟南芥中ERF/AP2转录因子的ERF（乙烯响应因子）亚家族VIII - B - 1a的成员。AtERF11的过表达通过上调GA3ox1和GA20ox基因的表达导致生物活性GA水平升高。下胚轴伸长试验进一步表明，AtERF11的过表达赋予了更高的GA响应，而功能缺失的erf11和erf11 erf4突变体表现出GA响应降低。此外，酵母双杂交、免疫共沉淀和瞬时表达试验表明，AtERF11通过直接的蛋白质 - 蛋白质相互作用拮抗DELLA蛋白的功能来增强GA信号转导。有趣的是，AtERF11的过表达还导致生长茎中另一种植物激素乙烯水平降低，这与最近的研究结果一致，即AtERF11抑制乙烯生物合成ACS基因的转录。AtERF11对促进GA生物合成基因表达的作用可能是通过其对乙烯生物合成的抑制功能实现的。这些结果表明，AtERF11在通过抑制乙烯生物合成以及激活GA生物合成和信号通路来促进节间伸长方面发挥双重作用。
