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Abstract：
Plant growth and development are coordinated by multiple environmental and endogenous signals. Brassinosteroid (BR) and ethylene (ET) have overlapping functions in a wide range of developmental processes. However, the relationship between the BR and ET signalling pathways has remained unclear. Here, we show that BR and ET interdependently promote apical hook development and cell elongation through a direct interaction between BR-activated BRASSINOZALE-RESISTANT1 (BZR1) and ET-activated ETHYLENE INSENSITIVE3 (EIN3). Genetic analysis showed that BR signalling is required for ET promotion of apical hook development in the dark and cell elongation under light, and ET quantitatively enhances BR-potentiated growth. BZR1 interacts with EIN3 to co-operatively increase the expression of HOOKLESS1 and PACLOBUTRAZOL RESISTANCE FACTORs (PREs). Furthermore, we found that BR promotion of hook development requires gibberellin (GA), and GA restores the hookless phenotype of BR-deficient materials by activating EIN3/EIL1. Our findings shed light on the molecular mechanism underlying the regulation of plant development by BR, ET and GA signals through the direct interaction of master transcriptional regulators.
摘要：
植物的生长发育由多种环境和内源信号协调。油菜素类固醇（BR）和乙烯（ET）在广泛的发育过程中具有重叠的功能。然而,BR和ET信号通路之间的关系尚不清楚.这里,我们表明，BR和ET通过BR激活的BRASSINOZALE-RESISTANT1（BZR1）和ET激活的乙烯不敏感3（EIN3）之间的直接相互作用相互依赖地促进根尖钩发育和细胞伸长。遗传分析表明，在黑暗中ET促进根尖钩发育和光照下细胞伸长需要BR信号，ET定量地增强了BR增强的生长。BZR1与EIN3相互作用以协同增加HOOKLESS1和广布唑耐药因子(PRES)的表达。此外，我们发现BR促进钩发育需要赤霉素(GA)，和GA通过激活EIN3/EIL1恢复BR缺陷材料的无钩表型。我们的发现揭示了BR调节植物发育的分子机制，ET和GA旌旗灯号经由过程掌握转录调控因子的直接互相感化。
