Su Xue, Zhang Xiaolong, Luo Jie, Wang Yu, Feng Bin, Yang Yanqi, Zhang Biaoming, Li Yan, Zhang Haitao, Yuan Wenya, Li Haitao
State Key Laboratory of Biocatalysis and Enzyme Engineering, School of Life Sciences, Hubei University, Wuhan, 430062, China.
Planta. 2025 Jun 3;262(1):12. doi: 10.1007/s00425-025-04731-z.
The IAA7-ARF7-ARF19 regulatory module employs Phox and Bem1 (PB1) domain-mediated interactions to suppress ARF7/ARF19 transcriptional activation, thereby diversely regulating auxin-dependent growth and development. Auxin plays a key role in regulating diverse plant developmental processes through canonical signaling pathways mediated by Auxin Response Factors (ARFs) and Auxin/INDOLE-3-ACETIC ACID (Aux/IAA) proteins. However, the ARF partners and their functional contribution to IAA7-mediated plant growth and auxin response remain poorly understood. Here we show that IAA7 and ARF7 or ARF19 are co-expressed across Arabidopsis development. IAA7 can interact physically with ARF7 and ARF19, and this interaction suppresses the transcriptional activation activity of both ARFs in auxin signaling. Genetic and phenotypic analyses reveal that ARF7 and ARF19 are major contributors to IAA7-mediated growth and development, including auxin sensitivity and gravitropism of root, root hair formation and elongation, and lateral root formation. In contrast, these ARFs only partially regulate IAA7-mediated hypocotyl gravitropism, root and inflorescence stem elongation, and leaf morphology. However, IAA7 regulates hypocotyl auxin sensitivity through ARF activators distinct from ARF7 and ARF19. Our results reveal the diverse degree of contribution by the ARF7 and ARF19, being pairs of IAA7, in regulating plant growth, and highlight the significance of multiple parallel IAA-ARF modules existing in the plant.
IAA7-ARF7-ARF19调控模块利用Phox和Bem1（PB1）结构域介导的相互作用来抑制ARF7/ARF19的转录激活，从而以多种方式调控生长素依赖的生长和发育。生长素通过由生长素响应因子（ARFs）和生长素/吲哚-3-乙酸（Aux/IAA）蛋白介导的经典信号通路，在调控多种植物发育过程中发挥关键作用。然而，ARF的伙伴及其对IAA7介导的植物生长和生长素响应的功能贡献仍知之甚少。在这里，我们表明IAA7与ARF7或ARF19在拟南芥整个发育过程中共同表达。IAA7能与ARF7和ARF19发生物理相互作用，这种相互作用抑制了生长素信号传导中两个ARF的转录激活活性。遗传和表型分析表明，ARF7和ARF19是IAA7介导的生长和发育的主要贡献者，包括根对生长素的敏感性和向地性、根毛的形成和伸长以及侧根的形成。相比之下，这些ARF仅部分调节IAA7介导的下胚轴向地性、根和花序茎的伸长以及叶片形态。然而IAA7通过不同于ARF7和ARF19的ARF激活剂调节下胚轴对生长素的敏感性。我们的结果揭示了作为IAA7配对的ARF7和ARF19在调控植物生长中不同程度的贡献，并突出了植物中存在多个平行IAA-ARF模块的重要性。
