Hardtke Christian S, Ckurshumova Wenzislava, Vidaurre Danielle P, Singh Sasha A, Stamatiou George, Tiwari Shiv B, Hagen Gretchen, Guilfoyle Tom J, Berleth Thomas
McGill University, Biology Department, 1205 Docteur Penfield Avenue, Montréal, Québec H3A 1B1, Canada.
Development. 2004 Mar;131(5):1089-100. doi: 10.1242/dev.00925.
Transcription factors of the auxin response factor (ARF) family have been implicated in auxin-dependent gene regulation, but little is known about the functions of individual ARFs in plants. Here, interaction assays, expression studies and combinations of multiple loss- and gain-of-function mutants were used to assess the roles of two ARFs, NONPHOTOTROPIC HYPOCOTYL 4 (NPH4/ARF7) and MONOPTEROS (MP/ARF5), in Arabidopsis development. Both MP and NPH4 interact strongly and selectively with themselves and with each other, and are expressed in vastly overlapping domains. We show that the regulatory properties of both genes are far more related than suggested by their single mutant phenotypes. NPH4 and MP are capable of controlling both axis formation in the embryo and auxin-dependent cell expansion. Interaction of MP and NPH4 in Arabidopsis plants is indicated by their joint requirement in a number of auxin responses and by synergistic effects associated with the co-overexpression of both genes. Finally, we demonstrate antagonistic interaction between ARF and Aux/IAA gene functions in Arabidopsis development. Overexpression of MP suppresses numerous defects associated with a gain-of-function mutation in BODENLOS (BDL)/IAA12. Together these results provide evidence for the biological relevance of ARF-ARF and ARF-Aux/IAA interaction in Arabidopsis plants and demonstrate that an individual ARF can act in both invariantly programmed pattern formation as well as in conditional responses to external signals.
生长素响应因子（ARF）家族的转录因子参与生长素依赖的基因调控，但对于植物中单个ARF的功能却知之甚少。本文通过相互作用分析、表达研究以及多个功能缺失和功能获得突变体的组合，来评估两个ARF，即非向光性下胚轴4（NPH4/ARF7）和单翅（MP/ARF5）在拟南芥发育中的作用。MP和NPH4都能与自身及彼此强烈且选择性地相互作用，并且在大量重叠的区域表达。我们发现这两个基因的调控特性远比其单突变体表型所显示的更为相关。NPH4和MP能够控制胚胎中的轴形成以及生长素依赖的细胞扩展。拟南芥植株中MP和NPH4的相互作用体现在它们在许多生长素反应中的共同需求以及与两者共过表达相关的协同效应上。最后，我们证明了ARF与Aux/IAA基因功能在拟南芥发育中的拮抗相互作用。MP的过表达抑制了与BODENLOS（BDL）/IAA12功能获得突变相关的众多缺陷。这些结果共同为ARF-ARF和ARF-Aux/IAA相互作用在拟南芥中的生物学相关性提供了证据，并表明单个ARF既能在固定程序的模式形成中发挥作用，也能在对外部信号的条件反应中发挥作用。
