转录调节因子 BBX24 削弱 DELLA 活性以促进拟南芥的避荫反应。

The transcriptional regulator BBX24 impairs DELLA activity to promote shade avoidance in Arabidopsis thaliana.

机构信息

IFEVA, Facultad de Agronomía, Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas, Avenue San Martín 4453, Buenos Aires C1417DSE, Argentina.

1] Instituto de Biología Molecular y Celular de Plantas, Consejo Superior de Investigaciones Científicas-Universidad Politécnica de Valencia, Valencia 46022, Spain [2] Department of Agronomy, Food, Natural Resources, Animals and the Environment (DAFNAE), Padova University, Viale dell'Universitá 16, Legnaro 35020, Italy.

出版信息

Nat Commun. 2015 Feb 6;6:6202. doi: 10.1038/ncomms7202.

DOI:10.1038/ncomms7202

PMID:25656233

Abstract

In response to canopy shade, plant vegetative structures elongate to gain access to light. However, the mechanism that allows a plastic transcriptional response to canopy shade light is not fully elucidated. Here we propose that the activity of PIF4, a key transcription factor in the shade signalling network, is modulated by the interplay between the BBX24 transcriptional regulator and DELLA proteins, which are negative regulators of the gibberellin (GA) signalling pathway. We show that GA-related targets are enriched among genes responsive to BBX24 under shade and that the shade-response defect in bbx24 mutants is rescued by a GA treatment that promotes DELLA degradation. BBX24 physically interacts with DELLA proteins and alleviates DELLA-mediated repression of PIF4 activity. The proposed molecular mechanism provides reversible regulation of the activity of a key transcription factor that may prove especially relevant under fluctuating light conditions.

摘要

为了应对树冠遮荫，植物的营养结构会伸长以获得光照。然而，允许对树冠遮荫光产生可塑性转录反应的机制尚未完全阐明。在这里，我们提出，关键转录因子 PIF4 的活性受转录调节因子 BBX24 和 DELLA 蛋白之间相互作用的调节，DELLA 蛋白是赤霉素（GA）信号通路的负调节剂。我们表明，在遮荫下，与 GA 相关的靶标在对 BBX24 有反应的基因中富集，并且 GA 处理可以挽救 bbx24 突变体的遮荫反应缺陷，该处理促进了 DELLA 的降解。BBX24 与 DELLA 蛋白相互作用，并减轻了 DELLA 对 PIF4 活性的抑制。所提出的分子机制为关键转录因子的活性提供了可逆调节，这在光照波动的条件下可能特别重要。