Oxygen-sensing through ERFVII action and modulation in Arabidopsis thaliana

Oxygen is a key signalling component of plant biology and, whilst an oxygen-sensing mechanism was previously described in Arabidopsis thaliana. However, key features of the associated PCO N-degron pathway and Group VII ETHYLENE RESPONSE FACTOR (ERFVII) transcription factor substrates remain unknown. We demonstrate that ERFVIIs show non-autonomous activation of root hypoxia tolerance, and are essential for root development and survival under oxygen limiting conditions in the soil. We determine the combined effects of ERFVIIs in controlling genome expression and define genetic and environmental components required for proteasome-dependent oxygen-regulated stability of ERFVIIs through the PCO N-degron pathway. Using a plant extract, unexpected amino-terminal cysteine oxidation to sulphonic acid oxidation level of ERFVIIs was defined, suggesting a requirement for additional enzymatic activity within the pathway. Our results provide a holistic understanding of the properties, functions and readouts of this oxygen-sensing mechanism defined through its role in modulating ERFVII stability.

氧气是植物生物学中关键的信号传导组分，尽管此前已在拟南芥（Arabidopsis thaliana）中报道过一种氧感知机制，但与之相关的PCO N-端降解通路（PCO N-degron pathway）以及VII类乙烯响应因子（ERFVII）转录因子底物的核心特征仍未明确。本研究证实，ERFVII可非自主激活根系低氧耐受性，且对于土壤中限氧环境下的根系发育与存活至关重要。本研究明确了ERFVII在调控基因组表达中的联合效应，并界定了通过PCO N-端降解通路实现蛋白酶体依赖型氧调控ERFVII稳定性所需的遗传与环境组分。通过植物提取物实验，本研究界定了ERFVII此前未被报道的氨基端半胱氨酸氧化至磺酸修饰的水平，提示该通路中尚存在其他未被发现的酶促活性需求。本研究结果全面阐明了这一通过调控ERFVII稳定性发挥功能的氧感知机制的核心属性、生物学功能及其检测特征。