Antag0onistic histone modifiers coordinate flooding stress tolerance and memory in plants

洪水是世界各地日益严重的问题。除了对人们的家庭和企业造成毁灭性影响外，它还严重影响牲畜和作物的生存，最终可能影响农民的生计和粮食生产。我们种植的许多主要作物（小麦、水稻、土豆）特别容易受到洪水的影响，洪水通过限制氧气的供应导致植物死亡。如果我们想要开发出更有可能抵御洪水的新改良作物品种，那么我们首先需要了解植物是如何在分子和基因水平上感知和应对洪水胁迫的。以拟南芥（一种常见的杂草）等模式植物物种为基础的实验室实验可以帮助确定控制洪水（和其他）胁迫反应的潜在生物学原理，这可以成为作物中更有针对性的育种和生物技术方法的重点。植物胁迫生物学中的一个新现象是植物可以通过化学修饰基因来感知和“记住”以前的胁迫（称为表观遗传学）。我们最近发现，一种名为VRN2的保守植物蛋白，通过关闭基因表达来帮助建立这种类型的环境表观遗传记忆，在洪水胁迫下增加。因此，我们预测它可能与促进洪水记忆有关。我们现在已经证明，先前暴露于洪水的拟南芥植物比没有接受过这种先前压力的植物有更好的存活率，这取决于VRN2。我们还发现了另一种蛋白质，称为REF6，它的目标是洪水相关基因。有趣的是，REF6也是一种表观遗传调节剂，但其作用方式与VRN2相反，通过激活基因表达。我们提出，这些拮抗记忆蛋白是一个以前未被描述的洪水响应调节因子网络的一部分，它对控制短期和长期基因表达变化很重要，从而促进洪水恢复能力，并为植物提供对胁迫的积极记忆。有了这笔拨款，我们将更详细地探索这一概念，特别关注REF6组件的特征。为了实现这一目标，我们将在拟南芥中使用一系列分子，遗传，生物化学和生理实验来回答以下问题：(1)REF6的洪水响应基因靶点是什么？(2)洪水期间REF6是如何靶向这些基因的？(3) REF6和VRN2有哪些共同和不同的基因靶点？(4)这些蛋白的联合活性如何协调全局基因表达，促进洪水胁迫耐受和记忆？通过回答这些问题，我们的工作将揭示洪水胁迫信号如何直接转化为表观遗传变化，为植物如何感知、响应和适应环境中的胁迫提供新的、详细的基础见解。虽然拟南芥不是一种作物，但人们希望这个项目的结果将为植物育种家和生物技术专家提供新的信息，帮助他们开发更能抵御洪水的重要作物的改良品种，这将有助于改善全球粮食安全。

Flooding is an increasing problem around the world. In addition to having devastating effects on people's homes and businesses, it severely impacts livestock and crop survival, which can ultimately affect farmer's livelihoods and food production. Many of the key crops we grow (wheat, rice, potatoes) are particularly susceptible to floods, which cause plant death by limiting oxygen availability. If we want to develop new improved crop varieties that have a better chance at withstanding floods, then we first need to understand how plants sense and respond to flooding stress at the molecular and genetic level. Lab based experiments on model plant species, such as Arabidopsis (a common weed), can help to identify the underlying biological principles that control flooding (and other) stress responses, which can then be the focus of more targeted breeding and biotechnology approaches in crops.An emerging phenomenon in plant stress biology is the concept that plants can sense and "remember" previous stresses by chemically modifying genes (referred to as epigenetics). We recently showed that a conserved plant protein called VRN2, which helps to establish this type of environmental epigenetic memory by switching off gene expression, increases in response to flooding stress. Therefore, we predicted it might be involved in promoting a memory of floods. We have now shown that Arabidopsis plants that were previous exposed to a flood have better survival rates than plants that did not receive this prior stress, and that this is dependent on VRN2. We have also identified a second protein, called REF6, that targets flood-associated genes. Interestingly, REF6 is also an epigenetic regulator, but works in the opposite way to VRN2 by activating gene expression. We propose that these antagonistic memory proteins are part of a previously uncharacterised network of flood-responsive regulators that is important or controlling short- and long-term gene expression changes that promote flooding resilience and provide plants with a positive memory of stress. With this grant, we will explore this concept in more detail, with particular focus on characterising the REF6 component.To achieve this, we will use a range of molecular, genetic, biochemistry and physiological experiments in Arabidopsis to answer the following questions: (1) What are flood-responsive gene targets of REF6? (2) How is REF6 targeted to these genes during floods? (3) What are the shared and distinct gene targets of REF6 and VRN2? (4) How does the combined activity of these proteins coordinate global gene expression to promote flooding stress tolerance and memory? By answering these questions, our work will reveal how flooding stress signals are directly converted into epigenetic changes, providing fundamental new and detailed insight into how plants can sense, respond, and adapt to stresses in their environment. Whilst Arabidopsis is not a crop, it is hoped that the results of this project will provide plant breeders and biotechnologists with new information that could help them to develop improved varieties of important crops that are better able to withstand floods, and which will help to improve global food security.