The Arabidopsis gene SCI2 encodes a RNA-binding protein which regulates the suppression of plant response to abiotic stress

我们的农业侧重于生产能够养活我们和我们的动物的农作物。然而，对于无数也想吃它们的食草动物昆虫和线虫来说，这些作物是有吸引力的食物。人们通常不知道植物是非常复杂的有机体：尽管它们可能看起来反应迟钝，但它们不断监测自己和环境，当它们感觉到自己受到虫害或病原体的攻击，或暴露在干旱或盐碱等非生物胁迫下时，它们会迅速做出反应，进行自卫。这些防御反应不仅是物理的，也是化学的。化学反应是基于这样一个事实：植物是合成有机化学的大师：为了应对害虫的攻击，它们合成各种有毒化合物，包括挥发性萜类化合物、有毒生物碱、酚类和类黄酮类化合物。这些化合物的产生使所有昆虫望而却步，除了最果断或防御最好的昆虫。一个意想不到的推论是，由于我们对农作物的早期选择和育种故意产生了缺乏许多这些化合物造成的苦味的品种，因此我们的驯化品种也在无意中被培育成容易受到害虫攻击的品种。其他导致产量下降的重要因素包括干旱、盐碱和机械损坏。我实验室的研究表明，植物对害虫的反应与植物对干旱、盐分和机械损伤的反应有许多相似之处：即植物对这些逆境的反应方式有共同的特征。我们希望了解植物如何检测逆境，然后转换这个信号来诱导适应植物抵抗逆境的反应。我们已经证明，当植物受到昆虫伤害或受到压力时，它们会产生一种名为茉莉酸的化合物，这种化合物似乎会穿过植物并诱导一条信号通路，诱导对压力的反应，包括产生次生化学产品。我们已经确定了一些调节茉莉酸信号通路的基因。这个项目是为了描述我们最近发现的这一途径的一个新组成部分，称为SCI2。当SCI2发生突变时，植物对伤害和胁迫的反应大大增强，抗逆性也大大增强。这意味着SCI2的正常功能是抑制这些反应。因此，应激反应途径包括反应的激活物和抑制物。由于SCI2的合成本身是由茉莉酸激活的，这表明茉莉酸信号激活了茉莉酸反应途径的抑制者。我们怀疑这样的机制可能有助于调节植物对茉莉酸的组织特异性反应。SCI2是一种预计会与其他基因的RNA产物结合的蛋白质。因此，我们预计SCI2将通过调节这些RNA的处理来发挥作用，通过增强或降低它们的稳定性。因此，我们将鉴定与SCI2结合的RNA，确定SCI2蛋白的水平是否影响这些RNA的稳定性，并发现SCI2基因的表达是如何调控的，以及SCI2调控哪些基因表达。

Our agriculture focuses on the production of crops that will feed us and our animals. However, these crops are attractive food for the myriad of herbivore insects and nematodes that also wish to eat them. It is not generally known that plants are extraordinarily sophisticated organisms: although they may appear to unresponsive, they constantly monitor themselves and their environment, and when they sense they have been attacked by insect pests or pathogens, or exposed to an abiotic stress such as drought or salinity, they respond rapidly to defend themselves. These defence responses are not only physical, but also chemical. The chemical response is based on the fact that plants are the masters of synthetic organic chemistry: in response to attack by pests they synthesise a variety of toxic compounds that include volatile terpenes, and toxic alkaloids, phenolics, and flavonoids. The production of these compounds deters all but the most determined, or well-defended, of insects. An unexpected corollary is that because the early selection and breeding of our crop plants deliberately produced varieties that lacked the bitter flavours many of these compounds cause, our domesticated varieties have therefore also been bred, unintentionally, to be vulnerable to pests. Other important factors that reduce yield include drought, salinity, and mechanical damage. Research in my laboratory has shown that plant response to pests has many similarities to plant response to drought, salinity, and to mechanical damage: that is, there are common features in the ways in which plants respond to these stresses. We wish to understand how the plant detect the stress, and then converts this signal to induce a response that adapts the plant to resist that stress. We have shown that when plants are wounded by insects, or are subject to stress, they make a compound called jasmonate, which appears to travel through the plant and induce a signal pathway that induces responses to stress, including the production of secondary chemical products. We have identified a number of genes that regulate the jasmonate signal pathway. This project is to characterise a new component of this pathway we recently discovered, called SCI2. When SCI2 is mutated the plant has greatly enhanced response to wounding and to stress, and greatly enhanced resistance. This means that the normal function of SCI2 is to suppress these responses. Therefore, the stress response pathway includes both activators and suppressers of the response. Because the synthesis of SCI2 is itself activated by jasmonate, this indicates that the jasmonate signal activates a suppresser of the jasmonate response pathway. We suspect that such a mechanism could assist in regulating the tissue-specificity of plant response to jasmonate. SCI2 is a protein predicted to bind to RNA products of other genes. We anticipate therefore that SCI2 will function by regulating the processing of these RNAs, by enchancing or reducing their stability. Therefore we shall identify the RNAs that bind SCI2, determine whether the level of the SCI2 protein affects the stability of these RNAs, and discover how expression of the SCI2 gene is regulated, and what gene expression SCI2 regulates.