Role of oxidative stress responses in aluminum and freezing tolerant wheat

氧化应激是对许多非生物和生物胁迫的一种常见反应，是一种关键的信号事件，对应激生存至关重要。我们的假设是，参与控制氧化胁迫的关键基因是耐受非生物胁迫如铝(Al)和低温(LT)所必需的。在9个与小麦耐铝性密切相关的基因中，至少有4个基因被认为直接减少氧化胁迫的影响；一个基因编码控制葡萄糖供应的关键酶，这是维持谷胱甘肽和抗坏血酸等抗氧化剂水平所需的重要前体；另外4个基因编码未知功能的蛋白质。为了了解这些基因在逆境耐受性中的作用，我们将通过以下几个方面对它们的功能进行研究：1)在拟南芥、酵母和小麦中进行功能研究，以证明它们在逆境耐性中的作用；2)为育种者开发简单的耐铝标记；3)分析耐铝基因的差异调控机制。一项对冷驯化小麦植株中存在的表达序列标签(EST)的调查发现，至少有4个基因可以提高对光抑制的抗性。其中三个基因编码的蛋白质可以通过改善能量流动和减少氧化损伤来保护叶绿体机制。这些基因的功能鉴定将通过以下几个方面进行：1)基因表达分析，以确定与耐性密切相关的基因；2)在拟南芥和小麦中进行功能研究。其中一些基因可能在提高植物在各种胁迫下的抗氧化性和生产力方面具有重要的应用。

Oxidative stress is a common response to many abiotic and biotic stresses and is a pivotal signalling event that is central to stress survival. Our hypothesis is that key genes involved in the control of oxidative stress are required for tolerance to abiotic stresses such as aluminum (Al) and low temperature (LT).I) Al tolerance is characterized by the ability to maintain root growth under high Al concentrations. Of the 9 genes shown to be strongly associated with Al tolerance in wheat, at least four are proposed to directly reduce the impact of oxidative stress; one gene encodes a key enzyme controlling glucose supply, an important precursor needed to maintain the level of antioxidants such as glutathione and ascorbate; and the other 4 genes encode proteins of unknown function. To understand the role of these genes in stress tolerance, we will pursue their functional characterization by: 1) Performing function studies in Arabidopsis, yeast and wheat to demonstrate their role in stress tolerance; 2) Developing simple markers of Al tolerance for breeders; 3) Analysing the mechanisms responsible for the differential regulation of Al-tolerance genes.II) LT tolerance is associated with the higher capacity of tolerant plants to resist to oxidative and high light stress at low temperature (photoinhibition). A survey of Expressed Sequence Tags (EST) present in cold acclimated wheat plants has identified at least 4 genes that could improve resistance to photoinhibition. Three of these genes encode proteins that could protect the chloroplast machinery by improving energy flow and by reducing oxidative damages. The functional characterization of these genes will be pursued by: 1) Analysis of gene expression to identify those that are closely associated with tolerance; and 2) Performing function studies in Arabidopsis and wheat.Some of these genes may have important applications to improve resistance to oxidative stress and increase plant productivity under a variety of stresses.