MOLECULAR AND CELLULAR BASIS OF UVB TOLERANCE IN PLANTS

最近到达生物圈的紫外线辐射的增加已经 增强了我们对了解 有机体保护自己免受这种环境压力的影响。这个 提出的研究目标是使用一种多细胞高等真核细胞 作为一个模型系统，以增加我们对 结果增加了对紫外线辐射的耐受性。特别注意的是 关于植物耐紫外线的分子和细胞学基础 因为它们不可避免地暴露在UVB辐射下。双子叶植物 拟南芥之所以被选中，是因为它作为一种 经典和分子遗传学研究的模型。我建议 一套使用不同工具(遗传、生化、 分子和生理学)，以了解有关特定角色的更多信息 机制在对紫外线的整体耐受性中发挥作用。在我们的实验室，我们 已经定义了一组拟南芥生态型，它们显示出 紫外线抵抗力的变化。提议的方法之一是首先 定义并研究具体的保护机制(例如 类黄酮类积聚，防止自由基，DNA修复， 等)它们参与了这种自然变异。我们还有 分离出一种化学产生的突变体，它表现出严重的敏感性 在紫外光照射下，黄酮类物质积累不足。这 突变体正在成为进一步了解紫外线耐受性的宝贵工具 在植物中。提出的第二种方法利用 缺乏某些黄酮类化合物会影响该突变体对紫外线的耐受性 深入分析类黄酮在紫外光辐射中的具体作用 抗性(例如，仅仅是紫外线屏蔽机制？)。第三种方法 利用了这种突变体对紫外线的严重敏感性(以及某些 紫外线敏感生态型)从基因上搜索其他保护性 可能能够弥补类黄酮类缺乏的机制 并提高抗紫外线能力。因此，这项工程的完成， 阐明紫外光耐受性的各种机制及其潜在意义 对植物抵御紫外线的贡献。与此同时，这一点 研究可能会提供有用的知识和新的途径 为更好地了解其分子机制而进行的研究 对环境压力的耐受性。最后，预计各方面 分子和遗传工具以及新技术将成为 这将对其他生物体的类似研究有用。

The recent increases in UV-radiation reaching the biosphere have heightened our interest in understanding the mechanisms by which organisms protect themselves against this environmental stress. The goal of the propose research is to use a multicellular higher eukaryote as a model system to increase our understanding of the mechanisms that result in increased tolerance of UV-radiation. special attention is given to the molecular and cellular basis of UV-tolerance in plants since they are inevitably exposed to UVB radiation. The dicot plant Arabidopsis thaliana has been chosen because of its versatility as a model for studies in both classical an molecular genetics. I propose a set of approaches using diverse tools (genetic, biochemical, molecular an physiological) to learn more about the role specific mechanisms play in the overall tolerance to UV. In our laboratory we have defined a set of Arabidopsis ecotypes that display large variations in UV-resistance. One of the proposed approaches is to first define and then study the specific protective mechanisms (e.g. flavonoid accumulation, protection against free radicals, DNA repair, etc.) which are involved in this natural variation. We have also isolated a chemically generated mutant which shows a severe sensitivity to UV-light because of deficiency in flavonoid accumulation. This mutant is becoming a valuable tool to further understand UV-tolerance in plants. The second approach proposed makes use of the effect the lack of certain flavonoids has on UV tolerance in this mutant to thoroughly analyze the specific role played by flavonoids in UV- resistance (e.g. is only a UV-screening mechanism?). The third approach makes use of the severe UV-sensitivity of this mutant (and of certain UV-sensitive ecotypes) to search genetically for other protective mechanisms that may be able to compensate for the lack of flavonoids and increase UV-resistance. Completion of this project has thus, the potential of elucidating various mechanisms of UV-tolerance and their contribution to protection against UV in plants. At the same time, this research is likely to provide useful knowledge and new avenues of research towards a better understanding of the molecular mechanisms of tolerance to environmental stress. Finally, it is expected that various molecular and genetic tools as well as novel techniques will be generated which will be useful for similar studies in other organisms.