MOLECULAR AND CELLULAR BASIS OF UVB TOLERANCE IN PLANTS

最近到达生物圈的紫外线辐射增加， 提高了我们对了解 生物保护自己免受这种环境压力。的 这项研究的目的是利用多细胞高等真核生物 作为一个模型系统来增加我们对机制的理解， 导致对紫外线辐射的耐受性增加。特别注意 植物耐紫外线的分子和细胞基础 因为它们不可避免地暴露于UVB辐射。双子叶植物 选择拟南芥是因为它的多功能性， 经典遗传学和分子遗传学的研究模型。我提议 一套使用不同工具的方法（遗传，生物化学， 分子和生理学），以了解更多关于 机制在对紫外线的整体耐受性中起作用。在我们的实验室里， 已经定义了一组拟南芥生态型， 抗紫外线的变化。其中一个建议的方法是首先 定义并研究特定的保护机制（例如， 类黄酮积累，保护免受自由基，DNA修复， 等等）。它们参与了这种自然变异。我们还 分离出一种化学产生的突变体， 紫外线照射，因为缺乏类黄酮的积累。这 突变体正在成为进一步了解紫外耐受性的有价值的工具 在植物中。第二种方法利用了 缺乏某些类黄酮对这种突变体的紫外线耐受性有影响， 深入分析黄酮类化合物在紫外线中所起的具体作用， 电阻（例如，仅仅是紫外线屏蔽机制？）。第三种方法 利用这种突变体的严重紫外线敏感性（以及某些 紫外线敏感的生态类型），以寻找其他保护基因 可能能够弥补类黄酮缺乏的机制 增加抗紫外线能力。因此，该项目的完成， 阐明紫外线耐受性的各种机制及其 有助于保护植物免受紫外线的侵害。同时这 研究可能提供有用的知识和新的途径， 为了更好地理解的分子机制的研究 对环境压力的耐受性。最后，预计各种 分子和遗传工具以及新技术将被 这将有助于其他生物体的类似研究。

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.