Gene regulation of active oxygen scavenging enzymes and breeding for environmental stress tolerant plant

阐明植物活性氧清除酶和主要修复活性氧损伤蛋白的修复酶的基因调控是本课题的目的。本研究成果将为植物耐环境胁迫育种提供参考。通过本项目的实施，对sod的基因调控机制有了更清晰的认识。与SOD基因协同清除活性氧分子和修复活性氧分子损伤的基因已被分离和分析。对水稻Fe-SOD cDNA、APXs、苹果脱氢酶cDNA和谷胱甘肽还原酶基因进行了结构分析，并对基因的具体调控进行了研究。结果表明，植物胞质SOD、glutaredoxin、thioredoxin具有77个碱基对的高度同源序列。这个特定的序列被认为是这些基因启动子的调控区域，这些基因对氧化还原反应起作用。我们进一步在这77个碱基对区域中发现了一个富含AT的28个碱基对区域，我们将其命名为COREII。这个COREII被发现是一个顺式因子，并认识到该因子与一些核蛋白特异性相互作用。我们培育了几种过表达SOD（菠菜）和APX（拟南芥）基因的转基因烟草植株。这些转基因植物表现出对寒冷和干旱胁迫的耐受性。这表明SOD和APX基因在培育耐环境胁迫植物中是有用的。

To clarify the gene regulation of active oxygen scavenging enzymes and the repairing enzyes that work for repairing mainly of the proteins damaged by the active oxygen species in plant has been the aim of this project. Results obtained through this project is expected to be useful for plant breeding of tolerant plants to environmental stresses. Through fulfillment of this project the gene regulation mechanisms of SODs became clearer. Isolation and analysis of the genes those are working cooperatively with SOD genesto scavenge active oxygen molecules and to repair damages of the molecules have been achieved.Rice Fe-SOD cDNA, APXs, malic dehydrogenase cDNA and rice gutathione reductase gene were structurally analyzed and the detailed gene regulations have been also studied.Plant cytosolic SOD, glutaredoxin, thioredoxin were revealed to have a highly homologous sequence composed of 77 base pairs. This specific sequence is considered to be a regulatory region for the promoter of these genes that work for Redox responses. We further found in this 77 base region an AT rich 28 base pairs region which we named as COREII. This COREII was revealed to be a cisfactor and recognized that this factor interacts specifically with some nucleoproteins.We produced several transgenic tobacco plants that over express SOD(Spinach) and/or APX(Arabidopsis) genes. Thses transgenic plants showed tolerance to cold and drought stresses. This fact indicates that SOD and APX genes are useful to breed environmental stress tolerant plants.