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

阐明植物体内活性氧清除酶的基因调控和修复酶主要作用于修复植物中受活性氧损伤的蛋白质，一直是本课题的目标。本项目的研究成果可望为耐环境胁迫植物的育种提供参考。通过本项目的实施，对超氧化物歧化酶的基因调控机制有了更清晰的认识。对水稻Fe-SOD基因、APXS基因、苹果酸脱氢酶基因和水稻谷胱甘肽还原酶基因进行了结构分析和详细的基因调控研究，发现植物细胞质中的SOD、谷氧还蛋白、硫氧还蛋白具有77个碱基的高度同源性。这个特定的序列被认为是这些基因的启动子的调节区，这些基因作用于氧化还原反应。我们进一步在这77个碱基区中发现了一个富含AT的28个碱基对区，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地相互作用。我们获得了几个过表达SOD(菠菜)和/或APX(拟南芥)基因的转基因烟草植株。转基因植株表现出对低温和干旱胁迫的耐受性。这一事实表明，SOD和APX基因在培育耐环境胁迫植物方面是有用的。

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.