Plant science:农科院曹立勇研究组发现克隆分离与氮代谢相关的水
近日，国际著名学术杂志《plant science》期刊上在线发表了中国农业科学院水稻研究所曹立勇研究组的一篇研究论文，研究报道了研究人员利用图位克隆技术，从水稻品种93-11突变体中分离了一个叶片早衰控制基因ES7。毕真真博士和张迎信副研究员为共同第一作者，曹立勇研究员和程式华研究员为共同通讯作者。
研究表明ES7基因编码一个铁氧还原蛋白依赖的谷氨酸合酶，参与水稻叶片内氨的同化和再利用，是水稻氮素代谢途径的关键基因。该基因突变后造成功能缺失，会导致水稻叶片在分蘖期开始黄化，生育后期衰老加剧，最终影响水稻产量。该突变体还表现出光呼吸表型，在高CO2环境下，表型恢复正常。另外在粳稻中花11中敲除该基因进行验证，发现缺失该基因导致水稻苗期致死。
氮素的利用和转运是影响水稻叶片衰老和产量的重要因素。在水稻育种及栽培管理中，为保障高产，增加氮素的利用和转运、延缓叶片衰老是重要的考虑。通过对不同品种中ES7等位基因的SNP筛选分析和比较，可为提高水稻氮素利用和转运提供新的思路。
原文链接：
ES7, encoding a ferredoxin-dependent glutamate synthase, functions in nitrogen metabolism and impacts leaf senescence in rice
原文摘要：
Glutamate synthase (GOGAT) is a key enzyme for nitrogen metabolism and ammonium assimilation in plants. In this study, an early senescence 7 (es7) mutant was identified and characterized. The leaves of the es7 mutant begin to senesce at the tillering stage about 60 day after sowing, and become increasingly senescent as the plants develop at the heading stage. When es7 plants are grown under photorespiration-suppressed conditions (high CO2), the senescence phenotype and chlorophyll content are rescued. qRT-PCR analysis showed that senescence-
associated GENEs were up-regulated significantly in es7. A map-based cloning strategy was used to identify ES7, which encodes a ferredoxin-dependent glutamate synthase (Fd-GOGAT). ES7 was expressed constitutively, and the ES7 protein was localized in chloroplast. qRT-PCR analysis indicated that several genes related to nitrogen metabolism were differentially expressed in es7. Further, we also demonstrated that chlorophyll synthesis-associated genes were significantly down-regulated in es7. In addition, when seedlings are grown under increasing nitrogen concentrations (NH4NO3) for 15 days, the contents of chlorophyll a, chlorophyll b and total chlorophyll were significantly lower in es7. Our results demonstrated that ES7 is involved in nitrogen metabolism, effects chlorophyll synthesis, and may also associated with photorespiration, impacting leaf senescence in rice.
DOI:10.1016/j.plantsci.2017.03.003
作者：曹立勇
