摘要
植物转录因子NAP(NAC-Like,Activated by AP3/PI)是近年来发现的一类与调控植物生长发育、控制叶片衰老以及响应外界环境胁迫等功能有关的转录因子,是NAC(NAM、ATAF1/2和CUC2)家族中的一个重要成员,也是一类植物特有的转录因子。转录因子NAP在结构上具有NAC家族的保守结构,即在N端具有保守的NAC区以及在C末端具有相对多样性的TAR区,但也有不同于其它NAC亚家族的一些特点,如其TAR区也有一定的保守性等;同时,NAP亚家族的基因表达产物主要集中在细胞核中,表明转录因子NAP是一个核蛋白;再者转录因子NAP的基因主要包括3个外显子和2个内含子。自从第一个转录因子NAP于1998年由Robert等在拟南芥中对控制花发育的AP3/PI的靶基因进行研究时发现以来,目前已在水稻、小麦、大豆、棉花、竹子、葡萄、番红花等植物中相继发现,表明NAP是存在于植物界中的一个特有的转录因子。转录因子NAP具有多种生物学功能,广泛参与植物种子、根、花等的生长发育,对植物生长发育过程起着重要的调节作用;与此同时,转录因子NAP也在叶片凋亡过程中起着举足轻重的作用,对叶片在衰老过程中涉及到的大分子物质的降解以及营养物质的再分配等过程起着重要的调控作用;而且,转录因子NAP对包括干旱、盐渍、冷害等外界环境胁迫有一定的响应,是一类参与调控植物体内各种生理反应的关键因子;同时,转录因子NAP也与植物尤其是农作物的品质有密切的关系,这也为农作物育种提供了一种新的思路和方法。最新研究表明,NAP主要受脱落酸和乙烯调控,已发现一个定位在高尔基体的PP2C家族中的成员SAG113为转录因子NAP的一个直接的靶基因,而且发现SAG113在控制气孔运动方面尤其是在衰老叶片中可能是ABA调控中的一个负调控元件,通过酵母杂交试验以及电泳迁移率变动分析技术得出转录因子NAP受到ABA的调控并直接与其靶基因SAG113启动子区域的一个特定的区域进行专一性的结合,即在衰老叶片中转录因子NAP通过ABA-NAP-SAG113 PP2C调节链提高其靶基因SAG113的表达,以及通过促进气孔开放从而导致水分丧失和通过足够的氧气进入到组织中使得乙烯释放进而使呼吸作用加快等加速叶片衰老的信号这一调控机制。文章主要对NAP转录因子的结构特点、生物学功能以及调控机制等方面在植物中的研究现况进行较为详细的阐述,以期为后续研究提供一定的参考。
Abstract: NAP (NAC-Like, Activated by APJPI) is a plant-specific transcription factor, which plays an important role in regulation of plant growth and development, leaf senescence and responses to various kinds of stresses. NAP belongs to NAC (NAM, ATAF1/2 and CUC2) transcription factor, which contains a conserved N-terminal NAC domain and a highly divergent transcription activation region (TAR) in C-terminal region. Furthermore, the NAP protein is localized in the nucleus, and the NAP gene structure contains three exons and two introns. Since the first NAP was found to be closely associated with Arabidopsis flower growth and development in 1998, NAP subfamily has been discovered in rice, wheat, cotton, bean, bamboo, grape and so on, which further confirms that NAP subfamily is one of plant-specific transcription factors. Moreover, NAP subfamily has various biological functions Firstly, NAP participates in the plant growth and development including seed, root and flower. Then NAP subfamily also takes an essential part in the leaf senescence, which indirectly regulates the macromolecules degradation and nutrient-recycling processes. NAP subfamily also responds to stresses such as drought, salt and cold. And then, NAP subfamily can contribute to the improvement of crop quality, which provides a novel method for crop breeding. In the recent researches, it was supposed that NAP is mainly regulated by abscisic acid (ABA) and ethylene, and a Golgi-localized protein phosphatase 2C SAG113 is its direct target gene. Subsequently, as a negative regulator of ABA signal transduction, SAG113 is closely related to the control of water loss especially during leaf.senescence. The results indicate that NAP is regulated by ABA and specifically interacts with its target gene (SAG113). Through ABA-NAP-SAGll3 PP2C regulatory chain, NAP will promote the expression of its target gene (SAGll3). Then the SAG113 expression inhibits the stomatal closure, which leads to water loss and enough oxygen diffusion for ethylene-stimulated fast respiration during leaf senescence. All the results in turn trigger leaf senescence. The study on NAP subfamily will have an effect on both theoretical and practical researches.
出处
《中国农业科学》
CAS
CSCD
北大核心
2014年第2期209-220,共12页
Scientia Agricultura Sinica
基金
农业部转基因项目(2009ZX08009-061B)
关键词
NAP
结构特点
生物功能
调控机制
: NAP
structure
biological function
regulated mechanism