OsNAP connects abscisic acid and leaf senescence by fine-tuning abscisic acid biosynthesis and directly targeting senescence-associated genes in rice
OsNAP connects abscisic acid and leaf senescence by fine-tuning abscisic acid biosynthesis and directly targeting senescence-associated genes in rice
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OsNAP通过微调脱落酸生物合成并直接靶向水稻衰老相关基因，将脱落酸与叶片衰老联系起来
DOI：
10.1073/pnas.1321568111
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发表时间：
2014-07-08
影响因子：
11.1
通讯作者：
Chu, Chengcai
中科院分区：
文献类型：
--
作者：
Liang, Chengzhen;Wang, Yiqin;Chu, Chengcai
水稻叶片早衰对产量稳定性有负面影响，这一点早已被证实，但驱动这种关系的潜在分子机制在很大程度上仍不清楚。在这里，我们确定了一个显性的过早叶片衰老突变体，过早衰老1（ps1-D）。PS1编码一种植物特异性NAC（无顶端分生组织、拟南芥ATAF 1/2和杯状子叶2）转录激活因子，即水稻NAC样转录激活因子，由apetala 3/pistillata（OsNAP）激活。过量表达OsNAP显著促进水稻衰老，而敲低OsNAP则显著延缓水稻衰老，证实了OsNAP基因在水稻衰老过程中的作用。OsNAP的表达与叶片衰老的发生密切相关。同样，ChIP-PCR和酵母单杂交试验表明，OsNAP通过直接靶向与叶绿素降解和养分运输相关的基因以及其他与衰老相关的基因来正向调节叶片衰老，表明OsNAP是水稻衰老开始的理想标记。进一步的分析表明OsNAP是由脱落酸（阿坝）特异性诱导的，而它的表达在两个阿坝生物合成突变体aba 1和aba 2中都受到抑制。此外，ps1-D突变体中阿坝含量显著降低，表明OsNAP对阿坝生物合成的反馈抑制。我们的数据表明OsNAP是阿坝和叶片衰老之间的重要联系。此外，OsNAP表达减少导致叶片衰老延迟和灌浆期延长，导致两个独立的代表性RNAi株系的籽粒产量分别增加6.3%和10.3%。因此，微调OsNAP的表达应该是一个有用的策略，提高水稻产量的未来。
It has long been established that premature leaf senescence negatively impacts the yield stability of rice, but the underlying molecular mechanism driving this relationship remains largely unknown. Here, we identified a dominant premature leaf senescence mutant, prematurely senile 1 (ps1-D). PS1 encodes a plant-specific NAC (no apical meristem, Arabidopsis ATAF1/2, and cup-shaped cotyledon2) transcriptional activator, Oryza sativa NAC-like, activated by apetala3/pistillata (OsNAP). Overexpression of OsNAP significantly promoted senescence, whereas knockdown of OsNAP produced a marked delay of senescence, confirming the role of this gene in the development of rice senescence. OsNAP expression was tightly linked with the onset of leaf senescence in an age-dependent manner. Similarly, ChIP-PCR and yeast one-hybrid assays demonstrated that OsNAP positively regulates leaf senescence by directly targeting genes related to chlorophyll degradation and nutrient transport and other genes associated with senescence, suggesting that OsNAP is an ideal marker of senescence onset in rice. Further analysis determined that OsNAP is induced specifically by abscisic acid (ABA), whereas its expression is repressed in both aba1 and aba2, two ABA biosynthetic mutants. Moreover, ABA content is reduced significantly in ps1-D mutants, indicating a feedback repression of OsNAP on ABA biosynthesis. Our data suggest that OsNAP serves as an important link between ABA and leaf senescence. Additionally, reduced OsNAP expression leads to delayed leaf senescence and an extended grain-filling period, resulting in a 6.3% and 10.3% increase in the grain yield of two independent representative RNAi lines, respectively. Thus, fine-tuning OsNAP expression should be a useful strategy for improving rice yield in the future.