National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200031, China.
National Key Laboratory of Plant Molecular Genetics, CAS Centre for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai 200031, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Mol Plant. 2022 Jan 3;15(1):167-178. doi: 10.1016/j.molp.2021.09.005. Epub 2021 Sep 13.
Nitrogen is an essential nutrient for plant growth and development, and plays vital roles in crop yield. Assimilation of nitrogen is thus fine-tuned in response to heterogeneous environments. However, the regulatory mechanism underlying this essential process remains largely unknown. Here, we report that a zinc-finger transcription factor, drought and salt tolerance (DST), controls nitrate assimilation in rice by regulating the expression of OsNR1.2. We found that loss of function of DST results in a significant decrease of nitrogen use efficiency (NUE) in the presence of nitrate. Further study revealed that DST is required for full nitrate reductase activity in rice and directly regulates the expression of OsNR1.2, a gene showing sequence similarity to nitrate reductase. Reverse genetics and biochemistry studies revealed that OsNR1.2 encodes an NADH-dependent nitrate reductase that is required for high NUE of rice. Interestingly, the DST-OsNR1.2 regulatory module is involved in the suppression of nitrate assimilation under drought stress, which contributes to drought tolerance. Considering the negative role of DST in stomata closure, as revealed previously, the positive role of DST in nitrogen assimilation suggests a mechanism coupling nitrogen metabolism and stomata movement. The discovery of this coupling mechanism will aid the engineering of drought-tolerant crops with high NUE in the future.
氮是植物生长和发育所必需的营养物质，在作物产量中起着至关重要的作用。因此，氮的同化会根据异质环境进行微调。然而，这一基本过程的调节机制在很大程度上仍然未知。在这里，我们报告了一个锌指转录因子，干旱和耐盐性（DST），通过调节 OsNR1.2 的表达来控制水稻中的硝酸盐同化。我们发现，DST 功能丧失会导致在存在硝酸盐的情况下氮利用效率（NUE）显著降低。进一步的研究表明，DST 是水稻中完整硝酸还原酶活性所必需的，并且直接调节 OsNR1.2 的表达，OsNR1.2 与硝酸还原酶具有序列相似性。反向遗传学和生物化学研究表明，OsNR1.2 编码一种 NADH 依赖性硝酸还原酶，是水稻高 NUE 所必需的。有趣的是，DST-OsNR1.2 调节模块参与了干旱胁迫下硝酸盐同化的抑制，这有助于耐旱性。考虑到先前揭示的 DST 在气孔关闭中的负作用，DST 在氮同化中的正作用表明了一种将氮代谢和气孔运动耦合的机制。该发现将有助于未来工程设计具有高 NUE 的耐旱作物。
