State Key Laboratory of Crop Genetics & Germplasm Enhancement and Utilization and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River, Sanya Institute of Nanjing Agricultural University, Nanjing Agricultural University, Nanjing, China.
Department of Plant Biotechnology and Bioinformatics, Ghent University, Ghent, Belgium.
Nat Plants. 2023 Sep;9(9):1514-1529. doi: 10.1038/s41477-023-01494-x. Epub 2023 Aug 21.
Ammonium toxicity affecting plant metabolism and development is a worldwide problem impeding crop production. Remarkably, rice (Oryza sativa L.) favours ammonium as its major nitrogen source in paddy fields. We set up a forward-genetic screen to decipher the molecular mechanisms conferring rice ammonium tolerance and identified rohan showing root hypersensitivity to ammonium due to a missense mutation in an argininosuccinate lyase (ASL)-encoding gene. ASL localizes to plastids and its expression is induced by ammonium. ASL alleviates ammonium-inhibited root elongation by converting the excessive glutamine to arginine. Consequently, arginine leads to auxin accumulation in the root meristem, thereby stimulating root elongation under high ammonium. Furthermore, we identified natural variation in the ASL allele between japonica and indica subspecies explaining their different root sensitivity towards ammonium. Finally, we show that ASL expression positively correlates with root ammonium tolerance and that nitrogen use efficiency and yield can be improved through a gain-of-function approach.
铵毒性会影响植物的新陈代谢和发育，是阻碍作物生产的全球性问题。值得注意的是，水稻（Oryza sativa L.）在稻田中优先选择铵作为其主要氮源。我们建立了正向遗传学筛选，以破译赋予水稻铵耐性的分子机制，并发现 rohans 由于精氨琥珀酸裂解酶（ASL）编码基因的错义突变而导致根系对铵过度敏感。ASL 定位于质体，其表达受铵诱导。ASL 通过将过量的谷氨酰胺转化为精氨酸来缓解铵对根系伸长的抑制。因此，精氨酸导致根分生组织中生长素的积累，从而在高铵条件下刺激根系伸长。此外，我们在粳稻和籼稻亚种之间发现了 ASL 等位基因的自然变异，这解释了它们对铵的不同根系敏感性。最后，我们表明 ASL 表达与根系对铵的耐受性呈正相关，并且可以通过功能获得方法提高氮利用效率和产量。
