State Key Laboratory of Plant Genomics and Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing, 100101, China.
University of Chinese Academy of Sciences, Beijing, 100049, China.
Plant J. 2018 Nov;96(4):842-854. doi: 10.1111/tpj.14072. Epub 2018 Sep 22.
Nitrogen is one of the most important nutrient element that is essential for plant growth and development. Many genes have been reported to contribute to nitrogen absorption and transportation. However, genes involved in nitrogen reutilization are seldom reported. Ornithine δ-aminotransferase (δOAT) is the enzyme connecting arginine cycling and proline cycling. Here, we found that OsOAT, the homologue of δOAT in rice, is essential for nitrogen reutilization through mediating arginase activity. In the Osoat mutant, metabolic abnormality induced by nitrogen deficiency in floret causes malformed glumes, incapable glume opening and anther indehiscence. These defects in the mutant affect the pollination process and lead to a low seed setting rate as well as abnormal seed shape. Intriguingly, urea can rescue the phenotypes of the Osoat mutant. Therefore, OsOAT is crucial for nitrogen reutilization and plays a critical role in floret development and seed setting in rice.
氮是植物生长和发育所必需的最重要的营养元素之一。许多基因已被报道有助于氮的吸收和运输。然而，很少有报道涉及氮的再利用基因。鸟氨酸 δ-氨基转移酶（δOAT）是连接精氨酸循环和脯氨酸循环的酶。在这里，我们发现水稻中 δOAT 的同源物 OsOAT 通过调节精氨酸酶活性对氮的再利用是必需的。在 Osoat 突变体中，氮缺乏引起小花中代谢异常导致颖壳畸形、颖壳不能张开和花药不开裂。这些突变体的缺陷影响授粉过程，导致结实率低和种子形状异常。有趣的是，尿素可以挽救 Osoat 突变体的表型。因此，OsOAT 对氮的再利用至关重要，在水稻小花发育和结实中起着关键作用。
