State Key Laboratory of Crop Genetics and Germplasm Enhancement, Key Laboratory of Plant Nutrition and Fertilization in Low-Middle Reaches of the Yangtze River, Ministry of Agriculture and Rural Affairs, Nanjing Agricultural University, Nanjing, 210095, China.
College of life sciences, Henan Agricultural University, Zhengzhou, 450002, China.
Plant Physiol Biochem. 2021 Dec;169:259-268. doi: 10.1016/j.plaphy.2021.11.021. Epub 2021 Nov 13.
Improving nitrogen use efficiency (NUE) has been a focal point for crop growth and yield throughout the world. Glutamine synthetase (GS), which plays a fundamental role in N metabolism, has been exploited to improve crop NUE. However, increased GS activity in rice by overexpressing its own GS genes hasn't shown superior plant productivity. Here, transgenic rice plants with increased GS activity by overexpressing TaGS1 were analyzed under field and culture conditions at two N rates. Transgenic expression of TaGS1 significantly increases GS activity in leaves, junctions and roots of rice plants relative to wide-type plants. When rice plants grown under consecutive field trials with N rates of 60 and 240 kg/ha, three transgenic lines have higher grain yield than wild-type plants, with increment of 15%-22% in T2 generation and with that of 28%-36% in T3 generation, respectively. And increased panicle numbers (effective tiller numbers) mainly contribute to the advantage of grain yield in transgenic plants. Analysis of N use-related traits shows that transgenic plants with enhanced GS activity promote root capacity to obtain N, N accumulation during growth stages and N remobilization to grains, ultimately conferring 31%-40% improvement of NUE relative to wild-type rice plants.
提高氮利用效率（NUE）一直是全球作物生长和产量的重点。谷氨酰胺合成酶（GS）在氮代谢中起着至关重要的作用，已被用于提高作物的 NUE。然而，通过过表达自身 GS 基因来提高水稻中的 GS 活性并没有表现出更高的植物生产力。在这里，通过过表达 TaGS1 来提高 GS 活性的转基因水稻植株在两种氮浓度下的田间和培养条件下进行了分析。与野生型植株相比，TaGS1 的转基因表达显著增加了水稻叶片、节间和根中的 GS 活性。当水稻植株在连续的田间试验中分别以 60 和 240 kg/ha 的氮浓度生长时，三个转基因系的籽粒产量均高于野生型植株，T2 代增加了 15%-22%，T3 代增加了 28%-36%。增加的穗数（有效分蘖数）是转基因植株获得籽粒产量优势的主要原因。对氮利用相关性状的分析表明，增强 GS 活性的转基因植株促进了根系获取氮的能力、生长阶段的氮积累和氮向籽粒的再转运，最终使氮利用效率相对于野生型水稻植株提高了 31%-40%。
