Yang Xiuyan, Yang Guo, Wei Xilin, Huang Weiting, Fang Zhongming
Institute of Rice Industry Technology Research, Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Agricultural Sciences, Guizhou University, Guiyang 550025, China.
Institute of Rice Industry Technology Research, Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Agricultural Sciences, Guizhou University, Guiyang 550025, China.
Plant Sci. 2023 May;330:111640. doi: 10.1016/j.plantsci.2023.111640. Epub 2023 Feb 15.
N is essential for plant architecture, particularly tillering. However, whether and how N mediates panicle branching and influences rice grain yield remains unclear. In order to identify genes and pathways associated with N-regulated panicle branching, we treated rice with different concentrations of N to determine the key genes by transcriptomic analysis and function verification. We measured panicle growth in response to N, and found that panicle branching benefits from 2 mM exogenous N, and 2-5 mM N is essential for vascular bundle, phloem, and xylem development in these branches. Interestingly, total N concentrations increased continuously with N 0-2 mM and decreased continuously with N 5-15 mM, whereas the concentrations of amino acids Tyr and Val increased continuously with N 0-15 mM in the panicle. Furthermore, N metabolism, phytohormone signal transduction, stress response, and photosynthesis pathways play important roles in response to nitrogen of regulating panicle branching. Altered expression of key N-response amino acid transporter gene OsAAP15 positively regulated panicle branching at low N concentrations, however, OsAAP15 negatively influenced it at high N concentrations. Overexpression of OsAAP15 in the field significantly increased primary and secondary branches, filled grain number, and grain yield by regulating the concentrations of amino acids Tyr and Val in the panicle. Taken together, OsAAP15, an amino acid transporter in response to nitrogen concentration, could mediate panicle branching and grain yield, and it may have applications in rice breeding to improve grain yield under extreme N concentrations.
氮对于植株形态，尤其是分蘖至关重要。然而，氮是否以及如何介导穗分枝并影响水稻产量仍不清楚。为了鉴定与氮调控穗分枝相关的基因和途径，我们用不同浓度的氮处理水稻，通过转录组分析和功能验证来确定关键基因。我们测定了穗对氮的生长响应，发现穗分枝受益于2 mM的外源氮，2 - 5 mM的氮对于这些分枝中的维管束、韧皮部和木质部发育至关重要。有趣的是，穗中总氮浓度在0 - 2 mM氮时持续增加，在5 - 15 mM氮时持续降低，而氨基酸酪氨酸（Tyr）和缬氨酸（Val）的浓度在0 - 15 mM氮时在穗中持续增加。此外，氮代谢、植物激素信号转导、应激反应和光合作用途径在调控穗分枝对氮的响应中起重要作用。关键氮响应氨基酸转运蛋白基因OsAAP15的表达改变在低氮浓度下正向调控穗分枝，然而，OsAAP15在高氮浓度下对其产生负向影响。在田间过表达OsAAP15通过调节穗中氨基酸酪氨酸和缬氨酸的浓度显著增加了一次枝梗和二次枝梗数量、实粒数和产量。综上所述，OsAAP15作为一种响应氮浓度的氨基酸转运蛋白，可以介导穗分枝和产量，并且可能在水稻育种中应用以提高极端氮浓度下的产量。
