Bioscience and Biotechnology Center, Nagoya University, Nagoya, 464-8601 Japan.
Faculty of Food and Agricultural Sciences, Fukushima University, Fukushima, 960-1248 Japan.
Plant Cell Physiol. 2021 Sep 30;62(6):942-947. doi: 10.1093/pcp/pcab051.
Traditional breeding for high-yielding crops has mainly relied on the widespread cultivation of gibberellin (GA)-deficient semi-dwarf varieties, as dwarfism increases lodging resistance and allows for high nitrogen use, resulting in high grain yield. Although the adoption of semi-dwarf varieties in rice and wheat breeding brought big success to the 'Green Revolution' in the 20th century, it consequently increased the demand for nitrogen-based fertilizer, which causes severe threat to ecosystems and sustainable agriculture. To make the 'Green Revolution' truly green, it is necessary to develop new varieties with high nitrogen use efficiency (NUE). Under this demand, research on NUE, mainly for rice, has made great strides in the last decade. This mini-review focuses on three aspects of recent epoch-making findings on rice breeding for high NUE. The first one on 'NUE genes related to GA signaling' shows how promising it is to improve NUE in semi-dwarf Green Revolution varieties. The second aspect centers around the nitrate transporter1.1B, NRT1.1B; studies have revealed a nutrient signaling pathway through the discovery of the nitrate-NRT1.1B-SPX4-NLP3 cascade. The last one is based on the recent finding that the teosinte branched1, cycloidea, proliferating cell factor (TCP)-domain protein 19 underlies the genomic basis of geographical adaptation to soil nitrogen; OsTCP19 regulates the expression of a key transacting factor, DLT/SMOS2, which participates in the signaling of four different phytohormones, GA, auxin, brassinosteroid and strigolactone. Collectively, these breakthrough findings represent a significant step toward breeding high-NUE rice in the future.
传统的高产作物育种主要依赖于广泛种植赤霉素（GA）缺陷的半矮化品种，因为矮化增加了抗倒伏性，并允许高氮利用，从而实现高谷物产量。虽然在水稻和小麦育种中采用半矮化品种为 20 世纪的“绿色革命”带来了巨大成功，但这也增加了对氮肥的需求，从而对生态系统和可持续农业造成了严重威胁。为了使“绿色革命”真正绿色化，有必要开发具有高氮利用效率（NUE）的新品种。在这种需求下，过去十年里，对 NUE 的研究，主要是针对水稻，已经取得了巨大的进展。这篇小综述主要关注水稻高 NUE 育种的三个方面的最新突破性发现。第一个方面是“与 GA 信号相关的 NUE 基因”，展示了在半矮化绿色革命品种中提高 NUE 的巨大潜力。第二个方面围绕硝酸盐转运蛋白 1.1B，NRT1.1B；通过发现硝酸盐-NRT1.1B-SPX4-NLP3 级联，研究揭示了一种营养信号通路。最后一个方面是基于最近的发现，即分支 1、环化、增殖细胞因子（TCP）结构域蛋白 19 是籼稻地理适应土壤氮的基因组基础；OsTCP19 调节关键转激活因子 DLT/SMOS2 的表达，该因子参与四种不同植物激素 GA、生长素、油菜素内酯和独脚金内酯的信号传递。总的来说，这些突破性发现代表着未来培育高 NUE 水稻的重要一步。
