Redesigning green revolution trait with increased grain yield and nitrogen utilization efficiency by reducing brassinosteroid signaling in semidwarf wheat
Redesigning green revolution trait with increased grain yield and nitrogen utilization efficiency by reducing brassinosteroid signaling in semidwarf wheat
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DOI：
10.1007/s11427-023-2401-3
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发表时间：
2023-06
期刊：
影响因子：
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通讯作者：
Hongqing Guo;Yanhai Yin
中科院分区：
文献类型：
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作者：
Hongqing Guo;Yanhai Yin
为日益增加的世界人口和日益减少的可耕地确保粮食和饲料是我们时代的主要挑战之一。自20世纪60年代以来，世界各地半矮秆水稻和小麦品种的使用推动了绿色革命或农业革命（Peng等人，1999年; Sasaki等人，2002年）。半矮秆性导致抗倒伏性，从而允许以高密度种植作物，这补偿了每株植物的谷物产量降低。水稻中的主要绿色革命基因参与植物激素赤霉素（GA）的生物合成，小麦中的GA信号转导。GA是植物生长和茎伸长所必需的。GA通过其受体发挥作用以降解一组阻遏蛋白（称为DELLA阻遏物），其随后阻遏GA调节的基因表达。半矮秆小麦中GA信号的减少是由功能获得性降低高度-1（Rht-1）等位基因（Rht-B1 b和Rht-D1 b）赋予的，这些等位基因编码稳定的DELLA阻遏物，导致GA信号减少，从而降低植株高度（图1，右）。虽然Rht-1的半矮秆性允许高种植密度，但是相同的基因也导致减小的谷粒尺寸和氮利用效率（NUE），因为GA信号传导促进调节氮利用的GFR 4（生长调节因子4）（Duan等人，2015; Li等人，2016年; Li等人，2018年）。目前的半矮秆品种需要大量的氮肥来维持高产，这造成了环境可持续性的问题。因此，克服传统绿色革命基因造成的这些限制对农业具有高度重要性。类甾醇（BR）是一类促进植物生长的类固醇激素，如GA，但具有完全不同的生物合成和信号传导途径（Nolan等人，2020; Tong和Chu，2018）。BR通过受体BRI 1和辅助受体发出信号，调节转录因子的活性，随后调节数千个基因的表达，以促进植物生长和协调胁迫反应（Li和Chory，1997）。BR信号传导受几种负调节剂负调节，包括结合BRI 1并抑制BRI 1功能的BKI 1（Wang和Chory，2006）。操纵BR水平和信号传导具有提高作物产量的潜力（Nolan等人，2020; Tong and Chu，2018）。（2023）发现了一种通过同时缺失半矮秆小麦中的Rht-1基因和新的BR信号传导组分ZnF-B来克服由Rht-1等位基因引起的限制的优雅的新策略（Song等人，2023年）。虽然半矮秆基因Rht-1的缺失恢复了植物高度、籽粒产量和NUE，但正BR信号传导组分ZnF-B的缺失导致“新的”半矮秆性状，其对籽粒产量和NUE的有害影响较小（图1）。
Securing food and feed for the increasing world population and decreasing arable land is one of the major challenges of our time. Green revolution or agriculture revolution was propelled by the use of semidwarf rice and wheat varieties around the world since the 1960s (Peng et al., 1999; Sasaki et al., 2002). The semi-dwarfness leads to lodging resistance and thus allows planting of crops in high densities, which compensates for the grain yield reduction on a per plant basis. The main green revolution genes are involved in the biosynthesis of plant hormone gibberellin (GA) in rice and GA signaling in wheat. GA is required for plant growth and stem elongation. GAs function through their receptors to degrade a group of repressor proteins (termed DELLA repressors), which subsequently represses GA regulated gene expression. The reduced GA signaling in semidwarf wheat is conferred by gain-of-function Reduced Height-1 (Rht-1) alleles (Rht-B1b and Rht-D1b) that encode stabilized DELLA repressors, leading to reduced GA signaling and hence reduced plant height (Figure 1, right). While semi-dwarfness of Rht-1 allows for high planting densities, the same gene also causes reduced grain size and nitrogen utilization efficiency (NUE), as GA signaling promotes GFR4 (GROWTHREGULATING FACTOR 4) that regulates nitrogen utilization (Duan et al., 2015; Li et al., 2016; Li et al., 2018). A large amount of nitrogen fertilizer is needed to maintain high yield of the current semidwarf varieties, causing issues in environmental sustainability. Overcoming these limitations caused by the traditional green revolution genes is therefore of high importance for agriculture. Brassinosterods (BRs) are a class of steroid hormones that promote plant growth, like GA, yet with completely different biosynthesis and signaling pathways (Nolan et al., 2020; Tong and Chu, 2018). BRs signal through receptor BRI1 and co-receptor to regulate the activity of transcription factors, which subsequently regulates the expression of thousands of genes to promote plant growth and coordinate stress responses (Li and Chory, 1997). BR signaling is negatively regulated by several negative regulators including BKI1 that binds to BRI1 and inhibits BRI1 function (Wang and Chory, 2006). Manipulating BR levels and signaling has potential in improving crop yield (Nolan et al., 2020; Tong and Chu, 2018).Recently, Song et al.(2023) discovered an elegant new strategy to overcome the limitation caused by Rht-1 allele by simultaneously deleting the Rht-1 gene and a new BR signaling component ZnF-B in semidwarf wheat (Song et al., 2023). While deletion of the semidwarf gene Rht-1 recovered plant height, grain yield, and NUE, deletion of the positive BR signaling component ZnF-B led to a “new” semidwarf trait that had less deleterious effects on grain yield and NUE (Figure 1).