Innovative Center of Molecular Genetics and Evolution, School of Life Sciences, Guangzhou University, 510006 Guangzhou, China.
State Key Laboratory of Crop Stress Adaptation and Improvement, School of Life Sciences, Henan University, 475004 Kaifeng, China.
Proc Natl Acad Sci U S A. 2021 Feb 23;118(8). doi: 10.1073/pnas.2010241118.
Photoperiod sensitivity is a key factor in plant adaptation and crop production. In the short-day plant soybean, adaptation to low latitude environments is provided by mutations at the locus, which confer extended flowering phase and thereby improve yield. The identity of as an ortholog of , a component of the circadian evening complex (EC), implies that orthologs of other EC components may have similar roles. Here we show that the two soybean homeologs of LUX ARRYTHMO interact with J to form a soybean EC. Characterization of mutants reveals that these genes are highly redundant in function but together are critical for flowering under short day, where the double mutant shows extremely late flowering and a massively extended flowering phase. This phenotype exceeds that of any soybean flowering mutant reported to date, and is strongly reminiscent of the "Maryland Mammoth" tobacco mutant that featured in the seminal 1920 study of plant photoperiodism by Garner and Allard [W. W. Garner, H. A. Allard, J. Agric. Res. 18, 553-606 (1920)]. We further demonstrate that the J-LUX complex suppresses transcription of the key flowering repressor and its two homologs via LUX binding sites in their promoters. These results indicate that the EC-E1 interaction has a central role in soybean photoperiod sensitivity, a phenomenon also first described by Garner and Allard. EC and E1 family genes may therefore constitute key targets for customized breeding of soybean varieties with precise flowering time adaptation, either by introgression of natural variation or generation of new mutants by gene editing.
光周期敏感性是植物适应和作物生产的关键因素。在短日照植物大豆中，对低纬度环境的适应是由 基因座的突变提供的，这些突变赋予了大豆扩展的开花阶段，从而提高了产量。 作为昼夜节律晚间复合物（EC）的组成部分的 的同源物的身份暗示，其他 EC 成分的同源物可能具有类似的作用。在这里，我们表明大豆 LUX ARRYTHMO 的两个同源物与 J 相互作用形成大豆 EC。突变体的特征表明，这些基因在功能上高度冗余，但共同作用对于短日照下的开花至关重要，其中 双突变体表现出极晚的开花和极大扩展的开花阶段。这种表型超过了迄今为止报道的任何大豆开花突变体，并且强烈类似于 Garner 和 Allard [W. W. Garner，H. A. Allard，J. Agric. Res. 18，553-606（1920）]在 20 世纪 20 年代对植物光周期现象的开创性研究中使用的烟草“马里兰猛犸象”突变体。我们进一步证明，J-LUX 复合物通过其启动子中的 LUX 结合位点抑制关键开花抑制因子 和其两个同源物的转录。这些结果表明，EC-E1 相互作用在大豆光周期敏感性中起核心作用，这一现象也是 Garner 和 Allard 首先描述的。因此，EC 和 E1 家族基因可能构成大豆品种精确开花时间适应性定制育种的关键目标，无论是通过自然变异的导入还是通过基因编辑产生新的突变体。
