Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China.
Plant Phenomics Research Center, Nanjing Agricultural University, Nanjing, 210095, China.
Plant Cell. 2020 Sep;32(9):2780-2805. doi: 10.1105/tpc.20.00123. Epub 2020 Jul 14.
Seedling emergence in monocots depends mainly on mesocotyl elongation, requiring coordination between developmental signals and environmental stimuli. Strigolactones (SLs) and karrikins are butenolide compounds that regulate various developmental processes; both are able to negatively regulate rice () mesocotyl elongation in the dark. Here, we report that a karrikin signaling complex, DWARF14-LIKE (D14L)-DWARF3 (D3)- SUPPRESSOR OF MAX2 1 (OsSMAX1) mediates the regulation of rice mesocotyl elongation in the dark. We demonstrate that D14L recognizes the karrikin signal and recruits the SCF ubiquitin ligase for the ubiquitination and degradation of OsSMAX1, mirroring the SL-induced and D14- and D3-dependent ubiquitination and degradation of D53. Overexpression of promoted mesocotyl elongation in the dark, whereas knockout of suppressed the elongated-mesocotyl phenotypes of and OsSMAX1 localizes to the nucleus and interacts with TOPLESS-RELATED PROTEINs, regulating downstream gene expression. Moreover, we showed that the GR24 enantiomers GR24 and GR24 specifically inhibit mesocotyl elongation and regulate downstream gene expression in a D14- and D14L-dependent manner, respectively. Our work revealed that karrikin and SL signaling play parallel and additive roles in modulating downstream gene expression and negatively regulating mesocotyl elongation in the dark.
单子叶植物的幼苗出土主要依赖于中胚轴的伸长，这需要发育信号和环境刺激之间的协调。独脚金内酯（SLs）和卡瑞琳是丁烯内酯类化合物，它们调节各种发育过程；两者都能负向调控黑暗中水稻（）中胚轴的伸长。在这里，我们报告说，卡瑞琳信号复合物 DWARF14-LIKE（D14L）-DWARF3（D3）- SUPPRESSOR OF MAX2 1（OsSMAX1）介导了黑暗中水稻中胚轴伸长的调控。我们证明 D14L 识别卡瑞琳信号，并招募 SCF 泛素连接酶对 OsSMAX1 进行泛素化和降解，这与 SL 诱导的和 D14 和 D3 依赖性的 D53 泛素化和降解相呼应。过表达 促进了黑暗中中胚轴的伸长，而 的敲除则抑制了 和 的伸长中胚轴表型。OsSMAX1 定位于细胞核并与 TOPLESS-RELATED PROTEINs 相互作用，调节下游基因表达。此外，我们表明 GR24 对映体 GR24 和 GR24 分别以 D14 和 D14L 依赖性的方式特异性抑制中胚轴伸长并调节下游基因表达。我们的工作揭示了卡瑞琳和独脚金内酯信号在调节下游基因表达和负向调控黑暗中中胚轴伸长方面发挥着平行和累加的作用。
