The Key Laboratory of Plant Development and Environmental Adaptation Biology, Ministry of Education, School of Life Sciences, Shandong University, Qingdao, 266237, People's Republic of China.
Shandong Provincial Key Laboratory of Applied Microbiology, Ecology Institute of Qilu University of Technology (Shandong Academy of Sciences), Jinan, 250013, China.
Plant J. 2024 Jul;119(2):645-657. doi: 10.1111/tpj.16806. Epub 2024 May 18.
The interplay between microRNAs (miRNAs) and phytohormones allows plants to integrate multiple internal and external signals to optimize their survival of different environmental conditions. Here, we report that miR394 and its target gene LEAF CURLING RESPONSIVENESS (LCR), which are transcriptionally responsive to BR, participate in BR signaling to regulate hypocotyl elongation in Arabidopsis thaliana. Phenotypic analysis of various transgenic and mutant lines revealed that miR394 negatively regulates BR signaling during hypocotyl elongation, whereas LCR positively regulates this process. Genetically, miR394 functions upstream of BRASSINOSTEROID INSENSITIVE2 (BIN2), BRASSINAZOLEs RESISTANT1 (BZR1), and BRI1-EMS-SUPPRESSOR1 (BES1), but interacts with BRASSINOSTEROID INSENSITIVE1 (BRI1) and BRI1 SUPRESSOR PROTEIN (BSU1). RNA-sequencing analysis suggested that miR394 inhibits BR signaling through BIN2, as miR394 regulates a significant number of genes in common with BIN2. Additionally, miR394 increases the accumulation of BIN2 but decreases the accumulation of BZR1 and BES1, which are phosphorylated by BIN2. MiR394 also represses the transcription of PACLOBUTRAZOL RESISTANCE1/5/6 and EXPANSIN8, key genes that regulate hypocotyl elongation and are targets of BZR1/BES1. These findings reveal a new role for a miRNA in BR signaling in Arabidopsis.
microRNAs（miRNAs）和植物激素之间的相互作用使植物能够整合多种内部和外部信号，以优化其在不同环境条件下的生存。在这里，我们报告 miR394 及其靶基因 LEAF CURLING RESPONSIVENESS（LCR），它们对 BR 有转录响应，参与 BR 信号转导，调节拟南芥下胚轴伸长。各种转基因和突变体系的表型分析表明，miR394 在拟南芥下胚轴伸长过程中负调控 BR 信号，而 LCR 则正调控这一过程。遗传上，miR394 在 BRASSINOSTEROID INSENSITIVE2（BIN2）、BRASSINAZOLEs RESISTANT1（BZR1）和 BRI1-EMS-SUPPRESSOR1（BES1）之前起作用，但与 BRASSINOSTEROID INSENSITIVE1（BRI1）和 BRI1 SUPRESSOR PROTEIN（BSU1）相互作用。RNA-seq 分析表明，miR394 通过 BIN2 抑制 BR 信号，因为 miR394 与 BIN2 共同调节大量基因。此外，miR394 增加了 BIN2 的积累，但降低了 BZR1 和 BES1 的积累，BIN2 磷酸化了 BZR1 和 BES1。miR394 还抑制了 PACLOBUTRAZOL RESISTANCE1/5/6 和 EXPANSIN8 的转录，这两个关键基因调节下胚轴伸长，是 BZR1/BES1 的靶标。这些发现揭示了 miRNA 在拟南芥 BR 信号转导中的一个新作用。
