A brassinosteroid responsive miRNA‐target module regulates gibberellin biosynthesis and plant development

Abstract

Plant growth and development are highly coordinated by hormones, including brassinosteroid (BR) and gibberellin (GA). Although much progress has been made in understanding the fundamental signaling transduction in BR and GA, their relationship remains elusive in rice. Here, we show that BR suppresses the level of OsmiR159d, which cleaves the target OsGAMYBL2 gene. The OsmiR159d-OsGAMYBL2 pair functions as an early BR-responsive module regulating the expression of BU1, a BR-regulated gene involved in BR signaling, and CPS1 and GA3ox2, two genes in GA biosynthesis, by binding to the promoters of these genes. Furthermore, OsGSK2, a key negative player in BR signaling, interacts with OsGAMYBL2 and prevents it from being degraded under 24-epibrassinolide treatment, whereas SLR1, a rice DELLA protein negatively regulating GA signaling, interacts with OsGAMYBL2 and prevents OsGAMYBL2 from binding to the target gene promoter. GA signaling induces degradation of OsGAMYBL2 and, consequently, enhances BR signaling. These results demonstrate that a BR-responsive module acts as a common component functioning in both BR and GA pathways, which connects BR signaling and GA biosynthesis, and thus coordinates the regulation of BR and GA in plant growth and development.

The Role of Dwarfing Traits in Historical and Modern Agriculture with a Focus on Rice

“…These results suggest cross talk between GA and BR signaling in controlling plant height (Tang et al 2018). There are additional complexities in BR-GA cross talk as well (Gao et al 2018;Tang et al 2018), including negative feedback by GA on BR synthesis (Tong et al 2014).…”

Exploring the Brassinosteroid Signaling in Monocots Reveals Novel Components of the Pathway and Implications for Plant Breeding

“…Importantly, the GA signaling promotes degradation of the OsGAMYBL2 protein, and consequently enhances the BR signaling. Generally, these results indicate that molecular mechanism of the BR-GA signaling interplay is highly complicated [117] (Figure 3). [87,126].…”

“…Biosynthesis and signaling processes of BR and GA interact to form a complex network [49,116]. However, in monocots molecular mechanisms of the interplay between the GA and BR signaling pathways remain largely unknown [117], although the crosstalk between these two phytohormones in regulation of various physiological processes was reported [116,118]. In rice the OsGSR1 protein constitutes one of the points of interaction between the GA and BR response pathways.…”

“…The OsGAMYBL2 transcription factor represses transcription of the GA biosynthetic genes. Interestingly, the GA application results in degradation of the OsGAMYBL2 protein [117]. It is also known that the GA application leads to a rapid degradation of the SLR1 (Slender Rice1) protein which belongs to the DELLA family of negative regulators of the GA signaling [128,129].…”

A Resource for Inactivation of MicroRNAs Using Short Tandem Target Mimic Technology in Model and Crop Plants

“…While expression of STTM159 in rice under the control of the enhanced 35S promoter led to smaller seed grains and plants (Zhao et al, 2017;Gao et al, 2018), tissue-specific knockdown of miRNAs led to an increase in seed size (Figure 6A-6D; Zhao et al, 2018). To apply STTM technology for crop improvement while avoiding adverse impacts on normal plant development, we used the endosperm-specific promoter Gt13a to downregulate two grain-filling-related miRNAs (miR167 and miR1432) in rice.…”