RSM1, an Arabidopsis MYB protein, interacts with HY5/HYH to modulate seed germination and seedling development in response to abscisic acid and salinity

Abstract

MYB transcription factors are involved in many biological processes, including metabolism, development and responses to biotic and abiotic stresses. RADIALIS-LIKE SANT/MYB 1 (RSM1) belongs to a MYB-related subfamily, and previous transcriptome analysis suggests that RSM1 may play roles in plant development, stress responses and plant hormone signaling. However, the molecular mechanisms of RSM1 action in response to abiotic stresses remain obscure. We show that down-regulation or up-regulation of RSM1 expression alters the sensitivity of seed germination and cotyledon greening to abscisic acid (ABA), NaCl and mannitol in Arabidopsis. The expression of RSM1 is dynamically regulated by ABA and NaCl. Transcription factors ELONGATED HYPOCOTYL 5 (HY5) and HY5 HOMOLOG (HYH) regulate RSM1 expression via binding to the RSM1 promoter. Genetic analyses reveal that RSM1 mediates multiple functions of HY5 in responses of seed germination, post-germination development to ABA and abiotic stresses, and seedling tolerance to salinity. Pull-down and BiFC assays show that RSM1 interacts with HY5/HYH in vitro and in vivo. RSM1 and HY5/HYH may function as a regulatory module in responses to ABA and abiotic stresses. RSM1 binds to the promoter of ABA INSENSITIVE 5 (ABI5), thereby regulating its expression, while RSM1 interaction also stimulates HY5 binding to the ABI5 promoter. However, no evidence was found in the dual-luciferase transient expression assay to support that RSM enhances the activation of ABI5 expression by HY. In summary, HY5/HYH and RSM1 may converge on the ABI5 promoter and independently or somehow dependently regulate ABI5 expression and ABI5-downstream ABA and abiotic stress-responsive genes, thereby improving the adaption of plants to the environment.

The Transcription Factors TCP4 and PIF3 Antagonistically Regulate Organ-Specific Light Induction of SAUR Genes to Modulate Cotyledon Opening during De-Etiolation in Arabidopsis

“…The tcp3 tcp4 tcp10, tcp3 tcp4 tcp5 tcp10, and tcp3 tcp4 tcp5 tcp10 tcp13 seeds were kindly provided by Tomotsugu Koyama (Kyoto University;Koyama et al, 2010). The hy5 hyh seeds were kindly provided by Liumin Fan (Peking University; Yang et al, 2018).…”

NtMYB12 Positively Regulates Flavonol Biosynthesis and Enhances Tolerance to Low Pi Stress in Nicotiana tabacum

“…Previous studies showed that MYB TFs are involved in various biotic and abiotic stresses (Abe, 2002;Agarwal et al, 2006;Yang et al, 2018;Zhao, 2019). Dai et al (2012) first reported that OsMYB2P-1, an R2R3-MYB transcription factor, is involved in the regulation of phosphate-starvation responses in rice.…”

Radial or Bilateral? The Molecular Basis of Floral Symmetry

“…For example, in Solanum lycopersicum Lefsm1, a SANT/MYB1-like1 protein seems to be involved in the early stage of fruit and plant development [66]. In A. thaliana, another SANT/MYB1 protein (RSM1) is involved in the apical hook formation [67], acts as a positive regulator of the sensitivity of ABA signaling during seed germination, and regulates the salinity levels [68]. These functions are also conserved in monocot species, such as O. sativa [69].…”