The Ubiquitin E3 Ligase RHA2b Promotes Degradation of MYB30 in Abscisic Acid Signaling

Abstract

The phytohormone abscisic acid (ABA) is critical for plants encountering abiotic stress. We reported previously that the Arabidopsis () transcription factor MYB30 participates in ABA responses via SUMO ligase SAP-MIZ Domain-Containing SIZ1-mediated sumoylation. Here, we show that the RING-type ubiquitin E3 ligase RHA2b, which positively regulates ABA signaling, interacted with and ubiquitinated MYB30 to modulate MYB30 stability through the 26S proteasome pathway. The degradation rate of MYB30 was repressed significantly in the mutant. Phenotypic analyses showed that acts genetically downstream of in ABA signaling. Substitutions of lysine-283 (K283) and K165 blocked ubiquitination, suggesting that these residues are sites of ubiquitination. K283 residue substitution significantly inhibited the degradation of MYB30 induced by ABA. The K165 site functioned additively with K283 in ABA-induced MYB30 degradation and ABA responses. At the same time, sumoylation protected MYB30 from degradation under cycloheximide and ABA treatment. Compared with MYB30, overexpression of MYB30-SUMO1 partially recovered the ABA sensitivity of But MYB30-SUMO1 exhibited similar localization with MYB30 in nuclei. Overall, our results suggest that RHA2b targets MYB30 for degradation to modulate ABA signaling. Considering that the K283 residue also is the major site for sumoylation, we propose that sumoylation and ubiquitination act antagonistically in the ABA response to regulate the stability of MYB30 by occupying the same residue.

Comparative Transcriptome Analysis of Two Aegilops tauschii with Contrasting Drought Tolerance by RNA-Seq

“…Transcription factors contribute greatly to regulating plant growth and development, and can also enhance the resistance to abiotic and biotic stresses through orchestrating regulatory networks [55]. Major plant TF families such as NAC, AP2, bZIP, MYB, and WRKY have been documented as important regulators in plant responses to various abiotic and biotic stresses [56][57][58]. In this study, the DEGs encoding WRKY and NAC families exhibited a more obvious difference between the two accessions.…”

Peer Review #3 of "Cytological and molecular characterizations of a novel 2A nullisomic line derived from a widely-grown wheat cultivar Zhoumai 18 conferring male sterility (v0.1)"

“…MYB TFs play pivotal roles in plant development and stress response (Verma, 2019;Zheng et al, 2018). Many MYB TFs have been functionally characterized in pollen development of Arabidopsis and rice, such as AtMYB32 (Preston et al, 2004), OsGAMYB (Aya et al, 2009) and OsTDF1 (Cai et al, 2015).…”

The Consequences of a Disruption in Cyto-Nuclear Coadaptation on the Molecular Response to a Nitrate Starvation in Arabidopsis

“…The roles of the 22 RING proteins are less known, except for three noteworthy of them. RHA2B (AT2G01150) regulates ABA signaling and drought tolerance [62,63]; RGL4 (AT1G79380) encodes an essential upstream modulator of JA signaling in response to various stimuli [64] and of iron sensing [65]; NLA (AT1G02860) is a major actor in the response to low-nitrogen conditions in Arabidopsis which interacts with ORE1 in the nucleus to induce leaf senescence during N deficiency [66] and regulates the phosphate homeostasis in interactions with microRNA miR827 [67]. A single protein of E1 complex, UBIQUITIN-ACTIVATING ENZYME 1 (ATUBA1), was quantified in this experiment.…”