The ubiquitin E3 ligase SR1 modulates the submergence response by degrading phosphorylated WRKY33 in Arabidopsis

Abstract

Oxygen deprivation caused by flooding activates acclimation responses to stress and restricts plant growth. After experiencing flooding stress, plants must restore normal growth; however, which genes are dynamically and precisely controlled by flooding stress remains largely unknown. Here, we show that the Arabidopsis thaliana ubiquitin E3 ligase SUBMERGENCE RESISTANT1 (SR1) regulates the stability of the transcription factor WRKY33 to modulate the submergence response. SR1 physically interacts with WRKY33 in vivo and in vitro and controls its ubiquitination and proteasomal degradation. Both the sr1 mutant and WRKY33 overexpressors exhibited enhanced submergence tolerance and enhanced expression of hypoxia-responsive genes. Genetic experiments showed that WRKY33 functions downstream of SR1 during the submergence response. Submergence induced the phosphorylation of WRKY33, which enhanced the activation of RAP2.2, a positive regulator of hypoxia-response genes. Phosphorylated WRKY33 and RAP2.2 were degraded by SR1 and the N-degron pathway during reoxygenation, respectively. Taken together, our findings reveal that the on-and-off module SR1-WRKY33-RAP2.2 is connected to the well-known N-degron pathway to regulate acclimation to submergence in Arabidopsis. These two different but related modulation cascades precisely balance submergence acclimation with normal plant growth.

Allelic shift in cis-elements of the transcription factor RAP2.12 underlies adaptation associated with humidity in Arabidopsis thaliana

“…After 7 days of recovery, the rosette leaf dry weights of the surviving plants and controls were weighed to calculate RRDWs in all submergence treatments. Plant cultivation and submergence procedures were described previously ( 36 ).…”

“…To construct pSic-RAP2.12:RAP2.12-GUS and pTib-RAP2.12:RAP2.12-GUS C-terminal GUS reporter protein fusion lines, 1.6-kb sequence upstream from the ATG and RAP2.12 CDSs with the stop codon removed by primers (table S4) were amplified and cloned into the pCXGUS-P vector ( 36 ) through the Xcm I enzyme sites. The pSic-RAP2.12:GUS , pTib-RAP2.12:GUS , and piecewise substitutions of promoter constructs were generated by overlapping PCR.…”

“…Ion leakage was measured as previously described ( 36 ). Rosettes of 18-day-old plants after submergence or 24-hour submergence and reoxygenation treatments were placed in 10 ml of deionized water.…”

“…Real-time PCR was performed as previously described ( 36 ). Total RNA was isolated from rosettes using TRIzol reagent (Invitrogen Life Technologies, Shanghai, China) following the manufacturer’s instructions.…”

RING Zinc Finger Proteins in Plant Abiotic Stress Tolerance

“…Zinc finger proteins maintain a finger-like spatial configuration by binding to zinc ions through amino acids in the peptide chain, and are widely distributed in eukaryotes ( Han et al, 2020a ). RING zinc finger proteins have been identified in many plants, including Arabidopsis thaliana ( Linden et al, 2021 ; Liu et al, 2021 ; Van Nguyen et al, 2021 ), rice ( Oryza sativa ) ( Kim et al, 2020 ; Kim and Jang, 2021 ; Zhu et al, 2021 ), maize ( Zea mays ) ( Gao et al, 2012 ; Xia et al, 2012 ; Yang et al, 2018 ), pepper ( Capsicum annuum ) ( Liu et al, 2007 ; Joo et al, 2019a , 2020 ), wheat ( Triticum aestivum ) ( Agarwal and Khurana, 2018 ; Liu et al, 2018 ; Wang et al, 2020 ), potato ( Solanum tuberosum ) ( Guo et al, 2003 ; Ni et al, 2010 ; Qi et al, 2020 ), wild tomato ( Solanum pimpinellifolium ) ( Yang et al, 2016 ), wild Chinese grape ( Vitis pseudoreticulata ) ( Yu et al, 2013 ; Wang et al, 2017 ), soybean ( Glycine max ) ( Du et al, 2010 ; Biniek et al, 2017 ; Zhao et al, 2020 ), Brassica rapa ( Jung et al, 2013 ), tobacco ( Nicotiana benthamiana) ( Wu et al, 2014 ), and cassava ( Manihot esculenta Crantz) ( Dos Reis et al, 2012 ). RING zinc finger proteins have a characteristic RING zinc finger domain.…”