The microtubule-associated RING finger protein 1 (OsMAR1) acts as a negative regulator for salt-stress response through the regulation of OCPI2 (O. sativa chymotrypsin protease inhibitor 2)

Abstract

Our results suggest that a rice E3 ligase, OsMAR1, physically interacts with a cytosolic protein OCPI2 and may play an important role under salinity stress. Salt is an important abiotic stressor that negatively affects plant growth phases and alters development. Herein, we found that a rice gene, OsMAR1 (Oryza sativa microtubule-associated RING finger protein 1), encoding the RING E3 ligase was highly expressed in response to high salinity, water deficit, and ABA treatment. Fluorescence signals of its recombinant proteins were clearly associated with the microtubules in rice protoplasts. Yeast two-hybrid (Y2H) and bimolecular fluorescence complementation (BiFC) showed that OsMAR1 interacted with a cytosolic protein OCPI2 (O. sativa chymotrypsin protease inhibitor 2) and led to its degradation via the 26S proteasome. Heterogeneous overexpression of OsMAR1 in Arabidopsis showed retarded root growth compared with that of control plants, and then led to hypersensitivity phenotypes under high salinity stress. Taken together, OsMAR1 negatively regulates the salt-stress response via the regulation of the OCPI2 protein in rice.

Arabidopsis RING E3 ubiquitin ligase JUL1 participates in ABA‐mediated microtubule depolymerization, stomatal closure, and tolerance response to drought stress

“…Although several RING-type E3 Ub ligases have been implicated in drought stress responses (Stone, 2014;Zhang et al, 2014;Yu et al, 2016;Shu and Yang, 2017;Miricescu et al, 2018;Xu and Xue, 2019), our knowledge concerning their roles in regulating microtubule structures, with regard to stomatal movements, is rudimentary. In monocot rice plants, two putative RING E3 ligases, Oryza sativa RING FINGER PROTEIN WITH MICROTUBULE-TARGETING DOMAIN 1 (OsRMT1) and Oryza sativa MICROTUBULE-ASSOCIATED RING FINGER PROTEIN 1 (OsMAR1), were shown to be associated with microtubules (Lim et al, 2015b;Park et al, 2018). However, their cellular roles in regulating microtubule structures and stomatal closure were not addressed in rice.…”

Identification of genes for salt tolerance and yield-related traits in rice plants grown hydroponically and under saline field conditions by genome-wide association study

“…We identified LOC_Os01g06590 , a gene encoding a zinc finger, C3HC4-type domain-containing protein that is associated with FGN. The functional annotation was the same as that of two previously-identified ST-related genes, Osdsg1 and OsMAR1 ; the proteins encoded by these genes have been shown to possess E3 ubiquitin ligase activity (Park et al 2010; Park et al 2017).…”

Research Progress on Plant RING-Finger Proteins

“…OsSIRP1 is a negative regulator of salt tolerance, and its target protein needs to be further studied [49,60]. The microtubule-associated RING finger protein 1 (OsMAR1), an E3 ligase, acts as a negative regulator for salt-stress response through the regulation of the O. sativa chymotrypsin protease inhibitor 2 (OsCPI2), but anther rice RING H2-type E3 ligase, OsSIRH2-14 (previously named OsRFPH2-14), plays a positive role in salinity tolerance by regulating salt-related proteins, including an HKT-type Na+ transporter (OsHKT2; 1) [55,59]. The RING-finger proteins M. esculenta RZF (MeRZF) and SpRing were found to respond to salt stress in cassava and wild tomato, respectively.…”