Plant Genomics Lab, Department of Applied Plant Sciences, Kangwon National University, Chuncheon, 200-713, Republic of Korea.
Planta. 2018 Apr;247(4):875-886. doi: 10.1007/s00425-017-2834-1. Epub 2017 Dec 19.
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.
我们的研究结果表明，水稻 E3 连接酶 OsMAR1 与细胞质蛋白 OCPI2 发生物理相互作用，可能在盐胁迫下发挥重要作用。盐是一种重要的非生物胁迫因子，它会对植物的生长阶段产生负面影响，并改变其发育过程。本研究发现，水稻基因 OsMAR1（水稻微管相关 RING 指蛋白 1）编码 RING E3 连接酶，其表达水平在高盐、水分亏缺和 ABA 处理下显著上调。其重组蛋白的荧光信号与水稻原生质体中的微管明显相关。酵母双杂交（Y2H）和双分子荧光互补（BiFC）实验表明，OsMAR1 与细胞质蛋白 OCPI2（水稻糜蛋白酶抑制剂 2）相互作用，并通过 26S 蛋白酶体导致其降解。拟南芥中 OsMAR1 的异源过表达与对照植物相比，根的生长受到抑制，随后在高盐胁迫下表现出超敏表型。综上所述，OsMAR1 通过调节水稻 OCPI2 蛋白负调控盐胁迫反应。
