Arabidopsis MKK4 mediates osmotic-stress response via its regulation of MPK3 activity |
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Authors: | Kim Sun-Ho Woo Dong-Hyuk Kim Jae-Min Lee Sun-Young Chung Woo Sik Moon Yong-Hwan |
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Institution: | aDepartment of Molecular Biology, Pusan National University, Busan 609-735, Republic of Korea;bDivision of Applied Life Science (BK21 Program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Jinju 660-701, Republic of Korea |
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Abstract: | Plants have developed disparate regulatory pathways to adapt to environmental stresses. In this study, we identified MKK4 as an important mediator of plant response to osmotic stress. mkk4 mutants were more sensitive to high salt concentration than WT plants, exhibiting higher water-loss rates under dehydration conditions and additionally accumulating high levels of ROS. In contrast, MKK4-overexpressing transgenic plants showed tolerance to high salt as well as lower water-loss rates under dehydration conditions. In-gel kinase assays revealed that MKK4 regulates the activity of MPK3 upon NaCl exposure. Semi-quantitative RT-PCR analysis showed that expression of NCED3 and RD29A was lower and higher in mkk4 mutants and MKK4-overexpressing transgenic plants, respectively. Taken together, our results suggest that MKK4 is involved in the osmotic-stress response via its regulation of MPK3 activity. |
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Keywords: | Abbreviations: ABA abscisic acid MKK MPK kinase MKKK MPK kinase kinase MPK mitogen-activated protein kinase NBT nitroblue tetrazolium ROS reactive oxygen species |
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