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    • Keywords


      Abiotic stress tolerance; MAPK; microarray; rice; transgenic plants

    • Abstract


      Mitogen-activated protein kinases (MAPK) signalling cascades are activated by extracellular stimuli such as environmental stresses and pathogens in higher eukaryotic plants. To know more about MAPK signalling in plants, a MAPK cDNA clone, OsMAPK33, was isolated from rice. The gene is mainly induced by drought stress. In phylogenetic analysis, OsMAPK33 (Os02g0148100) showed approximately 47–93% identity at the amino acid level with other plant MAPKs. It was found to exhibit organ-specific expression with relatively higher expression in leaves as compared with roots or stems, and to exist as a single copy in the rice genome. To investigate the biological functions of OsMAPK33 in rice MAPK signalling, transgenic rice plants that either overexpressed or suppressed OsMAPK33 were made. Under dehydration conditions, the suppressed lines showed lower osmotic potential compared with that of wild-type plants, suggesting a role of OsMAPK33 in osmotic homeostasis. Nonetheless, the suppressed lines did not display any significant difference in drought tolerance compared with their wild-type plants. With increased salinity, there was still no difference in salt tolerance between OsMAPK33-suppressed lines and their wild-type plants. However, the overexpressing lines showed greater reduction in biomass accumulation and higher sodium uptake into cells, resulting in a lower K+/Na+ ratio inside the cell than that in the wild-type plants and OsMAPK33-suppressed lines. These results suggest that OsMAPK33 could play a negative role in salt tolerance through unfavourable ion homeostasis. Gene expression profiling of OsMAPK33 transgenic lines through rice DNA chip analysis showed that OsMAPK33 altered expression of genes involved in ion transport. Further characterization of downstream components will elucidate various biological functions of this novel rice MAPK.

    • Author Affiliations


      Seong-Kon Lee1 2 Beom-Gi Kim1 Taek-Ryoun Kwon1 Mi-Jeong Jeong1 Sang-Ryeol Park1 Jung-Won Lee1 Myung-Ok Byun1 Hawk-Bin Kwon3 Benjamin F Matthews4 Choo-Bong Hong2 Soo-Chul Park1

      1. Department of Agricultural Biotechnology, National Academy of Agricultural Science, Rural Development Administration, Suwon 441–857, Republic of Korea
      2. Department of Biological Sciences, Seoul National University, Seoul 151–742, Republic of Korea
      3. Department of Biomedical Science, Sun Moon University, Asan 336–708, Republic of Korea
      4. Soybean Genomics and Improvement Lab, USDA-ARS, Beltsville, MD 20705, USA
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    • Supplementary Material

  • Journal of Biosciences | News

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