Article

Overexpression of the mitogen-activated protein kinase gene OsMAPK33 enhances sensitivity to salt stress in rice (Oryza sativa L.)

Department of Agricultural Biotechnology, National Academy of Agricultural Science, Rural Development Administration, Suwon 441-857, Republic of Korea.
Journal of Biosciences (Impact Factor: 2.06). 03/2011; 36(1):139-51. DOI: 10.1007/s12038-011-9002-8
Source: PubMed

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, aMAPK 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.

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Available from: Benjamin F Matthews, Jun 02, 2014
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    • "Perception and processing of extracellular signals through plasma membrane receptor-like protein kinases (RLKs) in plants lead to alterations in the concentrations of cellular ions and molecules that activate protein phosphorylation pathways. This in turn regulates expression of stress-responsive genes to generate physiological, biochemical, and other adaptive responses that reduce or eliminate the problem (Lee et al., 2011; Xing et al., 2011). RLKs belong to the serine/ threonine protein kinase family. "
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    ABSTRACT: Drought is a recurring climatic hazard that reduces the crop yields. To avoid the negative effects of drought on crop production, extensive efforts have been devoted to investigating the complex mechanisms of gene expression and signal transduction during drought stress. Receptor-like kinases (RLKs) play important roles in perceiving extracellular stimuli and activating downstream signalling responses. The rice genome contains >1100 RLK genes, of which only two are reported to function in drought stress. A leucine-rich repeat (LRR)-RLK gene named Leaf Panicle 2 (LP2) was previously found to be strongly expressed in leaves and other photosynthetic tissues, but its function remains unclear. In the present study, it was shown that the expression of LP2 was down-regulated by drought and abscisic acid (ABA). Transgenic plants overexpressing LP2 accumulated less H2O2, had more open stomata in leaves, and showed hypersensitivity to drought stress. Further investigation revealed that transcription of LP2 was directly regulated by the zinc finger transcription factor DROUGHT AND SALT TOLERANCE (DST). In addition, LP2 was identified as a functional kinase localized to the plasma membrane and interacted with the drought-responsive aquaporin proteins OsPIP1; 1, OsPIP1; 3, and OsPIP2; 3. Thus, the findings provided evidence that the LRR-RLK LP2, transcriptionally regulated by the drought-related transcription factor DST, served as a negative regulator in drought response.
    Full-text · Article · Sep 2014 · Journal of Experimental Botany
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    • "In fact, while many MAP kinases are described to be positively regulated under abiotic stresses, some MAP kinases play negative roles in stress tolerance. For example , overexpression of the MAP kinases, OsMAPK33 in rice (Lee et al. 2011) and MKK9 in Arabidopsis (Xu et al. 2008), results in high sensitivity of rice and Arabidopsis, respectively, to salt stress. Moreover, the inactivation of the Arabidopsis MKK9 by the insertion of transferred DNA (T- DNA) generates salt-insensitive phenotypes that germinate at up to 150 mM NaCl, with rapid induction of RD22 and RD29 stress genes (Alzwiy and Morris 2007). "
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    ABSTRACT: Plants have evolved with complex signaling circuits that operate under multiple conditions and govern numerous cellular functions. Stress signaling in plant cells is a sophisticated network composed of interacting proteins organized into tiered cascades where the function of a molecule is dependent on the interaction and the activation of another. In a linear scheme, the receptors of cell surface sense the stimuli and convey stress signals through specific pathways and downstream phosphorylation events controlled by mitogen-activated protein (MAP) kinases and second messengers, leading to appropriate adaptive responses. The specificity of the pathway is guided by scaffolding proteins and docking domains inside the interacting partners with distinctive structures and functions. The flexibility and the fine-tuned organization of the signaling molecules drive the activated MAP kinases into the appropriate location and connection to control and integrate the information flow. Here, we overview recent findings of the involvement of MAP kinases in major abiotic stresses (drought, cold and temperature fluctuations) and we shed light on the complexity and the specificity of MAP kinase signaling modules.
    Full-text · Article · May 2014 · Plant Cell Reports
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    • "In fact, while many MAP kinases are described to be positively regulated under abiotic stresses, some MAP kinases play negative roles in stress tolerance. For example , overexpression of the MAP kinases, OsMAPK33 in rice (Lee et al. 2011) and MKK9 in Arabidopsis (Xu et al. 2008), results in high sensitivity of rice and Arabidopsis, respectively, to salt stress. Moreover, the inactivation of the Arabidopsis MKK9 by the insertion of transferred DNA (T- DNA) generates salt-insensitive phenotypes that germinate at up to 150 mM NaCl, with rapid induction of RD22 and RD29 stress genes (Alzwiy and Morris 2007). "
    [Show abstract] [Hide abstract]
    ABSTRACT: Plants have evolved with complex signaling circuits that operate under multiple conditions and govern numerous cellular functions. Stress signaling in plant cells is a sophisticated network composed of interacting proteins organized into tiered cascades where the function of a molecule is dependent on the interaction and the activation of another. In a linear scheme, the receptors of cell surface sense the stimuli and convey stress signals through specific pathways and downstream phosphorylation events controlled by mitogen-activated protein (MAP) kinases and second messengers, leading to appropriate adaptive responses. The specificity of the pathway is guided by scaffolding proteins and docking domains inside the interacting partners with distinctive structures and functions. The flexibility and the fine-tuned organization of the signaling molecules drive the activated MAP kinases into the appropriate location and connection to control and integrate the information flow. Here, we overview recent findings of the involvement of MAP kinases in major abiotic stresses (drought, cold and temperature fluctuations) and we shed light on the complexity and the specificity of MAP kinase signaling modules.
    Full-text · Article · May 2014 · Plant Cell Reports
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