A cotton group C MAP kinase gene, GhMPK2, positively regulates salt and drought tolerance in tobacco
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Mitogen-activated protein kinase (MAPK) cascades play important roles in mediating biotic and abiotic stress responses. In plants, MAPKs are classified into four major groups (A–D) according to their sequence homology and conserved phosphorylation motifs. Compared with well-studied MAPKs in groups A and B, little is known about group C. In this study, we functionally characterised a stress-responsive group C MAPK gene (GhMPK2) from cotton (Gossypium hirsutum). Northern blot analysis indicated that GhMPK2 was induced by abscisic acid (ABA) and abiotic stresses, such as NaCl, PEG, and dehydration. Subcellular localization analysis suggested that GhMPK2 may activate its specific targets in the nucleus. Constitutive overexpression of GhMPK2 in tobacco (Nicotiana tabacum) conferred reduced sensitivity to ABA during both seed germination and vegetative growth. Interestingly, transgenic plants had a decreased rate of water loss and exhibited enhanced drought and salt tolerance. Additionally, transgenic plants showed improved osmotic adjustment capacity, elevated proline accumulation and up-regulated expression of several stress-related genes, including DIN1, Osmotin and NtLEA5. β-glucuronidase (GUS) expression driven by the GhMPK2 promoter was clearly enhanced by treatment with NaCl, PEG, and ABA. These results strongly suggest that GhMPK2 positively regulates salt and drought tolerance in transgenic plants.
KeywordsCotton (Gossypiumhirsutum) GhMPK2 Salt Drought Osmotic adjustment Transgenic tobacco
Green fluorescence protein
Inverse polymerase chain reaction
Mitogen-activated protein kinase
Open reading frame
Polymerase chain reaction
This work was financially supported by China National Transgenic Plant Research and Commercialization Projects (2009ZX08009-092B; 2009ZX08009-113B), and the National Natural Science Foundation of China (30970225).
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