title: ZmMKK4, a novel group C mitogen-activated protein kinase kinase in maize (Zea mays), confers salt and cold tolerance in transgenic Arabidopsis.
abstract: Mitogen-activated protein kinase (MAPK) cascades are signalling modules that transduce extracellular signalling to a range of cellular responses. Plant MAPK cascades have been implicated in development and stress response. In this study, we isolated a novel group C MAPKK gene, ZmMKK4, from maize. Northern blotting analysis revealed that the ZmMKK4 transcript expression was up-regulated by cold, high salt and exogenous H(2)O(2,) but down-regulated by exogenous abscisic acid (ABA). Over-expression of ZmMKK4 in Arabidopsis conferred tolerance to cold and salt stresses by increased germination rate, lateral root numbers, plant survival rate, chlorophyll, proline and soluble sugar contents, and antioxidant enzyme [peroxidase (POD), catalase (CAT)] activities compared with control plants. Furthermore, ZmMKK4 enhanced a 37 kDa kinase activity after cold and salt stresses. RT-PCR analysis revealed that the transcript levels of stress-responsive transcription factors and functional genes were higher in ZmMKK4-over-expressing plants than in control plants. In addition, ZmMKK4 protein is localized in the nucleus. Taken together, these results indicate that ZmMKK4 is a positive regulator of salt and cold tolerance in plants.
authors.affiliation: State Key Laboratory of Crop Biology, Shandong Key Laboratory of Crop Biology, College of Life Sciences, Shandong Agricultural University, Tai'an 271018, Shandong, China.
authors.forename: Xiangpei
authors.initials: X
authors.lastname: Kong
authors.forename: Jiaowen
authors.initials: J
authors.lastname: Pan
authors.forename: Maoying
authors.initials: M
authors.lastname: Zhang
authors.forename: Xin
authors.initials: X
authors.lastname: Xing
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Dapeng
authors.initials: D
authors.lastname: Li
authors.forename: Dequan
authors.initials: D
authors.lastname: Li
mesh_terms: D000040:Abscisic Acid / Q000494:pharmacology; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism; D002374:Catalase / Q000378:metabolism; D002467:Cell Nucleus / Q000201:enzymology; D002734:Chlorophyll / Q000378:metabolism; D058639:Cold-Shock Response; D004789:Enzyme Activation; D018506:Gene Expression Regulation, Plant; D005819:Genetic Markers; D018525:Germination; D020929:Mitogen-Activated Protein Kinase Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D010544:Peroxidases / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism; D011392:Proline / Q000378:metabolism; D055049:Salt Tolerance / Q000235:genetics*; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D015854:Up-Regulation; D003313:Zea mays / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism
chemical_list: D005819:Genetic Markers; D010940:Plant Proteins; D014157:Transcription Factors; D002734:Chlorophyll; D000040:Abscisic Acid; D011392:Proline; D010544:Peroxidases; D002374:Catalase; D020929:Mitogen-Activated Protein Kinase Kinases