title: Soybean homologs of MPK4 negatively regulate defense responses and positively regulate growth and development.
abstract: Mitogen-activated protein kinase (MAPK) cascades play important roles in disease resistance in model plant species such as Arabidopsis (Arabidopsis thaliana) and tobacco (Nicotiana tabacum). However, the importance of MAPK signaling pathways in the disease resistance of crops is still largely uninvestigated. To better understand the role of MAPK signaling pathways in disease resistance in soybean (Glycine max), 13, nine, and 10 genes encoding distinct MAPKs, MAPKKs, and MAPKKKs, respectively, were silenced using virus-induced gene silencing mediated by Bean pod mottle virus. Among the plants silenced for various MAPKs, MAPKKs, and MAPKKKs, those in which GmMAPK4 homologs (GmMPK4s) were silenced displayed strong phenotypes including stunted stature and spontaneous cell death on the leaves and stems, the characteristic hallmarks of activated defense responses. Microarray analysis showed that genes involved in defense responses, such as those in salicylic acid (SA) signaling pathways, were significantly up-regulated in GmMPK4-silenced plants, whereas genes involved in growth and development, such as those in auxin signaling pathways and in cell cycle and proliferation, were significantly down-regulated. As expected, SA and hydrogen peroxide accumulation was significantly increased in GmMPK4-silenced plants. Accordingly, GmMPK4-silenced plants were more resistant to downy mildew and Soybean mosaic virus compared with vector control plants. Using bimolecular fluorescence complementation analysis and in vitro kinase assays, we determined that GmMKK1 and GmMKK2 might function upstream of GmMPK4. Taken together, our results indicate that GmMPK4s negatively regulate SA accumulation and defense response but positively regulate plant growth and development, and their functions are conserved across plant species.
authors: Department of Plant Pathology, Iowa State University, Ames, Iowa 50011, USA.
authors: Jian-Zhong
authors: JZ
authors: Liu
authors: Heidi D
authors: HD
authors: Horstman
authors: Edward
authors: E
authors: Braun
authors: Michelle A
authors: MA
authors: Graham
authors: Chunquan
authors: C
authors: Zhang
authors: Duroy
authors: D
authors: Navarre
authors: Wen-Li
authors: WL
authors: Qiu
authors: Yeunsook
authors: Y
authors: Lee
authors: Dan
authors: D
authors: Nettleton
authors: John H
authors: JH
authors: Hill
authors: Steven A
authors: SA
authors: Whitham
mesh_terms: D029681:Arabidopsis Proteins / Q000737:chemistry*; D002467:Cell Nucleus / Q000201:enzymology; D060467:Disease Resistance / Q000235:genetics; D015536:Down-Regulation / Q000235:genetics; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D020868:Gene Silencing; D006861:Hydrogen Peroxide / Q000378:metabolism; D008163:Luminescent Measurements; D020928:Mitogen-Activated Protein Kinases / Q000737:chemistry*; D020411:Oligonucleotide Array Sequence Analysis; D044742:Peronospora / Q000502:physiology; D010766:Phosphorylation; D010935:Plant Diseases / Q000235:genetics / Q000276:immunology / Q000382:microbiology / Q000821:virology; D010940:Plant Proteins / Q000378:metabolism*; D010942:Plant Viruses / Q000502:physiology; D011485:Protein Binding; D021381:Protein Transport; D020156:Salicylic Acid / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013025:Glycine max / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000276:immunology*; D013347:Subcellular Fractions / Q000201:enzymology; D015854:Up-Regulation / Q000235:genetics
chemical_list: D029681:Arabidopsis Proteins; D010940:Plant Proteins; D006861:Hydrogen Peroxide; C436292:AtMPK4 protein, Arabidopsis; D020928:Mitogen-Activated Protein Kinases; D020156:Salicylic Acid