Disease resistance and abiotic stress tolerance in rice are inversely modulated by an abscisic acid-inducible mitogen-activated protein kinase.
Mitogen-activated protein kinase (MAPK) cascades play an important role in mediating stress responses in eukaryotic organisms. However, little is known about the role of MAPKs in modulating the interaction of defense pathways activated by biotic and abiotic factors. In this study, we have isolated and functionally characterized a stress-responsive MAPK gene (OsMAPK5) from rice. OsMAPK5 is a single-copy gene but can generate at least two differentially spliced transcripts. The OsMAPK5 gene, its protein, and kinase activity were inducible by abscisic acid as well as various biotic (pathogen infection) and abiotic (wounding, drought, salt, and cold) stresses. To determine its biological function, we generated and analyzed transgenic rice plants with overexpression (using the 35S promoter of Cauliflower mosaic virus) or suppression (using double-stranded RNA interference [dsRNAi]) of OsMAPK5. Interestingly, suppression of OsMAPK5 expression and its kinase activity resulted in the constitutive expression of pathogenesis-related (PR) genes such as PR1 and PR10 in the dsRNAi transgenic plants and significantly enhanced resistance to fungal (Magnaporthe grisea) and bacterial (Burkholderia glumae) pathogens. However, these same dsRNAi lines had significant reductions in drought, salt, and cold tolerance. By contrast, overexpression lines exhibited increased OsMAPK5 kinase activity and increased tolerance to drought, salt, and cold stresses. These results strongly suggest that OsMAPK5 can positively regulate drought, salt, and cold tolerance and negatively modulate PR gene expression and broad-spectrum disease resistance.
Xiong
Lizhong
L
Department of Plant Pathology and Program in Cell and Molecular Biology, University of Arkansas, Fayetteville, Arkansas 72701, USA.
Yang
Yinong
Y
D000040:Abscisic Acid / Q000494:pharmacology*; D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics* / Q000502:physiology; D000595:Amino Acid Sequence; D003080:Cold Temperature; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004190:Disasters; D005658:Fungi / Q000254:growth & development; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D007113:Immunity, Innate / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D012275:Oryza / Q000201:enzymology / Q000235:genetics* / Q000382:microbiology; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012965:Sodium Chloride / Q000494:pharmacology; D013314:Stress, Mechanical
D018076:DNA, Complementary; D010940:Plant Proteins; C053376:pathogenesis-related proteins, plant; D012965:Sodium Chloride; D000040:Abscisic Acid; D020928:Mitogen-Activated Protein Kinases