Essential role of the small GTPase Rac in disease resistance of rice.
Production of reactive oxygen intermediates (ROI) and a form of programmed cell death called hypersensitive response (HR) are often associated with disease resistance of plants. We have previously shown that the Rac homolog of rice, OsRac1, is a regulator of ROI production and cell death in rice. Here we show that the constitutively active OsRac1 (i) causes HR-like responses and greatly reduces disease lesions against a virulent race of the rice blast fungus; (ii) causes resistance against a virulent race of bacterial blight; and (iii) causes enhanced production of a phytoalexin and alters expression of defense-related genes. The dominant-negative OsRac1 suppresses elicitor-induced ROI production in transgenic cell cultures, and in plants suppresses the HR induced by the avirulent race of the fungus. Taken together, our findings strongly suggest that OsRac1 has a general role in disease resistance of rice.
Ono
E
E
Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0101, Japan.
Wong
H L
HL
Kawasaki
T
T
Hasegawa
M
M
Kodama
O
O
Shimamoto
K
K
D016960:Agrobacterium tumefaciens / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D020082:Magnaporthe / Q000502:physiology; D012275:Oryza / Q000201:enzymology* / Q000235:genetics; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010936:Plant Extracts / Q000096:biosynthesis / Q000235:genetics; D018515:Plant Leaves / Q000382:microbiology; D010940:Plant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D030821:Plants, Genetically Modified; D011523:Protoplasts / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012717:Sesquiterpenes; D013729:Terpenes; D014170:Transformation, Genetic; D020830:rac1 GTP-Binding Protein / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D000094162:Phytoalexins
D010936:Plant Extracts; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D012717:Sesquiterpenes; D013729:Terpenes; D020830:rac1 GTP-Binding Protein; D000094162:Phytoalexins