Overexpression of a Pathogen-Inducible Myb Gene Increases Disease Resistance in Transgenic Rice1

A jasmonic acid (JA)-inducible Myb transcription factor gene (JAmyb) was previously isolated from rice and shown to be closely associated with host cell death and fungal infection. To further elucidate the role of JAmyb in host cell death and defense response, the JAmyb cDNA was fused to the constitutive 35S promoter and the stress-inducible rice PBZ1 promoter, respectively, and introduced into rice cultivar ‘Drew’ by the Agrobacterium-mediated transformation. Inducible overexpression of JAmyb transgene led to host cell death and reddish lesions in leaves of transgenic rice. When infected with the rice blast fungus (Magnaporthe grisea), transgenic leaves with reddish lesions exhibited significantly enhanced blast resistance. Young transgenic seedlings, which had relatively low levels of JAmyb transgene expression but no reddish lesions, also showed increased tolerance to both rice blast and bacterial panicle blight (caused by Burkholderia glumae). These results suggest that JAmyb encodes a positive regulator of host cell death and may play a significant role in durable, broad-spectrum disease resistance.