ARS | Publication request: Characterization of the Pi-b Rice Blast Resistance Gene in the National Small Grains

Submitted to: American Phytopathology Society
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 2010
Publication Date: February 16, 2011
Citation: Roychowdhury, M., Jia, Y., Jia, M.H., Fjellstrom, R.G., Cartwright, R.D. 2011. Characterization of the Pi-b Rice Blast Resistance Gene in the National Small Grains. American Phytopathology Society. 101:S156.

Technical Abstract: The Pi-b gene in rice confers resistance to a wide range of races of the rice blast fungus, Magnaporthe oryzae, including race IE1k that overcomes Pi-ta. In the present study, Pi-b was identified in 164 rice germplasm accessions from the National Small Grains Collection using DNA markers and pathogenicity assays. The existence of Pi-b in rice germplasm was detected by using two simple sequence repeat (SSR) markers, RM 208 and RM 166, and a dominant marker Pibdom derived from Pi-b. Pathogenicity assays using an avirulent race (IE1k) and a virulent race (IB54) were performed to verify resistance specificity of Pi-b. Among the 164 germplasm accessions evaluated, 130 were found to contain the Pi-b gene using both SSR markers and pathogenicity assays, although with different haplotypes. The remaining 34 germplasm accessions were found to be different in their responses to the blast races IB54 and IE1k, suggesting the presence of Pi-b independent R gene(s). These characterized germplasm accessions can be used for genetic studies and marker-assisted breeding for improving blast resistance in rice.