ARS | Publication request: Linkage Block and Recombination Suppression at the Pi-ta locus at the Centromere Region of Rice Chromosome 12

Submitted to: American Phytopathology Society
Publication Type: Abstract Only
Publication Acceptance Date: November 1, 2010
Publication Date: February 16, 2011
Citation: Jia, Y., Jia, M.H., Liu, G. 2011. Linkage Block and Recombination Suppression at the Pi-ta locus at the Centromere Region of Rice Chromosome 12. American Phytopathology Society. 101:S82.

Technical Abstract: The Pi-ta gene, located near the centromeric region of chromosome 12 is an effective resistance gene to Magnaporthe oryzae that causes rice blast disease. Pi-ta has been incorporated into diverse resistant rice cultivars by classical plant breeding in the southern US and worldwide. Previously, large linkage blocks around Pi-ta ranging from 14 to 27 MB were observed in rice cultivars and in backcross progeny derived from an indica x japonica cross. In the present study, the same linkage block was further examined in 1600 random recombinant individuals possessing or lacking Pi-ta that were derived from indica x japonica, indica x indica crosses. Simple sequence repeat markers spanning Pi-ta and the centromeric region were used to detect recombination break points and to delimit the physical size of the linkage blocks. Large linkage blocks ranging from 4.1 to 10 MB on chromosome 12 were identified from recombinant individuals of indica x japonica crosses. However, significantly smaller blocks, ranging from less than 400 kb to 1 MB, were identified in indica x indica crosses regardless of the presence of Pi-ta. The large linkage blocks previously observed in rice cultivars and backcrossing progeny was predicted to be a result of recombination suppression and selection for blast resistance. These findings suggest that crosses of indica x japonica rice have significant recombination suppression at the centromeric region of chromosome 12.