Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/9/2002
Publication Date: 11/1/2002
Citation: Jia, Y., Wang, Z., Singh, P. 2002. DEVELOPMENT OF THE RICE BLAST PI-TA RESISTANCE GENE DOMINANT MARKERS. Crop Science. 42:2145-2149. Interpretive Summary: Rice is one of the most important crop plants in the world, and the rice blast disease caused by the fungus, Magnaporthe grisea, is one of the most destructive diseases. Incorporation of resistance genes into existing rice varieties is a common practice for the control of the disease. Therefore, it is essential for rice breeders to know whether breeding materials contain a particular blast resistance gene. The Pi-ta gene is one of the major blast resistance genes that can effectively fight against M. grisea strains expressing the corresponding avirulence gene AVR-Pita in a gene-for-gene manner. Pi-ta has been recently characterized at the molecular level and is important in breeding for rice blast resistance in the Southern U.S. Pi-ta is a single gene located along with other resistance genes (such as Pi-ta2) near the centromere of chromosome 12. Unusual low polymorphisms between resistant and susceptible Pi-ta allels have been discovered. Development of Pi-ta gene marker will allow rapid incorporation of Pi-ta and other resistance genes that are closely linked with Pi-ta. Oligonuleotides specific to the dominant Pi-ta allele were designed for detecting Pi-ta presence in 10 advanced rice breeding lines using polymerase chain reaction. The disease reactions of these breeding lines were also evaluated in both greenhouse and field plots. The correlation of Pi-ta presence and disease reaction is the basis for stacking resistance genes into advanced breeding lines in the Southern U.S.
Technical Abstract: Incorporation of resistance genes into existing rice cultivars is a common practice for the control of the rice blast disease. The rice blast resistance gene, Pi-ta, originally introgressed into japonica from indica rice is important in breeding for rice blast resistance in the Southern U.S. The rice cultivar Katy that contains Pi-ta is resistant to the predominant blast, Magnaporthe grisea, races IB-49 and IC-17 and has been used as the blast resistant breeding parent in Southern U.S. Three pairs of DNA primers specific to the dominant indica Pi-ta gene were designed to amplify the Pi-ta gene by polymerase chain reaction (PCR). PCR products amplified by these Pi-ta specific primers were cloned and sequenced. Sequence analysis confirmed the presence of the dominant indica Pi-ta allele. These Pi-ta primers have been used to examine the presence of Pi-ta alleles in advanced Arkansas rice breeding lines. The Pi-ta containing rice lines as determined by PCR analysis were resistant to both IB-49 and IC-17 in standard pathogenicity assays. In contrast, lines lacking the Pi-ta genes failed to protect rice plants against both races IB-49 and IC-17. The presence of Pi-ta markers correlated with the Pi-ta resistance spectrum. Thus, the Pi-ta gene markers provide a basis for stacking other blast resistance genes into high yielding and good quality advanced breeding rice lines.