Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 2/24/2002
Publication Date: N/A
Citation: Interpretive Summary:
Technical Abstract: Rice is one of the most important crop plants in the world, and the rice blast disease caused by 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 stains 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 cetromere of chromosome 12. Unusual low polymorphisms between resistant and susceptible Pi-ta alleles 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 dozens of 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. Current progress of Pi-ta assisted selection for new cultivar development will be described.