Submitted to: Chinese Journal of Rice Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 3/1/2005
Publication Date: 6/1/2005
Citation: Wang, Z., Redus, M., Jia, Y. 2005. Establishment of codominant markers for rice blast resistance gene Pi-ta. Chinese Journal of Rice Science. 19:483-488. Interpretive Summary: Rice blast disease caused by the fungal pathogen Magnaporthe grisea is one of the most devastating rice diseases worldwide. Complete resistance genes to this pathogen have been identified and utilized for the development of improved resistance in new rice cultivars. Breeding for improved resistance to the rice blast pathogen can be accelerated if DNA markers to a major resistance gene are established. In this work, a single nucleotide length polymorphism marker from a conserved region of a major blast resistance gene Pi-ta was identified and was successfully used to assist molecular marker assisted breeding via automation. A resistant allele of the Pi-ta gene should produce a PCR product of 181 base pairs whereas a susceptible allele of the Pi-ta gene should produce a PCR product approximately between 182-183 base pairs. Furthermore, by using three sets of primers where two forward primers were labeled using different colors of dyes, and with reverse primer unlabeled in a single PCR reaction one can detect the existence of the different alleles of the Pi-ta gene readily by visualizing different color of peaks separated by automatic DNA sequencers. This marker for Pi-ta was derived from a resistance gene thus it is the perfect marker for introduction of the Pi-ta gene into advanced breeding lines. The reliability and procedures for its application are illustrated in Chinese thus this work will have a major impact on the Chinese breeding community.
Technical Abstract: A single nucleotide length polymorphism (SNLP) was identified at the intron region of the Pi-ta gene to develop a codominant Pi-ta gene marker suitable for genotyping with an ABI automated machine. The DNA primer specific to the resistance Pi-ta allele was labeled with the blue dye as a forward primer, the DNA primer specific to the susceptibility pi-ta allele was labeled with green dye as another forward primer and the DNA primer identical to both Pi-ta/pi-ta alleles was unlabeled as the reverse primer for polymerase chain reaction (PCR). Using the three primers, a 181 bp blue peak in homozygous resistant and a green peak of 183 bp in homozygous susceptible, and both peaks in heterozygous plants were produced by PCR. The utility of marker was verified using 12 plants coming from segregation F2 population and 15 inbred varieties via dominant markers and pathogenicity test. A codominant Pi-ta marker is thus developed for effective Pi-ta assisted selection for rice disease resistance breeding program.