Submitted to: Euphytica
Publication Type: Peer reviewed journal
Publication Acceptance Date: 5/23/2004
Publication Date: 8/18/2004
Citation: Jia, Y., Redus, M.A., Wang, Z., Rutger, J.N. 2004. Development of a co-dominant resistance gene marker by tri-primer polymerase chain reaction. Euphytica. v. 138. p. 97-105. Interpretive Summary: The Pi-ta gene introgressed into japonica rice from indica has been used to control the blast disease caused by the fungal pathogen Magnaporthe grisea (Herbert) Borr. (anamorph Pyricularia oryza Cav.) worldwide. A single nucleotide length polymorphism was identified at the center of the Pi-ta gene to develop a co-dominant Pi-ta gene marker suitable for genotyping with an automated machine. The DNA primer specific to the resistant Pi-ta allele was labeled with blue dye as a forward primer, the DNA primer specific to the susceptible 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 these 3 primers a 181 bp blue peak in homozygous resistant and a green peak of 182-183 bp in homozygous susceptible, and both peaks in heterozygous plants were produced by PCR. The genotypes of 24 F2 progeny involving a Pi-ta containing rice cultivar and of an additional 25 rice cultivars were determined by this co-dominant Pi-ta gene marker and results were verified by a pair of dominant markers and further confirmed in F3 families by standard pathogenicity assays with a M. grisea strain containing the AVR-Pita gene. Homozygous dominant Pi-ta allele was only identified from Pi-ta containing rice cultivars and the genotype of Pi-ta in F2 was consistent with results obtained in F3 by pathogenicity assays. A codominant Pi-ta marker is thus developed for effective Pi-ta assisted selection for crop improvement.
Technical Abstract: The Pi-ta resistance gene controls the rice blast disease worldwide in a gene for gene manner and a codominant Pi-ta gene marker based on single nucleotide length polymorphism was developed for effective marker-assisted selection of blast resistance. Three DNA primers and two different labeling dyes were used in a single polymerase chain reaction and the genotypes of rice were rapidly determined by use of an automated machine. The first codominant marker from a cloned resistance gene was developed for crop improvement.