Characterization ofPi-tablast resistance gene in an international rice core collection

With 3 figures and 3 tables The Pi-ta gene in rice prevents the infections by races of Magnaporthe oryzae containing AVR-Pita. In the present study, 1790 accessions were characterized for Pi-ta, and Pi-ta independent resistance genes using marker analysis, disease evaluation with the race IB-49 carrying AVR-Pita, and IE-1k not carrying AVR-Pita and sequence analysis. A total of 183 accessions were identified using a Pi-ta-indel marker from the intron region. Sequence analysis revealed that resistance functional nucleotide polymorphism (FNP) was present in 163 accessions including reference cultivars. Among them, 89 were resistant to IB-49 and susceptible to IE-1k indicating that these accessions contain Pi-ta R alleles. Four accessions were susceptible to IB-49 suggesting that components were not intact in Pi-ta-mediated resistance. In contrast, 14 accessions with the susceptible FNP were resistant to IB-49 suggesting these 14 accessions may contain Pi-ta independent new R genes. Together, 83 accessions were identified to contain new R gene to IE-1k. These accessions were genetically distinct determined by simple sequence repeat markers. The results could impact breeding for blast resistance worldwide.