Title: Characterization of rice blast resistance gene Pi61(t) in rice germplasm Authors
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 24, 2014
Publication Date: N/A
Interpretive Summary: Rice blast is one of the most destructive diseases in the world. Genetic resistance, among other practices, is being used to manage this disease. This study examined a major quantitative resistance locus (QTL), qPi93-3, using fine mapping. A mapping population of 2381 individuals was derived from one recombinant inbred line individual, RIL171, developed from a cross between two cultivars, Nipponbare and 93-11. Twelve simple sequence repeat (SSR) markers were initially used to map qPi93-3 within a 4.2 Mb region delimited by SSR markers, RM3246 and RM7102. A major resistance gene, Pi61(t), identified by others, is known to be located in the same region. We determined that qPi93-3 was Pi61(t) using three insertion-deletion (InDel) markers. We then examined the existence of Pi61(t) in 136 germplasm collections using InDel markers and pathogenicity assay. Five germplasms out of 136 were found to have Pi61(t). These germplasms, along with InDel markers, will be useful in marker-assisted breeding for improved blast resistance.
Technical Abstract: Identification of resistance (R) genes to races of Magnaporthe oryzae in rice germplasm is essential for the development of rice cultivars with long lasting blast resistance. In the present study, one major quantitative trait locus, qPi93-3, was fine mapped using a recombinant inbred line (RIL), F8 RIL171, derived from the cross between Nipponbare and 9311. RIL171 contained a heterozygous qPi93-3 allele was found to be resistant against 9 U.S. common races, ID1, IA1, IB49, IE1, IA45, IB1, IC17, IB45 and IH1of M. oryzae. A F2 mapping population consisting of 2381 individuals derived from RIL171was evaluated with a field isolate (race) ARB82 (IA1) of M. oryzae under greenhouse conditions. Disease reaction of a ratio of 3 resistant: 1 susceptible was identified with F2:F3 families. A total of 12 SSR markers spanning qPi93-3 were used for fine mapping. Consequently, qPi93-3 was delimited to 4.2 Mb between RM3246 and RM7102. Three insertion-deletion (InDel) markers spanning Pi61(t) were used to determine if they are the same gene, and the results demonstrated that qPi93-3 is Pi61(t). The existence of Pi61(t) in 136 rice germplasm was evaluated using Pi61(t) specific InDel markers. Five germplasms out of 136 were found to have Pi61(t). These characterized germplasm are useful for rice breeders to use for improving blast resistance.