ARS | Publication request: Determination of resistance spectra of the Pi-ta and Pi-k genes to US races of Magnaporthe oryzae causing rice blast in a recombinant inbred line population

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 17, 2009
Publication Date: June 1, 2009
Citation: Jia, Y., Lee, F.N., McClung, A.M. 2009. Determination of resistance spectra of the Pi-ta and Pi-k genes to U.S. races of Magnaporthe oryzae causing rice blast in a recombinant inbred line population. Plant Disease. 93(6):639-644.

Interpretive Summary: Stacking resistance (R) genes with overlapped resistance spectra is one of the most powerful plant breeding strategies to control rice blast disease. We reported the determination of resistance spectrum of the two widely used R genes, Pi-ta and Pi-k, in the US using a new F10 recombinant inbred line population of the cross of a breeding line RU9101001 with a tropical japonica cultivar Katy. Katy was found to confer resistance to all common races IA-45, IB-1, IB-45, IB-49, IB-54, IC-17, ID-1, IE-1, IG-1, and IH-1 of M. oryzae. RU9101001 was found to confer resistance to races IA-45, IB-45, IB-54, IG-1, and IH-1 of M. oryzae. Twenty-three polymorphic simple sequence repeat (SSR) markers were used to map R genes. Segregation ratios of 1:1 resistance to susceptibility to races IB-1, IB-49, IC-17, ID-1 and IE-1 suggest the presence of a single dominant R gene in Katy. Ratios of 3 resistance:1 susceptibility to races IA-45, IB-45, IG-1 and IH-1 suggests that a single R gene was present in Katy, and another R gene was present in RU9101001. Resistance to the above mentioned races were correlated with the presences of the Pi-ta gene and 11 Katy SSR alleles suggesting that Pi-ta confers resistance to IA-45, IB-1, IB-49, IB-45, IC-17, IG-1, ID-1, IE-1 and IH-1. Katy, RU9101001 and all RILs were found resistant to IB-54 consistent with the presence of Pi-ks in Katy and Pi-kh in RU9101001. Resistance to IA-45, IB-45, IG-1 and IH-1 correlated with the presence of Pi-kh suggesting that Pi-kh confers resistance to IA-45, IB-45, IG-1 and IH-1. We suggest that Pi-ta and Pi-kh are effective R genes providing overlapped resistance to the ten common races of M. oryzae.

Technical Abstract: Resistance (R) genes to ten common races of Magnaporthe oryzae were mapped using an F10 recombinant inbred line population of a cross of a tropical japonica cultivar Katy with a breeding line RU9101001. Katy was found to confer resistance to all common races IA-45, IB-1, IB-45, IB-49, IB-54, IC-17, ID-1, IE-1, IG-1, and IH-1 of M. oryzae. RU9101001 was found to confer resistance to races IA-45, IB-45, IB-54, IG-1, and IH-1 of M. oryzae. Twenty-three polymorphic simple sequence repeat (SSR) markers were used to map R genes. Segregation ratios of 1:1 resistance to susceptibility to races IB-1, IB-49, IC-17, ID-1 and IE-1 suggest the presence of a single dominant R gene in Katy. Ratios of 3 resistance:1 susceptibility to races IA-45, IB-45, IG-1 and IH-1 suggests that a single R gene was present in Katy, and another R gene was present in RU9101001. Resistance to the above mentioned races were correlated with the presences of the Pi-ta gene and 11 Katy SSR alleles suggesting that Pi-ta confers resistance to IA-45, IB-1, IB-49, IB-45, IC-17, IG-1, ID-1, IE-1 and IH-1. Katy, RU9101001 and all RILs were found resistant to IB-54 consistent with the presence of Pi-ks in Katy and Pi-kh in RU9101001. Resistance to IA-45, IB-45, IG-1 and IH-1 correlated with the presence of Pi-kh suggesting that Pi-kh confers resistance to IA-45, IB-45, IG-1 and IH-1. These data suggest that Pi-ta and Pi-kh are effective R genes providing overlapped resistance to the ten common races of M. oryzae.