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United States Department of Agriculture

Agricultural Research Service

Title: Identification of a new locus Ptr(t) required for rice blast resistance gene Pi-ta-mediated resistance

Authors
item Jia, Yulin
item Marin, Roger - OAK RIDGE LAB

Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 17, 2008
Publication Date: April 1, 2008
Citation: Jia, Y., Marin, R. 2008. Identification of a new locus Ptr(t) required for rice blast resistance gene Pi-ta-mediated resistance. Molecular Plant-Microbe Interactions. 21(4):396-403.

Interpretive Summary: Understanding of molecular mechanisms of resistance gene mediated defense response will benefit the development of strategies to control rice blast disease. Resistance to the blast pathogen Magnaporthe oryzae is proposed to be initiated by physical binding of a putative cytoplasmic receptor encoded by a NBS-type resistance gene, Pi-ta, to the processed elicitor encoded by the corresponding avirulence gene AVR-Pita. Here we report the identification of a new locus, Ptr(t) that is required for Pi-ta-mediated signal recognition. A Pi-ta expressing susceptible mutant was identified using a genetic screen. Putative mutations at Ptr(t) do not alter recognition specificity to another resistance gene, Pi-ks, in the Pi-ta homozygote, indicating that Ptr(t) is more likely specific to Pi-ta-mediated signal recognition. Genetic crosses of Pi-ta Ptr(t) and Pi-ta ptr(t) homozygotes suggest that Ptr(t) segregates as a single dominant nuclear gene. A ratio of 1:1 (resistant:susceptible) of BC1 using Pi-ta Ptr(t) with pi-ta ptr(t) homozygotes indicates that Pi-ta and Ptr(t) are linked and co-segregate. Genotyping of mutants pi-ta ptr(t) and Pi-ta Ptr(t) homozygotes using ten simple sequence repeat markers of Pi-ta determined that Pi-ta and Ptr(t) are located within a 9 MB region and are of indica origin. Identification of Ptr(t) is a significant advancement in studying Pi-ta-mediated signal recognition and transduction.

Technical Abstract: Resistance to the blast pathogen Magnaporthe oryzae is proposed to be initiated by physical binding of a putative cytoplasmic receptor encoded by a NBS-type resistance gene, Pi-ta, to the processed elicitor encoded by the corresponding avirulence gene AVR-Pita. Here we report the identification of a new locus, Ptr(t), that is required for Pi-ta-mediated signal recognition. A Pi-ta expressing susceptible mutant was identified using a genetic screen. Putative mutations at Ptr(t) do no alter recognition specificity to another resistance gene, Pi-ks, in the Pi-ta-mediated signal recognition. Genetic crosses of Pi-ta Ptr(t) and Pi-ta ptr(t) homozygotes suggest that Ptr(t) segregates as a single dominant nuclear gene. A ratio of 1:1 (resistant:susceptible) of a population BC1 of Pi-ta Ptr(t) with pi-ta ptr(t) homozygotes indicated that Pi-ta and Ptr(t) are linked and co-segregate. Genotyping of mutants of pi-ta ptr(t) and Pi-ta Ptr(t) homozygotes using ten simple sequence repeat markers at the Pi-ta region determined that Pi-ta and Ptr(t) are located within a 9 MB region and are of indica origin. Identification of Ptr(t) is a significant advancement in studying Pi-ta-mediated signal recognition and transduction.

Last Modified: 4/23/2014
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