ARS | Publication request: RICE PI-TA GENE IS CLOSELY LINKED WITH RESISTANCE TO THE MAJOR PATHOTYPES OF THE RICE BLAST FUNGUS IN THE U.S.

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 7, 2003
Publication Date: March 1, 2004
Citation: Jia, Y., Wang, Z., Fjellstrom, R.G., Moldenhauer, K.A., Azam, M., Correll, J., Lee, F.N., Xia, Y., Rutger, J.N. 2004. Rice pi-ta gene is closely linked with resistance to the major pathotypes of the rice blast fungus in the U.S. Phytopathology. 94:296-301.

Interpretive Summary: Rice blast is one of the most serious diseases that threaten rice industry worldwide. The use of resistant cultivars is one of the most effective means to control the disease. The Pi-ta gene, allelic to Pi-ta2, in rice is effective in preventing the infection of Magnaporthe grisea isolates containing the corresponding avirulence gene AVR-Pita. Pi-ta encodes a putative cytoplasmic receptor that appears to bind to a predicted processed AVR-Pita to elicit a defense response. The presence of the Pi-ta gene was detected in 13 rice cultivars that reportedly contain Pi-ta and Pi-ta2. All of these Pi-ta containing cultivars were resistant to both major pathotypes IB-49 and IC-17 of M. grisea. The inheritance of Pi-ta with resistance to IC-17 was further investigated using a dominant Pi-ta marker in an F2 population of 1480 progeny of the cross with a Pi-ta containing rice cultivar. Resistance to IC-17 was conferred by a single dominant gene and Pi-ta was not detected in susceptible individuals, only in resistant ones. Another F2 population of 407 individuals of a reciprocal cross was used to verify the conclusion that resistance to IC-17 was conferred by a single dominant gene. In this cross, individuals resistant to IC-17 were also resistant to IB-49. The presence of Pi-ta and resistant to IB¿49 was also correlated with additional crosses involving another Pi-ta containing rice culitvar. A pair of primers that specifically amplifies a susceptible pi-ta allele was developed to verify the absence of the dominant Pi-ta gene. These data suggest that Pi-ta is responsible for resistance to IB-49 and IC-17. The correlation of Pi-ta with resistance to both M. grisea pathotypes suggesting they contain functional AVR-Pita genes.

Technical Abstract: The Pi-ta gene, allelic to Pi-ta2, in rice is effective in preventing the infection of Magnaporthe grisea isolates containing the corresponding avirulence gene AVR-Pita. Pi-ta encodes a putative cytoplasmic receptor that appears to bind to a predicted processed AVR-Pita to elicit a defense response. The presence of the Pi-ta gene was detected in 13 rice cultivars that reportedly contain Pi-ta and Pi-ta2. All of these Pi-ta containing cultivars were resistant to both major pathotypes IB-49 and IC-17 of M. grisea. The inheritance of Pi-ta with resistance to IC-17 was further investigated using a dominant Pi-ta marker in an F2 population of 1480 progeny of the cross with a Pi-ta containing rice cultivar. Resistance to IC-17 was conferred by a single dominant gene and Pi-ta was not detected in susceptible individuals, only in resistant ones. Another F2 population of 407 individuals of a reciprocal cross was used to verify the conclusion that resistance to IC-17 was conferred by a single dominant gene. In this cross, individuals resistant to IC-17 were also resistant to IB-49. The presence of Pi-ta and resistant to IB¿49 was also correlated with additional crosses involving another Pi-ta containing rice culitvar. A pair of primers that specifically amplifies a susceptible pi-ta allele was developed to verify the absence of the dominant Pi-ta gene. These data suggest that Pi-ta is responsible for resistance to IB-49 and IC-17. The correlation of Pi-ta with resistance to both M. grisea pathotypes suggesting they contain functional AVR-Pita genes.