ARS | Publication request: UNDERSTANDING MOLECULAR INTERACTION MECHANISMS OF RICE WITH FUNGAL PATHOGENS

Submitted to: Rice Technical Working Group Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: February 24, 2002
Publication Date: N/A

Technical Abstract: Diseases caused by fungal pathogens are the biggest hurdles for the rice industry. The primary focus of this project is to understand the plant's natural defense systems using rice blast as a model. Rice blast is a classical gene-for-gene interaction system. Interactions of blast resistance (R) genes and Magnaporthe grisea avirulence 9AVR) genes trigger plant recognition and activate the plant's defense systems. Rice blast 'R genes', Pi-ta and Pi-b, were recently characterized at the molecular level. A direct interaction of the product of Pi-ta with the product of the corresponding AVR gene AVR-Pita has recently been shown. To further understand mechanisms of Pi-ta recognition, the U.S. rice variety Katy that expresses Pi-ta has been mutagenized using the chemical mutagens, ethyl methane sulfonate (EMS) and N-methyl-N-nitrosourea (MNH). A total of12,545 (7,100 EMS and 5,346 MNH) M1 panicle lines of Katy have been recovered. In naddition, a yeast two-hybrid library using mRNAs of Katy after inoculation with an incompatible fungal pathogen was constructed. The Katy yeast two- hybrid library has been used for R-gene identification. To dissect the Pi- b-mediated signal transduction pathways, the U.S. cultivar Saber that contains Pi-b has been mutagenized with MNH and 4,800 M1 panicle lines have been recovered. Identification of mutants is underway. In addition, differential gene expression, protein-protein interaction such as in vitro binding and in vivo interaction via transient gene expression using a particle gene gun have been used to characterize plant defense genes. Methods for uniform infection with the rice blast and the sheath blight pathogens have been advanced to understand plant global gene expression upon fungal infection.