ARS | Publication request: RAPID DETERMINATION OF MAGNAPORTHE GRISEA PATHOGENECITY TOWARDS RICE

Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: July 25, 2001
Publication Date: N/A

Technical Abstract: Rice blast disease caused by the fungal pathogen Magnaporthe grisea is one of the most devastating agricultural diseases worldwide. Immediately after attaching to the hydrophobic rice leaf surface fungal spores begin to germinate and infect the leaf. Initial infection sites of the fungi are commonly restricted to areas where conidial spores attached. Commonly only ya few infection sites can be obtained in the laboratory, even after extensive spraying with conidial suspensions. We have developed a spot- inoculation method on cut leaves to examine the pathogenicity of fungal isolates towards rice in the laboratory. A series of dilutions (1/100, 1/500 and 1/1000) of Tween-20 were added to the final spore suspension that also contained 0.25% gelatin to assist conidial spore attachment to the leaf surface. Standard infection assays in the greenhouse indicated that there were not any side effects of Tween-20 and gelatin to the growth of the rice blast fungus. Pathogenicities of several known fungal isolates are being used to validate this method. Thus, we have developed a robust assay method to determine pathogenicity of the rice blast fungus towards rice. Successful application of this infection method will help to identify novel sources of blast resistance and accelerate the breeding for a broad-spectrum blast resistance.