Gain of virulence caused by insertion of a Pot3 transposon in a Magnaporthe grisea avirulence gene

The avirulence gene AVR-Pita in Magnaporthe grisea prevents the fungus from infecting rice cultivars carrying the disease resistance gene Pi-ta. Inser tion of Pot3 transposon into the promoter of AVR-Pita caused the gain of vi rulence toward Yashiro-mochi, a rice cultivar containing Pi-ta, which demon strated the ability of Pot3 to move within the M. grisea genome. The appear ance of Pot3 in M. grisea seems to predate the diversification of various h ost-specific forms of the fungus.