Importance of phytoalexin tolerance and detoxification for pathogenicity. Progress report, June 1983-June 1985

Previous studies showed the lack of ability to demethylate the phytoalexin pisatin reduces the ability of N. haematococca to cause disease on pea. The detoxification of pisatin requires two components: NADPH-cytochrome c reductase and cytochrome P-450. The ability to separate and reconstitute these two components has demonstrated that the reductase from a non-demethylating isolate of N. haematococca will support demethylating activity when combined with the cytochrome P-450 from a demethylating isolate. The finding that the critical genetic factor here is the cytochrome P-450 fraction reinforces the hypothesis that the multiple pda genes of this fungus encode different cytochrome P-450 isozymes. 4 refs., 1 fig., 1 tab