A Natural Variation of Fumonisin Gene Cluster Associated with Fumonisin Production Difference in .

, a member of the species complex, stands out as a rice bakanae disease pathogen with a high production of gibberellic acid. Not all, but some strains are known to produce a carcinogenic mycotoxin fumonisin. Fumonisin biosynthesis is dependent on the FUM cluster composed of 16 genes. The FUM cluster was detected not only from a fumonisin producing strain, but also from a fumonisin nonproducing strain that does not produce a detectable level of fumonisin. Genetic mapping indicated the causative mutation(s) of fumonisin nonproduction is present in the FUM cluster of the fumonisin nonproducing strain. Comparative analyses of genes between the fumonisin producing and the nonproducing strains and gene complementation indicated that causative mutation of fumonisin nonproduction is not a single occurrence and the mutations are distributed in and . Our research revealed a natural variation in the FUM cluster involving fumonisin production difference in .