A PCR-based assay for the detection and differentiation of potential fumonisin-producing Fusarium verticillioides isolated from Indian maize kernels

One hundred and three Fusarium isolates from maize samples collected from different districts of Karnataka state, India, were analyzed with genus-specific, species-specific, and potential fumonisin specific oligonucleotide primers. One set of genus-specific primers ITS F and ITS R based on a highly conserved ITS region of the genus Fusarium were used to differentiate Fusarium species from closely related genera. All the Fusarium species tested scored positive with the ITS pair of primers. Detection and identification of Fuslarium verticillioides species was done by using a newly designed reverse primer VERT-R (5'- CGA CTC ACG GCC AGG AAA CC -3') based on an intergenic spacer sequence (IGS) combined with an already designed forward primer VERTF-1 (5'-GCG GGA ATT CAA AAG TGG CC -3') published previously. Out of 103 Fusarium species tested, 83 isolates of F. verticillioides scored positive for VERTF-1/VERT-R species-specific pair of primers. Further to discriminate potential fumonisin-producing and nonproducing strains of F. verticilhoides, the VERTF-VVERTF-2 set of primers [VERTF-1 (5'-GCG GGA ATT CAA AAG TGG CC -3') and VERTF-2 (5'-GAG GGC GCG AAA CGG ATC GG -3')] were used. 64 isolates of F. verticillioides scored positive for VERTF-1/VERTF-2 pair of primers. In total, three primers, one forward primer VERTF-1 and two reverse primers VERT-R and VERTF-2, were used for the confirmation of F. verticillioides up to the species level and the second pair of primerswere used to confirm the potential for famonisin production. The developed PCR assay should provide a powerful tool for the detection and differentiation of potential fumonisin-producing F. verticillioides strains in a population.