Identification of select fumonisin forming Fusarium species using PCR applications of the polyketide synthase gene and its relationship to fumonisin production in vitro

Richard Baird; Hamed K Abbas; Gary Windham; Paul Williams; Sonya Baird; Peter Ma; Rowena Kelley; Leigh Hawkins; Mary Scruggs

doi:10.3390/ijms9040554

Identification of select fumonisin forming Fusarium species using PCR applications of the polyketide synthase gene and its relationship to fumonisin production in vitro

Int J Mol Sci. 2008 Apr;9(4):554-570. doi: 10.3390/ijms9040554. Epub 2008 Apr 8.

Authors

Richard Baird¹, Hamed K Abbas², Gary Windham³, Paul Williams³, Sonya Baird¹, Peter Ma¹, Rowena Kelley³, Leigh Hawkins³, Mary Scruggs¹

Affiliations

¹ Entomology and Plant Pathology Department, Mississippi State University, Mississippi State, MS 39762, USA.
² USDA-ARS, CG&PRU, Stoneville, MS 38776, USA.
³ USDA-ARS-CHPRRU, Mississippi State, MS 39792, USA.

Abstract

A polymerase chain reaction (PCR) based diagnostic assay was used to develop markers for detection of Fusarium verticillioides (=F. moniliforme), a fumonisin producing fungus in maize tissues. Species-specific primers were designed based on sequence data from the polyketide synthase (PKS) gene (FUM1- previously FUM5) responsible for fumonisin production in fungi. Four sets of oligonucleotide primers were tested for their specificity using 24 strains of F. verticillioides, 10 F. proliferatum, and 12 of other Fusarium species. In addition, 13 species of other fungal genera, from four phyla, were tested as negative controls. Among the four sets, primer set B consistently amplified a 419-bp fragment from the DNA 96% of all F. verticillioides strains and 83% of F. proliferatum. All other fungi tested were negative using primer set B. A total of 38% of the F. verticillioides strains grown on a selective liquid medium produced fumonisin and 92% formed the toxin on standard rice medium. When fumonisin formed in culture, PCR assay using primer set B detected every strain of F. verticillioides, but only amplified 80% of F. proliferatum strains that produced the toxin. PCR detection was consistent at 100 pg/microl concentration of genomic DNA from 4 F. verticillioides strains, but varied at 10 pg/microl. Two duplicate greenhouse tests using artificially inoculated maize plants, had greater levels of F. verticillioides detected after re-evaluting using primer set B than from culturing of the tissues. The molecular protocols described in this study requires only 1 day for completion compared to approximately 10 days for cultural work and morphological determination. In conclusion, conventional PCR assay using primer set B provides a sensitive and accurate detection assay that can be used as a primary or secondary confirmation method for identification and occurrence of F. verticillioides within the maize tissues. However, studies using primer set B for fumonisin production determined by strains of F. verticillioides and F. proliferatum will require further verification.

Keywords: Fusarium species; Fusarium verticillioides; PCR detection; fumonisin; fungi; maize; mycotoxin; polyketide synthase gene.