ARS | Publication request: Quantitative expression of Fusarium sporotrichioides genes in the presence of xanthotoxin

Submitted to: National Fusarium Head Blight Forum Proceedings
Publication Type: Abstract
Publication Acceptance Date: October 30, 2007
Publication Date: December 2, 2007
Citation: Alexander, N.J., Mc Cormick, S.P. 2007. Quantitative expression of Fusarium sporotrichioides genes in the presence of xanthotoxin [abstract]. National Fusarium Head Blight Forum. p. 23.

Technical Abstract: Xanthotoxin (8-methoxypsoralen) is a phototoxic furocoumarin that covalently binds to and crosslinks with deoxyribonucleic (DNA). It is also known to inhibit P450 oxygenases. To test the effect of xanthotoxin on gene expression in Fusarium sporotrichioides, we developed a reverse transcriptase quantitative polymerase chain reaction (RTqPCR) method to measure the expression of genes involved in the biosynthetic pathway of trichothecenes. We found that xanthotoxin treatment of wild-type F. sporotrichioides blocked production of T-2 toxin, and caused the accumulation of its hydrocarbon precursor, trichodiene. This suggested that FsTri5, the gene encoding trichodiene synthase, may be up-regulated, and that FsTri4, a trichodiene oxygenase, may be down-regulated. However, our RTqPCR results showed that 1 and 5 hours after xanthotoxin treatment, both FsTri5 and FsTri4 were up-regulated while FsTri101, encoding the trichothecene C-3 transacetylase, was down-regulated. When FsTri4¯ mutants that accumulate trichodiene in culture were treated with xanthotoxin, trichodiene accumulation increased. Although the FsTRI4 protein is non-functional in these mutants, the RTqPCR showed that FsTri4 was transcribed and was up-regulated in the presence of xanthotoxin. These results suggest that xanthotoxin may be involved in the up-regulation of FsTri5 expression, but that factors other than gene regulation account for the increased accumulation of trichodiene.