Differential effect of environmental conditions on the growth and regulation ofthe fumonisin biosynthetic gene FUM1 in the maize pathogens and fumonisinproducers Fusarium verticillioides and Fusarium proliferatum

摘要

The effects of ecophysiological factors, temperature and solute potential, onboth the growth and the regulation of the fumonisin biosynthetic FUM1 gene werestudied and compared in one isolate each of the two closely related fumonisin-producing and maize pathogens Fusarium verticillioides and Fusariumproliferatum. The effect of solute potential and temperature was examined on invitro mycelia growth and on the expression of the FUM1 gene, quantified byspecies-specific real-time reverse transcriptase-PCR assays. Although bothisolates showed similar two-dimensional profiles of growth, for F.verticillioides, optimal growth conditions were maintained at highertemperatures and lower solute potential values. FUM1 gene expression wasmarkedly induced at 20 degrees C in both isolates, under suboptimal conditionsfor growth; however, their expression patterns differed in relation to solutepotential. Whereas FUM1 expression was induced in response to increasing waterstress in the isolate of F. verticillioides, the F. proliferatum one showed astable expression pattern regardless of water potential conditions. Theseresults suggest a differential regulation of fumonisin biosynthesis in theseisolates of the two species that might be related to their different host range,and play an ecological role. Additionally, environmental conditions leading towater stress (drought) might result in increased risk of fumonisin contaminationof maize caused by F. verticillioides.