Browsing by Author "Marin, P."

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    Differential effect of environmental conditions on the growth and regulation of the fumonisin biosynthetic gene FUM1 in the maize pathogens and fumonisin producers Fusarium verticillioides and Fusarium proliferatum
    (Blackwell Publishing Ltd., 2010-08-31T00:00:00Z) Marin, P.; Magan, Naresh; Vazquez, C.; Gonzalez-Jaen, M. T.
    The effects of ecophysiological factors, temperature and solute potential, on both the growth and the regulation of the fumonisin biosynthetic FUM1 gene were studied and compared in one isolate each of the two closely related fumonisin- producing and maize pathogens Fusarium verticillioides and Fusarium proliferatum. The effect of solute potential and temperature was examined on in vitro mycelia growth and on the expression of the FUM1 gene, quantified by species-specific real-time reverse transcriptase-PCR assays. Although both isolates showed similar two-dimensional profiles of growth, for F. verticillioides, optimal growth conditions were maintained at higher temperatures and lower solute potential values. FUM1 gene expression was markedly induced at 20 degrees C in both isolates, under suboptimal conditions for growth; however, their expression patterns differed in relation to solute potential. Whereas FUM1 expression was induced in response to increasing water stress in the isolate of F. verticillioides, the F. proliferatum one showed a stable expression pattern regardless of water potential conditions. These results suggest a differential regulation of fumonisin biosynthesis in these isolates of the two species that might be related to their different host range, and play an ecological role. Additionally, environmental conditions leading to water stress (drought) might result in increased risk of fumonisin contamination of maize caused by F. verticillioides.
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    Effect of solute stress and temperature on growth rate and TRI5 gene expression using real time RT-PCR in Fusarium graminearum from Spanish wheat
    (Elsevier Science B.V., Amsterdam., 2010-06-15T00:00:00Z) Marin, P.; Jurado, M.; Magan, Naresh; Vazquez, C.; Gonzalez-Jaen, M. T.
    The objective of this work was to study the effect of ecophysiological factors on trichothecene gene expression and growth in Fusarium graminearum. The effect of non-ionic solute water potentials and temperature was examined on in vitro mycelial growth rates and on expression of the TRI5 gene, involved in trichothecene biosynthesis, quantified by real time RT-PCR. This study showed optimal values of 25 degrees C and -2.8 MPa (0.982 a(w)) for growth. Marginal temperatures such as 15 degrees C and 30-35 degrees C, particularly in combination with water potentials below -2.8 MPa, drastically reduced growth. The expression of TRI5 was reasonably constant although some induction was observed between 20 and 30 degrees C, the most favourable temperatures for growth, depending on the water potential imposed, particularly at -7.0 MPa. A temporal kinetic experiment at 25 degrees C examined the effect of ionic solute stress on TRI5 gene expression and growth rate. The results indicated independence of growth rate and TRIS expression, as the fungal biomass increased with time while the gene expression remained constant. This suggested that favourable conditions for growth will result in higher trichothecene production, and that toxin production would always accompany the colonization process at a steady rate while the conditions for growth are permissive. Quantification of key biosynthetic toxin genes by real time RT-PCR was shown to be a valuable tool to gain knowledge of the ecophysiological basis for trichothecene biosynthesis and enable better control strategies to be developed during the life cycle of this important mycotoxigenic pathogen of cereals. (C) 2010 Elsevier B.V. All rights reserved.