Effect of solute stress and temperature on growth rate and TRI5 gene expression using real time RT–PCR in Fusarium graminearum from Spanish wheat

• Published in: International journal of food microbiology 2010-06, Vol.140 (2), p.169-174
• Main Authors: Marín, Patricia, Jurado, Miguel, Magan, Naresh, Vázquez, Covadonga, González-Jaén, María Teresa
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; Biomass; Cereal and baking product industries; F. graminearum; food contamination; Food industries; Food microbiology; Fundamental and applied biological sciences. Psychology; Fungal Proteins - genetics; Fungal Proteins - metabolism; Fusarium - genetics; Fusarium - growth & development; Fusarium - isolation & purification; Fusarium - physiology; Fusarium graminearum; gene expression; Gene Expression Regulation, Fungal; genes; Gibberella zeae; Growth; microbial contamination; plant pathogenic fungi; plant stress; reverse transcriptase polymerase chain reaction; Reverse Transcriptase Polymerase Chain Reaction - methods; Solute stress; solutes; Stress, Physiological; Temperature; TRI5 gene; TRI5 gene expression; Trichothecenes; Trichothecenes - biosynthesis; Triticum - microbiology; wheat
• ISSN: 0168-1605; 1879-3460
• DOI: 10.1016/j.ijfoodmicro.2010.03.041

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 °C and − 2.8 MPa (0.982 a w) for growth. Marginal temperatures such as 15 °C and 30–35 °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 °C, the most favourable temperatures for growth, depending on the water potential imposed, particularly at − 7.0 MPa. A temporal kinetic experiment at 25 °C examined the effect of ionic solute stress on TRI5 gene expression and growth rate. The results indicated independence of growth rate and TRI5 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.