Growth rate and TRI5 gene expression profiles of Fusarium equiseti strains isolated from Spanish cereals cultivated on wheat and barley media at different environmental conditions

• Environmental in vitro conditions affected F. equiseti growth and TRI5 expression.
• Fusarium equiseti growth profiles ranged from 15 to 35 °C and − 0.7 to (− 9.8) MPa.
• Growth was optimal at 20–30 °C and − 0.7–(− 2.8) MPa in barley and wheat media.
• Highest TRI5 induction was produced at 25–35 °C and − 0.7–(− 2.8) MPa in barley medium.
• This species has potential risk at present/future Mediterranean climate scenarios.

Fusarium equiseti is a toxigenic species that often contaminates cereal crops from diverse climatic regions such as Northern and Southern Europe. Previous results suggested the existence of two distinct populations within this species with differences in toxin profile which largely corresponded to North and South Europe (Spain). In this work, growth rate profiles of 4 F. equiseti strains isolated from different cereals and distinct Spanish regions were determined on wheat and barley based media at a range of temperatures (15, 20, 25, 30, 35 and 40 °C) and water potential regimens (− 0.7, − 2.8, − 7.0, and − 9.8 MPa, corresponding to 0.99, 0.98, 0.95 and 0.93 aw values). Growth was observed at all temperatures except at 40 °C, and at all the solute potential values except at − 9.8 MPa when combined with 15 °C. Optimal growth was observed at 20–30 °C and − 0.7/− 2.8 MPa. The effect of these factors on trichothecene biosynthesis was examined on a F. equiseti strain using a newly developed real time RT-PCR protocol to quantify TRI5 gene expression at 15, 25 and 35 °C and − 0.7, − 2.8, − 7.0 and − 9.8 MPa on wheat and barley based media. Induction of TRI5 expression was detected between 25 and 35 °C and − 0.7 and − 2.8 MPa, with maximum values at 35 °C and − 2.8 MPa being higher in barley than in wheat medium. These results appeared to be consistent with a population well adapted to the present climatic conditions and predicted scenarios for Southern Europe and suggested some differences depending on the cereal considered. These are also discussed in relation to other Fusarium species co-occurring in cereals grown in this region and to their significance for prediction and control strategies of toxigenic risk in future scenarios of climate change for this region.