**Three-Dimensional Study of** *F. graminearum* **Colonisation of Stored Wheat: Post-Harvest Growth Patterns, Dry Matter Losses and Mycotoxin Contamination**

### **Xavier Portell 1, Carol Verheecke-Vaessen 2, Rosa Torrelles-Ràfales 2, Angel Medina 2, Wilfred Otten 1, Naresh Magan 2 and Esther García-Cela 2,3,\***



Received: 6 July 2020; Accepted: 30 July 2020; Published: 1 August 2020

**Abstract:** *Fusarium* causes significant post-harvest quality losses and mycotoxin contamination in stored wheat but the colonisation dynamics of the grain and how this may be a ffected by the initial inoculum position in the grain mass is poorly understood. This study examined the 3D growth kinetics and mycotoxin production (deoxynivalenol and zearalenone) by *F. graminearum* during hyphal colonisation from di fferent initial inoculum positions in wheat microcosms (top-centre, bottom-centre, and bottom-side) maintained at two water activities (a w; 0.95 and 0.97). Clear jars were used to visually follow the colonisation dynamics. Fungal respiration and associated dry matter loss (DML) and ergosterol were also quantified. Colonisation dynamics was shown to be a ffected by the inoculation position. At the end of the colonisation process, fungal respiration and DML were driven by the inoculation position, and the latter also by the prevailing a w. Fungal biomass (ergosterol) was mainly a ffected by the a w. The initial inoculum position did not a ffect the relative mycotoxin production. There was a positive correlation between respiration and ergosterol, and between mycotoxin production and colonisation indicators. We sugges<sup>t</sup> that spatially explicit predictive models can be used to better understand the colonisation patterns and mycotoxin contamination of stored cereal commodities and to aid more e ffective post-harvest management.

**Keywords:** Cereals; silo; fungi; modelling; 3D colonisation; respiration; ergosterol; zearalenone; deoxynivalenol; trichothecenes.
