Modeling Temperature Requirements for Growth and Toxin Production of Alternaria spp. Associated with Tomato

Concerns about mycotoxin contamination by Alternaria spp. in tomato-based products emphasize the need for understanding the effect of the environment on their production. In the current study, we focused on three species frequently associated with tomato (A. alternata, A. solani, and A. tenuissima) by evaluating the effects of different temperatures (5 to 40 degrees C) and substrata (PDA and V8) on mycelial growth and the production of mycotoxins (alternariol, alternariol monomethyl ether, and tenuazonic acid). Both biological processes were supported between 5 and 35 degrees C, with optimal temperatures between 20 and 30 degrees C, depending on the species. Temperature and its interaction with species significantly (p < 0.05) affected both processes. However, the species factor alone was not significant (p > 0.05), indicating that environmental conditions affect Alternaria spp. growth and mycotoxin production more than the species itself does. Mathematical equations were developed to describe the effect of temperature on mycelial growth, as well as on the production of AOH, AME, and TeA, for each Alternaria species. High concordance (CCC >= 0.807) between observed and predicted data and low levels of residual error (RMSE <= 0.147) indicated the high goodness of fit of the developed equations, which may be used for the development of models to predict Alternaria contamination both in field and during post-harvest storage.