Concealed metabolic reprogramming induced by different herbicides in tomato

Herbicide application is a common procedure in agriculture, whose potentially adverse effects are assessed mainly with respect to weeds or in terms of residues and environmental impact. However, recent evidence has highlighted possible effects of pesticide treatments on plant metabolism, with potential implications for fruit quality. Therefore, the goal of this study was to investigate the impact of four different herbicides on the metabolic processes in industrial tomato plants. To this aim, plants were treated either with the selective herbicides metribuzin and rimsulfuron or with the non-selective herbicides glyphosate and pelargonic acid. Thereafter, leaves were analyzed using a metabolomics approach, and 247 differential compounds were selected by multivariate statistics and used to examine the changes at the molecular level. Data interpretation via the PlantCyc Pathway Tool revealed that the tested herbicides induced distinctive responses to the treatments, with the phytohormone profile (gibberellins and jasmonates) and secondary metabolism (including stress-related compounds, such as phenylpropanoids and glucosinolates) showing the largest modulation. Surprisingly, such metabolic reprogramming also affected several aspects of the fruits even though the herbicides were applied several weeks before, thus opening the possibility of effects on food quality. To date, these hidden effects have been largely underestimated even though they deserve to be carefully considered since they may affect the qualitative and quantitative traits of the yield.