Multidimensional effects of a glyphosate-based herbicide on Joannesia princeps Vell. (Euphorbiaceae): Morphoanatomical, metabolic, and genotoxic biomarkers as indicators of damage in a non-target native tree species

Abstract

Glyphosate may negatively affect non-target tree species due to improper application management. We hypothesize that Joannesia princeps is sensitive to glyphosate and would show metabolic alterations and genome damage when exposed to this herbicide even at doses below those commonly applied in the field for weed control. We aimed: (i) evaluate the morphoanatomical, physiological, biochemical, and genotoxic responses induced by a glyphosate-based herbicide in J. princeps leaves; (ii) identify potential phytotoxicity biomarkers for biomonitoring environments exposed to herbicides. Three-month-old J. princeps seedlings were sprayed with a glyphosate-based herbicide at doses 0, 180, 360, 720, and 1440 g.ae.ha^-1. These values correspond to 0%, 12.5%, 25%, 50%, and 100% of the field doses applied in crops. After 12 days, we performed morphoanatomical, physiological, biochemical, and genotoxic analysis. Glyphosate exposure increased shikimic acid content in leaves, causing visible damage and structural changes. In treated plants, there was a reduction in CO₂ assimilation, stomatal conductance, transpiration, and chlorophyll. The oxidative stress increased lipid peroxidation and increased superoxide dismutase and peroxidase activities. The glyphosate induced dose-dependent genotoxicity and cell death, mainly at higher doses. In conclusion, J. princeps is sensitive to the glyphosate-based herbicide, which causes multidimensional deleterious effects even in leaves without visual symptoms of phytotoxicity. Anatomical changes, shikimic acid, lipid peroxidation, and DNA damage are potential prognostic markers to assess glyphosate-induced damage in biomonitoring programs.