Morphoanatomical and biochemical changes in Zeyheria tuberculosa exposed to glyphosate drift

During glyphosate application, a portion of the herbicide can reach adjacent vegetation and impact the natural plant community structure and diversity over the long term. This study evaluated the response of leaves of Zeyheria tuberculosa (Vell.) Bureau ex Verl. (Bignoniaceae) to the herbicide glyphosate. Plants were exposed to aerial applications of the herbicide at concentrations of 0, 360, 720, 1080 and 1440 g a. e. ha-1. The shikimic acid concentrations in leaves of herbicide-treated plants were always higher than the control. Visual symptoms became apparent 4 DAA from 720 g a. e. ha-1. Glyphosate induced an increase in malondialdehyde in Z. tuberculosa leaves. The lowest values of chlorophyll a content were found for the three last applied doses and protein content decreased with the glyphosate treatment. Necrosis was observed on the epidermis and in the mesophyll. Glandular trichomes were also plasmolyzed. On the midrib there was plasmolysis of non-lignified cells. Micromorphologically, there were cell plasmolysis and rupture of glandular trichomes Glyphosate is phytotoxic to Z. tuberculosa by promoting biochemical, anatomical and morphological alterations. The morphoanatomical injuries found on Z. tuberculosa are severe, suggesting that the presence of glyphosate can impact this species irreversibly and compromise its survival.