Glyphosate excessive use chronically disrupts the shikimate pathway and can affect photosynthesis and yield in citrus trees.

Autor: Martinelli R; Agronomic Institute (IAC), Sylvio Moreira Citrus Center, Cordeirópolis, São Paulo, Brazil. Electronic address: martinelli@ccsm.br., Rufino LR Jr; Federal University of São Carlos (UFSCar), Araras, São Paulo, Brazil., de Melo AC; Federal University of São Carlos (UFSCar), Araras, São Paulo, Brazil., Alcántara-de la Cruz R; Federal University of São Carlos (UFSCar), Buri, São Paulo, Brazil., da Silva MFDGF; Federal University of São Carlos (UFSCar), São Carlos, São Paulo, Brazil., da Silva JR; Agronomic Institute (IAC), Sylvio Moreira Citrus Center, Cordeirópolis, São Paulo, Brazil., Boaretto RM; Agronomic Institute (IAC), Sylvio Moreira Citrus Center, Cordeirópolis, São Paulo, Brazil., Monquero PA; Federal University of São Carlos (UFSCar), Araras, São Paulo, Brazil., Mattos D Jr; Agronomic Institute (IAC), Sylvio Moreira Citrus Center, Cordeirópolis, São Paulo, Brazil., de Azevedo FA; Agronomic Institute (IAC), Sylvio Moreira Citrus Center, Cordeirópolis, São Paulo, Brazil.
Jazyk: angličtina
Zdroj: Chemosphere [Chemosphere] 2022 Dec; Vol. 308 (Pt 3), pp. 136468. Date of Electronic Publication: 2022 Sep 15.
DOI: 10.1016/j.chemosphere.2022.136468
Abstrakt: Glyphosate excessive use is reported in Brazilian citrus orchards, whereas there is speculation about its consequences and the published studies are contradictory and inconclusive. This study aimed to describe the possible harmful effects by simulating glyphosate drift directly to the leaves of ∼4-yr-old citrus plants. As major results, glyphosate doses >360 g ae ha -1 increased the shikimate accumulation in leaves (up to 2.3-times above control), which was increased after a second glyphosate application (up to 3.5-times above control), even after a 240-d interval. Interestingly, shikimate accumulation was occasionally related to a dose-response of the herbicide at specific times; however, the doses had their accumulation peak on determined dates. These accumulations were directly correlated to reduced net photosynthesis even months after the glyphosate sprays. Quantum productivity based on electron transport through the photosystem II and apparent electron transport reductions up to 17% were also observed during the entire experiment course. Similarly, quantum productivity based on CO 2 assimilation of glyphosate sprayed leaves decreased up to four times compared to the control after the second application. Glyphosate doses >360 g ae ha -1 increased stomatal conductance and transpiration as the carboxylation efficiency decreased, evidencing a carbon drainage in the Calvin-Benson cycle. These metabolic and physiological disturbances suggest possible photooxidative damage and an increase in photorespiration, which may be a mitigation strategy by the citrus plants to glyphosate effects, by the cost of reducing the citrus fruit yield (up to 57%). It is concluded that glyphosate phytotoxicity damages citrus plants over time due to chronic disturbances in the shikimate pathway and photosynthesis, even when there are no symptoms. This study is the first report to demonstrate how glyphosate damages citrus trees beyond the shikimate pathway.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Rodrigo Martinelli reports financial support was provided by Coordination of Higher Education Personnel Improvement. Fernando Alves de Azevedo reports financial support was provided by State of Sao Paulo Research Foundation. Dirceu de Mattos Jr reports financial support was provided by State of Sao Paulo Research Foundation. Fernando Alves de Azevedo reports financial support was provided by National Council for Scientific and Technological Development.
(Copyright © 2022 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
Externí odkaz: