Searching for biomarkers of early detection of 2,4-D effects in a native tree species from the Brazilian Cerrado biome

Abstract

Biodiversity in the Brazilian Cerrado biome has been declining sharply with the continued expansion of agriculture and the excessive use of herbicides. Thus, the aim of this study was to evaluate the morphophysiological and biochemical responses in Dipteryx alata plants to various doses of the herbicide 2,4-D. Specific biomarkers that characterize the phytoindicator potential of this species were determined. Gas exchange, chlorophyll a fluorescence, photosynthetic pigments, and the activities of antioxidant enzymes and cellulase were performed after 24, 96 and/or 396 hours after 2,4-D application (HAA). The herbicide caused higher antioxidant enzymatic activity 24 HAA and damage to the photosynthetic machinery after 96 HAA. Reduction in gas exchange, chlorophyll content, and photochemical traits were observed. Increased respiratory rates, non-photochemical quenching, and carotenoid concentrations in 2,4-D-treated plants were important mechanisms in the defense against the excess energy absorbed. Furthermore, the absence of leaf symptoms suggested tolerance of D. alata to 2,4-D. Nevertheless, changes in the photosynthetic and biochemical metabolism of D. alata are useful as early indicators of herbicide contamination, especially in the absence of visual symptoms. These results are important for early monitoring of plants in conserved areas and for preventing damage to sensitive species.

Keywords:

• Bioindicator
• photosynthesis
• chlorophyll a fluorescence
• oxidative stress
• auxin herbicide

Acknowledgments

FBS, CM, PFBC, RBV, and CAM are grateful to the Coordination for the Improvement of Higher Education Personnel (CAPES) and KJTN for the Goiás Research Foundation (FAPEG) for scholarships.

Author contributions

Conceptualization: Fábia Barbosa Silva, Alan Carlos Costa, Clarice Aparecida Megguer; Methodology: Fábia Barbosa Silva, Priscila Ferreira Batista, Roberto Gomes Vital, Danilo Guimarães Silva; Formal analysis and investigation: Fábia Barbosa Silva, Kelly Juliane Telles Nascimento, Priscila Ferreira Batista; Writing - original draft preparation: Fábia Barbosa Silva, Caroline Müller, Clarice Aparecida Megguer; Gabriel Martins Almeida, Marisa Domingos; Writing - review and editing: Caroline Müller, Gabriel Martins Almeida, Marisa Domingos; Funding acquisition: Alan Carlos Costa, Marisa Domingos; Resources: Alan Carlos Costa, Adriano Jakelaitis; Supervision: Alan Carlos Costa, Clarice Aparecida Megguer

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

The data that support the findings of this study are available on request from the corresponding author, ACC.

Supplementary material

Figure S1. Daily midranges of temperature (°C) and relative humidity (%) in the climatized greenhouse during the experimental period.

Additional information

Funding

This work was funded by the National Council for Scientific and Technological Development (CNPq, grants no. 551456/2010-8, 552689/2011-4, and 563335/2010), the Goiano Federal Institute of Education, Science and Technology, Rio Verde campus (IFGoiano-RV, grants no. DPPG 052/2015), and CNPq-SISBIOTA-BRASIL Program by the São Paulo Research Foundation (FAPESP, grant no. 2010/52319-2).