Low doses of triazine xenobiotics mobilize ABA and cytokinin regulations in a stress- and low-energy-dependent manner

Abstract

The extent of residual contaminations of pesticides through drift, run-off and leaching is a potential threat to non-target plant communities. Arabidopsis thaliana responds to low doses of the herbicide atrazine, and of its degradation products, desethylatrazine and hydroxyatrazine, not only in the long term, but also under conditions of short-term exposure. In order to investigate underlying molecular mechanisms of low-dose responses and to decipher commonalities and specificities between different chemical treatments, parallel transcriptomic studies of the early effects of the atrazine-desethylatrazine-hydroxyatrazine chemical series were undertaken using whole-genome microarrays. All of the triazines under study produced coordinated and specific changes in gene expression. Hydroxyatrazine-responsive genes were mainly linked to root development, whereas atrazine and desethylatrazine mostly affected molecular signaling networks implicated in stress and hormone responses. Analysis of signaling-related genes, promoter sites and shared-function interaction networks highlighted the involvement of energy-, stress-, abscisic acid- and cytokinin-regulated processes, and emphasized the importance of cold-, heat- and drought-related signaling in the perception of low doses of triazines. These links between low-dose xenobiotic impacts and stress-hormone crosstalk pathways give novel insights into plant-pesticide interactions and plant-pollution interactions that are essential for toxicity evaluation in the context of environmental risk assessment.

Plant pharmacology: Insights into in-planta kinetic and dynamic processes of xenobiotics

“…The desired action of triazine is dependent on ADMA processes, which result in accumulation of the required concentration at the site of action, the chloroplasts. Exposure to low concentrations of triazine has been shown to have non-photosystem II complex interactions which impact root development and molecular signaling networks, as well as hormone response that involves processes regulated by energy, stress, abscisic acid and cytokinin (Alberto et al, 2018). The exposure of plants to low concentrations of non-target herbicides affects plant growth and timing, influencing the plant-insect relationships and ecosystem interactions (Bohnenblust et al, 2016;Russo et al, 2020).…”

“…There is a lack of comparative data between these methods and a need for standards and quality control of xylem sap measurements. Experiments need to take into consideration the rate of absorption, time of exposure, concentration dependence, circadian rhythm, pharmacodynamic response, effect of mixtures and plant health (Alberto et al, 2018;Belbin et al, 2019). Erroneous results and conclusions could be the result of any of these factors, and have caused misinterpretation and confusion in the field.…”

Effect of interspecific competition on species sensitivity distribution models: Analysis of plant responses to chemical stress

“…The pesticide used for exposure was isoproturon, a phenyl-urea photosystem II inhibitor. Despite its recent banning in EU, isoproturon environmental persistence, use in some no-EU countries, and common mode of action, similar to numerous worldwide used herbicides, still make this molecule a relevant pesticide model to study (Alberto et al [2018], Eker [2019], Johnson et al [2001]). Ecotoxicological bioassays were realized for the six tested species and the two competition modalities (absence or presence of the competitor).…”

Structure, Synthesis, and Bioassays of Sex Pheromone for Pyrausta machaeralis (Lepidoptera: Crambidae)

“…Nevertheless, the frequent use of chemical pesticides led to several issues, including toxic food residues, environmental degradation, and the development of resistance . The excessive dosage of pesticides can also result in strong resistance and toxicity concerns in both plants and the environment. − Moreover, pesticides do not always target specific species and thus might harm nontargeted organisms …”

“…9−13 Moreover, pesticides do not always target specific species and thus might harm nontargeted organisms. 14 Insect sex pheromone application technology is an ecofriendly alternative to pesticides that provides highly selective, nontoxic, and beneficial insect species-safe pest management solutions, which meet the demand for sustainable food production and environmental security. 15 The use of pheromone trapping technology has been widely adopted for monitoring, mass trapping, mating disruption, and tracking of the population dynamics of target insects during future outbreaks.…”