Agricultural herbicides and response of fungi to the presence of herbicides in the soil.

BARBERIS C.L.; MAGNOLI C.E,; CARRANZA C.S.; BENITO N.; ALUFFI M.E.

Pesticides in crop production: physiological and biochemical action

Editorial John Wiley & Sons, Prabhat Kumar Srivastava

Año: 2020;

Agriculture is one of the bases of worldwide economy. In the last decades, the use of genetically modified crops caused a continuous increase in pesticides and fertilizers application. In productive countries, the adoption of these products together with other technologies allowed to maximize the world crops production with great economic benefits. The herbicides represent about 40 to 60% of the total pesticides used in agricultural environment. Several herbicides are used for control weeds worldwide, being glyphosate one of the most common. The excessive use of this product has led to the development of herbicide-resistant weeds, thus a wider variety of herbicides are being used such has clodinafoppropargyl, 2,4-dichlorophenoxyacetic acid, atrazine, metolachlor, diuron, imazapyr, pendimethalin, and paraquat. As a consequence, the intensive use of herbicides has become a matter of environmental concern, partially because of the potential hazardous effects of these chemicals on soil biological processes and non-target organisms. The widespread incorporation of herbicides in soils every year has a significant impact on their quality, and on both decomposition and nutrient cycling. This fact has generated a great concern for the potential threat that herbicides represent for animal and human health. Herbicides interact with target and non-target organisms, so they could damage the ecosystem and also they can enter the food chain. Biodegradation is the main mechanism involved in the destruction of these contaminants. Several metabolic processes participate in the degradation of xenobiotic compounds. In this context, fungi have a dominant role in bioremediation processes. Fungi present certain advantages over other microorganisms with respect to bioremediation due to their mycelia growth, rapid colonization of solid substrates and enzymatic capacity. In addition, these microorganisms have a great tolerance to pollutants and unfavorable environmental conditions. Fungal genera as Fusarium spp., Penicillium spp., Aspergillus spp., Trichoderma spp., Cladosporium spp., Mucor spp. and Saccharomyces spp. have shown the ability to degrade herbicides. They can produce high amounts of extracellular enzymes during soil colonization, resulting in enhanced xenobiotic biodegradation rates. Recently, this aspect has been focused in the development of eco-friendly bioremediation strategies. The present chapter presents information about the toxicity of the main herbicides used in agriculture and also about the tolerance and degradation of them by fungal species.