Caracterização genômica de cepas de cianobactérias com foco na resistência ao herbicida glifosato

Abstract

The popularization of new technologies in agriculture, during the 90’s, significantly increased pesticide use in Brazil and around the world. Glyphosate (N-(phosphonomethyl)glycine), the active component in many widely used glyphosate-based herbicides (HGBs), is applied to control weeds, especially in monocultures that use genetically modified seeds resistant to this active ingredient. Although glyphosate resistance mechanisms are well-established in some prokaryotes, the interaction between emerging contaminants, such as glyphosate, and cyanobacteria is an under-explored area of research. These organisms are strongly linked to harmful algal blooms (HABs) and the production of toxins that compromise water quality and public health. Thus, the aim of this study was to investigate the presence of genetic mechanisms of glyphosate resistance in cyanobacterial strains. Nineteen cyanobacterial strains, belonging to four different genera, were sequenced using the Nanopore platform, and the gene clusters responsible for producing cyanotoxins (saxitoxin and microcystin) were characterized. We performed a search for the genes responsible for encoding the enzymes of interest, EPSP synthase, glyphosate oxidoreductase (GOX), and C-P lyase, using BLASTp. All strains presented the EPSPS class II enzyme, which is commonly associated with glyphosate resistance. The C-P lyase gene cluster appears to be present exclusively in Raphidiopsis raciborskii. Based on these findings, we propose that cyanobacteria possess glyphosate resistance mechanisms and R. raciborskii may have the ability to use glyphosate as a nutrient source.