Genetic heritage of the resistance of sourgrass to glyphosate

Abstract

The gene flux through pollen and glyphosate resistance genetic inheritance in sourgrass (Digitaria insularis) is important to understand this species spread, but it was not previously characterized. This information is essential for the understanding of herbicide resistance evolution rate in agriculture and the gene flux between resistant and susceptible biotypes in the field. Therefore, the objective of this research was to quantify resistance gene inheritance among glyphosate resistant and susceptible biotypes, through the determination of the level of susceptibility to the herbicide in the F1 progeny. it was compared to the F1 generation susceptibility of resistant biotypes (MG) and susceptible (S), which remained isolated or induced to cross-pollination through pollination bags. The sensitivity to glyphosate was measured in the F1 progeny using dose-response curves. The F1 generation plants originating from a possible crossing between biotypes showed the same pattern of glyphosate susceptibility than the parent plant. Comparing the average of glyphosate resistant with susceptible biotypes a resistance factor of 4.01 was calculated. We conclude that there is no transfer of resistance genes after cross-pollination induction between susceptible and resistant biotypes. Further research is needed to determine if this occurred due to D. insularis species be exclusively autogamous or if the resistance is determined by more alleles, and thus does not follow the model of monogenic inheritance. Therefore, the dispersibility of sourgrass resistance genes can be attributed to seed dispersal and not for gene transfer between biotypes through cross pollination among plants, since this study shows imperceptible cross-pollination rates.