Evolution, growth and phenology of Phalaris minor biotypes resistant to ACCase-inhibiting herbicides in Mexico

Abstract

<p><strong>Background:</strong> Herbicide application to control weeds can promote a rapid selection of resistant phenotypes in small geographic areas. Also, in areas with a spatial heterogeneous management, resistance may evolve independently, promoting local adaptation in weeds. In the Mexican region known as “El Bajio,” 100,000 ha are cultivated with wheat, and the weed  <em>Phalaris minor</em>, resistant to ACCase-inhibiting herbicides is present common.</p><p><strong>Question:</strong> We aim to identify the population structure of two genes in four different <em>P. minor</em> biotypes from “El Bajio” and to determine their association with phenology and plant growth differences (biomass and seed yield) that may contribute to survival in the agricultural environment.</p><p><strong>Studied species</strong><strong>:</strong> <em>Phalaris minor </em>Retz<em>.</em></p><p><strong>Study site and years of study</strong><strong>:</strong></p><p><strong>Methods:</strong> The diversity of the <em>psbA </em>gene and the sequence of two ACCase gene fragments as well as phenology, growth and biomass allocation were evaluated.</p><p><strong>Results:</strong> Results indicated different polymorphism levels for the two genes. There were no differences in the <em>psbA</em> gene between biotypes, although the ACCase gene exhibited high polymorphism level. In addition, each biotype showed differences in phenology, biomass accumulation and fecundity.</p><p><strong>Conclusions:</strong> The ACCase-inhibiting herbicide resistance in “El Bajio” region might be a resistance hotspot leading to the local adaptation of weeds.</p>