Isoenzymatic variations in populations of Chenopodium album L. resistant and susceptible to triazines

As part of a study of triazine resistance in weed species, the authors have collected several resistant populations of Chenopodium album in different areas in France. A study of intra- and inter-population variability between different susceptible and resistant populations has been made using polyacrylamide gel electrophoresis of foliar isoenzymes. The separation of esterases and malate dehydrogenase isoenzymes was carried out in a modified vertical apparatus.

Within each resistant population, all individuals have the same pattern of esterase and populations collected in the same area have the same zymogram. However, populations from different areas have distinct zymograms. These data suggest that the resistant populations originated in the region where they now occur, and that there is a high rate of self-pollination in each resistant population.

After treating a susceptible population with a low dose of atrazine, about 1% of plants survived and these have a high frequency of the esterase zymogram typical of resistant individuals. The offspring of these plants are completely resistant. The resistant and susceptible populations grew near each other so that they may have a common origin. The pattern of occurrence of resistance in relation to its inheritance and the level of inbreeding in populations is discussed.