Experimental methods for estimation of plant fitness costs associated with herbicide-resistance genes

VILA AIUB, MM; GUNDEL, P.E.; PRESTON, C

WEED SCIENCE

WEED SCI SOC AMER

Lugar: Laurence, KS; Año: 2015 vol. 63 p. 203 - 216

0043-1745

In seeking to address fitness costs associated with herbicide resistance genes and alleles, it is important to start with the correct plant material. Much of the literature on the topic is of little value in addressing fitness costs because it compares populations from different locations that differ by more than the resistance alleles. Two populations from adjacentfields may have different cultural histories as well as different herbicide histories that select for different traits. Minimizing the differences between genotypes by using near-isogenic lines or by averaging the background genetics across genotypes allows the effect of the resistance trait on fitness to be more accurately identified. It is also important to match the experimental protocol to the hypothesis being tested. Frequently, fitness cost studies estimate ecological fitness by measuring biomass under glasshouse conditions. Such an experimental approach does not measure ecological fitness. Measurements of ecological fitness require the genotypes to be grown under the conditions in which they would normally grow. If the hypothesis is to address some of the components of fitness, such as biomass accumulation, then that can be done in the glasshouse. Tracking the frequency of herbicide resistance alleles over several generations provides the most accurate measure of total fitness costs. However, that approach is rarely useful in identifying the factors that contribute to the fitness cost and has to be supplemented by experiments under moredefined conditions.