Alterations in life-history associated with non-target-site herbicide resistance in Alopecurus myosuroides

A - Papers appearing in refereed journals

Comont, D., Knight, C., Crook, L., Hull, R. I., Beffa, R. and Neve, P. 2019. Alterations in life-history associated with non-target-site herbicide resistance in Alopecurus myosuroides. Frontiers in Plant Science. 10.

AuthorsComont, D., Knight, C., Crook, L., Hull, R. I., Beffa, R. and Neve, P.

The evolution of resistance to herbicides is a classic example of rapid contemporary adaptation in the face of a novel environmental stress. Evolutionary theory predicts that selection for resistance will be accompanied by fitness trade-offs in environments where the stress is absent. Alopecurus myosuroides, an autumn-germinating grass weed of cereal crops in North-West Europe, has evolved resistance to seven herbicide modes-of-action, making this an ideal species to examine the presence and magnitudes of such fitness costs. Here, we use two contrasting A. myosuroides phenotypes derived from a common genetic background, one with enhanced metabolism resistance to a commercial formulation of the sulfonylurea (ALS) actives mesosulfuron and iodosulfuron, and the other with susceptibility to these actives (S). Comparisons of plant establishment, growth, and reproductive potential were made under conditions of intraspecific competition, interspecific competition with wheat, and over a gradient of nitrogen deprivation. Herbicide dose response assays confirmed that the two lines had contrasting resistance phenotypes, with a 20-fold difference in resistance between them. Pleiotropic effects of resistance were observed during plant development, with R plants having a greater intraspecific competitive effect and longer tiller lengths than S plants during vegetative growth, but with S plants allocating proportionally more biomass to reproductive tissues during flowering. Direct evidence of a reproductive cost of resistance was evident in the nitrogen deprivation experiment with R plants producing 27 percent fewer seed heads per plant, and a corresponding 23 percent reduction in total seed head length. However, these direct effects of resistance on fecundity were not consistent across experiments. Our results demonstrate that a resistance phenotype based on enhanced herbicide metabolism has pleiotropic impacts on plant growth, development and resource partitioning but does not support the hypothesis that resistance is associated with a consistent reproductive fitness cost in this species. Given the continued difficulties associated with unequivocally detecting costs of herbicide resistance, we advocate future studies that adopt classical evolutionary quantitative genetics approaches to determine genetic correlations between resistance and fitness-related plant life history traits

KeywordsNon-target site resistance, resistance cost, fitness, life-history, trade-offs.
Year of Publication2019
JournalFrontiers in Plant Science
Journal citation10
Digital Object Identifier (DOI)
Web address (URL)
Open accessPublished as ‘gold’ (paid) open access
FunderBiotechnology and Biological Sciences Research Council
BBSRC Industrial Strategy Challenge
Agriculture and Horticulture Development Board
Funder project or codeBBSRC Strategic Programme in Smart Crop Protection
Multiple Herbicide Resistance in Grass Weeds: from Genes to AgroEcosystems
Publisher's version
Output statusPublished
Publication dates
Online26 Jun 2019
Publication process dates
Accepted12 Jun 2019
PublisherFrontiers Media SA

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