Microevolution of ALS inhibitor herbicide resistance in loose silky bentgrass (Apera spica-venti)

TY - GEN

T1 - Microevolution of ALS inhibitor herbicide resistance in loose silky bentgrass (Apera spica-venti)

AU - Babineau, Marielle

PY - 2017

Y1 - 2017

N2 - Apera spica-venti is one of the most serious weed in Central and Eastern Europe and the Baltic countries. Many populations have evolved resistance to three herbicide site of action, especially to the ALS inhibitors, and some populations evolved multiple resistance to all three sites of action. The genetic mechanisms of herbicide resistance remain tentative in this species. Chemical control has become a less viable solution in view of multiple resistance and stricter legislation to reduce pesticide use. A better understanding of the evolutionary processes involved in the early development of herbicide resistance in A. spica-venti could improve non-chemical management strategies. This PhD study aimed to 1) determine cross and multiple resistance of ALS resistant neighboring populations of A. spica-venti as well as the spatial distribution pattern of ALS resistance, 2) identify genes involved in non-target site resistance in A. spica-venti, and 3) evaluate the fitness of ALS resistant and susceptible individuals. Dose-responses bioassays were conducted on the neighboring populations using different ALS chemistries, as well as ACCase and fatty acid elongation inhibitor herbicide sites of action. Using RNA-Seq, a reference transcriptome from different tissues of ALS susceptible individuals was assembled, then was used to perform a differential gene expression analysis between 48 ALS resistant and susceptible biotypes after herbicide treatment. A germination and target-neighborhood experiments were conducted with ALS resistant and susceptible populations with a randomized genetic background, vegetative and reproductive growth stages were compared. The results show a large variation in the response of neighboring populations to ALS herbicide. Multiple resistance is observed between ALS and ACCase and low-levels of cross resistance within ALS chemistries. The spatial trend indicates an ALS resistance epicenter with susceptible populations the furthest away from it. Non-target site resistance is confirmed as the most important herbicide resistance mechanism in A. spica-venti. Different genes from known metabolic herbicide resistance pathways, such as cytochrome P450s, ABC-transporters, UDP-glycosyltransferase and glutathione S-transferase, are identified and quantified. Different gene families are up-regulated at different times after herbicide treatment. In low competition conditions, the ALS resistant biotypes have a fitness advantage over the susceptible biotype in time to germination and time to flowering and seed production growth stages. This study increased the understanding of the spatial, phenotypic, genetic and ecological processes and consequences in ALS herbicide resistance for A. spica-venti. The applications for IPM management strategies are discussed.

AB - Apera spica-venti is one of the most serious weed in Central and Eastern Europe and the Baltic countries. Many populations have evolved resistance to three herbicide site of action, especially to the ALS inhibitors, and some populations evolved multiple resistance to all three sites of action. The genetic mechanisms of herbicide resistance remain tentative in this species. Chemical control has become a less viable solution in view of multiple resistance and stricter legislation to reduce pesticide use. A better understanding of the evolutionary processes involved in the early development of herbicide resistance in A. spica-venti could improve non-chemical management strategies. This PhD study aimed to 1) determine cross and multiple resistance of ALS resistant neighboring populations of A. spica-venti as well as the spatial distribution pattern of ALS resistance, 2) identify genes involved in non-target site resistance in A. spica-venti, and 3) evaluate the fitness of ALS resistant and susceptible individuals. Dose-responses bioassays were conducted on the neighboring populations using different ALS chemistries, as well as ACCase and fatty acid elongation inhibitor herbicide sites of action. Using RNA-Seq, a reference transcriptome from different tissues of ALS susceptible individuals was assembled, then was used to perform a differential gene expression analysis between 48 ALS resistant and susceptible biotypes after herbicide treatment. A germination and target-neighborhood experiments were conducted with ALS resistant and susceptible populations with a randomized genetic background, vegetative and reproductive growth stages were compared. The results show a large variation in the response of neighboring populations to ALS herbicide. Multiple resistance is observed between ALS and ACCase and low-levels of cross resistance within ALS chemistries. The spatial trend indicates an ALS resistance epicenter with susceptible populations the furthest away from it. Non-target site resistance is confirmed as the most important herbicide resistance mechanism in A. spica-venti. Different genes from known metabolic herbicide resistance pathways, such as cytochrome P450s, ABC-transporters, UDP-glycosyltransferase and glutathione S-transferase, are identified and quantified. Different gene families are up-regulated at different times after herbicide treatment. In low competition conditions, the ALS resistant biotypes have a fitness advantage over the susceptible biotype in time to germination and time to flowering and seed production growth stages. This study increased the understanding of the spatial, phenotypic, genetic and ecological processes and consequences in ALS herbicide resistance for A. spica-venti. The applications for IPM management strategies are discussed.

KW - Apera spica-venti

KW - acetolactate synthase (ALS)

KW - Herbicide resistance

KW - fitness

KW - non-target site resistance

M3 - PhD thesis

SN - 978-87-93398-58-0

PB - Aarhus Universitet, Institut for Agroøkologi

ER -