Iranian Society of Weed Science Iranian Journal of Weed Science 1735-3548 16 1 2020 04 20 Relative Fitness of Acetyl-CoA Carboxylase susceptible and resistant Alopecurus myosuroides biotypes: germinability and seedling pre-emergence growth under salinity and drought stress conditions Relative Fitness of Acetyl-CoA Carboxylase susceptible and resistant Alopecurus myosuroides biotypes: germinability and seedling pre-emergence growth under salinity and drought stress conditions 49 61 120824 10.22092/IJWS.2020.1601.1329 FA Zahra Ghazali Department of Agronomy, Faculty of Agriculture, Tarbiat Modares University, P.O. Box: 14115-336, Tehran, Iran Eshag Keshtkar University of Tarbiat Modares Majid AghaAlikhani Department of Agronomy, Faculty of Agriculture, Tarbiat Modares University, P.O. Box: 14115-336, Tehran, Iran Per Kudsk Department of Agroecology, Aarhus University, Forsøgsvej 1, DK-4200, Slagelse, Denmark Journal Article 2019 05 16 Fitness costs of herbicide resistance may be more evident and increase under stress environmental conditions. To test this hypothesis, a herbicide-resistant (R) and a herbicide-susceptible (S) phenotype with controlled and homogenized genetic background were isolated within a non–target-site resistant (NTSR) black-grass population. Accumulated maximum germination (Gmax) and time to reach the Gmax(G50) of biotypes were examined under non-stress and abiotic-stress conditions (salinity at 16 dSm-1, drought at -0.8 Mpa). In addition, seedling pre-emergence biotypes growths were evaluated under non-stress condition. There was no difference in Gmaxbetween the R and S biotypes, whereas the Gmaxof R phenotype was 28% and 49% lower than that of the S phenotype under salinity- and drought-stress conditions, respectively. The R phenotype germinated around seven to 16 hours later than the S phenotype under all non-stress and abiotic-stress conditions, i.e. the R phenotype had higher G50 than the other phenotype. The experiments of seedling pre-emergence growth showed that the R and S biotypes had similar root and shoot length under non-stress condition. The results clearly showed that the germinability fitness costs of NTSR black-grass increase when the plants are grown under salinity and drought stress conditions. Fitness costs of herbicide resistance may be more evident and increase under stress environmental conditions. To test this hypothesis, a herbicide-resistant (R) and a herbicide-susceptible (S) phenotype with controlled and homogenized genetic background were isolated within a non–target-site resistant (NTSR) black-grass population. Accumulated maximum germination (Gmax) and time to reach the Gmax(G50) of biotypes were examined under non-stress and abiotic-stress conditions (salinity at 16 dSm-1, drought at -0.8 Mpa). In addition, seedling pre-emergence biotypes growths were evaluated under non-stress condition. There was no difference in Gmaxbetween the R and S biotypes, whereas the Gmaxof R phenotype was 28% and 49% lower than that of the S phenotype under salinity- and drought-stress conditions, respectively. The R phenotype germinated around seven to 16 hours later than the S phenotype under all non-stress and abiotic-stress conditions, i.e. the R phenotype had higher G50 than the other phenotype. The experiments of seedling pre-emergence growth showed that the R and S biotypes had similar root and shoot length under non-stress condition. The results clearly showed that the germinability fitness costs of NTSR black-grass increase when the plants are grown under salinity and drought stress conditions.

https://ijws.areeo.ac.ir/article_120824_5f72cafb4f18ef8c1a7bab69fca35658.pdf