School of Agriculture and Environment (PN 433), Massey University, Private Bag 11-222, Palmerston North, 4442, New Zealand.
Planta. 2019 Mar;249(3):787-797. doi: 10.1007/s00425-018-3040-5. Epub 2018 Nov 7.
Detrimental pleiotropic effects of resistance mutation(s) were observed for multiple-resistant phenotypes (resistant to both atrazine and dicamba). The multiple-resistant phenotypes had lower growth rates and less capacity for vegetative growth compared to the phenotypes only resistant to atrazine. The fitness costs that are conferred by herbicide resistance alleles can affect the rate of herbicide resistance evolution within populations. We evaluated the direct fitness costs involved with multiple resistance to dicamba and atrazine (R1 and R2) in Chenopodium album by comparing the performance of multiple-resistant phenotypes to those phenotypes that were only resistant to atrazine (S1 and S2). The R1 and R2 phenotypes were consistently shorter and produced less dry matter than the S1 and S2 phenotypes. The R1 and R2 phenotypes were shown to have lower relative growth rates (RGR) and net assimilation rates (NAR) than the S1 and S2 phenotypes at an early stage of growth. However, there was no significant difference in RGR between the R1 and R2 and, S1 and S2 phenotypes at a later stage of growth, though the R1 and R2 phenotypes still had a lower NAR at this later stage. Further investigations using a neighbouring crop competition approach showed that the R1 and R2 phenotypes were weaker competitors, and exhibited significantly less capacity for vegetative growth compared to the S1 and S2 phenotypes during competition. Overall, the results of this study revealed multiple- resistance to atrazine and dicamba endowed a significant fitness penalty to C. album, and it is possible that the frequency of multiple-resistant individuals would gradually decline once selection pressure from herbicides was discontinued.
对多种抗性表型（对莠去津和麦草畏均有抗性）观察到抗性突变（s）的有害多效性。与仅对莠去津有抗性的表型相比，多种抗性表型的生长速度较慢，营养生长能力较低。除草剂抗性等位基因赋予的适合度成本可能会影响种群内除草剂抗性进化的速度。我们通过比较对莠去津和麦草畏具有多重抗性的表型（R1 和 R2）与仅对莠去津有抗性的表型（S1 和 S2）在生长过程中的表现，评估了对麦草畏和莠去津（R1 和 R2）的多重抗性所涉及的直接适合度成本。R1 和 R2 表型始终比 S1 和 S2 表型短，产生的干物质少。在生长的早期阶段，R1 和 R2 表型的相对生长率（RGR）和净同化率（NAR）均低于 S1 和 S2 表型。然而，在生长的后期阶段，R1 和 R2 表型与 S1 和 S2 表型之间的 RGR 没有显著差异，尽管在这个后期阶段，R1 和 R2 表型的 NAR 仍然较低。使用邻近作物竞争方法进行的进一步研究表明，R1 和 R2 表型的竞争力较弱，与 S1 和 S2 表型相比，在竞争过程中，其营养生长能力明显较低。总的来说，这项研究的结果表明，对莠去津和麦草畏的多重抗性赋予了 C. album 显著的适应度惩罚，一旦停止除草剂的选择压力，多重抗性个体的频率可能会逐渐下降。
