Ecological Evidence for the Fitness Trade-Off in Triazine Resistant Chenopodium Album L.: Can We Exploit the Cost of Resistance?

Pest Management Science

Harrington

et al. 2022

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BACKGROUND Chenopodium album L. is a troublesome weed in spring‐planted crops, and different levels of ploidy have been documented for this weed species. A population of C. album has evolved resistance to dicamba. The level of ploidy and inheritance of dicamba resistance was studied in this population. RESULTS The resistant and susceptible individuals of C. album were confirmed as tetraploid by flow cytometry. Pair‐crosses were made between ten resistant and susceptible individuals. Eight F1 individuals from five crosses were confirmed resistant after treating with dicamba at 400 g a.e. ha−1. These individuals were selfed, and the response of their progenies to dicamba was assessed in dose–response experiments, and the results confirmed the resistance trait was dominant. Furthermore, an analysis of the segregation patterns revealed that the segregation response of all F2 progenies fitted a 3:1 (resistant/susceptible) ratio when treated with dicamba at 200, 400 and 800 g a.e. ha−1, suggesting a single gene was responsible for dicamba resistance. CONCLUSIONS Dicamba resistance in the studied tetraploid population of C. album is governed by a single dominant gene. This type of inheritance suggests that selection for dicamba resistance can occur readily. © 2022 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Inheritance of dicamba‐resistance in allotetraploid Chenopodium album

Pest Management Science

Harrington

et al. 2022

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“…Response to haloxyfop. The seeds (n = 20) from populations R and S were placed at a depth of 1 cm in pots (1.2 L) filled with bark, fibre, Pacific Pumice (0.5:0.3:0.2) 45 plus fertiliser (Woodace) 46 . The pots were kept in a heated glasshouse with automated capillary irrigation at 21.5/18.2 °C under natural light and an average relative humidity (RH) of 50%.…”

Section: Dose-response Experimentsmentioning

confidence: 99%

Molecular characteristics of the first case of haloxyfop-resistant Poa annua

Mesarich

Harrington

2020

Sci Rep

Haloxyfop is one of two acetyl-coenzyme A carboxylase (Accase) inhibitors that is recommended for controlling Poa annua. We have characterised a population of P. annua that had developed resistance to haloxyfop. This resistant population was found to be almost 20 times less sensitive to haloxyfop than a susceptible population based on percentage survival of individuals in two dose-response experiments. However, the haloxyfop-resistant population was still susceptible to clethodim. pre-treatment of resistant individuals with a cytochrome P450 inhibitor, malathion, did not change the sensitivity level of the resistant plants to haloxyfop, suggesting that a non-target site mechanism of resistance involving enhanced metabolism, was not responsible for this resistance in P. annua. Gene sequencing showed that a target site mutation at position 2041, which replaced isoleucine with threonine in the carboxyltransferase (ct) domain of the Accase enzyme, was associated with resistance to haloxyfop in the resistant population. An evaluation of the 3-D structure of the CT domain suggested that, unlike Asn-2041, which is the most common mutation at this position reported to date, Thr-2041 does not change the conformational structure of the CT domain. This is the first study investigating the molecular mechanism involved with haloxyfop resistance in P. annua. Poa annua, an annual C 3 weedy grass in both agricultural and urban systems 1,2 , is one of the world's most widely distributed plant species 2. It is particularly problematic in turf grass, where it is highly tolerant of disturbance and has high fecundity 3. The occurrence of P. annua is often associated with human activities, and is one of the weedy grass species that is often found in seedbanks 4. P. annua is a prolific annual weed with a very short life 2. Notably, it can produce seed throughout most of the year 1. Collectively, these features predispose P. annua to herbicide resistance, since, at any one time, a large number of individuals will experience selection pressure under intense herbicide use 5. P. annua is an allotetraploid (2n = 4 × = 28) species, originating from the hybridization of P. supina as the male parent and P. infirma as the female parent 6. Cultural practices that can help desirable species compete well with P. annua can be used for management of this weedy grass species in turf grasses 7 ; i.e. in an effort to stop it re-establishing from seed after it completes its life cycle. Techniques such as soil aerification, fertilization management and modifying irrigation regimens are useful cultural practices for P. annua management in turf 8. However, cultural techniques should be part of a management package 9 , as these techniques do not result in complete control of P. annua in turf. Indeed, application of herbicides is desirable for complete management of this weed species in turf 10. There are, however, only a limited number of herbicides that can selectively remove P. annua from turf grasses 11. Hence, the best strategy to manage P. annua in tur...

“…Globally, there are over 40 cases of resistance to synthetic auxin herbicide in weed species (both monocotyledon and dicotyledon) [4]. In New Zealand, there are five cases of resistance to synthetic auxin herbicides [28][29][30], of which S. sessilis is the only synthetic auxin herbicide-resistant species reported in turfgrass [5]. Clopyralid-resistant S. sessilis was initially reported in the early 2000s [5]; however, the level of resistance to clopyralid and the pattern of cross-resistance to other synthetic auxin herbicides were unknown in this resistant population.…”

Section: Discussionmentioning

confidence: 99%

Characterization of clopyralid resistance in lawn burweed (Soliva sessilis)

et al. 2021

PLoS ONE

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Soliva sessilis is a troublesome annual weed species in New Zealand turfgrass. This weed has been controlled selectively in New Zealand turfgrass for many years using pyridine herbicides such as clopyralid. However, in some golf courses, the continuous application of pyridine herbicides has resulted in the selection of S. sessilis populations that are resistant to these herbicides. This study focuses on a clopyralid-resistant population of S. sessilis collected from a golf course with a long history of clopyralid applications. The resistant phenotype of S. sessilis was highly resistant to clopyralid (over 225-fold). It was also cross-resistant to dicamba, MCPA and picloram but not mecoprop. The level of resistance to dicamba was high (7-14-fold) but much lower (2-3-fold) for both MCPA and picloram. The phenotype was morphologically distinct from its susceptible counterpart. Individuals of the clopyralid-resistant phenotype had fewer lobes on their leaves and were slightly larger compared to the susceptible phenotype. Resistant individuals also had a larger leaf area and greater root dry weight than the susceptible plants. An evaluation of internal transcribed spacer (ITS) regions confirmed that clopyralid-resistant phenotypes are conspecific with S. sessilis. In summary, the cross-resistance to several auxinic herbicides in this S. sessilis phenotype greatly reduces chemical options for controlling it; thus, other integrated management practices may be needed such as using turfgrass competition to reduce weed germination. However, the morphological differences between resistant and susceptible plants make it easy to see, which will help with its management.