Figure - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Survival percentage of Italian ryegrass progenies at the six-leaf stage before glyphosate application, and percentage of susceptible and resistant plants evaluated after glyphosate application in crosses involving different ploidy levels and glyphosate-resistant diploid genotype.
Source publication
Italian ryegrass (Lolium multiflorum Lam.) is a grass weed found in winter cereals, with several glyphosate-resistant diploid populations. Furthermore, the use of Italian ryegrass tetraploid genotypes creates an opportunity to increase the forage demand in replacement of diploid populations. The aim of this research was to evaluate the crossing cap...
Contexts in source publication
Context 1
... progeny from DRR♂ × TSC♀ crossing showed a low survival ratio, with 46% of transplanted seedlings death before glyphosate application (Table 2). Similar results were found for crosses of diploid and tetraploid ryegrass, in which the seeds showed germination problems or death of seedlings soon after germination ( Bustamante et al. 2015). ...Context 2
... extreme changes in gene expression during this period can cause problems to seedlings with the duplicate genome, affects the gene expression regulation and losses of functional genes (Adams and Wendel 2005;Van Zanten et al. 2013). Seedling mortality from DRR♂ × TSC♀ progeny can probably be triggered as a result of different ploidy level from their genitors, in which the interference of gene regulation and expression lead to the loss of essential functional genes needed to growth and survival (Table 2). ...Context 3
... the glyphosate resistance inheritance, no glyphosate-resistant plants were identified for TSC♂ × TSC♀ and DRR♂ × TSC♀ progenies (Table 2, Fig. 2). In Italian ryegrass, glyphosate-resistance is encoded by a nuclear semidominant gene and can be disseminated to susceptible populations by pollen ( Ghanizadeh and Harrington 2018). ...Context 4
... susceptible glyphosate plants can be originated from self-fertilization from crossing between diploid and tetraploid genitors (Fearon et al. 1983). Although the DRR♂ × DRR♀ crosses had been considered homozygous to the resistance, 28% of the plants died after glyphosate application (Table 2, Fig. 2). In this case, glyphosate-resistance of Italian ryegrass can be explained by alleles with incomplete dominance and segregation of a 3:1 ratio ( Vargas et al. 2007). ...Similar publications
Amana Honda (Liliaceae), known as ‘east Asian tulips’, is a spring ephemeral genus endemic to Sino-Japanese Floristic Subregion, mainly distributed in eastern and central China, Japan and the Korean peninsula. Chromosome numbers are reported here for the first time from 89 populations of Amana (representing all seven accepted species, two new speci...
Citations
... Resulting triploid progeny, found in the weedy population GER-13, can occur under field conditions but often die prematurely or have reduced fertility and potential loss of aneuploidy (Myers, 1944;Schmitz et al., 2020). Furthermore, the presence of herbicide resistance-conferring genes under selection pressure could favour diploid weedy ryegrass, as traits like resistance to ACCase inhibitors are expressed co-dominantly (Délye, Menchari, et al., 2013;Tal & Rubin, 2004) resulting in a lower resistance level in polyploid plants. ...
Ryegrass species ( Lolium spp.) are both cultivated crops and troublesome weeds. Weedy ryegrasses are prone to evolve herbicide resistance and are particularly widespread in regions of intense ryegrass propagation, like Saxony in Germany and the Pacific Northwest in the USA. In such cases, pre‐emergence herbicides become key control measures. Therefore, 39 German weedy ryegrass populations, which survived herbicide applications in the field, were assessed for their species, ploidy and resistance to three different herbicide modes of action (MoAs). Additionally, 34 commercial cultivars of the Festuca–Lolium complex were screened for resistance, followed by target gene sequencing of surviving individuals. Resistance was widespread among weedy ryegrass populations, with 77% exhibiting resistance to acetyl‐CoA carboxylase (ACCase) inhibitors, 59% to acetolactate synthase (ALS) inhibitors and 18% to very‐long‐chain fatty acid (VLCFA) biosynthesis inhibitors. Resistance was confirmed in two ryegrass cultivars: A L. perenne cultivar exhibited resistance to flufenacet (VLCFA inhibitor) biosynthesis and to ALS and ACCase inhibitors due to single‐nucleotide polymorphisms (SNPs). SNPs in the ACCase gene were furthermore found in a tetraploid L. hybridum cultivar. Despite the prevalence of tetraploid varieties, most weedy ryegrasses were diploid L. multiflorum . Nevertheless, the occurrence of tetraploid weedy ryegrass confirms that cultivars can become weeds. In conclusion, herbicide‐resistant diploid L. multiflorum dominated among weedy ryegrass populations. Diploid populations establish more easily as weeds and possibly evolve resistance faster. Furthermore, unidentified resistance in ryegrass cultivars can be a source of weed resistance. Therefore, preventing flowering and seed shattering, particularly of diploid ryegrass cultivars, is crucial under field conditions.
... However, this approach may not be effective if herbicide resistance is highly likely to evolve in tetraploid populations. 31 In conclusion, frequencies of resistance to haloxyfop and iodosulfuron in commercial ryegrass seed lots were high for both species but higher still for L. multiflorum Lam. compared with L. perenne. ...
Background
Ryegrass (Lolium spp.) is a key forage providing a $14 billion contribution to New Zealand's gross domestic product (GDP). However, ryegrass can also act as a weed and evolve resistance to herbicides used for its control. Farmers suspected that imported seed might contribute to resistance issues. Herbicide resistance frequencies were investigated in commercial ryegrass seed lines intended for multiplication in New Zealand. Samples from 56 basic seed lots and 52 unique cultivars sourced from regions including New Zealand, United States, Europe and Japan were planted in field trials. Seedlings were then sprayed with three common herbicides: glyphosate, iodosulfuron, and haloxyfop. Surviving plants were retested to confirm resistance.
Results
Resistance to haloxyfop and or iodosulfuron was detected in 79% of seed lines. However, frequencies were not significantly higher in imported lines (from United States and Europe) compared with New Zealand lines. Resistance was detected at frequencies between 0.00112% and 10% for haloxyfop and between 0.00212% and 14.28% for iodosulfuron Resistance to glyphosate was not found. There was no significant difference between the resistance detected in seed samples sourced from different seed companies.
Conclusions
It was found that 63% of resistant lines had resistance frequencies rarer than 0.1%, but this is potentially problematic considering typical sowing rates. Imported versus domestic seed sources were not significantly different; they pose similar levels of resistance risk to farmers. Lolium multiflorum had a higher resistance frequency compared to Lolium perenne (although only six L. multiflorum lots were evaluated). Breeders should screen progeny of early crosses for herbicide resistance. © 2025 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
... The phylogenetic analysis suggests that these haplotypes have close evolutionary origins with other non-resistant, diploid individuals, suggesting that the resistance alleles might have been present in the breeding programs prior to chromosome duplication and release of the varieties. Because tetraploid cultivars are not compatible with their diploid counterparts(Schmitz et al., 2020), if evolution F I G U R E 3 Best-scoring maximum-likelihood phylogenetic tree of Lolium multiflorum based on ACCase sequence. Numbers indicate bootstrapping values (values smaller than 60 were omitted). ...
Herbicide resistance in weeds is one of the greatest challenges in modern food production. The grass species Lolium multiflorum is an excellent model species to investigate evolution under similar selection pressure because populations have repeatedly evolved resistance to many herbicides, utilizing a multitude of mechanisms to neutralize herbicide damage. In this work, we investigated the gene that encodes acetyl‐CoA carboxylase (ACCase), the target site of the most successful herbicide group available for grass weed control. We sampled L. multiflorum populations from agricultural fields with history of intense herbicide use, and studied their response to three ACCase‐inhibiting herbicides. To elucidate the mechanisms of herbicide resistance and the genetic relationship among populations, we resolved the haplotypes of 97 resistant and susceptible individuals by sequencing ACCase amplicons using long‐read DNA sequencing technologies. Our dose–response data indicated the existence of many, often unpredictable, resistance patterns to ACCase‐inhibiting herbicides, where populations exhibited as much as 37‐fold reduction in herbicide response. The majority of the populations exhibited resistance to all three herbicides studied. Phylogenetic and molecular genetic analyses revealed multiple evolutionary origins of resistance‐endowing ACCase haplotypes, as well as widespread admixture in the region regardless of cropping system. The amplicons generated were diverse, with haplotypes exhibiting 26–110 polymorphisms. Polymorphisms included insertions and deletions 1–31 bp in length, none of which were associated with the resistance phenotype based on an association analysis. We also found evidence that some populations have multiple mechanisms of resistance. Our results highlight the astounding genetic diversity in L. multiflorum populations, and the potential for repeated evolution of herbicide resistance across the landscape that challenges weed management approaches and jeopardizes sustainable weed control practices. We provide an in‐depth discussion of the evolutionary and practical implications of our results.
... [8,9] Although the crossing between diploid and tetraploid cultivars still does not have a high percentage of success, the use of tetraploid cultivars can also contribute to the management of glyphosate resistance by diploid ryegrass. [10] Even though it is widely used as a forage, ryegrass can be considered an annual or perennial weed of difficult control, [11][12][13] commonly found in wheat, maize, oats, and barley. [14] The control of this weed is carried out mainly with the herbicide glyphosate, an inhibitor of the enzyme5-enolpyruvylshikimate-3-phosphate (EPSPS). ...
Lolium multiflorum Lam. is a winter weed of difficult control found as diploid (2n) and tetraploid plants (4n). Our study aimed to evaluate the responses of antioxidant enzymes and lipid peroxida-tion, in both diploid and tetraploid ryegrass varieties. Treatments consisted of control plants (with-out any herbicide application), and four herbicides with different mechanisms of action. Leaf material was collected 36 h after treatment imposition to determine the lipid peroxidation by fer-rous oxidation-xylenol (FOX) content, and the activity of the enzymes superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), guaiacol peroxidase (GPX), glutathione-S-transferase (GST), and d-aminolevulinic acid dehydratase (ALAD). Both ryegrass varieties showed oxidative stress mainly due to a downregulated decreased (>31%) in SOD activity and an increase (>32%) in lipid peroxidation (FOX), mainly in ryegrass genotypes exposed to haloxyfop, glyphosate, and iodosulfuron. On the other hand, clethodim-treated plants had an increase in SOD and APX activities , associated with a reduced ALAD activity in both 2n (32%) and 4n (11%) genotypes. In general , the 2n genotype was more affected than the 4n genotype. ARTICLE HISTORY
Herbicide resistance in weeds is one of the greatest challenges in modern food production. The grass species Lolium multiflorum is an excellent model species to investigate convergent evolution under similar selection pressure because populations have repeatedly evolved resistance to many herbicides, utilizing a multitude of mechanisms to neutralize herbicide damage. In this work, we investigated the gene that encodes acetyl-CoA carboxylase (ACCase), the target-site of the most successful herbicide group available for grass weed control. We sampled L. multiflorum populations from agricultural fields with history of intense herbicide use, and studied their response to three ACCase-inhibiting herbicides under controlled conditions. To elucidate the mechanisms of herbicide resistance and the genetic relationship among sampled populations, we resolved the haplotypes of 97 resistant and susceptible individuals by performing an amplicon-seq analysis using long-read DNA sequencing technologies, focusing on the DNA sequence encoding the carboxyl-transferase domain of ACCase. Our dose-response data indicated the existence of many, often unpredictable, resistance patterns to ACCase-inhibiting herbicides, where populations exhibited as much as 37-fold reduction in herbicide response. The majority of the populations exhibited resistance to all three herbicides studied. Phylogenetic and molecular genetic analyses revealed multiple evolutionary origins of resistance-endowing ACCase haplotypes, as well as widespread admixture in the region regardless of cropping system. The amplicons generated were very diverse, with haplotypes exhibiting 26 to 110 polymorphisms. Polymorphisms included insertions and deletions 1-31 bp in length, none of which were associated with the resistance phenotype. We also found evidence that some populations have multiple mechanisms of resistance. Our results highlight the astounding genetic diversity in L. multiflorum populations, and the potential for convergent evolution of herbicide resistance across the landscape that challenges weed management and jeopardizes sustainable weed control practices. We provide an in-depth discussion of the evolutionary and practical implications of our results.
