International Survey of Herbicide-Resistant Weeds

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Saturday, November 23, 2024

GOOSEGRASS (Eleusine indica) with GROUP G/9 resistance: (INHIBITION OF ENOLPYRUVYL SHIKIMATE PHOSPHATE SYNTHASE ) Inhibition of EPSP synthase

MUTATION: PROLINE 106 to SERINE

Goosegrass (Eleusine indica) is a monocot plant in the poaceae family. A single amino acid substitution from Proline 106 to Serine has led to resistance to Inhibition of Enolpyruvyl Shikimate Phosphate Synthase as indicated in the table below.		Goosegrass

Chemical Family	Example Herbicide	Resistance Level
Glycines	glyphosate	Intermediate Resistance < 10 fold

NOTE

REFERENCES

Kaundun, S. S. ; Zelaya, I. A. ; Dale, R. P. ; Lycett, A. J. ; Carter, P. ; Sharples, K. R. ; McIndoe, E.. 2008. Importance of the P106S target-site mutation in conferring resistance to glyphosate in a goosegrass (Eleusine indica) population from the Philippines. Weed Science 56 : 637 - 646.

Few studies on herbicide resistance report data to establish unambiguously the correlation between genotype and phenotype. Here we report on the importance of the EPSPS prolyl¹⁰⁶ point mutation to serine (P106S) in conferring resistance to glyphosate in a goosegrass population from Davao, Mindanao Island, the Philippines (Davao). Initial rate-response studies showed clear survivors within the Davao population at glyphosate rates that completely controlled the standard sensitive goosegrass population (STD1). Assessment of potential resistance mechanisms identified the presence of P106S mutant individuals in the Davao population. Polymerase chain reaction (PCR) amplification of specific alleles (PASA) analysis established that the mixed-resistant Davao population was comprised of 39.1% homozygous proline wild-type (PP106), 3.3% heterozygous serine mutant (PS106), and 57.6% homozygous serine mutant (SS106) genotypes. Further rate-response studies on plants with a predetermined genotype estimated the Davao SS106 individuals to be approximately 2-fold more resistant to glyphosate compared to Davao PP106 individuals. Extensive analysis at different goosegrass growth stages and glyphosate rates established strong correlation (P<0.001) between presence of P106S in EPSPS and the resistant phenotype. Importantly, no differences in the pattern of absorbed or translocated ¹⁴C-glyphosate were observed between PP106 and SS106 Davao genotypes or Davao and STD1 individuals, suggesting that glyphosate resistance in the Davao population was attributable to an altered target site mechanism. This study demonstrates that whilst P106S in EPSPS confers a moderate resistance level to glyphosate, the mechanism is sufficient to endow glyphosate failure at the recommended field rates..

Ng, C. H. ; Wickneswari, R. ; Salmijah, S. ; Teng, Y. T. ; Ismail, B. S.. 2003. Gene polymorphisms in glyphosate-resistant and -susceptible biotypes of Eleusine indica from Malaysia. Weed Research (Oxford) 43 : 108 - 115.

Resistant (R) and susceptible (S) biotypes of Eleusine indica were collected from four areas, namely Chaah, Lenggeng, Bidor and Temerloh, in Malaysia. Restriction fragment length polymorphism (RFLP) and polymerase chain reaction (PCR)-RFLP analyses using SphI restriction enzyme were able to differentiate the R biotype from the S biotype by showing R-specific and S-specific polymorphisms in E. indica from three of the areas, with the exception of Temerloh where no polymorphisms were detected. The different DNA profiles for the R biotypes obtained indicate that SphI is not a useful diagnostic marker. The DNA polymorphisms detected in the 5-enolpyruvylshikimate 3-phosphate (EPSP) synthase gene suggest that there are different mutation events leading to development of resistance to glyphosate. Partial sequencing of the EPSP synthase gene confirmed different mutations occurring with substitution of proline with serine or threonine at amino acid 106 for the R biotype in Chaah, Bidor and Temerloh..

Baerson, S. R. ; Rodriguez, D. J. ; Tran, M. ; Feng, Y. M. ; Biest, N. A. ; Dill, G. M.. 2002. Glyphosate-resistant goosegrass. Identification of a mutation in the target enzyme 5-enolpyruvylshikimate-3-phosphate synthase. Plant Physiology 129 : 1265 - 1275.

The spontaneous occurrence of resistance to the herbicide glyphosate in weed species has been an extremely infrequent event, despite over 20 years of extensive use. Recently, a glyphosate-resistant biotype of goosegrass (Eleusine indica) was identified in Malaysia exhibiting an LD₅₀ value approximately 2- to 4-fold greater than the sensitive biotype collected from the same region. A comparison of the inhibition of 5-enolpyruvylshikimate-3-phosphate synthase [3-phosphoshikimate 1-carboxyvinyltransferase] (EPSPS) activity by glyphosate in extracts prepared from the resistant (R) and sensitive (S) biotypes revealed an approximately 5-fold higher IC₅₀(glyphosate) for the (R) biotype. Sequence comparisons of the predicted EPSPS mature protein coding regions from both biotypes revealed four single-nucleotide differences, two of which result in amino acid changes. One of these changes, a proline to serine substitution at position 106 in the (R) biotype, corresponds to a substitution previously identified in a glyphosate-insensitive EPSPS enzyme from Salmonella typhimurium. Kinetic data generated for the recombinant enzymes suggests that the second substitution identified in the (R) EPSPS does not contribute significantly to its reduced glyphosate sensitivity. Escherichia coli aroA (EPSPS deficient) strains expressing the mature EPSPS enzyme from the (R) biotype exhibited an approximately 3-fold increase in glyphosate tolerance relative to strains expressing the mature EPSPS from the (S) biotype. These results provide the first evidence for an altered EPSPS enzyme as an underlying component of evolved glyphosate resistance in any plant species..

Yu, Q., A. Jalaludin, H. Han, M. Chen, R.D. Sammons, and S. Powles. 2015. Evolution of a Double Amino Acid Substitution in the 5-Enolpyruvylshikimate-3-Phosphate Synthase in Eleusine indica Conferring High-Level Glyphosate Resistance. Plant Physiology 167 : 1440 - 1447.

Glyphosate is the most important and widely used herbicide in world agriculture. Intensive glyphosate selection has resulted in the widespread evolution of glyphosate-resistant weed populations, threatening the sustainability of this valuable once-in-a-century agrochemical. Field-evolved glyphosate resistance due to known resistance mechanisms is generally low to modest. Here, working with a highly glyphosate-resistant Eleusine indica population, we identified a double amino acid substitution (T102I + P106S [TIPS]) in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene in glyphosate-resistant individuals. This TIPSmutation recreates the biotechnology-engineered commercial first generation glyphosate-tolerant EPSPS in corn (Zea mays) and now in other crops. In E. indica, the naturally evolved TIPS mutants are highly (more than 180-fold) resistant to glyphosate compared with the wild type and more resistant (more than 32-fold) than the previously known P106S mutants. The E. indica TIPS EPSPS showed very high-level (2,647-fold) in vitro resistance to glyphosate relative to the wild type and is more resistant (600-fold) than the P106S variant. The evolution of the TIPSmutation in crop fields under glyphosate selection is likely a sequential event, with the P106S mutation being selected first and fixed, followed by the T102I mutation to create the highly resistant TIPS EPSPS. The sequential evolution of the TIPS mutation endowing high-level glyphosate resistance is an important mechanism by which plants adapt to intense herbicide selection and a dramatic example of evolution in action..

Chen, J., H. Huang, C. Zhang, S. Wei, Z. Huang, J. Chen, and X. Wang. 2015. Mutations and amplification of EPSPS gene confer resistance to glyphosate in goosegrass (Eleusine indica). Planta 242 : 859 - 868.

Glyphosate has been used widely in the south of China. The high selection pressure from glyphosate use has led to the evolution of resistance to glyphosate in weeds. We investigated the molecular mechanisms of three recently discovered glyphosate-resistant Eleusine indicapopulations (R1, R2 and R3). The results showed that R1 and R2 had double Thr102Ile and Pro106Ser mutation and a single mutation of Pro106Leu in the 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene, respectively. Escherichia coli containing the mutated EPSPS genes was tolerant to glyphosate. EPSPS activity in R1 and R2 plants was higher than in the sensitive plants. There was no amino acid substitution in EPSPS gene in R3. However, expression of EPSPS in R3 plants was higher than in glyphosate-susceptible (S) population (13.8-fold) after glyphosate treatment. EPSPS enzyme activity in both R3 and S plants was inhibited by glyphosate, while shikimate accumulation in R3 was significantly lower than for the S population. Further analysis revealed that the genome of R3 contained 28.3-fold more copies of the EPSPS gene than that of susceptible population. EPSPS expression was positively correlated with copy number of EPSPS. In conclusion, mutation of the EPSPS gene and increased EPSPS expression are part of the molecular mechanisms of resistance to glyphosate in Eleusine indica..

Gherekhloo, J., Fernández-Moreno, P.T., Alcántara-de la Cruz, R., Sánchez-González, E., Cruz-Hipolito, H.E., Domínguez-Valenzuela, J.A. and De Prado, R.. 2017. Pro-106-Ser mutation and EPSPS overexpression acting together simultaneously in glyphosate-resistant goosegrass (Eleusine indica). Scientific Reports 7 : 6702 - .

Glyphosate has been used for more than 15 years for weed management in citrus groves in the Gulf of Mexico, at up to 3–4 applications per year. Goosegrass (Eleusine indica (L.) Gaertn.) control has sometimes failed. In this research, the mechanisms governing three goosegrass biotypes (Ein-Or from an orange grove, and Ein-Pl1 and Ein-Pl2 from Persian lime groves) with suspected resistance to glyphosate were characterized and compared to a susceptible biotype (Ein-S). Dose-response and shikimate accumulation assays confirmed resistance of the resistant (R) biotypes. There were no differences in glyphosate absorption, but the R biotypes retained up to 62–78% of the herbicide in the treated leaf at 96 h after treatment (HAT), in comparison to the Ein-S biotype (36%). The 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) activity in the Ein-Or and Ein-S biotypes was over 100-fold lower than the Ein-Pl1 and Ein-Pl2 ones. The latter showed a high EPSPS-basal activity, a mutation at Pro-106-Ser position in the EPSPS gene, and EPSPS overexpression. The EPSPS basal and EPSPS overexpression were positively correlated. The R goosegrass biotypes displayed poor glyphosate translocation. Furthermore, this grassweed showed, for the first time, two mechanisms at the target-site level (Pro-106-Ser mutation + EPSPS overexpression) acting together simultaneously against glyphosate..

Takano, H., R. Mendes, L. Scoz, R. Ovejero, J. Constantin, T. Gaines, P. Westra, F. Dayan, and R. Oliveira. 2019. Proline 106 EPSPS mutation imparting glyphosate resistance in goosegrass (Eleusine indica) emerges in South America. Weed Science 67 : 48 - 56.

Glyphosate-resistant (GR) goosegrass [Eleusine indica (L.) Gaertn.] was recently identified in Brazil, but its resistance mechanism was unknown. This study elucidated the resistance mechanism in this species and developed a molecular marker for rapid detection of this target-site resistance trait. The resistance factor for the resistant biotype was 4.4-fold compared with the glyphosate-susceptible (GS) in greenhouse dose–response experiments. This was accompanied by a similar (4-fold) difference in the levels of in vitro and in planta shikimate accumulation in these biotypes. However, there was no difference in uptake, translocation, or metabolism of glyphosate between the GS and GR biotypes. Moreover, both biotypes showed similar values for 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) copy number and transcription. Sequencing of a 330-bp fragment of the EPSPS gene identified a single-nucleotide polymorphism that led to a Pro-106-Ser amino acid substitution in the enzyme from the GR biotype. This mutation imparted a 3.8-fold increase in the amount of glyphosate required to inhibit 50% of EPSPS activity, confirming the role of this amino acid substitution in resistance to glyphosate. A quantitative PCR–based genotyping assay was developed for the rapid detection of resistant plants containing this Pro-106-Ser mutation..

This case was entered by Ian Heap Email: ianheap@weedsmart.com

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