Inheritance of glyphosate resistance in rigid ryegrass (Lolium rigidum) from California

Glyphosate resistance was found in a rigid ryegrass population in northern California. A sample of the resistant plants were collected and grown under greenhouse conditions. The objective of this study was to evaluate glyphosate resistance in the progeny of the collected plants by recurrent selection, obtain the homozygous resistant and sensitive lines to establish dose-response curves, and to determine the inheritance of glyphosate resistance in rigid ryegrass. Diverse levels of resistance were observed in the first generation with survival of 89, 59, 45, and 9% from glyphosate at 1x, 2x, 4x, and 8x respectively, where x = 1.12 kg ha−1isopropylamine salt of glyphosate. Clones of plants that died from 1x were allowed to produce seed and were further subjected to recurrent selection to generate the most sensitive plants (S lines), which died from 0.125x glyphosate. The most resistant plants (R lines) were generated from the survivors receiving 8x glyphosate. The ratio between I50rates for the glyphosate resistant and the glyphosate sensitive plants was > 100-fold. The R and S lines were crossed reciprocally and F1progeny of both (R × S) and (S × R) showed intermediate resistance. These survived up to 2x glyphosate. The F2progeny were generated by intercrossing of F1plants. The ratio of sensitive, intermediate, and resistant plants in the F2population before the treatment of glyphosate at 0.125x followed by 8x was 1 : 16, 14 : 16, and 1 : 16 respectively, which corresponded to the Mendelian segregation ratio of two genes. The results indicated that the inheritance of glyphosate resistance in rigid ryegrass from California appeared to be nuclear, incompletely dominant, multigenic, and pollen-transmitted with no indication of maternal inheritance.

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An Herbicide-Susceptible Rigid Ryegrass (Lolium rigidum) Population Made Even More Susceptible

Weed Science ◽

10.1614/ws-d-11-00076.1 ◽

2012 ◽

Vol 60 (1) ◽

pp. 101-105 ◽

Cited By ~ 10

Author(s):

Sudheesh Manalil ◽

Roberto Busi ◽

Michael Renton ◽

Stephen B. Powles

Keyword(s):

Genetic Variation ◽

Phenotypic Variation ◽

Recurrent Selection ◽

Wild Population ◽

Rapid Evolution ◽

Differential Susceptibility ◽

Variable Cross ◽

Lolium Rigidum ◽

Rigid Ryegrass ◽

Low Rate

A wild population of a plant species, especially a cross-pollinated species, can display considerable genetic variation. Genetic variability is evident in differential susceptibility to an herbicide because the population can show continuous phenotypic variation. Recent, recurrent selection studies have revealed that phenotypic variation in response to low herbicide rates is heritable and can result in rapid evolution of herbicide resistance in genetically variable cross-pollinated rigid ryegrass. In this study, the heritable genetic variation in an herbicide-susceptible rigid ryegrass population was exploited to shift the population toward greater herbicide susceptibility by recurrent selection. To enhance herbicide susceptibility, herbicide-susceptible rigid ryegrass plants were divided into two identical clones, and one series of cloned plants was treated with a low rate of herbicide (diclofop). The nontreated clones of individuals that did not survive the herbicide treatment were selected and bulk-crossed to obtain the susceptible progeny. After two cycles of selection, the overall susceptibility to diclofop was doubled. The results indicate that minor genes for resistance are present in an herbicide-susceptible rigid ryegrass population, and their exclusion can increase susceptibility to diclofop.

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Inheritance of glyphosate resistance in goosegrass (Eleusine indica)

Weed Science ◽

10.1614/ws-03-105r2 ◽

2004 ◽

Vol 52 (4) ◽

pp. 564-570 ◽

Cited By ~ 42

Author(s):

Chin-Hong Ng ◽

Wickneswary Ratnam ◽

Salmijah Surif ◽

B. S. Ismail

Keyword(s):

Maternal Inheritance ◽

Dominant Gene ◽

Glyphosate Resistance ◽

Segregation Ratio ◽

Reciprocal Crosses ◽

Eleusine Indica ◽

Isozyme Analyses

The inheritance of glyphosate-resistant goosegrass was studied by making reciprocal crosses between resistant (R) and susceptible (S) biotypes. Eighty-four F1hybrids were confirmed using isozyme analyses. Reciprocal F1hybrids displayed uniform levels of resistance intermediate (I) to that of the parental types, with no indication of maternal inheritance. The F1hybrids were selfed to produce F2populations. F3populations were produced by selfing resistant and intermediate F2phenotypes. A segregation ratio of 1:2:1 (S:I:R) was observed in the F2and subsequently in the F3generations derived from selfing intermediate F2phenotypes. Individuals in F3families derived from selfing resistant F2phenotypes were resistant. Results from the present study show that glyphosate resistance in goosegrass is inherited as a single, nuclear, and incompletely dominant gene.

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Evidence, Mechanism and Alternative Chemical Seedbank-Level Control of Glyphosate Resistance of a Rigid Ryegrass (Lolium rigidum) Biotype from Southern Spain

Frontiers in Plant Science ◽

10.3389/fpls.2017.00450 ◽

2017 ◽

Vol 8 ◽

Cited By ~ 12

Author(s):

Pablo T. Fernández-Moreno ◽

Fernando Bastida ◽

Rafael De Prado

Keyword(s):

Glyphosate Resistance ◽

Southern Spain ◽

Lolium Rigidum ◽

Level Control ◽

Rigid Ryegrass

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First Case of Multiple Resistance to Glyphosate and PPO-inhibiting Herbicides in Rigid Ryegrass (Lolium rigidum) in Spain

Weed Science ◽

10.1017/wsc.2017.49 ◽

2017 ◽

Vol 65 (6) ◽

pp. 690-698 ◽

Cited By ~ 5

Author(s):

Pablo Tomas Fernandez-Moreno ◽

Antonia Maria Rojano-Delgado ◽

Julio Menendez ◽

Rafael De Prado

Keyword(s):

Dose Response ◽

Selection Pressure ◽

Protoporphyrin Ix ◽

Glyphosate Resistance ◽

Resistance Pattern ◽

Multiple Resistance ◽

Lolium Rigidum ◽

First Case ◽

Natural Tendency ◽

Rigid Ryegrass

Five rigid ryegrass populations suspected of being resistant to both glyphosate and oxyfluorfen were collected in southern Spain and tested under laboratory-controlled conditions. Four populations (Depuradora, Condado, AlamoRasilla, and Portichuelo) were treated with glyphosate for at least 15 consecutive years, and treatments during the last 5 yr were mixed with oxyfluorfen. The fifth population (4alamos) followed the same glyphosate treatment, although oxyfluorfen was never used to control it. Dose–response assays confirmed glyphosate resistance in all populations, with resistance indexes ranging from 11.7 to 37.5 (GR90). Shikimate accumulation assays consistently supported these data, as the most glyphosate-resistant populations (Depuradora and Condado) displayed the lowest shikimate levels. Surprisingly, four populations (Depuradora, Condado, AlamoRasilla, and Portichuelo) displayed 7.93- to 70.18-fold more resistance (GR90) to oxyfluorfen, despite limited selection pressure, showing a similar resistance pattern as that for glyphosate. The 4alamos population displayed oxyfluorfen GR90values that were similar to those observed in susceptible plants; however, this population was significantly more resistant in terms of plant survival (LD90). Protoporphyrin IX accumulation assays supported the results of dose–response assays, in that the most oxyfluorfen-resistant populations accumulated less protoporphyrin IX. Although more studies are needed, it seems that these five glyphosate-resistant weed populations display a natural tendency to easily develop resistance to oxyfluorfen, with the populations that have higher resistance to glyphosate also having higher resistance to oxyfluorfen.

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Resistance to bixlozone and clomazone in cross-resistant rigid ryegrass (Lolium rigidum) populations from southern Australia

Weed Science ◽

10.1017/wsc.2021.6 ◽

2021 ◽

pp. 1-6

Author(s):

David J. Brunton ◽

Gurjeet Gill ◽

Christopher Preston

Keyword(s):

Recurrent Selection ◽

Selection Process ◽

Resistance Mechanism ◽

Fold Increase ◽

Elevated Risk ◽

Cross Resistance ◽

Lolium Rigidum ◽

Rigid Ryegrass

Abstract Three resistant (R) rigid ryegrass (Lolium rigidum Gaudin) populations from southern Australia (EP162, 375-14, and 198-15) with cross-resistance to thiocarbamate, chloroacetamide, and sulfonylisoxazoline herbicides displayed reduced sensitivity to the isoxazolidinone herbicides bixlozone and clomazone. Each of these R populations was exposed to two cycles of recurrent selection (RS) in which plants were treated with the field rate of bixlozone, survivors were bulk crossed, and seed was collected. After the first cycle of recurrent selection (RS1), the LD50 to bixlozone in population 198-15 increased to 17.5-fold compared with the S population and increased further to 26.9-fold after a second cycle of recurrent selection (RS2). The recurrent selection process also increased the level of resistance to bixlozone in populations EP162 and 375-14 (7.8- to 18.4-fold) compared with the S population. Phorate antagonized bixlozone and clomazone in SLR4 (34.6- and 28.1-fold increase in LD50) and both herbicides in populations EP162 (36.5- to 46.6-fold), 375-14 (71.4- to 73.9-fold), and 198-15 (86.4- to 91.5-fold) compared with the absence of phorate. The increase in LD50 of all L. rigidum RS populations when treated with phorate suggests a lack of herbicide activation is not the likely resistance mechanism to these herbicides. This research highlights the elevated risk of thiocarbamate-resistant L. rigidum populations to rapidly evolve resistance to the isoxazolidinone herbicides bixlozone and clomazone.

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Identification of glyphosate resistance in Lolium rigidum Gaudin

Pesticidi i fitomedicina ◽

10.2298/pif1104393p ◽

2011 ◽

Vol 26 (4) ◽

pp. 393-399 ◽

Cited By ~ 2

Author(s):

Danijela Pavlovic ◽

Charlie Reinhardt ◽

Igor Elezovic ◽

Sava Vrbnicanin

Keyword(s):

Shikimic Acid ◽

Glyphosate Resistance ◽

The Other ◽

Population Difference ◽

Lolium Rigidum ◽

Susceptible Population ◽

Dry Biomass ◽

Rigid Ryegrass ◽

Susceptible Populations ◽

Two Populations

Glyphosate resistance was found in Lolium rigidum Gaudin (Rigid ryegrass, LOLRI) in South Africa. Suspected glyphosate-resistant L. rigidum populations were collected and grown under greenhouse conditions. The plants were sprayed with a range of doses of glyphosate 35 days after planting and shoot dry biomass was determined 17 days after herbicide treatment. Based on the dose-response experiment conducted in the greenhouse, one population of L. rigidum suspected to be resistant to glyphosate was approximately 5.3 fold more resistant than susceptible population. The other population was 2.8 fold more resistant than susceptible population. Difference between the two suspected resistant populations was 1.9 fold. All plants were treated with glyphosate (1000 g a.i. ha-1) and shikimic acid was extracted 2, 4 and 6 days after treatment. The plants of susceptible populations accumulated more shikimic acid than other two populations.

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Rigid Ryegrass (Lolium rigidum) Populations Containing a Target Site Mutation in EPSPS and Reduced Glyphosate Translocation Are More Resistant to Glyphosate

Weed Science ◽

10.1614/ws-d-11-00154.1 ◽

2012 ◽

Vol 60 (3) ◽

pp. 474-479 ◽

Cited By ~ 31

Author(s):

Yazid Bostamam ◽

Jenna M. Malone ◽

Fleur C. Dolman ◽

Peter Boutsalis ◽

Christopher Preston

Keyword(s):

Weed Control ◽

Glyphosate Resistance ◽

Resistance Mechanisms ◽

Target Site ◽

Lolium Rigidum ◽

Site Mutation ◽

Susceptible Population ◽

Intensive Use ◽

Rigid Ryegrass ◽

Two Populations

Glyphosate is widely used for weed control in the grape growing industry in southern Australia. The intensive use of glyphosate in this industry has resulted in the evolution of glyphosate resistance in rigid ryegrass. Two populations of rigid ryegrass from vineyards, SLR80 and SLR88, had 6- to 11-fold resistance to glyphosate in dose-response studies. These resistance levels were higher than two previously well-characterized glyphosate-resistant populations of rigid ryegrass (SLR77 and NLR70), containing a modified target site or reduced translocation, respectively. Populations SLR80 and SLR88 accumulated less glyphosate, 12 and 17% of absorbed glyphosate, in the shoot in the resistant populations compared with 26% in the susceptible population. In addition, a mutation within the target enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) where Pro106had been substituted by either serine or threonine was identified. These two populations are more highly resistant to glyphosate as a consequence of expressing two different resistance mechanisms concurrently.

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Evolved resistance to glyphosate in rigid ryegrass (Lolium rigidum) in Australia

Weed Science ◽

10.1017/s0043174500091165 ◽

1998 ◽

Vol 46 (5) ◽

pp. 604-607 ◽

Cited By ~ 274

Author(s):

Stephen B. Powles ◽

Debrah F. Lorraine-Colwill ◽

James J. Dellow ◽

Christopher Preston

Keyword(s):

Dose Response ◽

Glyphosate Resistance ◽

Cross Resistance ◽

Lolium Rigidum ◽

Weed Species ◽

Susceptible Population ◽

Use Patterns ◽

Rigid Ryegrass ◽

Susceptible Populations ◽

Grass Weed

Following 15 yr of successful use, glyphosate failed to control a population of the widespread grass weed rigid ryegrass in Australia. This population proved to be resistant to glyphosate in pot dose-response experiments conducted outdoors, exhibiting 7- to 11-fold resistance when compared to a susceptible population. Some cross-resistance to diclofop-methyl (about 2.5-fold) was also observed. Similar levels of control of the resistant and susceptible populations were obtained following application of amitrole, chlorsulfuron, fluazifop-P-butyl, paraquat, sethoxydim, sirnazine, or tralkoxydim. The presence of glyphosate resistance in a major weed species indicates a need for changes in glyphosate use patterns.

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