Inheritance of glyphosate resistance in several populations of rigid ryegrass (Lolium rigidum) from Australia

Weed Science ◽  
2006 ◽  
Vol 54 (02) ◽  
pp. 212-219 ◽  
Author(s):  
Angela M. Wakelin ◽  
Christopher Preston
Keyword(s):  
Single Gene ◽  
Management Strategies ◽  
Nuclear Genome ◽  
South Australia ◽  
Glyphosate Resistance ◽  
Resistant Parent ◽  
Susceptible Population ◽  
South Wales ◽  
Filial Generation ◽  
Rigid Ryegrass

In Australia, glyphosate resistance has been observed in rigid ryegrass in several states including New South Wales (NSW) and South Australia (SA). Several populations of glyphosate-resistant rigid ryegrass were analyzed for the inheritance of glyphosate resistance. Eight glyphosate-resistant populations were crossed to the same susceptible population to create first filial generation (F1) families. Individuals from the F1families were subsequently treated with glyphosate. The response to glyphosate of F1families from all eight crosses was more similar to the resistant parent than the susceptible parent. Within crosses, dose responses of reciprocal F1families were not significantly different from each other, indicating glyphosate resistance is encoded on the nuclear genome in all eight populations. The level of dominance observed in dose–response experiments ranged from partial to total within the herbicide doses tested. F1individuals from five of the populations were crossed with susceptible (S) individuals to create backcross (BC) populations. Most of the families from these BC populations segregated in a manner consistent with a single gene controlling glyphosate resistance. These results indicate that resistance is inherited as a single dominant allele in four out of the five glyphosate-resistant rigid ryegrass populations. Such information is vital in the development of management strategies for glyphosate resistance in Australia.

Inheritance of Glyphosate Resistance in Hairy Fleabane (Conyza bonariensis) from California

Weed Science ◽  
2014 ◽  
Vol 62 (2) ◽  
pp. 258-266 ◽  
Author(s):  
Miki Okada ◽  
Marie Jasieniuk
Keyword(s):  
Resistance Mechanism ◽  
Glyphosate Resistance ◽  
Population Based ◽  
Single Individual ◽  
Resistance Level ◽  
Backcross Population ◽  
Resistant Parent ◽  
Susceptible Population ◽  
Locus Model ◽  
Hairy Fleabane

Inheritance of glyphosate resistance was investigated in hairy fleabane populations from California as part of providing the information needed to predict and manage resistance and to gain insight into resistance mechanism (or mechanisms) present in the populations. Three glyphosate-resistant individuals grown from seed collected from distinct sites near Fresno, CA, were crossed to individuals from the same susceptible population to create reciprocal F1populations. A single individual from each of the F1populations was used to create a backcross population with a susceptible maternal parent, and an F2population. Based on dose response analyses, reciprocal F1populations were not statistically different from each other, more similar to the resistant parent, and statistically different from the susceptible parent, consistent with nuclear control of the trait and dominance to incomplete dominance of resistance over susceptibility in all three crosses. Glyphosate resistance in two of the three crosses segregated in the backcross and the F2populations as a single-locus trait. In the remaining cross, the resistant parent had approximately half the resistance level as the other two resistant parents, and the segregation of glyphosate resistance in backcross and F2populations conformed to a two-locus model with resistance alleles acting additively and at least two copies of the allele required for expression of resistance. This two-locus model of the segregation of glyphosate resistance has not been reported previously. Variation in the pattern of inheritance and the level of resistance indicate that multiple resistance mechanisms may be present in hairy fleabane populations in California.

Diet of the Large-footed Myotis Myotis Mcropus at A Forest Stream Roost in Northern New South Wales

2000 ◽  
Vol 22 (2) ◽  
pp. 121 ◽  
Author(s):  
B Law ◽  
CA Urquhart
Keyword(s):  
New South ◽  
Management Strategies ◽  
South Australia ◽  
South Wales ◽  
Forest Stream ◽  
Small Streams ◽  
Murray River ◽  
Myotis Myotis ◽  
Rivers And Lakes ◽  
Fish Remains

RECENT evidence indicates that the large-footed myotis Myotis macropus (previously Myotis adversus) is the sole representative of its genus in Australia (Cooper et al. in press). These are small bats that forage over pools of water in small streams, rivers and lakes, using large feet to trawl for prey along water surfaces (Dwyer 1970; Thompson and Fenton 1982). Little is known about their diet. Fish have been confirmed in the diet of M. macropus at a population that forages over a large lake, near Brisbane (Robson 1984). Unidentified insect material formed the bulk of the species? diet in Robson?s study. A small number of scats were also examined from M. macropus caught on the Murray River in South Australia (Jansen 1987). These contained fish remains and insects, particularly Chironominae (midges) and Culicidae (mosquitoes). We studied the diet of M. macropus at a forest stream to determine the importance of aquatic prey and thus to help guide management strategies for the species.

scholarly journals Inheritance of Evolved Glyphosate Resistance in a North Carolina Palmer Amaranth (Amaranthus palmeri) Biotype

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Aman Chandi ◽  
Susana R. Milla-Lewis ◽  
Darci Giacomini ◽  
Philip Westra ◽  
Christopher Preston ◽  
...  
Keyword(s):  
North Carolina ◽  
Dose Response ◽  
Genome Analysis ◽  
Copy Number ◽  
Single Gene ◽  
Nuclear Genome ◽  
Glyphosate Resistance ◽  
Palmer Amaranth ◽  
Amaranthus Palmeri ◽  
Dose Responses

Inheritance of glyphosate resistance in a Palmer amaranth biotype from North Carolina was studied. Glyphosate rates for 50% survival of glyphosate-resistant (GR) and glyphosate-susceptible (GS) biotypes were 1288 and 58 g ha−1, respectively. These values for F1 progenies obtained from reciprocal crosses (GR×GSandGS×GRwere 794 and 501 g ha−1, respectively. Dose response of F1 progenies indicated that resistance was not fully dominant over susceptibility. Lack of significant differences between dose responses for reciprocal F1 families suggested that genetic control of glyphosate resistance was governed by nuclear genome. Analysis of F1 backcross (BC1F1) families showed that 10 and 8 BC1F1 families out of 15 fitted monogenic inheritance at 2000 and 3000 g ha−1glyphosate, respectively. These results indicate that inheritance of glyphosate resistance in this biotype is incompletely dominant, nuclear inherited, and might not be consistent with a single gene mechanism of inheritance. Relative 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) copy number varied from 22 to 63 across 10 individuals from resistant biotype. This suggested that variableEPSPScopy number in the parents might be influential in determining if inheritance of glyphosate resistance is monogenic or polygenic in this biotype.

A Decade of Glyphosate-ResistantLoliumaround the World: Mechanisms, Genes, Fitness, and Agronomic Management

Weed Science ◽  
2009 ◽  
Vol 57 (4) ◽  
pp. 435-441 ◽  
Author(s):  
Christopher Preston ◽  
Angela M. Wakelin ◽  
Fleur C. Dolman ◽  
Yazid Bostamam ◽  
Peter Boutsalis
Keyword(s):  
Weed Management ◽  
Single Gene ◽  
Glyphosate Resistance ◽  
Resistance Mechanisms ◽  
Target Site ◽  
Italian Ryegrass ◽  
Shoot Meristem ◽  
Agronomic Management ◽  
Translocation Mechanism ◽  
Rigid Ryegrass

Glyphosate resistance was first discovered in populations of rigid ryegrass in Australia in 1996. Since then, glyphosate resistance has been detected in additional populations of rigid ryegrass and Italian ryegrass in several other countries. Glyphosate-resistant rigid ryegrass and Italian ryegrass have been selected in situations where there is an overreliance on glyphosate to the exclusion of other weed control tactics. Two major mechanisms of glyphosate resistance have been discovered in these two species: a change in the pattern of glyphosate translocation such that glyphosate accumulates in the leaf tips of resistant plants instead of in the shoot meristem; and amino acid substitutions at Pro 106 within the target site, 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS). There are also populations with both mechanisms. In the case of glyphosate resistance, the target site mutations tend to provide a lower level of resistance than does the altered translocation mechanism. Each of these resistance mechanisms is inherited as a single gene trait that is largely dominant. As these ryegrass species are obligate outcrossers, this ensures resistance alleles can move in both pollen and seed. Some glyphosate-resistant rigid ryegrass populations appear to have a significant fitness penalty associated with the resistance allele. Field surveys show that strategies vary in their ability to reduce the frequency of glyphosate resistance in populations and weed population size, with integrated strategies—including alternative weed management and controlling seed set of surviving plants—the most effective.

Reduced Glyphosate Translocation in Two Glyphosate-Resistant Populations of Rigid Ryegrass (Lolium rigidum) from Fence Lines in South Australia

Weed Science ◽  
2014 ◽  
Vol 62 (1) ◽  
pp. 4-10 ◽  
Author(s):  
Patricia Adu-Yeboah ◽  
Jenna M. Malone ◽  
Gurjeet Gill ◽  
Christopher Preston
Keyword(s):  
Dose Response ◽  
South Australia ◽  
Lolium Rigidum ◽  
Gene Encoding ◽  
Susceptible Population ◽  
Mechanism Of Resistance ◽  
Treated Leaf ◽  
Rigid Ryegrass ◽  
Susceptible Populations ◽  
Fence Line

Populations of rigid ryegrass with resistance to glyphosate have started to become a problem on fence lines of cropping fields of southern Australian farms. Seed of rigid ryegrass plants that survived glyphosate application were collected from two fence line locations in Clare, South Australia. Dose–response experiments confirmed resistance of these fence line populations to glyphosate. Both populations required 9- to 15-fold higher glyphosate dose to achieve 50% mortality in comparison to a standard susceptible population. The mechanism of resistance in these populations was investigated. Sequencing a conserved region of the gene encoding 5-enolpyruvyl-shikimate-3-phosphate synthase identified no differences between the resistant and susceptible populations. Absorption of glyphosate into leaves of the resistant populations was not different from the susceptible population. However, the resistant plants retained significantly more herbicide in the treated leaf blades than did the susceptible plants. Conversely, susceptible plants translocated significantly more herbicide to the leaf sheaths and untreated leaves than the resistant plants. The differences in translocation pattern for glyphosate between the resistant and susceptible populations of rigid ryegrass suggest resistance is associated with altered translocation of glyphosate in the fence line populations.

scholarly journals Identification of glyphosate resistance in Lolium rigidum Gaudin

2011 ◽  
Vol 26 (4) ◽  
pp. 393-399 ◽  
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.

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

Weed Science ◽  
2012 ◽  
Vol 60 (3) ◽  
pp. 474-479 ◽  
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.

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

Weed Science ◽  
1998 ◽  
Vol 46 (5) ◽  
pp. 604-607 ◽  
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.

In A Fix: Fixed-Term Parliaments in the Australian States

2013 ◽  
Vol 41 (2) ◽  
pp. 265-298
Author(s):  
Peter Congdon
Keyword(s):  
Western Australia ◽  
Prime Minister ◽  
New South ◽  
New South Wales ◽  
South Australia ◽  
Constitutional Amendments ◽  
South Wales

Constitutional systems of Westminster heritage are increasingly moving towards fixed-term parliaments to, amongst other things, prevent the Premier or Prime Minister opportunistically calling a ‘snap election’. Amongst the Australian states, qualified fixed-term parliaments currently exist in New South Wales, South Australia and Victoria. Queensland, Tasmania and Western Australia have also deliberated over whether to establish similar fixed-term parliaments. However, manner and form provisions in those states' constitutions entrench the Parliament's duration, Governor's Office and dissolution power. In Western Australia and Queensland, unlike Tasmania, such provisions are doubly entrenched. This article considers whether these entrenching provisions present legal obstacles to constitutional amendments establishing fixed-term parliaments in those two states. This involves examining whether laws fixing parliamentary terms fall within section 6 of the Australia Acts 1986 (Cth) & (UK). The article concludes by examining recent amendments to the Electoral Act 1907 (WA) designed to enable fixed election dates in Western Australia without requiring a successful referendum.

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