Glyphosate influence on the physiological parameters of Conyza bonariensis biotypes

Várgas, Leandro; Silva, D.R.O.; Agostinetto, Dirceu; Matallo, Marcus Barifouse; Santos, Fernando Machado dos; Almeida, S.D.B.; Chavarria, Geraldo; Silva, D.F.P.

doi:10.1590/s0100-83582014000100017

Cited by 10 publications

(8 citation statements)

References 25 publications

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“…Both R and S C. bonariensis biotypes accumulated shikimic acid (i.e., glyphosate was equally loaded in the phloem and reached the EPSPS in both biotypes) [29]. Similar results have been found in different studies where both R and S biotypes/populations of Conyza species accumulated shikimic acid [4,30,31]; however, the accumulation rates of shikimic acid in R plants was always lower than the accumulation observed in S plants. The low accumulation of shikimic acid between our R C. bonariensis biotypes suggests different resistance mechanism(s), which reduced the amount of glyphosate that reached or interacted with the EPSPS [27].…”

Section: Discussionsupporting

confidence: 84%

Stressful Conditions Affect Seed Quality in Glyphosate Resistant Conyza bonariensis (L.)

et al. 2020

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Conyza bonariensis (L.) Cronquist is one of the main glyphosate-resistant weeds in no-till fields in Brazil. Here, the seed quality of glyphosate-resistant (R) and -susceptible (S) C. bonariensis biotypes, collected from different sites, was evaluated under stressful conditions by different seed tests. Glyphosate resistance was confirmed by dose-response and shikimate accumulation assays. The resistance factors were 6.9 (R1/S1), 4.5 (R2/S2), and 5.8 (R3/S3). Biotypes S1, S2, and S3 accumulated 2.7, 2.4, and 2.8 times more shikimic acid than biotypes R1, R2, and R3, respectively. Stress-free seed viability and germination potential ranged from 39% to 57% and from 37% to 57%, respectively, with no difference between R and S biotypes within each collection site. Seed incubation at 8 °C over 7 days (cold test) promoted greater germination in S biotypes (54% to 79%) compared to R ones (28% to 39%). In the accelerated aging tests (incubation at 42 °C over 48 hours), the germination decreased in both S (11% to 27%) and R (6% to 16%) biotypes. In the high-temperature stress tests, there were no differences in germination within biotypes at 35 and 45 °C; however, at 60 °C, the germination of the S1, R1, S2, R2, S3, and R3 biotypes was reduced by approximately 51%, 54%, 63%, 59%, 40%, and 30%, respectively. Under non-stressful conditions, germination potential and seed viability were similar in R and S biotypes; however, under cold or heat stress conditions, R biotypes reduced their germination rates, revealing that glyphosate resistance causes a fitness penalty in C. bonariensis at the seed level. However, because seed viability was not determined after experiments, it cannot be stated that such reduction in germination was due to the death or only a dormant phase of the seeds.

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Section: Discussionsupporting

confidence: 84%

Stressful Conditions Affect Seed Quality in Glyphosate Resistant Conyza bonariensis (L.)

et al. 2020

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“…On the other hand, the resistant population, although showing negative values at 3 DAA, at 7 DAA recovered. Vargas et al (2014) have not found differences in water-use efficiency (WUE) at 3 DAA of glyphosate between the biotypes of horseweed susceptible and resistant to it. However, at 7 DAA there was a large difference.…”

Section: Cs Cr Cs Cr Cs Crmentioning

confidence: 82%

“…Several studies have been carried out to understand the plants physiology after the application of herbicides (Zobiole et al, 2010a;Orcaray et al, 2012;Yanniccari et al, 2012a, b;Vargas et al, 2014). Physiological knowledge about weeds -in this case, ryegrass is important for an efficient management, as it may help in understanding glyphosate resistance mechanisms, as well as the intensity of effects on susceptible and resistant biotypes.…”

Section: Introductionmentioning

confidence: 99%

Influence of Glyphosate on Susceptible and Resistant Ryegrass Populations to Herbicide

et al. 2017

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-In Brazil, ryegrass (Lolium multiflorum) has been identified as resistant to glyphosate, becoming a major problem, especially in crops cultivated in the winter season. This herbicide can indirectly affect photosynthesis by inhibiting biosynthesis of many compounds. Thus, the aim of this study was to investigate the influence of glyphosate on the physiological profile of susceptible and resistant ryegrass populations to the herbicide. The experimental design was completely randomized with two treatments (720 and 1,080 g e.a. ha ) and four replications plus control with no treatment. Two ryegrass populations were sown, one susceptible and another one resistant to glyphosate. After the treatments, evaluations were carried out at 1, 3, 7 and 28 days after application (DAA). Variables analyzed were: CO 2 net assimilation rate, stomatal conductance, CO 2 internal concentration, transpiration, water use efficiency and instantaneous carboxylation efficiency. The glyphosate herbicide caused irreversible damage in a susceptible population which at 28 DAA in all variables analyzed this population was already dead and it was impossible to analyze it, but it was shown that the effects of this herbicide were intensified from the third day after application. In the case of the resistant population, at 3 DAA in all variables, it suffered significant effects comparing to the control, showing that even with a high level of resistance the herbicide can affect its metabolism. Keywords

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“…Among these, the most notorious are Conyza canadensis (L.) Cronq., Conyza bonariensis (L.) Cronq., and Conyza sumatrensis (Retz.) E. Walker [1], which are known as major invaders in different crops across continents [2] [3].…”

Section: Introductionmentioning

confidence: 99%

<i>Conyza sumatrensis</i> Intrapopulation Variation in Response to Glufosinate

Brito¹,

Carbonari²,

Marchesi³

et al. 2019

AJPS

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We aimed to study the response of Conyza sumatrensis to different doses of glufosinate, intrapopulation variation in sensitivity to the herbicide, and the heritability of phenotypic response, and model the evolution of resistance. Three studies were conducted in the greenhouse with two repetitions. First, we tested doses of glufosinate (0, 50, 100, 200, 400, 800 g a.i. ha −1) plus a nontreated check, with four replications. Second, we examined the range in sensitivity of 44 plants to 200 g a.i. ha −1 glufosinate. Third, we evaluated the sensitivity of the progeny of six glufosinate-treated plants to 200 g a.i. ha −1 glufosinate. Plant response was evaluated visually and the ammonium content in leaf tissues was measured. Glufosinate at 400 g a.i. ha −1 caused the highest injury to C.sumatrensis plants. Ammonia accumulation occurred in response to glufosinate treatment, regardless of dose. Ammonia accumulation was correlated strongly with the level of visible plant injury; thus, it is a good indicator of herbicide efficacy. Sensitivity to glufosinate was highly variable within the population. Plants with high ammonia concentration (high injury) after treatment with glufosinate produced progenies that also had high ammonia concentrations after herbicide treatment. The variation in ammonia accumulation among siblings was high. Simulating the exclusion of plants that accumulated more ammonia produced a population that is expected to be less sensitive to glufosinate in the next generation. The stronger the selection pressures by a simulated treatment with glufosinate, the greater the reduction in ammonia accumulation in the progeny and expected sensitivity to glufosinate.

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Glyphosate influence on the physiological parameters of Conyza bonariensis biotypes

Cited by 10 publications

References 25 publications

Stressful Conditions Affect Seed Quality in Glyphosate Resistant Conyza bonariensis (L.)

Stressful Conditions Affect Seed Quality in Glyphosate Resistant Conyza bonariensis (L.)

Influence of Glyphosate on Susceptible and Resistant Ryegrass Populations to Herbicide

<i>Conyza sumatrensis</i> Intrapopulation Variation in Response to Glufosinate

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Glyphosate influence on the physiological parameters of Conyza bonariensis biotypes

Cited by 10 publications

References 25 publications

Stressful Conditions Affect Seed Quality in Glyphosate Resistant Conyza bonariensis (L.)

Stressful Conditions Affect Seed Quality in Glyphosate Resistant Conyza bonariensis (L.)

Influence of Glyphosate on Susceptible and Resistant Ryegrass Populations to Herbicide

&lt;i&gt;Conyza sumatrensis&lt;/i&gt; Intrapopulation Variation in Response to Glufosinate

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<i>Conyza sumatrensis</i> Intrapopulation Variation in Response to Glufosinate