Resistance of barnyardgrass (Echinochloa crus-galli) to atrazine and quinclorac (original) (raw)
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Weed Science, 2016
Determining the mechanisms of herbicide resistance in weeds allows for the development and implementation of applied management practices aimed to control and to prevent further spread of herbicide-resistant populations in crop fields. This research was conducted to determine propanil resistance and cross-resistance to other photosystem II (PSII) inhibitors in ricefield bulrush biotypes and to elucidate the mechanism of propanil resistance. To this end, propanil-resistant (R) and propanil-susceptible (S) biotypes were selected from field-collected populations after propanil spraying at the field rate, and whole-plant, dose–response experiments were conducted to evaluate cross-resistance to PSII inhibitors and interactions between propanil and the insecticides malathion and carbaryl. In addition, the psbA gene from R and S biotypes was sequenced for amino acid alterations following polymerase chain reaction (PCR) amplification. Plant survival data indicated the R biotype displayed a ...
The Journal of Agricultural Science, 2014
The lack of control of barnyardgrass in flooded rice cultivated with imidazolinone-resistant rice cultivars is challenging the utilization of this system, which is continuously expanding for new rice areas worldwide. The objectives of the present study were to evaluate the frequency, distribution and mechanisms of imidazolinone resistance in barnyardgrass to establish the best practices to control and prevent this problem. The distribution of resistance was evaluated in 624 populations collected in Southern Brazil. The frequency of imidazolinoneherbicide resistance was 0·81, broadly distributed in all sampled regions. Resistance to quinclorac was also found in 0·19 of the populations, but all of the evaluated populations were susceptible to cyhalofop-butyl. Further studies were conducted in six populations. The enhanced metabolism was assessed with the metabolic inhibitors that reversed the resistance to quinclorac from 0·54 to 1·00 in two populations and the resistance to imazethapyr from 0·15 to 0·41 in three populations. The acetolactase synthase (ALS) enzyme activity also indicated the occurrence of altered target site resistance in two populations caused by the ALS gene mutations Trp574Leu and Ser653Asn, which is a novel finding in this species. The herbicide resistance in barnyardgrass in Southern Brazil presented a complex basis of resistance because it is associated with resistance to multiple herbicides due to multiple mechanisms and with multiple mutations of the ALS gene. This indicates that it is necessary to adopt specific measures to prevent and control the evolution of multiple herbicide resistance in this species.
Journal of Agricultural and Food Chemistry, 2007
Fenoxaprop-p-ethyl (FE), 2-{4-[(6-chloro-2-benzoxazolyl)oxy]phenoxy} propanoate, ethyl ester (R), is an aryloxyphenoxypropionate herbicide for postemergence control of annual and perennial grasses in paddy fields; its site of action is acetyl-coenzyme A carboxylase (ACCase), an enzyme in fatty acids biosynthesis. The possible mechanism(s) of resistance to FE in a resistant biotype of Echinochloa phyllopogon was examined, namely, absorption, translocation, and metabolism of FE and ACCase susceptibility to fenoxaprop acid (FA). Studies of the in vitro inhibition of ACCase discounted any differential active site sensitivity as the basis of resistance to FE. There were differences in absorption rates between biotypes from 3 to 48 h after application (HAA). Biotypes did not differ in either the amounts or the rates of FE translocated; 98% of applied [ 14 C]FE remaining in the treated leaf. However, there was a good correlation between the rate of herbicide metabolism and the plant resistance. The R biotype produced 5-fold less FA and approximately 2-fold more nontoxic (polar) metabolites 48 HAA than the S biotype. Moreover, the higher rate of GSH conjugation in the resistant biotype as compared to the susceptible one indicates that GSH and cysteine conjugation is the major mechanism of resistance of the R biotype against FE toxicity.
Action of propanil on in vivo chlorophyll a fluorescence in Echinochloa crus-galli and rice
Weed Research, 1981
When sprayed as a post-emergent, foliar herbicide propanil destroyed Echinochloa crus-galli (L.) with little or no visible injury to rice., confirming its selective contact action. In treated rice leaves there was, however, a temporary decrease in dry weight, pigments, proteins and photosynthetic products followed by complete recovery in 4-5 days. In both rice and E. crusgalli, at lower concentrations propanil inhibited the electron flow in a manner similar to that of DCMU, but at higher concentrations it damaged the primary electron donor.
Resistance mechanism of Leptochloa chinensis Nees to propanil
Weed Biology and Management, 2011
The resistance mechanism of Leptochloa chinensis Nees to propanil was investigated, based on propanil metabolism, aryl acylamidase activity, and chlorophyll fluorescence at the 8 week growth stage of L. chinensis.The concentration of propanil in the leaf and culm extracts of the resistant (R) and susceptible (S) biotypes, as measured by gas chromatography (GC), was found to increase after propanil treatment.The concentration of propanil in the leaf and culm extracts of the S biotype at 72 h was 1.55 and 0.49 mg mL -1 , respectively. However, a lower concentration of propanil was observed in the R biotype, as compared to that in the S biotype.The residue of 3,4-dichloroaniline, as measured by GC, was detected only in the leaf extracts of the R biotype. In contrast, no residue of 3,4-dichloroaniline was observed in the S biotype.The level of aryl acylamidase in the leaf tissue extracts of the R biotype was~140% higher than that in the S biotype. The fluorescence studies showed that propanil inhibited the quantum efficiency of the photosystem II in both the R and S biotypes after 2 h of incubation time. However, when the leaf disks were transferred and incubated in deionized water for 48 h, the quantum efficiency increased in the R biotype but decreased in the S biotype. These results suggest that propanil metabolism, enhanced by aryl acylamidase activity, is the most likely factor contributing towards the mechanism of propanil resistance in L. chinensis plants at the 8 week growth stage.
Toxicity of the herbicide Stam f-34 (propanil) onNostoc calcicola
Zeitschrift für allgemeine Mikrobiologie, 1984
The biological effect of the post-emergence rice field herbicide Stam f-34 on the nitrogen-fixing cyanobacterium (blue-green alga) Nostoc eokicola has been studied under cultural conditions. The herbicide caused an ir hibition of the nitrogen-fixing growth of the alga which was concentrationdependent and lethal a t 30 iJ.g/ml. Both glucose and acetate quite efficiently reversed the inhibitory action of Stam f-34 even when i t was present at it lethal dose. Also, an addition of the amino acids arginine, aspartic acid, serine, threonine and glutamine readily reversed the toxic effects of Stam f-34 even a t lethal concentrations of the herbicide (except glutamine). Low pH values enhanced the toxicity while high pH levels lowered the found to herbicide to the alga. The herbicide was not be toxicity of the mutagenic since it did not induce in the alga mutations to streptomycin and methylamine resistance.