A nonsynonymous mutation in an acetolactate synthase gene (Gh_D10G1253) is required for tolerance to imidazolinone herbicides in cotton

Background Herbicide tolerance in crops enables them to survive when lethal doses of herbicides are applied to surrounding weeds.Herbicide-tolerant crops can be developed through transgenic approaches or traditional mutagenesis approaches.At present,no transgenic herbicide tolerant cotton have been commercialized in China due to the genetically-modified organism(GMO)regulation law.We aim to develop a non-transgenic herbicide-tolerant cotton through ethyl methanesulfonate(EMS)mutagenesis,offering an alternative choice for weed management.Results Seeds of an elite cotton cultivar Lumianyan 37(Lu37)were treated with EMS,and a mutant Lu37-1 showed strong tolerance to imidazolinone(IMI)herbicides was identified.A novel nonsynonymous substitution mutation Ser642Asn at acetolactate synthase(ALS)(Gh_D10G1253)in Lu37-1 mutant line was found to be the potential cause to the IMI herbicides tolerance in cotton.The Ser642Asn mutation in ALS did not present among the genomes of natural Gossypium species.Cleaved amplified polymorphic sequence(CAPS)markers were developed to identify the ALS mutant allele.The Arabidopsis overexpressing the mutanted ALS also showed high tolerance to IMI herbicides.Conclusion The nonsynonymous substitution mutation Ser642Asn of the ALS gene Gh_D10G1253 is a novel identi-fied mutation in cotton.This substitution mutation has also been identified in the orthologous ALS genes in other crops.This mutant ALS allele can be used to develop IMI herbicide-tolerant crops via a non-transgenic or transgenic approach.

Generation of a series of mutant lines resistant to imidazolinone by screening an EMS-based mutant library in common wheat

The breeding of herbicide-resistant wheat varieties has helped control weeds in wheat fields economically and effectively.Imidazolinone (IMI) herbicides are popular as they have low toxicity in mammals,are effective at small doses,and exhibit broad-spectrum herbicidal action in the field.Therefore,the isolation and genetic and molecular characterization of IMI-resistant wheat mutants will enhance weed management in wheat fields.In the present study,352 IMI-resistant plants were isolated by genetic screening from a mutant pool prepared by EMS-based random mutagenesis.Cloning of the mutated genes from the IMI-resistant plants indicated that ten taals alleles had been isolated,and mutation in one of three Ta ALS homolog genes conferred IMI resistance,and such a mutation is a dominant trait.Further analysis showed that taals-d exhibited the greatest IMI resistance,whereas taals-b exhibited the weakest resistance to IMI among three homologous taals mutants.In terms of IMI resistance,the taals triple mutant was stronger than the taals double mutants,and the taals double mutants were stronger than the single mutants,indicating a dose-dependent effect of the Ta ALS mutation on IMI resistance in wheat.Biochemical analysis indicated that the mutation in Ta ALS increased the tolerance of Ta ALS to inhibition by IMI.Our work details the genetic and molecular characterization of als wheat mutants,provides a foundation for understanding IMI resistance and breeding wheat varieties with herbicide resistance,and indicates that genetic screening using a mutagenized pool is an effective and important means of breeding crops with additional desired agricultural traits.

Carryover Effect of Imidazolinone Herbicides for Crops Following Rice

We aimed with this study to evaluate the effects of residual activity in soil of formulated mixtures of the herbicides imazethapyr + imazapic and imazapyr + imazapic on ryegrass and on rice cultivars, IRGA 424 and BRS Querencia. Two experiments were conducted under greenhouse in randomized blocks design with four replications in split-plot and split-split-plot designs, respectively for the first (E1) and second (E2) experiments. For E1, main plots allocated herbicides (imazethapyr + imazapic and imazapyr + imazapic), and subplots the doses [(0, 0.5, 1.0, 1.5 and 2.0 fold the label dose of imazethapyr + imazapic (1 L·ha-1) and imazapyr + imazapic (140 g·ha-1) plus 0.5% of the adjuvant Dash→)];for E2, sub-subplots allocated rice cultivars (BRS 424 and IRGA Querência). Phytotoxicity, plant height and shoot dry weight (E1 and E2) and plant stand (E2) were evaluated. Results showed that the annual ryegrass and rice cultivars IRGA 424 and BRS Querencia are sensitive to imazethapyr + imazapic and imazapyr + imazapic, serving as bioindicators of its residual activity in soils following Clearfield→rice. Imazapyr + imazapic, applied post-emergence in irrigated rice at doses of 1.0, 1.5 and 2.0× the label dose, present longer residual activity in soil compared to imazethapyr + imazapic for ryegrass and non-Clearfield→rice.

Effects of Imazethapyr-Based Herbicide Formulation in the Zebrafish (Danio rerio) Hepatocyte Cell Line (ZF-L): Cytotoxicity and Oxidative Stress

Seizures of agrochemical formulations have increased in Brazil and Rio Grande do Sul is among the Brazilian states with the highest number of seizures of these products obtained illicitly. The use of illicit formulations can cause significant harm to agricultural production, the environment, and non-target species. This study evaluated the cytotoxicity and oxidative stress of a seized formulation containing the herbicide imazethapyr (IMZT). Characterization of the herbicide included gas chromatography-mass spectrometry (GC-MS) and thermal analyses (thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC)). Hemolytic and cytotoxicity assays in ZF-L hepatic cells showed IC50 values of 12.75 µg/mL, 3.01 µg/mL, 2.67 µg/mL, and 1.61 µg/mL for erythrocytes, [3(4,5-dimethyl)-2 bromide-5 diphenyl tetrazolium] (MTT), neutral red (NR), and lactate dehydrogenase (LDH) assays, respectively. The median IC50 of 2.84 µg/mL was used in oxidative stress assays, revealing increased reactive oxygen species (ROS) production, reduced total sulfhydryl content, and decreased superoxide dismutase (SOD) and catalase (CAT) activity. This study is the first to report in vitro oxidative stress induced by IMZT in the ZF-L cell line, emphasizing the importance of in vitro assays for assessing the toxic effects of seized agrochemicals on human health and the environment.

Inheritance and molecular characterization of resistance to AHAS- inhibiting herbicides in rapeseed

Rapeseed is a very important oil crop in China; however, its production is challenging due to the absence of effective weed management strategies. This is predominantly because of a shortage of herbicide resistance genes. Acetohydroxyacid synthase （AHAS） herbicides inhibit AHAS, a key enzyme involved in branched-chain amino acid synthesis that is required for plant growth. A rapeseed line designated M342 with AHAS herbicide resistance was developed through seed muta- genesis and was studied to assess the level and mode of inheritance of the resistance and to identify the molecular basis of resistance. M342 possessed a high level of cross-resistance to sulfonylureas （SUs） and imidazolinones （IMIs）. This resistance was due to AHAS insensitivity to these herbicides and was inherited as a dominant trait conferred by a single nuclear-encoded gene. Molecular analysis revealed the presence of a Trp574Leu mutation in M342, and an allele-specific cleaved amplified polymorphic sequence （AS-CAPS） marker was developed and cosegregated with herbicide resistance in the F2, BC1, and BC2 populations. This mutation altered the transcript levels of BnAHAS1 and BnAHAS3 in M342 compared with those in the wild type, but it did not affect the agronomic or quality traits. The simple genetic inheritance of this mutation and the availability of the cleaved amplified polymorphic sequence （CAPS） marker and herbicide resistance gene should facilitate the development of herbicide-resistant rapeseed cultivars for effective weed control in China.

Efficient Synthesis of 2-(8-Quinolinoxy)-4H-imidazolin-4-ones

The title compounds 2-(8-quinolinoxy)-4 H -imidazolin-4-ones(4) were synthesized by means of base catalytic reactions of 8-hydroxyquinoline with each of carbodiimides 2, which were obtained via aza-Wittig reactions of iminophosphoranes 1 with the corresponding aromatic isocyanates.

An efficient synthesis of 3'-quinolinyl substituted imidazole-5-one derivatives catalyzed by zeolite and their antimicrobial activity

A series of some new quinoline based imidazole-5-one derivatives have been synthesized by the fusion of oxazol-5-ones,various p-substituted anilines and zeolite in pyridine.All the derivatives were subjected to an in vitro antimicrobial screening against a representative panel of bacteria and fungi and results worth further investigations.

Effects of imazethapyr spraying on plant growth and leaf surface microbial communities in Arabidopsis thaliana

Imazethapyr (IM) is an acetolactate synthase (ALS)-inhibiting herbicide that has been widely used in recent years.However,IM spraying can lead to the accumulation of herbicide residues in leaves.Here,we determined the effects of IM spraying on the plant growth and leaf surface microbial communities of Arabidopsis thaliana after 7 and 14 days of exposure.The results suggested that IM spraying inhibited plant growth.Fresh weight decreased to 48% and 26% of the control value after 7 and 14 days,respectively,of 0.035 kg/ha IM exposure.In addition,anthocyanin content increased 9.2-fold and 37.2-fold relative to the control content after 7 and 14 days of treatment,respectively.Furthermore,IM spraying destroyed the cell structures of the leaves,as evidenced by increases in the number of starch granules and the stomatal closure rate.Reductions in photosynthetic efficiency and antioxidant enzyme activity were observed after IM spraying,especially after 14 days of exposure.The diversity and evenness of the leaf microbiota were not affected by IM treatment,but the composition of community structure at the genus level was altered by IM spraying.Imazethapyr application increased the abundance of Pseudomonas,a genus that includes species pathogenic to plants and humans,indicating that IM potentially increased the abundance of pathogenic bacteria on leaves.Our findings increase our understanding of the relationships between herbicide application and the microbial community structures on plant leaves,and they provide a new perspective for studying the ecological safety of herbicide usage.