Effective weed control through post-emergence herbicides to enhance blackgram (Vigna mungo L.) productivity in South India.

Pulses are essential components of vegetarian diet and play a pivotal role in addressing malnutrition by providing a vital source of dietary protein. However, weed competition remains as a significant obstacle to blackgram (Vigna mungo L) production, resulting in 25 to 35% yield losses. A field experiment was carried out at the National Pulses Research Centre, Tamil Nadu Agricultural University, Vamban, Pudukkottai, India during Kharif seasons of 2020 and 2021, to assess the suitable post-emergence herbicides for appropriate weed control in blackgram grown under irrigated conditions. The experimental field was observed to contain notable grass weed flora, specifically Dactyloctenium aegyptium and Chloris barbata, as well as broadleaved weeds, such as Flaveria australica, Cleome gynandra, Eclipta alba, Convolvulus arvensis, Digera arvensis, Vicia spp., and Celosia argentea. The results demonstrated that among the chemical weed management methods, spraying of Fomesafen @ 220 g + Fluzifop p-butyl @ 220 g ha-1 at 20 days after sowing (DAS) as a post-emergence herbicide treatment exhibited superior weed control efficiency, recording 66.80% and 68.53% at 30 and 45 DAS, respectively and recorded higher seed yield of 1088 kg ha-1. Additionally, this method generated 8.1% higher net income and 12.5% more benefit-cost ratio than hand weeding, making it an economically profitable strategy for maximizing blackgram yield and effective labour management.

Evaluation of herbicidal potential of Siderophores produced by Amycolatopsis lurida strain 407.

The urgent need for sustainable agriculture has intensified the search for environmentally friendly alternatives to chemical herbicides. This study investigates the herbicidal potential of siderophores produced by Amycolatopsis lurida strain 407, focusing on its effects on the growth of ryegrass and redroot weeds. Strain 407 exhibited two distinct colony morphologies-red and white-when cultured under varying environmental conditions. The cell-free culture filtrate (CFCF) from both colony types significantly inhibited the growth of ryegrass and redroot. The concentration of siderophore produced in the iron-deficient medium was measured to be 613.4 ppm for 407 red and 388.5 ppm for 407 white, which indicates significant iron chelating activity. This study also showed a direct relationship between the presence of siderophore in plant culture medium and reduced growth. Also, analysis of fractions of the aqueous phase resulting from column chromatography revealed that all fractions from the 407 red reduced ryegrass shoot length by up to 45% and root length by 83-86%, while redroot seedling length decreased by up to 36%. Fractions from 407 white completely inhibited germination or reduced ryegrass root length by up to 94% and redroot seedling length by 52%. Fractions F4 W to F7 W and F2 R to F8 R, which showed iron chelating activity were most effective in reducing plant growth, suggesting that there are metabolites, alone or in company with siderophores, synergistically do herbicidal activity. The innovative application of siderophores as bioherbicide presents a promising environmentally friendly alternative to chemical herbicides.

Elucidating the eco-friendly herbicidal potential of microbial metabolites from Bacillus altitudinis.

Microbial herbicides play a vital role in agricultural preservation, amid growing concerns over the ecological impact from extensive development and use of chemical herbicides. Utilizing beneficial microbial metabolites to combat weeds has become a significant focus of research. This study focused on isolating herbicidal active compounds from Bacillus altitudinis D30202 through activity-guided methods. First, the n-butanol extract (n-BE) of B. altitudinis D30202 underwent fractionation using macroporous adsorption resin D101 and Sephadex LH-20, identifying Fr. F as the most potent segment against wild oats (Avena fatua L.). Ultra-performance liquid chromatography - quadrupole time-of-flight mass spectrometry (UPLC - QTOF-MS) identified nine compounds in the active fraction Fr. F. Subsequently, three subfractions (Fr.F-1 to Fr.F-3) were derived from Fr.F via semi-preparative liquid chromatography, resulting in methyl indole-3-acetate (MeIAA) purification. MeIAA, functioning as an auxin analog, exhibited effects of indole-3-acetic acid (IAA) on wild oats' growth, with a root length median inhibitory concentration of 81.06 µg/ml. Furthermore, we assessed MeIAA's herbicidal impact on five weed species across diverse families and genera, providing a first-time analysis of MeIAA's mechanism on wild oats. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed structural damage to leaves and roots post-MeIAA treatment. MeIAA treatment increased superoxide anion and hydrogen peroxide levels in wild oat roots, alongside with elevated peroxidase (POD) and superoxide dismutase (SOD) activity, chlorophyll-degrading enzymes (Chlase, MDACase), malondialdehyde (MDA) content, and relative conductivity in leaves. Conversely, it decreased catalase (CAT) activity and chlorophyll content. Therefore, this study provides a new material source and theoretical foundation for ecologically sustainable agricultural weed control.

Glyphosate Resistance in Eleusine indica: Involvement of CYP71AK44 in Addition to EPSPS Gene Overexpression.

Intensive application of glyphosate has resulted in resistance evolution in many weed populations, including Eleusine indica. This study characterized glyphosate resistance and investigated the underlying mechanisms in a glyphosate-resistant population (R-JX) of E. indica from China. The R-JX population was 8.5 times resistant to glyphosate relative to the glyphosate-susceptible population (SA). Point mutations were not observed in the target gene 5-enolypyruvyl-shikimate-3-phosphate synthase gene (EPSPS). However, the expression level and copy number of EPSPS were 8.8 times and 15.2 times, respectively, greater in R-JX than that in the SA population. Pre-application of the P450 inhibitor lowered the resistance level to glyphosate from 8.5 times to 3.6 times in the R-JX population. RNA-Seq and RT-qPCR revealed that the CYP71AK44 gene was consistently upregulated in R-JX and five other glyphosate-resistant populations. Rice calli and seedlings overexpressing CYP71AK44 showed glyphosate resistance. In conclusion, overexpression of the target EPSPS plus CYP71AK44 collectively contributes to glyphosate resistance in these E. indica populations.

Radiometric approaches with carbon-14-labeled molecules for determining herbicide fate in plant systems.

Weeds cause economic losses in cropping systems, leading to the use of 1.7 million tons of herbicides worldwide for weed control annually. Once in the environment, herbicides can reach non-target organisms, causing negative impacts on the ecosystem. Herbicide retention, transport, and degradation processes determine their environmental fate and are essential to assure the safety of these molecules. Radiometric strategies using carbon-14 herbicides (14C) are suitable approaches for determining herbicide absorption, translocation, degradation, retention, and transport in soil, plants, and water. In this work, we demonstrate how 14C-herbicides can be used from different perspectives. Our work focused on herbicide-plant-environment interactions when the herbicide is applied (a) through the leaf, (b) in the soil, and (c) in the water. We also quantified the mass balance in each experiment. 14C-mesotrione foliar absorption increased with oil and adjuvant addition (5-6 % to 25-46 %), and translocation increased only with adjuvant. More than 80 % of 14C-quinclorac and 14C-indaziflam remained in the soil and cover crops species absorbed less than 20 % of the total herbicides applied. In water systems, Salvinia spp. plants removed 10-18 % of atrazine from the water. Atrazine metabolism was not influenced by the presence of the plants. The radiometric strategies used were able to quantify the fate of the herbicide in different plant systems and the mass balance varied from 70 % to 130 %. Importantly, we highlight a critical and practical view of tracking herbicides in different matrices. This technique can aid scientists to explore other pesticides as environmental contaminants.

Study of Amino Acid-Derived 3-Acyltetramic Acids as Herbicidal Agents.

The growing problem of herbicide resistance necessitates the development of novel herbicidal active ingredients, together with other integrated weed management approaches. Natural products are a major source of inspiration for novel actives. In previous research, we identified a 3-acyltetramic acid of microbial origin that inhibited algal growth in marine biofilms, at least in part through inhibition of photosystem II. In this work, we demonstrate the herbicidal effect of this lead compound and construct multiple libraries to test the impact of the different substituents of the central scaffold in order to study the structure-activity relationships. Among these analogues, the highest activities were found for medium- to long-chain acyl groups and apolar secondary amino acid residues. Finally, we provide first insights into the herbicidal mechanisms and present preliminary field-trial and ecotoxicological results for TA12-Pro, the most active analogue in our library. Together, this research shows the potential of 3-acyltetramic acids for herbicide development.

Optimizing planting times and weed management for enhanced yield and nutritional quality of baby corn and green fodder.

A study was carried out to ascertain the impact of planting time and weeding schedule on the yield and quality of baby corn. The trial included three planting times viz. 15 November, 15 December and 14 January and five levels of weeding regime viz. no weeding, two hand weeding (HW) at 15 days after sowing (DAS) and 30 DAS, herbicide pendimethalin @ 2.5 L ha-1 (pre-emergence) + one HW at 30 DAS, herbicide pyrazosulfuran-ethyl @ 2.0 L ha-1 (post-emergence) + one HW at 30 DAS and combined herbicide of pendimethalin + pyrazosulfuran-ethyl. The maximum cob yield with husk (11.93 t ha-1) and cob yield without husk (3.07 t ha-1) were obtained from the 15 December sowing with the application of pendimethalin followed by pyrazosulfuran-ethyl. Plants sown on 15 December with the application pyrazosulfuran-ethyl with one HW at 30 DAS gave the highest protein content in cobs (20.20%), while the leaf protein content showed the highest result (18.70%) in the plants sown on 15 December with no weeding. Therefore, it can be concluded that the baby corn might be planted on December 15 with the combined application of pendimethalin + pyrazosulfuran-ethyl herbicides and pyrazosulfuran-ethyl + one HW at 30 DAS for maximum cob yield and protein content, respectively.

Low expression of auxin receptor EcAFB4 confers resistance to florpyrauxifen-benzyl in Echinochloa crus-galli (L.) P. Beauv.

Echinochloa crus-galli (L.) P. Beauv is a monocotyledonous weed that seriously infests rice fields. Florpyrauxifen-benzyl, a novel synthetic auxin herbicide commercialized in China in 2018, is an herbicide for controlling E. crus-galli. However, a suspected resistant population (R) collected in 2012 showed resistance to the previously unused florpyrauxifen-benzyl. Whole-plant dose-response bioassay indicated that the R population evolved high resistance to quinclorac and florpyrauxifen-benzyl. Pretreatment with P450 inhibitors did not influence the GR50 of E. crus-galli to florpyrauxifen-benzyl. The expression of target receptor EcAFB4 was down-regulated in the R population, leading to the reduced response to florpyrauxifen-benzyl (suppresses over-production of ethylene and ABA). We verified this resistance mechanism in the knockout OsAFB4 in Oryza sativa L. The Osafb4 mutants exhibited high resistance to florpyrauxifen-benzyl and moderate resistance to quinclorac. Furthermore, DNA methylation in the EcAFB4 promoter regulated its low expression in the R population after florpyrauxifen-benzyl treatment. In summary, the low expression of the auxin receptor EcAFB4 confers target resistance to the synthetic auxin herbicide florpyrauxifen-benzyl in the R- E. crus-galli.

Metproxybicyclone, a Novel Carbocyclic Aryl-dione Acetyl-CoA Carboxylase-Inhibiting Herbicide for the Management of Sensitive and Resistant Grass Weeds.

Postemergence control of grass weeds has become problematic due to the evolution of resistance to 5-enolpyruvylshikimate-3-phosphate synthase, acetyl-CoA carboxylase (ACCase), and acetolactate synthase-inhibiting herbicides. Herein we describe the invention and synthesis journey toward metproxybicyclone, the first commercial carbocyclic aryl-dione ACCase-inhibiting herbicide for the cost-effective management of grass weeds in dicotyledonous crops and in preplant burndown applications. Glasshouse and field experiments have shown that metproxybicyclone is safe for use on soybean, cotton, and sugar beet, among other crops. It is effective on a variety of key grass weeds including Eleusine indica, Digitaria insularis, Sorghum halepense, and Echinochloa crus-galli. Importantly, metproxybicyclone was more efficacious at killing resistant grass weed populations than current ACCase herbicides. Metproxybicyclone controlled the main ACCase target-site and nontarget site resistant mechanisms in characterized Lolium multiflorum and E. indica populations under glasshouse conditions. Excellent control of a broad resistance-causing D2078G target-site mutant E. indica population was also observed under field conditions.

Glyphosate-based herbicides reduced overwintering population and reproduction of agrobiont spiders.

Spiders are important in ecosystem and serve as predators in the biological control of pest insects in agroecosystem, where they encounter various harsh challenges including pesticides and low temperature in winter. Glyphosate-based herbicides (GBH) are widely and frequently applied to diminish weeds, exposing spiders a disturbed habitat, especially to overwintering spiders. We conducted a study combining field surveys and lab assays, to assess the effects of a GBH on the overwintering of the agrobiont wolf spider, Pardosa pseudoannulata. The GBH significantly reduced the overall overwintering spider population by about 69 %, and reduced the number of vulnerable juveniles by about 80 %. The survivors exhibited substantial fitness costs such as reproductive dysfunctions and enhanced oxidative stress responses. We then mimicked the overwinter process in lab. We housed spiders on soil patches with and without weeds to examine whether weeds contributed to the GBH's sublethal effects. Spiders overwintered independent of weeds when GBH was not applied. When GBH was applied before or during overwintering, juvenile spiders overwintered in weedy habitats exhibited reduced survival and fecundity, and increased oxidative stress compared to their counterparts in weed-free habitats. Therefore, GBH-containing weeds contributed to the persistent adverse effects of GBH on overwintering spiders. The findings revealed the cross-talk among weeds, herbicides, low temperature, and non-target organisms. The study provides novel information on the environmental risk assessment of pesticides and rational scheduling of pesticide application.

Involvement of P450s in the metabolic resistance of Digitaria sanguinalis (L.) Scop. To ALS-inhibiting herbicides.

Weed resistance to a range of herbicides has rapidly evolved, often with different mechanisms of action. The resulting uninhibited growth of weeds poses demonstrable threats to crop production and sustainable agriculture. Digitaria sanguinalis (L.) Scop., a troublesome weed in corn and other agricultural fields, has developed resistance to herbicides that inhibiting ALS (Acetolactate Synthase), such as nicosulfuron. Understanding the weed's resistance patterns and mechanisms is crucial. However, little is known of the non-target site resistance (NTSR) mechanisms of D. sanguinalis owing to a lack of relevant genome sequences and other materials. Therefore, in this study, a population of D.sanguinalis presenting multiple resistance was tested and found that its high level of resistance to ALS-inhibiting herbicides was not associated with target-related alterations.Administration of P450 inhibitors reversed the resistance to ALS-inhibiting herbicides. Following the application of ALS-inhibiting herbicides, the activities of NADPH-P450 reductase and p-nitroanisole O-demethylase (PNOD) were notably greater in the resistant population of D. sanguinalis than those in the susceptible population. The results suggested P450 enzyme familyplays a major role in the metabolic resistance mechanism, that increased P450 enzyme activity promote cross-resistance in D. sanguinalis to ALS-inhibiting herbicides. RNA-seq analysis showed that five genes from the P450 family (CYP709B2, CYP714C2, CYP71A1, CYP76C2, and CYP81E8) were upregulated in resistant D. sanguinalis. In conclusion, the upregulation of several P450 genes is responsible for establishing resistance to ALS-inhibiting herbicides in D. sanguinalis.

Synthesis of Novel Propionamide-Methylpyrazole Carboxylates as Herbicidal Candidates.

Transketolase (TKL; EC 2.2.1.1) is a highly promising potential target for herbicidal applications. To identify novel TKL inhibitors, we designed and synthesized a series of 3-oxopropionamide-1-methylpyrazole carboxylate analogues and assessed their herbicidal activities. Ethyl 3-((1-((2,4-dichlorophenyl)amino)-1-oxopropan-2-yl)oxy)-1-methyl-1H-pyrazole-5-carboxylate (D15) and ethyl 1-methyl-3-((1-oxo-1-((thiophen-2-ylmethyl)amino)propan-2-yl)oxy)-1H-pyrazole-5-carboxylate (D20) exhibited superior growth inhibition activities against both the root and stem of Amaranthus retroflexus (A. retroflexus) compared to nicosulfuron and mesotrione. Additionally, D15 achieved an inhibition rate of more than 90% against the roots and stems of Digitaria sanguinalis (D. sanguinalis), outperforming the four control agents at a concentration of 200 mg/L using the small cup method. In the pre-emergence herbicidal activity test, D15 effectively inhibited D. sanguinalis by more than 90% at 150 g ai/ha, surpassing the efficacy of the control, mesotrione. Conversely, in the postemergence herbicidal activity test, D20 exhibited efficient inhibition of A. retroflexus by more than 90% at 150 g ai/ha, outperforming the control agents nicosulfuron, mesotrione, and metamifop. The results of the TKL enzyme activity test showed that the IC50 values of compounds D15 and D20 were 0.384 and 0.655 mg/L, respectively, which were close to those of the control agents. Furthermore, molecular docking and molecular dynamics simulation studies revealed that D15 and D20 interacted favorably with the TKL of Setaria viridis. Such findings highlight the promising potential of D15 and D20 as lead TKL inhibitors for the optimization of new herbicides.

Multisite Mutagenesis of 4-Hydroxyphenylpyruvate Dioxygenase (HPPD) Enhances Rice Resistance to HPPD Inhibitors and Its Carotenoid Contents.

While frequently used herbicides display limited efficacy against herbicide-resistant weeds, it becomes imperative to explore novel herbicides that ensure both effective weed management and environmental safety. Though 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibitory herbicides like mesotrione are prevalent in maize weed management, their integration into rice production is hindered due to the inherent sensitivity of rice HPPD (OsHPPD). In this study, a mutant allele of OsHPPD featuring six amino acid substitutions, termed OsHPPD-6M, maintains enzymatic activity in 200 µm mesotrione while the wild type can only withstand 1 µm. Enzymatic assays in vitro indicated that the HPPD activity of OsHPPD-6M surpassed that of the WT by 2-fold through enhanced substrate-binding. Its overexpression in transgenic rice conferred greater tolerance to mesotrione, topramezone, and isoxaflutole by 36.7-, 41.6-, and 37.1-fold relative to that in the WT rice. Interestingly, these 6M-OE plants demonstrated substantially elevated contents of carotenoids compared to WT plants without a significant impact on agronomic traits.

Design, Synthesis, and Herbicidal Activities of N-(5-(3,5-Methoxyphenyl)-(thiazole-2-yl))phenoxyacetamide Derivatives.

Thiazole and phenoxyacetic acid are key moieties in many natural and synthetic biologically active agents. A series of N-(5-(3,5-methoxyphenyl)-(thiazole-2-yl))phenoxyacetamide derivatives 6an-6bd were designed and synthesized, and their structures were confirmed by NMR and HRMS. Most of derivatives exhibited superior inhibition of Echinochloa crusgalli (E.c.) and Lactuca sativa (L.s.) seed germination by the Petri dish bioassay. Indeed, herbicidal bioassays indicated that 6an (2-(2,4-dichlorophenoxy)-N-(5-(3,5-dimethoxyphenyl)-1,3,4-thiadiazol-2-yl)acetamide) had the best inhibition against L.s. (IC50 = 42.7 g/ha, 375 g/ha at field experiments). 6an also had no harmful effect on Zea mays at 2- to 4-fold field usage. Moreover, transcriptomics and metabolomics analysis showed that 6an significantly influenced cell metabolism, including galactose metabolism and ascorbate and aldarate metabolism. These discoveries highlight that 6an shows promise to be developed as a potential herbicide.

Simulated herbicide mixtures delay both specialist monogenic and generalist polygenic resistance evolution in weeds.

BACKGROUND: Evolution of herbicide-resistant weed populations is a major challenge to world food production. Using different herbicides in rotation and/or using different herbicides together as mixtures are strategies that may delay the selection of resistance. This study used simulation modelling to investigate whether mixtures and rotations can delay the selection of both generalist polygenic and specialist monogenic herbicide resistance, and whether these strategies are more likely to lead to the selection of generalist resistance in weed types with varying biological characteristics. RESULTS: Our simulations suggest that well-designed effective herbicide mixtures should delay evolution of both polygenic and monogenic resistance better than rotations and single herbicides across all weed types. Both mixture and rotation strategies increased the likelihood of polygenic resistance compared to single-herbicide use, and the likelihood of polygenic resistance increased as the fecundity and competitiveness of the weed increased. Whether monogenic or polygenic resistance occurred in each case depended most on the relative initial allele frequencies. We did not find that herbicide mixtures were more likely than rotations to lead to the selection of generalist polygenic resistance. The simulated efficacy of mixtures over rotations decreased if components were used at reduced rates or when individual components had already been used solo. CONCLUSION: Herbicide rotations and particularly well-designed mixtures should delay evolution of both polygenic and monogenic resistance, especially if used as part of an effective integrated weed management programme. However, herbicide mixtures and rotations may also increase the risk that resistance will be generalist polygenic rather than specialist monogenic. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Amphiphilic Cationic Carbon Dots for Efficient Delivery of Light-Dependent Herbicide.

The inefficient delivery of herbicides causes unpleasant side effects on the ecological environment. Protoporphyrinogen oxidase (PPO)-inhibiting herbicides rely on the presence of external light to exert the activities and thus their performance in the field is extremely susceptible to the light environment. Here, taking acifluorfen (ACI) as a model PPO-inhibiting herbicide to enhance efficacy by boosting the utilization rate of sunlight, amphiphilic cationic CDs (CPC-CDs) from cetylpyridinium chloride (CPC) as a precursor, is first prepared as a supplementary light source generator, and subsequently co-assembled with ACI through non-covalent bond interactions to obtain the stable fluorescent nanoparticles (ACI@CPC-CDs). ACI@CPC-CDs with fascinating physicochemical properties can penetrate the leaves of weeds through the stomata and undergo a long-distance transport in the cell intervals. Under low light intensity, CPC-CDs can be applied as the internal light source to promote the formation of more singlet oxygen to damage the leaf cell membrane, consequently improving the herbicidal activity of ACI. Moreover, the safety evaluation of ACI@CPC-CDs demonstrates no risk to non-target organisms and the environment. Therefore, this work offers a promising strategy for the efficient delivery of light-dependent PPO-inhibiting herbicides and opens new insights into the application of CDs in the development of sustainable agriculture.

Naturally Occurring Dehydrocostus Lactone Covalently Binds to KARRIKIN INSENSITIVE 2 by Dual Serine Modifications in Orobanche cumana and Arabidopsis.

Parasitic weeds, such as Orobanche and Striga, threaten crops globally. Contiguous efforts on the discovery and development of structurally novel seed germination stimulants targeting HYPOSENSITIVE TO LIGHT/KARRIKIN INSENSITIVE 2 (HTL/KAI2) have been made with the goal of weed control. Here, we demonstrate that a natural compound dehydrocostus lactone (DCL) exhibits effective "suicide germination" activity against Orobanche cumana and covalently binds to OcKAI2d2 on two catalytic serine sites with the second modification dependent on the first one. The same interactions and covalent modifications of DCL are also confirmed in AtKAI2. Further in-depth evolution analysis indicates that the proposed two catalytic sites are present throughout the streptophyte algae, hornworts, lycophytes, and seed plants. This discovery is particularly noteworthy as it signifies the first confirmation of a plant endogenous molecule directly binding to KAI2, which is valuable for unraveling the elusive identity of the KAI2 ligand and for targeting KAI2 paralogues for the development of novel germination stimulants.

The Evaluation of Debranone Series Strigolactone Agonists for Germination Stimulants in Orobanche Species.

Strigolactones (SLs) are plant hormones that regulate shoot branching. In addition, SLs act as compounds that stimulate the germination of root parasitic weeds, such as Striga spp. and Orobanche spp., which cause significant damage to agriculture worldwide. Thus, SL agonists have the potential to induce suicidal germination, thereby reducing the seed banks of root parasitic weeds in the soil. Particularly, phenoxyfuranone-type SL agonists, known as debranones, exhibit SL-like activity in rice and Striga hermonthica. However, little is known about their effects on Orobanche spp. In this study, we evaluated the germination-inducing activity of debranones against Orobanche minor. Analysis of structure-activity relationships revealed that debranones with electron-withdrawing substituents at the 2,4- or 2,6-position strongly induced the germination of Orobanche minor. Lastly, biological assays indicated that 5-(2-fluoro-4-nitrophenoxy)-3-methylfuran-2(5H)-one (test compound 61) induced germination to a comparable or even stronger extent than GR24, a well-known synthetic SL. Altogether, our data allowed us to infer that this enhanced activity was due to the recognition of compound 61 by the SLs receptor, KAI 2d, in Orobanche minor.

The effect of natural herbicide from Fusarium equiseti crude extract on the aquatic weed water hyacinth (Eichornia crassipes (Mart.) Solms).

In this study, Fusarium equiseti was isolated from the weed plant Tridax procumbens in an agricultural field and a crude extract produced with 75% ethanol for use as active ingredient material in natural herbicides. The herbicidal effect of F. equiseti extract was tested on water hyacinth (Eichornia crassipes), an invasive aquatic weed, by leaf disk assay at concentrations of 0.05%, 0.1%, and 0.2% w/v crude extract. Dose-dependent visual toxicity symptoms were evident after three days, namely chlorosis, yellow leaves surrounded by dark brown edges. Photosynthetic pigments (chlorophyll a, b, and carotenoids) and membrane integrity (as electrolyte leakage and malondialdehyde content) were evaluated following the leaf disk test. 3 days after treatment, photosynthetic pigment contents showed dose-dependent decreases, while both measures of membrane integrity showed dose-dependent increases with increasing extract concentration. In addition, a cytogenetic assay was conducted on Allium cepa L. root, in which mitotic index reduction and depigmentation were evident as early as 24 h after herbicide application. Finally, anatomical analysis of treated E. crassipes leaves revealed degradation or damage of the ground tissue. All told, our results support the F. equiseti crude-based natural herbicide cloud as a sustainable alternative in agriculture.

The mutation Asp-376-Glu in the ALS gene confers resistance to mesosulfuron-methyl in Beckmannia syzigachne.

Understanding the mechanisms by which weeds develop herbicide resistance is crucial for managing resistance effectively and optimizing herbicide use. Beckmannia syzigachne, a harmful grass weed prevalent in wheat and rice-wheat rotation areas, poses a significant threat to crop productivity. A field herbicide resistance survey identified a resistant population with a new ALS mutation (Asp-376-Glu). The Glu-376-Asp population displayed varying resistance levels to seven ALS herbicides, verified using the dCAPS method. qRT-PCR analysis showed that no significant difference existed in the ALS gene expression between the Asp-376-Glu and S populations. P450 and GST inhibitors failed to reverse resistance to mesosulfuron-methyl, suggesting no involvement of P450- and GST-based metabolic resistance. Molecular docking indicated that the Asp-376-Glu mutation reduces the binding affinity between ALS-inhibitors and BsALS. The findings provide valuable insights into herbicide resistance mechanisms for weed resistance control.