Low Phytotoxicity Research Articles

Ecotoxicological effects of new C-substituted derivatives of N-phosphonomethylglycine (glyphosate) and their preliminary evaluation towards herbicidal application in agriculture.

In this paper, comparison of ecotoxicological and herbicidal effect of newly synthesized N‑[(phosphono)(aryl)methyl]glycines 1a-g (C-substituted glyphosate derivatives) with pure glyphosate (N-phosphonomethylglycine) (2) was demonstrated. All of tested glyphosate derivatives (1a-g) in contrast to glyphosate, were found to be completely safe for oat (Avena sativa) and classified as not harmful for marine bacteria Aliivibrio fischeri. Compounds 1a-g were also found rather harmless to radish (Raphanus sativus) as compared to N-phosphonomethylglycine, but they were moderately toxic against freshwater crustaceans Heterocypris incongruens. One of synthesized compounds, namely N-[(phosphono)(4-hydroxyphenyl)methyl]glycine (1f) was found to possess stronger herbicidal properties against gallant soldier (Galinsoga parviflora) and common sorrel (Rumex acetosa) when compared to pure glyphosate and demonstrated total death of these weeds being ranked 1 in the European Weed Research Council (EWRC) scale. Considering lower phytotoxicity of compound 1f against cultivated plants and tested microorganisms when compared to pure glyphosate, this aminophosphonate may be good candidate for further, more comprehensive study toward its agrochemical application, especially that this active agent demonstrated much stronger herbicidal properties than N-phosphonomethylglycine.

Photocatalytic ozonation of parabens mixture using 10% N-TiO2 and the effect of water matrix

Nitrogen-doped TiO2 was applied in photocatalytic ozonation reactions for the degradation of a mixture of five parabens under UVA radiation, being evaluated the influence of the reaction medium. The initial mixture parabens concentration considered in these experiments was 50 mg L−1. The parabens degradation rate was considerably enhanced under neutral pH, specially using a buffered solution, leading to a complete removal under 60 min and with transferred ozone dose (TOD) 36% lower compared to reaction under natural conditions. Isopropanol, known radical scavenger, impeded the complete contaminants removal, affecting the reaction route and by-products formation, but when KI was jointly added, total removal was achieved under 30 min and with a TOD of 25.9 mg L−1. Parabens depletion was also improved in the presence of Cl−, SO42− and HCO3−, commonly present in wastewaters. The use of river water (RW) and a secondary wastewater (SWW) as water matrices maintained the process efficiency with lower TOD required, and treated solutions presented lower phytotoxicity towards Lepidium sativum.

Phytotoxic Metabolites from Three Neofusicoccum Species Causal Agents of Botryosphaeria Dieback in Australia, Luteopyroxin, Neoanthraquinone, and Luteoxepinone, a Disubstituted Furo-α-pyrone, a Hexasubstituted Anthraquinone, and a Trisubstituted Oxepi-2-one from Neofusicoccum luteum.

Different phytotoxic metabolites were isolated from the organic extract of Neofusicoccum luteum, Neofusicoccum australe, and Neofusicoccum parvum, causal agents of Botryosphaeria dieback in Australia. N. luteum produced a new disubstituted furo-α-pyrone, a hexasubstituted anthraquinone, and a trisubstituted oxepi-2(7H)-one, luteopyroxin (4), neoanthraquinone (5), and luteoxepinone (7), respectively, together with the known (±)-nigrosporione (6), tyrosol (8), (R)-(-)-mellein (1), and (3R,4S)-(-)- and (3R,4R)-(-)-4-hydroxymellein (2 and 3). The three melleins and tyrosol were also produced by N. parvum, while N. australe produced (R)-(-)-mellein (1), neoanthraquinone (5), tyrosol (8), and p-cresol (9). Luteopryoxin (4), neoanthraquinone (5), and luteoxepinone (7) were characterized by analyses of physical data, essentially one- and two-dimensional nuclear magnetic resonance and high-resolution electrospray ionization mass spectrometry. The relative and absolute configurations of luteopyroxin (4) were determined by nuclear Overhauser effect spectroscopy and experimental and calculated electronic circular dichroism data. When assayed on grapevine leaves, neoanthraquinone (5) showed the highest toxic effect, causing severe shriveling and withering. Luteopyroxin (4), nigrosporione (6), and luteoxepinone (7) also showed different degrees of toxicity, while p-cresol (9) displayed low phytotoxicity.

Solidification and multi-cytotoxicity evaluation of thermally treated MSWI fly ash

Municipal solid waste incineration (MSWI) fly ash produced in waste-to-energy plants possesses a serious threat to human health. Although the traditional methods including toxicity characteristic leaching procedure and sequential extraction approach can partially evaluate the reduction of heavy metals leaching from thermally treated MSWI fly ash, the potential threat towards organisms is frequently ignored in previous literature. Considering this, herein we systematically assess the cytotoxicity of heat-treated samples using multiple cells from different biological tissues/organs for the first time. The results indicate that the leachability and transferability of heavy metals are declined after treatment. The biological assays demonstrate that the leachates from the treated residues induce lower phytotoxicity and cytotoxicity compared with the original samples. Moreover, according to the cellular responses of multiple cells to the leachates, normal cells (MC3T3-E1, HUVEC, and L929) are more tolerant to the leachates than cancerous cells (4T1, MG63), and the skin fibroblasts (L929), which often interact with the external circumstance, have the best cellular tolerance. This work provides a novel platform to determine the potential biosecurity of MSWI fly ash-derived products towards organisms, when they are served as secondary building materials in the constructional industry that may be contact with animals and human beings.

Genotoxicity of the food additive E171, titanium dioxide, in the plants Lens culinaris L. and Allium cepa L.

E171 (titanium dioxide, TiO2), an authorized foods and beverage additive, is also used in food packaging and in pharmaceutical and cosmetic preparations. E171 is considered to be an inert and non-digestible material, not storable in animal tissues, but the possible presence of TiO2 nanoparticles (NP) may present a risk to human health and the environment. We determined the presence of 15% TiO2 NP in a commercial E171 food additive product, by electron microscopy. The biological effects of E171 were assessed in Lens culinaris and Allium cepa for the following endpoints: percentage of germination, root elongation, mitotic index, presence of chromosomal abnormalities, and micronuclei. The results indicated low phytotoxicity but dose-dependent genotoxicity. We also observed internalization of TiO2 NP and ultrastructural alterations in the root systems.

Weed management in glyphosate-resistant maize

ABSTRACT The application of glyphosate associated with other herbicides is an important alternative for weed control in maize, to increase control spectrum and to minimize problems with resistance and tolerance from some species to the product. The objective of this work was to evaluate the efficacy, selectivity and effects on the grain yield components of glyphosate-resistant maize as a function of its application, associated or not with other pre- and postemergence herbicides. The design used was randomized blocks with four replications. Treatments consisted in the use of glyphosate combined with the herbicides: atrazine, [atrazine + simazine], [atrazine + oil], [atrazine + S-metolachlor], applied pre- and/or postemergence and [nicosulfuron + mesotrione] only postemergence, plus two controls, one weeded and one infested. The evaluated variables were maize phytotoxicity, weed control, ear insertion height, number of rows per ear, number of grains per row, one thousand grain mass and grain yield. Herbicide treatments caused low phytotoxicity to maize, less than 6%; control greater than 88, 95 and 95% for alexandergrass, turnip and sunflower, respectively, and did not affect grain yield components. The tested herbicides are selective to the hybrid Forseed 2A521 PW and effective in weed control. Weed control with weeding or herbicide increased maize Forseed 2A521 PW yield by 43%. The association of glyphosate with pre- or postemergence herbicides increased maize grain yield by approximately 14%.

Novel ammonium dichloroacetates with enhanced herbicidal activity for weed control.

Dichloroacetic acid (DCA) exhibits great potential as an herbicide (nontoxic, easily biodegradable), but its application in agriculture has scarcely been investigated. Since DCA readily undergoes photolysis when exposed to natural light or UV irradiation, there is a large activity loss in controlling weeds. To improve the activity of DCA, we proposed the transformation of DCA into an ionic salt form by using an herbicidal ionic liquids (HILs) strategy. Herein, fifteen novel ammonium dichloroacetates were designed and achieved for the first time. When compared to the anionic precursor DCA, three salts with longer alkyl chains ranging from dodecyl to hexadecyl chains were found to enhance not only the post emergence herbicidal activity but also the rates of activity against some broadleaf weeds under greenhouse conditions. The enhancement was due to the synergistic effect of structural factors, such as the surface activity, solubility and stability arising from their ionic nature. In addition, IL 13 possesses a low phytotoxicity to cotton plants with a favorable selectivity index above 2. This study will be useful for the design of new, high-performance herbicidal formulations.

Review: Essential Oils A Viable Pest Control Alternative

Indiscriminate use of pesticides is troublesome in our environment, creating toxic soils, groundwater, ponds and lakes, and oceans. Application of chemical pest control results in the death of many insects. These toxic chemicals interrupt entire ecosystems, causing havoc on pollinators such as bees and other beneficial insects, birds and animals as well as humans. It has been estimated that about 2.5 million tons of pesticides are used on crops each year, and that the worldwide damage caused by pesticides reaches $100 billion annually. This paper summarizes the results found in the scientific literature and highlights the fact that secondary metabolites of plants are involved in the interaction with other species, primarily in the defense response of plants against pests. These secondary metabolites sometimes called botanicals represent a huge reservoir of chemical structures with pesticidal activity largely underutilized in modern times compared to the industrial scale seen with chemical pesticides. There are several advantages of botanical pesticides including fast degradation by sunlight and moisture or by detoxifying enzymes. The target-specific nature and lower phytotoxicity of these botanicals have prompted researchers to investigate more in depth the mechanisms of action and structure-activity relationship of these botanicals in order to evaluate their potential as a viable pest management system. Higher plants produce a diverse array of secondary metabolites, which include phenols, terpenes, alkaloids, lignans and their glycosides. This variety of active compounds plays a significant role in the defense mechanisms of plants, and potentially offers a more sustainable platform to develop structural prototypes in order to identify lead molecules/products that can eventually serve as new environmentally friendly pest control agents. Alternative green methods of pest control are found in essential oils as single or multi component preparations. The positive results in repellency and killing of predatory insects proved to be both safe and biodegradable and have a broad spectrum of applications with no re-entry time. Essential oil pest controls are widely used in organic pest management practices globally, and the emerging market reflects steady growth in agriculture, home and garden, equine, livestock, turf, pets and more. Moreover, new fields of business, research and development for understanding the complexities of plant-based oils and their benefits can be created.

The influence of EDTA on the accumulation, movement, and distribution of cadmium in dwarf elephant grass

Abstract This research aims to study the influence of EDTA on the accumulation and distribution of Cd in dwarf elephant grass. The research studied concentrations of Cd and EDTA at 20, 40, 60, 80, and 100 mg/L as well as mixtures of Cd and EDTA at molar ratios of 1:0.5, 1:1, and 1:2 mol. Plants were analyzed with AAS and LA-ICP-MS every 15 days over a total of 45 days. A Cd concentration of 40 mg/L was used to test the mixtures of Cd and EDTA. A 1:2 molar ratio of Cd and EDTA was found to be the most appropriate for phytoremediation. The plants showed effective growth, low phytotoxicity, and a high accumulation of Cd. The highest Cd accumulation in plants at the end of the experiment was 1,017.39 mg/plant, which accumulated in the underground parts (roots) and aboveground parts (stems and leaves) at 683.70 and 333.69 mg/plant, respectively. LA-ICP-MS analysis showed that Cd accumulation was highest in the underground parts of plants. This result was in accordance with the quantitative data from the AAS. Therefore, it can be concluded that plants mostly accumulate Cd in their underground parts, especially with added EDTA (1:2 mol at 105 days). LA-ICP-MS can be used to conclude with certainty that EDTA is an important factor for effectively inducing Cd into the root system.

Advanced determination of the spatial gradient of human health risk and ecological risk from exposure to As, Cu, Pb, and Zn in soils near the Ventanas Industrial Complex (Puchuncaví, Chile)

The townships of Puchuncaví and Quintero, on the coast of central Chile, have soils contaminated by atmospheric deposition of sulfur dioxide and trace elements from the nearby Ventanas Industrial Complex. The purpose of this study was to evaluate potential human health and ecological risks, by determining the spatial distribution of soil total concentrations arsenic (As), copper (Cu), lead (Pb), and zinc (Zn) in these townships. Total concentrations of these elements were determined in 245 topsoil samples, used to generate continuous distribution maps. The background concentrations of Cu, As, Pb, and Zn in the studied soils were 100, 16, 35, and 122 mg kg−1, respectively. The concentrations of Cu, As, and Pb were positively correlated with each other, suggesting that their source is the Ventanas copper smelter. On the other hand, correlations for Zn were weaker than for other trace elements, suggesting low impact of the Ventanas copper smelter on spatial distribution of Zn. Indeed, only 6% of the study area exhibited Zn concentrations above the background level. In contrast, 77, 32 and 35% of the study area presented Cu, As, and Pb concentrations, respectively, above the background level. The carcinogenic risk due to exposure to As was above the threshold value of 10−04 in the population of young children (1–5 years old) on 27% of the study area. These risk values are classified as unacceptable, which require specific intervention by the Chilean government. Based on the estimated concentrations of exchangeable Cu, 10, 15, and 75% of the study area exhibited high, medium, and low phytotoxicity risk, respectively.

Urease Inhibitory Potential and Soil Ecotoxicity of Novel “Polyphenols–Deep Eutectic Solvents” Formulations

New formulations based on red grape pomace polyphenols and deep eutectic solvents (DES) have been here evaluated as inhibitors of urease of agricultural interest (jack bean urease, JBU). DES based on choline chloride (CHO) and betaine (BET), combined with ethylene glycol (EG), citric acid (CA), and urea (U), were used both as extracting and carrying agents for polyphenols, becoming active components of the formulations here obtained. Among the various DES combinations, U- and CA-based ones gave the best polyphenol extraction performances, 1.2–1.4-times higher than those of the hydroalcoholic mixture. Among the various DES–polyphenols formulations, the one composed by CHO–EG showed the best antioxidant potential and urease inhibition: 60–90% inhibition of the total JBU activity was achieved with a CHO concentration of 5–20 mM. Good results were also achieved with the BET–EG polyphenol formulation, which was able to inhibit ca. 50% of urease activity at 20 mM concentration of BET. Low phytotoxicity of DES a...

Potential use of composts and vermicomposts as low-cost adsorbents for dye removal: an overlooked application.

The use of composts and vermicomposts as adsorbents is an important topic of study in the field of environmental remediation. These materials are rich in organic matter and have functional groups that can interact with organic and inorganic compounds. They also contain microorganisms that can promote biodegradation of organic substances. Composts that cannot be used for agronomic purposes (owing to e.g. low nutrient levels or phytotoxicity) may be valuable for soil remediation or pollutant removal. In this review, we discuss papers on this topic, with the objective of drawing attention to the potential use of composts/vermicomposts and to recommend further investigation on this subject. Few published studies have investigated the use of composts/vermicomposts to remove dyes and other coloured compounds. However, preliminary results show that these materials are potentially good adsorbents, at least comparable to other low-cost adsorbents, and that, in general, basic dyes are more efficiently removed than direct, reactive or acid dyes. The results of the works reviewed also show that dye removal takes place by adsorption mechanisms, in most studies following a Langmuir model, and that the kinetics of removal are fast and follow a pseudo-second order model. However, there remain several uncertainties regarding this application. For example, very few dyes have been studied so far, and little is known about the influence of the properties of composts/vermicomposts on the dye removal process. Moreover, the possible use of compost/vermicompost to enhance biodegradation processes has not been explored. All these questions should be addressed in future research.

Phytotoxicity of imazapyr+imazapic on tolerant rice varieties Guri INTA CL and IRGA 424 RI

ABSTRACT Rice varieties from the Clearfield® system may present different tolerance levels to imidazolinone herbicides in function of application rate. The objective of this research was to evaluate the phytotoxicity of different rates of the formulated mixture of the herbicides imazapyr+imazapic applied on two tolerant irrigated rice varieties. The experiment was carried out in 2015/16 and 2016/17 growing seasons. A randomized complete block design was used in a factorial 2x6 with five replications. The factor A was composed by the tolerant rice varieties Guri INTA CL and IRGA 424 RI, and the factor B by rates of the formulated mixture of the herbicides imazapyr+imazapic (525+175 g a.i. kg-1) of 0, 140, 210, 280, 350, and 420 g c.p. ha-1. In the first growing season, it was observed maximum phytotoxicity of 8.5% while in the second the highest percentage was 13%. The number of stems m-2, plant height, shoot dry matter, SPAD index, and grain yield were not influenced (p≥0.05) by herbicide rates. The application of the formulated mixture of the herbicides imazapyr+imazapic causes low initial phytotoxicity to the tolerant rice varieties Guri INTA CL and IRGA 424 RI up to three times the recommended rate, not influencing their grain yield.

Association of Herbicides for Management of Weed Plants in Pre-emergence of Soybean Culture

One of the big challenges to the soybean cultivation is the control of weed plants, because of the competitive potential that they presente and the resistance index in relation to the herbicides. In front of this, the work had as objective to evaluate the mix of herbicides in tanks to initial control of weed plants in the soybean culture. The experiment was installed in field in sistem of no-tillage in an área that presented the cultute of the wheat as precedente. The design used was that one of randomized blocks, with four repetitions. The herbicide’s treatments used in the test were: glyphosate, glyphosate + (diuron+sulfentrazone), glyphosate + diclosulam, glyphosate + (imazethapyr + flumioxazin), glyphosate + flumioxazin, glyphosate + 2,4-D, glyphosate + S-metolachlor, amônio-glufosinate + (diuron + sulfentrazone). The variable used was phytotoxicity in the culture, weed plants’ control Urochloa plantaginea and Raphanus sp., thousand grains weight and productivity of the soybean. The data were submitted to analysis of variance by the F test and the compared averages by the Scott-Knott test, in 5% of error probability. The phytotoxicity caused by the herbicides in the culture is not significative in the point of decrease the grains yield. The herbicides that presented better control of U. plantaginea were the associations of glyphosate with diuron + sulfetrazone, imazethapyr + flumioxazin and s-metolaclhor. Already in the control of Raphanus sp., the association of diclosulam and imazethapyr + flumioxazin with glyphosate presents results next of 100% of control. The variable thousand grains weight it was not affected by the association of the herbicides. In relation to the soybean grains productivity the herbicides (glyphosate + diclosulam and glyphosate + (imazethapyr + flumioxazin)) that provide low phytotoxicity and high control of the weed plants had their productivity compared to the weeded control.

Removal of toxic dyes from aqueous solution by adsorption onto highly recyclable xGnP® graphite nanoplatelets

The adsorptive capacity of xGnP® graphite nanoplatelets (GNP) was evaluated for the removal of Drimaren Dark Blue CL-R (DDB), Direct Red 80 (DR80), Chrysophenine (CH) and Eosin Yellowish (EY). Kinetic pseudo-second-order (PSO) model best fitted the experimental data for all evaluated dyes. Moreover, sorption capacity at equilibrium state for DDB, DR80, CH and EY were 22.14, 38.36, 28.68 and 156.77 mg g−1, respectively. Equilibrium data for the DDB dye were best fitted to the BET type IV model, while DR80, CH and EY dyes were adjusted by BET Type II. From these models, it was achieved the following maximum monolayer adsorption capacities: 20.51, 26.41, 39.41 and 66.00 mg.g−1 for DDB, DR80, CH and EY, respectively. Furthermore, investigations over the effect of pH on adsorption revealed that its behavior is governed by strong electrostatic and π−π stacking interactions. Thermodynamic studies exhibited negative values, of enthalpy and Gibbs free energy, for all dyes, indicating the spontaneous and exothermic nature of adsorption. Hence, adsorption tends to be more favorable as the temperature decreases. GNP also showed high regeneration capacity, keeping its sorption efficiency after six adsorption-desorption cycles. Dyes solutions also showed low phytotoxicity after their adsorption on GNP.

A quinoline-based ratiometric fluorescent probe for discriminative detection of Zn2+ and Cd2+ with different binding modes, and its Zn2+ complex for relay sensing of pyrophosphate and adenosine triphosphate

A new and simple quinoline-based fluorescent probe for discriminative sensing of Zn2+ and Cd2+ has been synthesized by inserting an amide group into the 8-aminoquinoline fluorophore and a propargylamine chelating site. This easily-available chemosensor displayed selective and distinct ratiometric fluorescence responses to Zn2+ in almost totally water solution through its amide tautomer binding form, and to Cd2+ in CH3CN aqueous medium through its imidic acid tautomer binding form, respectively. Moreover, the in situ prepared probe 1–Zn2+ complex could act as a relay fluorescent sensor selectively toward pyrophosphate (PPi) and adenosine 5′-triphosphate (ATP) anions via further complexation. Thus, with good specificity, low detection limits and fast response time, a highly efficient fluorescence platform for simultaneous multi-analyte detection has been developed by using the uncomplicated single molecule. Finally, this multi-functional probe was applied successfully for analysis of all the target ions in the tap water sample and on test paper strips, and bioimaging of Zn2+ in mung bean sprouts with low phytotoxicity.

Grape pomace compost as a source of organic matter: Evolution of quality parameters to evaluate maturity and stability

The Pisco and wine industry in Chile generates about 400,000 tonnes/year of grape pomace as organic wastes (OWs). This material can be composted and used as organic fertilizer or amendment in grape orchards located in inceptisol soils with a very low organic matter as a strategy to increase soil and grape quality. The maturity and the stabilization of compost define the potential use of OWs as an amendment. Therefore, the objectives of the present study were focused to evaluate the evolution of chemical, microbiological, biochemical and phytotoxicity parameters during the composting process using grape marc and other components. The experimental study consisted of nine opened piles constituted by grape pomace, goat or horse manure. The piles were evaluated for 180 days in winter-spring seasons and mechanical turns were carried out every 10 days. The results indicated that humic to fulvic acids content ratio (Ha/Fa) could be used as process evolution indicator. The potential enzymatic activity of alkaline phosphatase and β-glucosidase, and microbiological functional groups like cellulolytic, amylolytic and phosphate solubilizing bacteria were strongly correlated with production of fulvic and humic acids (p ≤ 0.01). The compost derived from treatments complies with Chilean National Standard - NCh 2880/04, 2016 for the quality of organic amendments including low phytotoxicity with a radish germination %> 92% and absence of Salmonella sp., and fecal coliforms <1000 NMP/g. In conclusion, quality parameters evaluated showed sensitivity to evaluate both the composting process and compost quality.

CHLORIMURON-ETHYL IN CONVENTIONAL AND TRANSGENIC SOYBEAN CULTIVARS UNDER WATER DEFICIT STRESS

ABSTRACT Water deficit is a limiting factor for the soybean yield; it triggers different physiological and anatomical adaptations that have deleterious effects on the plants and can affect the selectivity of herbicides, causing production losses. In this context, the objective of this work was to evaluate the action of the chlorimuron-ethyl herbicide when applied at different stages of soybean plants, using conventional and transgenic cultivars, and different soil water potentials. A rate of 20 g ha-1 of the chlorimuron-ethyl herbicide was applied to two soybean cultivars (MG/BR46-Conquista - conventional, and BRS-Valiosa-RR - transgenic) at two phenological stages (V2 - first fully expanded trifoliate leaves, and V4 - third fully expanded trifoliate leaves), using three soil water potentials (-0.03 MPa, -0.07 MPa, and -0.5 MPa). Phytotoxicity, and plant height were evaluated at 3, 7, 14, and 21 days after the herbicide application. The shoot dry weight, root dry weight, and root system nodulation were evaluated. The soybean plants had lower phytotoxicity when subjected to application of chlorimuron-ethyl under water deficit conditions. The use of chlorimuron-ethyl reduced the growth and biomass of soybean plants and affected the plants' root system nodulation. The transgenic cultivar (BRS-Valiosa-RR) presented better performance when subjected to a moderate water deficit (-0.07 MPa), which contributes to biological nitrogen fixation.

Antimicrobial peptide KSL-W and analogues: Promising agents to control plant diseases

Recent strong restrictions on the use of pesticides has prompted the search for safer alternatives, being antimicrobial peptides promising candidates. Herein, with the aim of identifying new agents, 15 peptides reported as plant defense elicitors, promiscuous, multifunctional or antimicrobial were selected and tested against six plant pathogenic bacteria of economic importance. Within this set, KSL-W (KKVVFWVKFK-NH2) displayed high antibacterial activity against all the tested pathogens, low hemolysis and low phytotoxicity in tobacco leaves. This peptide was taken as a lead and 49 analogues were designed and synthesized, including N-terminal deletion sequences, peptides incorporating a d-amino acid and lipopeptides. The screening of these sequences revealed that a nine amino acid length was the minimum for activity. The presence of a d-amino acid significantly decreased the hemolysis and endowed KSL-W with the capacity to induce the expression of defense-related genes in tomato plants. The incorporation of an acyl chain led to sequences with high activity against Xanthomonas strains, low hemolysis and phytotoxicity. Therefore, this study demonstrates that KSL-W constitutes an excellent candidate as new agent to control plant diseases and can be considered as a lead to develop derivatives with multifunctional properties, including antimicrobial and plant defense elicitation.

Identification and validation of QTL and their associated genes for pre-emergent metribuzin tolerance in hexaploid wheat (Triticum aestivum L.)

BackgroundHerbicide tolerance is an important trait that allows effective weed management in wheat crops. Genetic knowledge of metribuzin tolerance in wheat is needed to develop new cultivars for the industry. Here, we evaluated metribuzin tolerance in a recombinant inbred line (RIL) mapping population derived from Synthetic W7984 and Opata 85 over two consecutive years to identify quantitative trait loci (QTL) contributing to the trait. Herbicide tolerance was measured by two chlorophyll traits, SPAD chlorophyll content index (CCI) and visual senescence score (SNS). The markers associated with major QTL from Synthetic W7984, positively contributing to reduced phytotoxic effects under herbicide treatment were validated in two F3/4 recombinant inbred populations developed from crosses of Synthetic W7984 × Westonia and Synthetic W7984 × Lang.ResultsComposite interval mapping (CIM) identified four QTL, two on chromosome 4A and one each on chromosomes 2D and 1A. The chromosomal position of the two QTL mapped on 4A within 10 cM intervals was refined and validated by multiple interval mapping (MIM). The major QTL affecting both measures of tolerance jointly explained 42 and 45% of the phenotypic variation by percentage CCI reduction and SNS, respectively. The identified QTL have a pure additive effect. The metribuzin tolerant allele of markers, Xgwm33 and Xbarc343, conferred lower phytotoxicity and explained the maximum phenotypic variation of 28.8 and 24.5%, respectively. The approximate physical localization of the QTL revealed the presence of five candidate genes (ribulose-bisphosphate carboxylase, oxidoreductase (rbcS), glycosyltransferase, serine/threonine-specific protein kinase and phosphotransferase) with a direct role in photosynthesis and/or metabolic detoxification pathways.ConclusionMetribuzin causes photo-inhibition by interrupting electron flow in PSII. Consequently, chlorophyll traits enabled the measure of high proportion of genetic variability in the mapping population. The validated molecular markers associated with metribuzin tolerance mediating QTL may be used in marker-assisted breeding to select metribuzin tolerant lines. Alternatively, validated favourable alleles could be introgressed into elite wheat cultivars to enhance metribuzin tolerance and improve grain yield in dryland farming for sustainable wheat production.