Differential expression of genes associated with non-target site resistance in Poa annua with target site resistance to acetolactate synthase inhibitors.

BACKGROUND: Poa annua is a pervasive grassy, self-pollinating, weed that has evolved resistance to 10 different herbicide modes-of-action, third most of all weed species. We investigated constitutive overexpression of genes associated with non-target site resistance (NTSR) in POAAN-R3 and the response of those genes when treated with trifloxysulfuron despite the biotype having a known target site mutation in acetolactate synthase (ALS). RESULTS: Despite having an ALS target site mutation, POAAN-R3 still had a transcriptomic response to herbicide application that differed from a susceptible biotype. We observed differential expression of genes associated with transmembrane transport and oxidation-reduction activities, with differences being most pronounced prior to herbicide treatment. CONCLUSIONS: In the P. annua biotype we studied with confirmed target site resistance to ALS inhibitors, we also observed constitutive expression of genes regulating transmembrane transport, as well as differential expression of genes associated with oxidative stress after treatment with trifloxysulfuron. This accumulation of mechanisms, in addition to the manifestation of target site resistance, could potentially increase the chance of survival when plants are challenged by different modes of action.

Environmental effects on efficacy of herbicides for postemergence goosegrass (Eleusine indica) control.

Experiments were conducted to understand environmental effects on efficacy of herbicides used to control goosegrass (Eleusine indica L. Gaertn.). Herbicides were applied to goosegrass maintained at soil moisture contents (VMC) of < 12%, 12 to 20%, or > 20%. Herbicides included fenoxaprop-p-ethyl (140 g ha-1), topramezone (25 g ha-1), foramsulfuron (44 g ha-1), 2,4-D + dicamba + MCPP + carfentrazone (860 + 80 + 270 + 28 g ha-1), and thiencarbazone-methyl + foramsulfuron + halosulfuron-methyl (22 + 45 + 69 g ha-1). Goosegrass control increased as VMC increased. Vapor pressure deficit (VPD) and air temperature were manipulated to determine effects of evaporative demand on foramsulfuron. Effects of soil drying were also studied following foramsulfuron application. Reductions in transpiration rate (TR) and leaf area were greatest with foramsulfuron applications to goosegrass in silt-loam under high evaporative demand (3 kPa VPD, 38 °C). Foramsulfuron had no effect on goosegrass in silica-sand regardless of evaporative demand. TR dropped to 0.2 mmh-1 within eight days after application to goosegrass in silt-loam compared to 18 days in silica-sand. Overall, foramsulfuron efficacy on goosegrass was maximized under conditions of high soil moisture and evaporative demand, and may be reduced in sandy soils that hold less water.

DFG-based mid-IR tunable source with 0.5 mJ energy and a 30 pm linewidth.

We report on a laser system based on difference frequency generation (DFG) to produce tunable, narrow-linewidth (<30pm), and comparatively high-energy mid-IR radiation in the 6.8 µm region. The system exploits a lithium thioindate (LiInS2) nonlinear crystal and nanosecond pulses generated by single-frequency Nd:YAG and Cr:forsterite lasers at 1064 and 1262 nm, respectively. Two experimental configurations are used: in the first one, single-pass, the mid-IR energy achieved is 205 µJ. Additional increments, up to 540 µJ, are obtained by performing double-pass through the nonlinear crystal. This laser has been developed for high-resolution photon-hungry spectroscopy in the mid-IR.

Annual bluegrass (Poa annua) resistance to indaziflam applied early-postemergence.

BACKGROUND: Indaziflam is an alkylazine herbicide used to control annual bluegrass (Poa annua L.). Several locations in the southeastern USA reported poor annual bluegrass control following treatment with indaziflam during autumn 2015. A series of controlled environment experiments were conducted to confirm putative resistance to indaziflam in annual bluegrass collected from these field locations. RESULTS: Indaziflam (25 g ha-1 ) effectively controlled all putative-resistant annual bluegrass collections when applied preemergence (PRE), but was ineffective when applied early-postemergence (< 2.5 cm plant height; BBCH scale = 1; EPOST). In agarose-based plate assays, EPOST I50 values for putative-resistant collections ranged from 2424 to 4305 pm compared with 633 pm for the herbicide-susceptible control; therefore, resistance indexes (R/S) ranged from 3.8 to 6.8. Resistant collections were not controlled by foramsulfuron, flumioxazin, glyphosate, glufosinate, metribuzin, pronamide, or simazine applied EPOST. Indaziflam content in herbicide-susceptible annual bluegrass was greater than a resistant collection from 0 to 10 days after treatment (DAT). Susceptibility was not restored when resistant collections were treated with indaziflam plus 1-aminobenzotriazole (10 mg L-1 ), tebuconazole (1510 g ha-1 ), or malathion (400 g ha-1 ). CONCLUSIONS: This is a first report of resistance to indaziflam in any plant. Additionally, we confirm that these annual bluegrass collections are resistant to several other herbicidal modes-of-action. It is unclear if this multi-herbicide resistance is due to a single resistance gene, multiple resistance genes, non-target site mechanisms, or a combination thereof. Additional research to better understand resistance mechanisms in these annual bluegrass collections is warranted. © 2020 Society of Chemical Industry.

24 mJ Cr+4:forsterite four-stage master-oscillator power-amplifier laser system for high resolution mid-infrared spectroscopy.

We present the design of a Cr:forsterite based single-frequency master-oscillator power-amplifier laser system delivering much higher output energy compared to previous literature reports. The system has four amplifying stages with two-pass configuration each, thus enabling the generation of 24 mJ output energy in the spectral region around 1262 nm. It is demonstrated that the presented Cr:forsterite amplifier preserves high spectral and pulse quality, allowing a straightforward energy scaling. This laser system is a promising tool for tunable nonlinear down-conversion to the mid-infrared spectral range and will be a key building block in a system for high-resolution muonic hydrogen spectroscopy in the 6.8 µm range.

Several Pesticides Influence the Nutritional Content of Sweet Corn.

Herbicides are pesticides used to eradicate unwanted plants in both crop and non-crop environments. These chemistries are toxic to weeds due to inhibition of key enzymes or disruption of essential biochemical processes required for weedy plants to survive. Crops can survive systemic herbicidal applications through various forms of detoxification, including metabolism that can be enhanced by safeners. Field studies were conducted near Louisville, Tennessee and Painter, Virginia to determine how the herbicides mesotrione, topramezone, nicosulfuron, and atrazine applied with or without the safener isoxadifen-ethyl would impact the nutritional quality of "Incredible" sweet corn ( Zea mays L. var. rugosa). Several herbicide treatments increased the uptake of the mineral elements phosphorus, magnesium, and manganese by 8-75%. All herbicide treatments increased protein content by 4-12%. Applied alone, nicosulfuron produced similar levels of saturated, monounsaturated, and polyunsaturated fatty acids when compared to the nontreated check, but when applied with isoxadifen-ethyl, fatty acids increased 8 to 44% relative to the check or control. Nicosulfuron plus isoxadifen-ethyl or topramezone or the combination of all three actives increased the concentrations of fructose and glucose (40-68%), whereas reducing levels of maltose or sucrose when compared to the nontreated check (-15 to -21%). Disruptions in biochemical pathways in plants due to the application of herbicides, safeners, or other pesticides have the potential to alter the nutrient quality, taste, and overall plant health associated with edible crops.

Design, Synthesis, and Evaluation of Novel Auxin Mimic Herbicides.

Due to the key roles of auxins as master regulators of plant growth, there is considerable interest in the development of compounds with auxin-like properties for growth management and weed control applications. Herein, we describe the design and multistep synthesis of ten compounds bearing combinations of functional groups commonly associated with auxin-type properties. Following synthesis, these compounds were tested against multiple weed species as well as sweet corn. In general, while these structures were not quite as active as commercial auxin mimic herbicides, multiple compounds exhibited broadleaf weed activity with concurrent selectivity in sweet corn (Zea mays L. var. saccharum). In addition, differential results were observed upon subtle changes to structure, providing insights into the structural properties required for activity.

A new amino acid substitution (Ala-205-Phe) in acetolactate synthase (ALS) confers broad spectrum resistance to ALS-inhibiting herbicides.

MAIN CONCLUSION: This is a first report of an Ala-205-Phe substitution in acetolactate synthase conferring resistance to imidazolinone, sulfonylurea, triazolopyrimidines, sulfonylamino-carbonyl-triazolinones, and pyrimidinyl (thio) benzoate herbicides. Resistance to acetolactate synthase (ALS) and photosystem II inhibiting herbicides was confirmed in a population of allotetraploid annual bluegrass (Poa annua L.; POAAN-R3) selected from golf course turf in Tennessee. Genetic sequencing revealed that seven of eight POAAN-R3 plants had a point mutation in the psbA gene resulting in a known Ser-264-Gly substitution on the D1 protein. Whole plant testing confirmed that this substitution conferred resistance to simazine in POAAN-R3. Two homeologous forms of the ALS gene (ALSa and ALSb) were detected and expressed in all POAAN-R3 plants sequenced. The seven plants possessing the Ser-264-Gly mutation conferring resistance to simazine also had a homozygous Ala-205-Phe substitution on ALSb, caused by two nucleic acid substitutions in one codon. In vitro ALS activity assays with recombinant protein and whole plant testing confirmed that this Ala-205-Phe substitution conferred resistance to imidazolinone, sulfonylurea, triazolopyrimidines, sulfonylamino-carbonyl- triazolinones, and pyrimidinyl (thio) benzoate herbicides. This is the first report of Ala-205-Phe mutation conferring wide spectrum resistance to ALS inhibiting herbicides.

Polynomial law for controlling the generation of n-scroll chaotic attractors in an optoelectronic delayed oscillator.

Controlled transitions between a hierarchy of n-scroll attractors are investigated in a nonlinear optoelectronic oscillator. Using the system's feedback strength as a control parameter, it is shown experimentally the transition from Van der Pol-like attractors to 6-scroll, but in general, this scheme can produce an arbitrary number of scrolls. The complexity of every state is characterized by Lyapunov exponents and autocorrelation coefficients.

Diverse routes to oscillation death in a coupled oscillator system.

We study oscillation death (OD) in a well-known coupled-oscillator system that has been used to model cardiovascular phenomena. We derive exact analytic conditions that allow the prediction of OD through the two known bifurcation routes, in the same model, and for different numbers of coupled oscillators. Our exact analytic results enable us to generalize OD as a multiparameter-sensitive phenomenon. It can be induced, not only by changes in couplings, but also by changes in the oscillator frequencies or amplitudes. We observe synchronization transitions as a function of coupling and confirm the robustness of the phenomena in the presence of noise. Numerical and analogue simulations are in good agreement with the theory.

Obtencion de trioxido de tungsteno a partir de wolframita

Los concentrados de wolframita de E.M. Bolsa negra-COMIBOL que contienen scheelita en cantidades considerables, fueron sometidos a trituracion y pulverizacion para ser tratados por el metodo combinado de: Sinterizacion-Lixiviacion-Purificacion-Precipitacion de CaW04- formacion de H2W04 y deshidratacion. la optimizacion de parametros se realizo mediante diseno factorial para dos niveles y metodo de yates: La solubilidad del tungsteno durante la sinterizacion alcanzo a 98 a temeperaturas entre 800 C y 900 C, 20 de exceso estequiometrico de Na2C03, 16-20 de salitre en peso, 45 minutos de sinterizacion y un tamano de grano del concentrado de -150 mallas Tyler. La recuperacion de tungsteno soluble -Na2W04- en la etapa de lixiviacion alcanzo a 98, tiempos de lixiviacion en molienda 6 min. y agitacion 30 min. a 20 C, 1/1 de relacion solido/liquido y 5 lavados. Las soluciones optimas resultaron con 151.36 g/l W03, 0.04 g/l Si02, 0.003 g/l Fe,, 0.001 g/l As y 0.001 g/l Mo y 11.9 a 12.9 de pH.