Mode of action of fluopyram in plant-parasitic nematodes.

Plant-parasitic nematodes (PPN) are responsible for severe yield losses in crop production. Management is challenging as effective and safe means are rare. Recently, it has been discovered that the succinate dehydrogenase (SDH) inhibitor fluopyram is highly effective against PPN while accompanying an excellent safety profile. Here we show that fluopyram is a potent inhibitor of SDH in nematodes but not in mammals, insects and earthworm, explaining the selectivity on molecular level. As a consequence of SDH inhibition, fluopyram impairs ATP generation and causes paralysis in PPN and Caenorhabditis elegans. Interestingly, efficacy differences of fluopyram amongst PPN species can be observed. Permanent exposure to micromolar to nanomolar amounts of fluopyram prevents Meloidogyne spp. and Heterodera schachtii infection and their development at the root. Preincubation of Meloidogyne incognita J2 with fluopyram followed by a recovery period effectively reduces gall formation. However, the same procedure does not inhibit H. schachtii infection and development. Sequence comparison of sites relevant for ligand binding identified amino acid differences in SDHC which likely mediate selectivity, coincidently revealing a unique amino acid difference within SDHC conserved among Heterodera spp. Docking and C. elegans mutant studies suggest that this minute difference mediates altered sensitivity of H. schachtii towards fluopyram.

Phytostabilization of a contaminated military site using Miscanthus and soil amendments.

Military activities can contaminate productive land with potentially toxic substances. The most common trace metal contaminant on military bases is lead (Pb). A field experiment was begun in 2016 at Fort Riley, KS, in an area with total soil Pb concentrations ranging from 900 to 1,500 mg kg-1 and near-neutral pH. The main objectives were to test the potential of Miscanthus sp. for phytostabilization of the site and to evaluate the effects of soil amendments on Miscanthus growth, soil-plant Pb transfer, bioaccessibility of soil Pb, and soil health. The experimental design was a randomized complete block, with five treatments and four replications. Treatments were (a) existing vegetation; (b) Miscanthus planted in untilled soil, no amendments; (c) Miscanthus planted in tilled soil; (d) Miscanthus planted in tilled soil amended with inorganic P (triple superphosphate applied at 5:3 Pb:P); and (e) Miscanthus planted in tilled soil amended with organic P (Class B biosolids applied at 45 Mg ha-1 ). Tilling and soil amendments increased dry matter yields only in the establishment year. Total Pb uptake, plant tissue Pb concentration, and soil Pb bioaccessibility were significantly less in the Miscanthus plots amended with biosolids than the Miscanthus plots with no added P across all 3 yr. Enzyme activities, organic carbon, and microbial biomass were also greater in biosolids-treated plots. Results show that planting-time addition of soil amendments to Pb-contaminated soil supported Miscanthus establishment, stabilized and reduced bioaccessibility of soil Pb, reduced concentration and uptake of Pb by Miscanthus, and enhanced soil health parameters.

First record of the ectoparasitic nematode Amplimerlinius macrurus (Nematoda: Tylenchida) on the perennial grass Miscanthus × giganteus (Angiosperms: Poaceae) in Ukraine.

The growing interest in biomass production of Miscanthus × giganteus (M × g) (Poaceae) on agricultural and marginal lands has prompted researches to identify plant pathogens and diseases affecting this crop which has a great potential for production of biofuels and different bioproducts. A soil survey of nematodes in the M × g rhizosphere and a report on the collection of the plant-parasitic nematode Amplimerlinius macrurus (Belonolaimidae) were accomplished in two locations in Ukraine. It is known that this family of nematodes can reduce the root system and biomass of Poaceae family plants. Both molecular and morphological characters were used to identify the nematodes; measurements and photomicrographs of the species were presented. This is the first documentation and description of A. macrurus in Ukraine to the best of our knowledge. Further investigation is underway to confirm the pathogenicity of this species on perennial grasses plantations.

Multiyear phytoremediation and dynamic of foliar metal(loid)s concentration during application of Miscanthus × giganteus Greef et Deu to polluted soil from Bakar, Croatia.

The multiyear cultivation of Miscanthus × giganteus Greef et Deu (M.×giganteus) at the soils polluted by metal(loid)s were researched. The biomass parameters and concentrations of elements: Ti, Mn, Fe, Cu, Zn, As, Sr, and Mo were determined in the plant's organs at harvest. The same metal(loid)s were monitored in the plant's leaves throughout three vegetation seasons. The principal component analysis and general linear model approaches were applied for statistical evaluation followed by Box-Cox transformation. The difference in the distribution of elements in the plant, the content of elements in the soil, various regime of uptake to the plant tissues, and the year of vegetation were analyzed as driving factors of the phytoremediation. The results showed that the leading promoter was the factor of the zone, which was the most essential for Ti, Fe, and Cu and the smallest for Mn. The factor of differences in soil pollution was essential for Zn and Mo, much less for As, Sr, and Mn, limited for Fe, and was not seen for Ti and Cu. The factor of the interrelation effects of the zone and experiment reflected the different regime of uptake for the plant tissues was seen for two elements: more prominent for Cu and smaller for Ti. While analyzing the dynamic of foliar concentrations of the metal(loid)s during 3 years, two groups were defined. Firstly, Fe, Ni, Mn, and Sr showed stable curves with limited distribution of the plant life cycle. Secondly, As, Zn, Cu, and Mo showed different fluctuations in the curves, which can be attributed to essential influence of those elements to the plant life cycle. Further research will be focused on the application of M.×giganteus to the polluted soil in a bigger scale and comparison results of laboratory and field experiments.

The ecological risk assessment of soil contamination with Ti and Fe at military sites in Ukraine: avoidance and reproduction tests with Folsomia candida.

The aim of this research was to assess the effect of soil contamination with titanium (Ti) and iron (Fe) at military sites in Ukraine using the avoidance and reproduction tests with Folsomia candida (springtail). The soil used for the tests was sampled in 2017 from Dolyna, Ivano-Frankivsk region, Ukraine from two plots, namely a contaminated and a control site. The sample site is a former military site previously used for tank training. At the control site mainly the concentrations of Ti and Fe were exceeded. The control soil was free from contamination. The avoidance test and reproduction test were conducted with the use of springtail species F. candida. The following nine levels of contamination with heavy metals were established: 1%, 1.5%, 5%, 10%, 15%, 25%, 50%, 75% and 100%. The duration of the avoidance test was 7 days, and that of the reproduction test was 28 days. Overall, the results show that the avoidance and reproduction tests with collembolans have the potential to be used as screening tools in an ecological risk assessment of heavy metals. In the avoidance test, the concentrations from 1.5 to 100% significantly decreased the number of F. candida in the contamination site in comparison to the control site. At the same time, avoidance was not observed in the first concentration (1%). According to the reproduction test, the negative effect on the number of F. candida juveniles was observed beginning at the 10% dose. The half maximal effective concentration (EC50) for the avoidance test was 50.12%, while that for the reproduction test was 22.39%. The contamination with heavy metals at the military areas indicated the short- and long-term toxicity risk on the springtail F. candida.

Impact of plant growth regulators and soil properties on Miscanthus x giganteus biomass parameters and uptake of metals in military soils.

The impact of plant growth regulators (PGRs) "Stimpo" and "Regoplant" on Miscanthus x giganteus (Mxg) biomass parameters was investigated when the plant was grown in military soils with different properties from Dolyna, Ukraine and Hradcany, Czech Republic. The results showed that PGRs positively influenced the biomass parameters when the plant was grown in soil in Dolyna with good agricultural characteristics, the influence of "Regoplant" was higher and the best results were obtained with combined treatment: application to rhizomes before planting and spraying on the biomass during vegetation. Using of PGRs did not improve the biomass parameters when the plant was grown in poor soil in Hradcany. In parallel the peculiarities of the metals uptake process were studied for the following metals: chromium (Cr), manganese (Mn), nickel (Ni), copper (Cu), zinc (Zn), strontium (Sr) and lead (Pb). The uptake behavior of the monitored elements differed based on the soil quality. According to the bioconcentration factor uptake of the abiogenic elements, Cr and Pb, was dominant in the plant roots in both soils, whereas Ni was not detected in any plant tissues. The behavior of biogenic elements (Mn, Cu, Zn) and their analogs (Sr) was different. Those elements were more intensively taken up in shoot tissues in low-nutrient sandy Hradcany soils, while they were mainly taken up in plant roots in fertile Dolyna soils. The unusual behavior of biogenic elements in the low-nutrient soils may be explained by the effect of stress. However, more research is needed focused mainly on soil properties and nutrient availability in order to confirm or disprove this hypothesis and to explore the cause of the stress. The summarized results here show that soil properties influenced Mxg biomass parameters, affected the uptake behavior of metals significantly and tested PGRs cannot be utilized universally in the production of Mxg in the poor military soils.

Comparative assessment of using Miscanthus × giganteus for remediation of soils contaminated by heavy metals: a case of military and mining sites.

Contamination of soil by heavy metals is among the important environmental problems due to their toxicity and negative impact to human health and the environment. An effective method for cleaning the soil from heavy metals is phytoremediation using the second-generation bioenergy species Miscanthus × giganteus. The purpose of this research is to study the benefits of M. × giganteus cultivation at the soils taken from the mining and former military sites contaminated by As, Pb, Zn, Co, Ni, Cr, Cu, V, Mn, Sr, and U as well as at the soil artificially contaminated by Zn and Pb, to evaluate the physiological parameters of the plant, to establish peculiarities of the phytoremediation process, and to characterize the behavior of the plant in relation to the nature and concentrations of the metals in the soils. Results showed that M. × giganteus was resistant to heavy metals (tolerance index ≥ 1) and that the greatest portion of metals accumulated in the root system. The morphological parameters of the plant while grown on different soils are influenced by soil type and the content of contaminants. The stress effect while growing M. × giganteus on soil artificially contaminated by Zn and Pb was evaluated by measuring the content of pigments (chlorophylls a, b, and carotenoids) in the plant's leaves. The decrease in the total content of chlorophylls, Сa + b/Сcar and transpiration rate of water along with the increase in the water absorbing capacity were observed. The accumulation of heavy metals in different parts of the plant was determined; bioaccumulation coefficient and values of translocation factor were calculated. The obtained results showed that M. × giganteus was an excluder plant for nine highly toxic elements (As, Pb, Zn, Co, Ni, Cr, Cu, V, U) and an accumulator species for the moderately dangerous elements (Mn, Sr). Further research will be focused on the extraction of stable stimulated plant-growth-promoting rhizobacteria from the rhizosphere of M. × giganteus and formulation on that base the plant-bacterial associations as well as on the comparison of the plant physiological parameters, biochemical soil activity, and accumulation of heavy metals in the Miscanthus tissues between first and second vegetations.

Potential phytomanagement of military polluted sites and biomass production using biofuel crop miscanthus x giganteus.

This study aims to summarize results on potential phytomanagement of two metal(loid)-polluted military soils using Miscanthus x giganteus. Such an option was tested during 2-year pot experiments with soils taken from former military sites in Sliac, Slovakia and Kamenetz-Podilsky, Ukraine. The following elements were considered: As, Cu, Fe, Mn, Pb, Sr, Ti, Zn and Zr. M. x giganteus showed good growth at both military soils with slightly higher maximum shoot lengths in the second year of vegetation. Based on Principal Component Analysis similarities of metal(loid) uptake by roots, stems and leaves were summarized. Major part of the elements remained in M. x giganteus roots and rather limited amounts moved to the aerial parts. Levels taken up decreased in the second vegetation year. Dynamics of foliar metal(loid) concentrations divided the elements in two groups: essential elements required for metabolism (Fe, Mn, Cu, and Zn) and non-essential elements without any known metabolic need (As, Sr, Ti, and Zr). Fe, Mn, Ti and Sr showed similar S-shaped uptake curve in terms of foliar concentrations (likely due to dilution in growing biomass), while Cu exhibited a clear peak mid-season. Behavior of Zn was in between. Foliar Zr and As concentrations were below detection limit. The results illustrated a good potential of M. x giganteus for safely growing on metal-polluted soils taken from both military localities.

The estimation of Miscanthus×giganteus' adaptive potential for cultivation on the mining and post-mining lands in Ukraine.

The possibility of Miscanthus×giganteus cultivation as an energy crop on the different types of mining rocks was studied. It was revealed that a loess-like loam and red-brown clay with the added black soil were the most suitable for plant growing. The yield of dry above-ground biomass ranged from 4.3 to 6.8 t DM ha-1 after the first year of cultivation and from 8.9 to 9.7 t DM ha-1 after the second year while using these substrates. The application of amendments stimulated the growth and development of plants and increased productivity from 50 to 140%. M.×giganteus showed sufficient tolerance and good enough growth on the geochemically active dark-gray schist clay with yield from 2 to 3 t DM ha-1 after the first year of cultivation already. For plants grown on the different strata of dark-gray schist clay, the thermal decomposition of the biomass took place in four stages in the temperature range from 30 to 640 °C. The samples grown on stratum 0-20 cm showed the highest reactivity with a peak 30.6%/min at 290 °C. There were differences in the concentrations of determined heavy metals: iron, zinc, copper, and lead in the plant tissues depending on the layer depth of dark-gray schist clay from 0 to 20 cm to 40-60 cm. The relatively limited content of heavy metals in the above-ground biomass was due to the preferential accumulation in the roots.