Phenol-mediated suppression of soil-borne root-infecting fungi in mungbean

Under field conditions, there is a variety of phenolic acids as well as other toxic and non-toxic organic compounds that interact with plant seeds and roots; but in laboratory bioassays, with few exceptions, only single phenolic acids are usually tested. In this study, the effect of various concentrations of two phenolics (caffeic acid and p-hydroxybenzoic acid) on the wilt-inducing fungus Fusarium solani and the damping-off fungus Rhizoctonia solani was tested in pot experiments. The effect of these phenolics on the biocontrol efficacy of Pseudomonas aeruginosa, a plant growth-promoting rhizobacterium, was also evaluated. Caffeic acid and p-hydroxybenzoic acid significantly suppressed F. solani and R. solani infection in mungbean. However, high concentrations of the phenolic acids interfered with plant growth. P. aeruginosa in the rhizosphere declined in the presence of caffeic acid and p-hydroxybenzoic acid

Factors influencing the effectiveness of non-pathogenic Fusarium solani strain Fs5 in the suppression of root-knot nematode in tomato

Four experiments were carried out under greenhouse conditions to evaluate the effectiveness of Fusarium solani strain Fs5 against the root-knot nematode Meloidogyne javanica. The effect of population densities of M. javanica, various application rates of F. solani, moisture regimes and levels of benzaldehyde, a volatile compound of plant origin affecting the plant-nematode-fungus interaction, were also studied. F. solani parasitized eggs and females of M. javanica and thereby reduced root-knot severity in tomato. Although the fungus was frequently isolated from root tissues, it did not produce phytotoxic symptoms; instead, there was enhanced plant growth. At higher nematode densities, inner root colonization by the fungus increased. The rates of fungal infection on M. javanica eggs and females also increased with increasing nematode densities and fungal inoculum levels. Nematode invasion and subsequent root-knot increased with increasing soil moisture, in both F. solani-treated and untreated plants. However, root-knot development was lower at all moisture regimes when F. solani was applied to the soil. Root colonization by F. solani and parasitism on female nematodes was highest at 50% moisture holding capacity (MHC) whereas egg parasitism by the fungus was greatest at 75% MHC. With increasing concentration of benzaldehyde in soil, nematode penetration and subsequent root-knot infection were progressively reduced. Root colonization by F. solani was greatest in soil treated with benzaldehyde at 2 µg g-1 of soil in the presence of M. javanica. Increasing benzaldehyde concentrations resulted in increased parasitism of M. javanica females by F. solani but in lower parasitism of the eggs. Treatments with F. solani led to better plant growth when they were combined with benzaldehyde at 2 µg g-1 of soil

Avicennia marina (mangrove) soil amendment changes the fungal community in the rhizosphere and root tissue of mungbean and contributes to control of root-knot nematodes

The effect of soil amendment with Avicennia marina (mangrove) on mungbean growth and mungbean infestation with Meloidogyne javanica was determined in greenhouse pot experiments. Galling and final nematode population densities were reduced by all soil amendments with mangrove. To better understand whether nematode suppression by A. marina was caused directly by the release of nematicidal factor(s) into the soil, or was due indirectly to changes in the fungal community, the diversity of the rhizosphere populations of culturable fungi was assessed before organic amendment (day 0), after decomposition but before seed sowing (day 15) and at harvest (day 73). Thirteen out of 20 fungal species were isolated from both A. marina-amended and unamended soils, the most frequent genera being Alternaria, Aspergillus, Fusarium, Penicillium, Trichoderma, Mucor, Myrothecium and Rhizoctonia. The other seven were found only in amended soils. At different times in the course of the experiment amended and unamended soils differed significantly in the fungi isolated from the rhizosphere and/or in the concentrations of A. marina. Trichoderma viride was isolated only from surface-sterilized mungbean roots grown in amended soils, whereas Chaetomium sp. was isolated only from unamended soils

Non-Newtonian effects in the peristaltic flow of a Maxwell fluid

We analyzed the effect of viscoelasticity on the dynamics of fluids in porous media by studying the flow of a Maxwell fluid in a circular tube, in which the flow is induced by a wave traveling on the tube wall. The present study investigates novelties brought about into the classic peristaltic mechanism by inclusion of non-Newtonian effects that are important, for example, for hydrocarbons. This problem has numerous applications in various branches of science, including stimulation of fluid flow in porous media under the effect of elastic waves. We have found that in the extreme non-Newtonian regime there is a possibility of a fluid flow in the direction {\it opposite} to the propagation of the wave traveling on the tube wall.Comment: to Appear in Phys. Rev. E., 01 September 2001 issu

Nematicidal and allelopathic responses of Lantana camara root extract

The impact of root leachates of Lantana camara L., a tropical weed, against Meloidogyne javanica, the root-knot nematode, was tested under laboratory and pot conditions. Concentrated and diluted root leachate caused substantial mortality of M. javanica juveniles. Significant suppression of the nematode was achieved when soil was treated with a full-strength concentration of the leachate. Whilst this high concentration retarded plant height and shoot fresh weight, more diluted concentrations actually enhanced plant growth. To establish whether this inhibition of plant growth from the leachate was the result of depleted nitrogen levels in the soil due to the leachate, soil treated with such leachates was given urea as an additional nitrogen source. Urea not only enhanced nematode suppression activity of the root leachates but also increased seedling emergence and growth of mungbean. Application of the L. camara root leachates in combination with Pseudomonas aeruginosa, a plant growth-promoting rhizobacterium, significantly reduced nematode population densities in roots and subsequent root-knot infection, and enhanced plant growth. While a high concentration of root leachate slightly reduced P. aeruginosa colonization in the rhizosphere and inner root tissues, the nematicidal efficacy of the bacterium was unaffected. The root leachate of L. camara was found to contain phenolic compounds, including p-hydroxybenzoic acid, vanillic acid, caffeic acid, ferulic acid and a quercetin glycoside, 7-glucoside. It also contained weak enzymic hydrogen cyanide

Multi-trait analysis characterizes the genetics of thyroid function and identifies causal associations with clinical implications

To date only a fraction of the genetic footprint of thyroid function has been clarified. We report a genome-wide association study meta-analysis of thyroid function in up to 271,040 individuals of European ancestry, including reference range thyrotropin (TSH), free thyroxine (FT4), free and total triiodothyronine (T3), proxies for metabolism (T3/FT4 ratio) as well as dichotomized high and low TSH levels. We revealed 259 independent significant associations for TSH (61% novel), 85 for FT4 (67% novel), and 62 novel signals for the T3 related traits. The loci explained 14.1%, 6.0%, 9.5% and 1.1% of the total variation in TSH, FT4, total T3 and free T3 concentrations, respectively. Genetic correlations indicate that TSH associated loci reflect the thyroid function determined by free T3, whereas the FT4 associations represent the thyroid hormone metabolism. Polygenic risk score and Mendelian randomization analyses showed the effects of genetically determined variation in thyroid function on various clinical outcomes, including cardiovascular risk factors and diseases, autoimmune diseases, and cancer. In conclusion, our results improve the understanding of thyroid hormone physiology and highlight the pleiotropic effects of thyroid function on various diseases.</p

Multi-trait analysis characterizes the genetics of thyroid function and identifies causal associations with clinical implications

To date only a fraction of the genetic footprint of thyroid function has been clarified. We report a genome-wide association study meta-analysis of thyroid function in up to 271,040 individuals of European ancestry, including reference range thyrotropin (TSH), free thyroxine (FT4), free and total triiodothyronine (T3), proxies for metabolism (T3/FT4 ratio) as well as dichotomized high and low TSH levels. We revealed 259 independent significant associations for TSH (61% novel), 85 for FT4 (67% novel), and 62 novel signals for the T3 related traits. The loci explained 14.1%, 6.0%, 9.5% and 1.1% of the total variation in TSH, FT4, total T3 and free T3 concentrations, respectively. Genetic correlations indicate that TSH associated loci reflect the thyroid function determined by free T3, whereas the FT4 associations represent the thyroid hormone metabolism. Polygenic risk score and Mendelian randomization analyses showed the effects of genetically determined variation in thyroid function on various clinical outcomes, including cardiovascular risk factors and diseases, autoimmune diseases, and cancer. In conclusion, our results improve the understanding of thyroid hormone physiology and highlight the pleiotropic effects of thyroid function on various diseases.</p

Gaia Early Data Release 3: The celestial reference frame (Gaia-CRF3)

Context. Gaia-CRF3 is the celestial reference frame for positions and proper motions in the third release of data from the Gaia mission, Gaia DR3 (and for the early third release, Gaia EDR3, which contains identical astrometric results). The reference frame is defined by the positions and proper motions at epoch 2016.0 for a specific set of extragalactic sources in the (E)DR3 catalogue. Aims. We describe the construction of Gaia-CRF3 and its properties in terms of the distributions in magnitude, colour, and astrometric quality. Methods. Compact extragalactic sources in Gaia DR3 were identified by positional cross-matching with 17 external catalogues of quasi-stellar objects (QSO) and active galactic nuclei (AGN), followed by astrometric filtering designed to remove stellar contaminants. Selecting a clean sample was favoured over including a higher number of extragalactic sources. For the final sample, the random and systematic errors in the proper motions are analysed, as well as the radio-optical offsets in position for sources in the third realisation of the International Celestial Reference Frame (ICRF3). Results. Gaia-CRF3 comprises about 1.6 million QSO-like sources, of which 1.2 million have five-parameter astrometric solutions in Gaia DR3 and 0.4 million have six-parameter solutions. The sources span the magnitude range G = 13-21 with a peak density at 20.6 mag, at which the typical positional uncertainty is about 1 mas. The proper motions show systematic errors on the level of 12 μas yr-1 on angular scales greater than 15 deg. For the 3142 optical counterparts of ICRF3 sources in the S/X frequency bands, the median offset from the radio positions is about 0.5 mas, but it exceeds 4 mas in either coordinate for 127 sources. We outline the future of Gaia-CRF in the next Gaia data releases. Appendices give further details on the external catalogues used, how to extract information about the Gaia-CRF3 sources, potential (Galactic) confusion sources, and the estimation of the spin and orientation of an astrometric solution