Dm6 compound microscope

Soil samples containing needle nematodes resembling L. leptocephalus were collected at a depth of 10 to 30 cm from the rhizosphere of grapevine in the area of Thessaloniki, northern Greece. Nematodes were extracted from soil by modified sieving and a decanting method (Brown and Boag, 1988 ). Extracted specimens were handpicked, heat killed, fixed in TAF (triethanolamine formalin), processed using glycerol by a slow evaporation method, and mounted on permanent slides (Hooper, 1986 ). The light micrographs and measurements of nematodes population, including the main diagnostic characteristics, were performed using a Leica DM6 compound microscope with a Leica DFC7000 T digital camera. All other abbreviations used were as defined in the study by Jairajpuri and Ahmad (1992) .

Ten sunflower root pieces with O. cumana seedlings attached were cut from the sunflower plants of the rhizotron assay at 14, 21, 28, and 35 dpi using a binocular microscope. Samples were prepared as in Chabaud et al. (2022 ). Half of the samples were fixed in ethanol: acetic acid (3:1 by volume) for 10 min under vacuum, cleared in chloral hydrate 5 g/ml for 48 h under agitation and visualized with an Axioplan 2 light microscope (Zeiss, Jena, Germany). The remaining samples were fixed in FAA solution (10% formaldehyde, 5% acetic acid, and 50% ethanol) for 5 min under vacuum, dehydrated in alcohol series, and embedded in Technovit 7100 resin (Heraeus Kulzer, Germany). Thin sections of 10 µm were then made using a Reichert-Jung 2040 microtome (Leica Biosystems, Nussloch, Germany), stained with 0.2% toluidine blue for 3 min, mounted in DePeX mounting medium and scanned using a NanoZoomer image scanner (Hamamatsu Photonics, Japan). For the detection of phenolic compounds, hand-cut sections (with a razor blade) obtained from fresh root samples at 14, 21, 28, and 35 dpi were observed under epifluorescence (340–380 nm), as described in Lozano-Baena et al. (2007 (link)), in a Leica DM6 compound microscope with a Leica DFC7000 T digital camera (Wetzlar, Germany).