Scanning electron microscopy of conidia of Trichoderma stromaticum, a biocontrol agent of witches' broom disease of cocoa

Abstract

A field emission electron microscope (SEM) was used to study the conidia surface of Trichoderma stromaticum, a biocontrol of witches broom disease of cocoa. Surface features of conidia were difficult distinguish by light microscope. Conidia appeared to be verrugose and minutely roughened, but the nature of the roughening was not easy to discern. It was common to observe sheath-like structures that completely covered groups of conidia, and also details of wide cells that form the pustules. This paper presents results of scanning electron microscopy of conidial surface ornamentation of T. stromaticum.Strain and culture methods. One strain of T. stromaticum, TVC, isolated from dead cocoa broom was provided by Dr. J. C. B. Costa of CEPEC / CEPLAC, Bahia State, Brazil. Cultures were maintained on 2% malt extract agar.Material for SEM examination of conidial surfaces was obtained from cultures that were grown on 2% MEA for 12 days at 26ºC, and grown under cool white fluorescent lamp with an alternating cycle of 12h of light and 12h of darkness.Agar blocks were cut into small pieces with conidiating hyphae and fixed in 2% glutaraldehyde in 0.1 M-NaPO 4 buffer and post-fixed in buffered 1% O5O4 for 2h. The material was then dehydrated in an ethanol series (10, 25, 40, 60, 75, 85, 95, 100%) with 15 min per change. The specimens were dried in a critical point drying apparatus and sputter-coated with gold and viewed using a field emission scanning electron microscope, Leo 982 (Zeiss + Leica).

Trichoderma stromaticum spores induce autophagy and downregulate inflammatory mediators in human peripheral blood-derived macrophages

“…1 A) and microscopical oval-shaped appearance with surface folding ( Figs. 1 B and C), as previously reported ( De Melo and Faull, 2004 ).

Fig.

…”

Mycoparasitic nature of Bionectria sp. strain 6.21

“…Preparation of the material was performed according to Melo and Faull (2004). The images were observed in a Field Emission Scanning Electron Microscope (Leo 982, Zeiss+Leica).…”

Changes in hyphal morphology due to chitosan treatment in some fungal species

“…Scanning electron microscopy was carried out in accordance to the methodology described by Melo and Faull (2004) on the materials described below. In case of control suspension, the hyphae was removed from the media by using the clamp and the suspension treated with chitosans were filtered in Millipore membrane PTFE hydrophilic of pore size 0.45 µm and ∅=13 mm (São Paulo, SP, Brazil).…”