Compostos de reserva e permeabilização de basidiósporos de Pisolithus microcarpus

• Autor(a) principal: Godinho, Carla Soares
• Data de Publicação: 2011
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/5377
• topic: Basidiósporos; Pisolithus microcarpus; Germinação; Basidiospores; Pisolithus microcarpus; Germination; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::MICROBIOLOGIA AGRICOLA

The basidiospores of Pisolithus show low germination percentages despite possessing conspicuous reserve compounds for the provision of carbon and energy during the initial growth of the fungal hyphae. The highly hydrophobic and resistant cell wall of the basidiospore can contribute to basidiospores recalcitrance to germination. Thus, this study aimed at demonstrating the presence of glycogen, polysaccharides, lipids, RNA and proteins in mature basidiospores of Pisolithus microcarpus, determining the fatty acid profile of the basidiospores of ectomycorrhizal fungi, and evaluating methods of permeabilization of the basidiospore cell wall. Hystochemical techniques used in the detection of different reserve compounds in the basidiospores revealed the presence of glycogen, polysaccharides, proteins, RNA, lipids, lipoproteins, neutral lipids, and acidic lipids. The presence of 11 different fatty acids in the basidiospores of P. microcarpus, nine in those of Scleroderma sp. and 16 in the basidiospores of Suillus sp. was observed in our study. The most abundant fatty acids in the fungal basidiospores were 18:1w9c and 16:0. Besides oleic and palmitic acids, the following fatty acids showed significant contents: 16:1w5c 16:0, 18:1w5c for P. microcarpus; 12:1 AT11-12, 18:00 for Scleroderma sp.; 15:00 and 18:00 for Suillus sp. The fatty acid profile of the basidiospores of P. microcarpus showed 36.8 % similarity to that of Scleroderma sp. The fatty acid profile of these two species showed a similarity of only 5.2 % compared to that of Suillus sp. The use of chitinase, cellulase, and lyticase for 1, 2, 3, 4, 6, 8, 12, and 24 h, at 30 °C, under stirring at 80 rpm, and of sulfuric acid at concentrations of 5, 10, 25, 50 % (v / v) for 5, 10, 25, 50 or 80s did not promote cell wall permeability. The treatment with sodium hypochlorite at concentrations of 5, 10, 20, 30, 40, 50, 60, 70, 90 and 100 % of original concentration of active chlorine (20 g L-1) and contact times of 5, 10 , 20, 30, 40, 50, 60, 70, and 80s promoted the permeabilization of the basidiospore cell wall as evaluated by the staining of internal fatty acids with Sudan Black B. The highest percentage of permeabilized basidiospores, 97 %, was obtained with the treatment with hypochlorite at 100 % for 80s. However, the viability tests and the observation of basidiospores by scanning electron microscopy revealed the loss of viability and cell wall integrity. The exposure of the basidiospores to sodium hypochlorite at 5 % for 40s promoted the highest percentages of permeabilized basidiospores, 83 %, without loss of viability and morphological damages to the spore cell wall. These results contribute to the understanding of the variables that may play a role in the process of germination of basidiospores of P. microcarpus and allow the development of strategies to improve the isolation of monokaryons in vitro.