Cogumelo "shiitake" (Lentinula edodes) reduz o crescimento de fitopatógenos e a severidade de manchas foliares em sorgo “shiitake” (Lentinula edodes) mushroom reduces growth of plant pathogens and leaf spot severity in sorghum

Lentinula edodes (cogumelo "shiitake") é um fungo basidiomiceto que apresenta propriedades nutricionais, medicinais e antibióticas. Compostos de interesse para o homem têm sido isolados do basidiocarpo e dos filtrados de cultura obtidos a partir do crescimento micelial. O presente trabalho teve como objetivos avaliar o efeito de diferentes preparações de L. edodes sobre patógenos da cultura do sorgo, Exserohilum turcicum e Colletotrichum sublineolum, bem como a proteção das plantas de sorgo contra estes patógenos. Em testes com placas de Petri e lâminas de vidro para microscopia, extratos aquosos obtidos do basidiocarpo inteiro e de suas partes individualizadas, píleo e estipe, reduziram a taxa de crescimento micelial e inibiram a germinação de esporos dos fungos, enquanto a atividade antifúngica do filtrado de crescimento micelial foi menos pronunciada. Em mesocótilos de sorgo, as diferentes preparações do "shiitake" não provocaram o acúmulo de fitoalexinas. O extrato aquoso do basidiocarpo e o composto lentinana reduziram parcialmente a severidade das doenças provocadas por E. turcicum na cv. Brandes e por C. sublineolum na cv. Tx-398-B, quando pulverizados 48 horas antes da inoculação das plantas, sob condições de casa de vegetação. Portanto, L. edodes apresenta potencial como agente de controle biológico ou como um modelo para a síntese de substâncias fungicidas.<br>Lentinula edodes ("shiitake" mushroom) is a fungus that presents nutritional, medicinal and antibiotic properties. Valuable compounds have been isolated from the fruiting bodies and from mycelium growth filtrates. The present work had as objectives the evaluation of the effect of L. edodes preparations on two sorghum pathogens, Exserohilum turcicum and Colletotrichum sublineolum, as well as the protection of sorghum plants against those fungi. When in vitro studies were carried out, aqueous extracts from the whole fruiting bodies and also from fruiting body parts, cap and stem, reduced the mycelium growth and the spore germination of the plant pathogens, while the antifungal activity of L. edodes´s mycelium growth filtrate was less pronounced. The shiitake preparations did not induce phytoalexin accumulation in sorghum mesocotyls. Aqueous extracts from fruiting bodies and lentinan partially reduced disease severity caused by E. turcicum in the cv. Brandes and by C. sublineolum in the cv. Tx-398-B, when applied 48 hours before plant inoculation. Therefore, L. edodes exhibits potential as a biological control agent or as a model for the synthesis of fungicidal compounds

Purification and characterization of a novel antifungal protein from Bacillus subtilis strain B29*

An antifungal protein was isolated from a culture of Bacillus subtilis strain B29. The isolation procedure comprised ion exchange chromatography on diethylaminoethyl (DEAE)-52 cellulose and gel filtration chromatography on Bio-Gel® P-100. The protein was absorbed on DEAE-cellulose and Bio-Gel® P-100. The purified antifungal fraction was designated as B29I, with a molecular mass of 42.3 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), pI value 5.69 by isoelectric focusing (IEF)-PAGE, and 97.81% purity by high performance liquid chromatography (HPLC). B29I exhibited inhibitory activity on mycelial growth in Fusarium oxysporum, Rhizoctonia solani, Fusarium moniliforme, and Sclerotinia sclerotiorum. The 50% inhibitory concentrations (IC50) of its antifungal activity toward Fusarium oxysporum and Rhizoctonia solani were 45 and 112 μmol/L, respectively. B29I also demonstrated an inhibitory effect on conidial spore germination of Fusarium oxysporum and suppression of germ-tube elongation, and induced distortion, tumescence, and rupture of a portion of the germinated spores