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Eighty four different fungal endophytes isolated from sea grasses (5), marine algae (36) and leaves or barks of forest trees (43) were grown in vitro and the secondary metabolites secreted by them were harvested by immobilizing them on XAD beads. These metabolites were eluted with methanol and screened using SYBR Green I assay for their antiplasmodial activity against blood stage Plasmodium falciparum in human red blood cell culture. Our results revealed that fungal endophytes belonging to diverse genera elaborate antiplasmodial metabolites. A Fusarium sp. (580, IC50: 1.94 μg ml−1) endophytic in a marine alga and a Nigrospora sp. (151, IC50: 2.88 μg ml−1) endophytic in a tree species were subjected to antiplasmodial activity-guided reversed phase high performance liquid chromatography separation. Purification led to potentiation as reflected in IC50 values of 0.12 μg ml-1 and 0.15 μg ml−1 for two of the fractions obtained from 580. Our study adds further credence to the notion that fungal endophytes are a potential storehouse for a variety of novel secondary metabolites vested with different bioactivities including some that can stall the growth of the malaria parasite.
Puccinellia distans is a non-agricultural halophytic grass that has become another host plant for Epichloe typhina, hitherto not reported from Poland. In 1992 we noticed the first symptoms of choke disease in a single population of P. distans in central Poland. Since then we have observed choke disease in 5 populations of P. distans only in man-made habitats. These habitats are strongly anthropogenically salinated but they exhibit the pattern of species composition characteristic of natural salines. In this paper we test the hypothesis that the level of salinity affects the infection of P. distans by the fungus E. typhina. Seven plots were established in the field and each plot was divided into 25 subplots. Within each plot the level of infection in a spring generation of shoots was negatively correlated with salinity (common regression within the plots, beta = -0.674, df = 117, p < 0.001). Negative correlation was also found in an autumn generation within the plots (beta = -0.682, df = 94, p < 0.001) after excluding plot P in which the frequency of infected individuals was the lowest and equal only to 0.05. The proportion of individuals infected by the endophytic stage of the fungus in the populations was assessed using diagnostic polymerase chain reaction. The greatest percentage (98.3%) of infected individuals was found in the population growing in the habitat of the lowest salinity. The high salinity reduces the chance of P. distans to become infected, but may promote the stroma formation of E. typhina twice in the season. Disease expression in autumn clearly represents a misadaptation which could be explained by the fact that the species interactions described here appeared relatively recently as a result of human activity. This hypothesis requires further experimental verification.
The aim of the study was to assess the influence of environmental conditions on the composition of endophytic assemblages associated with fir clubmoss, Huperzia selago (L.) Bernh. ex Schrank et Mart. This clubmoss is a cosmopolitan species widely spread in Eurasia and North America, and its gametophytes and sporophytes are colonised by endophytic fungi. Plants for this study were collected in October 2004 and between April and October 2007 from seven European sites, differing in altitude, average annual precipitation, temperature and plant community. Endophytes were isolated on PDA medium (4% potato-dextrose agar) and identified through morphological observations. Different ecological indices were calculated for each site like colonization factor, Fisher’s alpha, Shannon’s diversity, Morista-Horn and Jaccard’s indices. Our results prove that altitude positively correlates with species diversity (Fisher’s alpha) and species richness (number of species). Moreover, the similarity assessed from Jaccard’s (0.66 for Larici-Piceetum sites) and Morista-Horn indices (0.77 for Juncetea trifidi sites) suggest the influence of plant community on fungal endophyte composition.
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