Role of sugars in early stage of spore germination in filamentous fungi, aspergillus nidulans

Abstract

Initiation of spore germination in filamentous fungi such as Aspergillus nidulans and Botrytis cinerea requires the presence of nutrients. In this study, involvement of sugar sensing machinery was suggested in the germination of A. nidulans spores. Germination did not occur when the spores of A. nidulans were incubated in distilled water, whereas they were successfully germinated in the presence of 5% glucose with a germination rate of over 98% after 6hr incubation. Similar results were obtained when the spores were incubated in the presence of various sugars such as fructose, sucrose, and starch. Interestingly, spore germination was not observed in the presence of D-arabinose, whereas L-arabinose could induce germination as determined by the formation of germ tubes, indicating the presence of sugar sensing machinery that distinguish between the enantiomers of sugars. This inference was further supported by a decrease in germination rate (less than 25%) upon treatment of spores with trypsin. Subsequent MALDI-TOF mass spectrometry analysis of the surface proteins of spores identified ten proteins among which eight were involved in sugar metabolism. Taken together, our results suggest that spore germination in A. nidulans is initiated by the interaction of sugars with sugar binding proteins on the surface of spores. ? 2018 THE KOREAN SOCIETY OF MYCOLOGY.