Glucose-initiated Germination ofMucor racemosus Sporangiospores

Treatments leading to the initiation of germination of Mucor racemosus sporangiospores were examined. The results support the hypothesis that glucose is a specific trigger molecule for the initiation of Mucor racemosus sporangiospores. Glucose and some of the glucose analogues tested could initiate germination, mannose, 3-O-methyl-D-glucose, 5-thio-D-glucose and 6-deoxy-D-glucose being the most effective. The initiation event appeared to depend on the concentration of the initiator, with glucose and 3-O-methyl-D-glucose exhibiting nearly identical kinetic constants. Spores accumulated not only glucose and 3-O-methyl-D-glucose, but also the 1-O-methyl-D-glucose analogue, which did not initiate germination. The accumulated 3-O-methyl-D-glucose was not metabolized. The initiation sequence appeared to require the continued presence of the initiator as well as protein synthesis.