Cyclic AMP, Trehalase and Germination of Phycomyces blakesleeanus Spores

Abstract

When heat activated Phycomyces blakesleeanus spores were incubated at room temperature a rapid and transient increase in cyclic AMP content was observed. A similar increase was observed during the heat treatment itself but the cyclic AMP content had returned to the value of dormant spores at the end of the 5 min treatment. The cyclic AMP content increased only after treatments at temperatures which also induced spore germination. A more gradual rise in cyclic AMP was also found during activation at room temperature with acetate and after activation of the spores with pyrosulphite. The increase in cyclic AMP content is the earliest event known to occur after activation of the spores. It clearly preceded the increase in trehalase activity observed during and/or after all the activating treatments, suggesting that, as shown for in vitro activation, the in vivo activation of trehalase is due to a cyclic AMP-dependent phosphorylation. An increase in cyclic AMP was a common feature of all activation methods investigated and appears to be the factor triggering spore germination.