Glucose-induced Trehalase Activation and Trehalose Mobilization during Early Germination of Phycomyces blakesleeanus Spores

Abstract

SUMMARY: When dormant spores of Phycomyces blakesleeanus were activated without concomitant activation of trehalase, breakdown of storage trehalose during early germination was not prevented. Measurement of trehalase activity during early germination of spores activated in this way indicated a subsequent rapid activation of trehalase upon incubation of the spores in germination medium. Trehalase activity reached a maximum after about 10 min of germination; thereafter it declined to values somewhat higher than those found in dormant spores. The same was observed when the activation of trehalase which normally occurs during heat activation of the spores was suppressed by adding long-chain alcohols to the activation medium. These results argue against previous speculation that trehalase is a ‘luxury’ molecule in the spores and that its activation has no significant role in the induction of germination. They point, on the other hand, to an important role for trehalase in the induction of germination. The main factor in the germination medium responsible for the activation of trehalase was found to be glucose. When spores were incubated under conditions in which they reverted to the dormant state, this subsequent trehalase activation was not seen. The increase in trehalase activity was not dependent on protein synthesis. A less pronounced increase was seen with glucose analogues. In the presence of azide the activation was only retarded, whereas in the presence of azide and salicylhydroxamic acid strong inhibition of trehalase activation was observed.