Characterization of Phycomyces blakesleeanus mutants temperature-sensitive for heat-shock induced germination.

Sixty-nine mutants of the fungus Phycomyces blakesleeanus, temperature-sensitive for heat-shock induced germination, have been characterized. All of them show a low viability at 26 degrees C and normal viability at 16 degrees C. Eleven mutants recover the wild type phenotype if yeast extract is added to the minimal medium; the mutant phenotype of eight of these mutants is also suppressed by the addition of putrescine or other polyamines. The majority of the mutants are affected very early in germination. Spontaneous, heat-shock and acetate induced germination are not equally impaired by some of the mutations, so specific and independent steps seem to be involved in part of the activation mechanism of germination.