The ultrastructure of germinating conidia of Penicillium digitatum inhibited by sec-butylamine

Electron micrographs of germinating conidia of P. digitatum showed osmiophilic inclusions scattered in the ground plasm or located within membrane-bound vacuoles where they were associated with various membranes and “myelin-like” structures. Cytochemical studies suggested that the osmiophilic inclusions within the vacuoles contained phospholipids and proteins. These phospholipoprotein inclusions may provide precursors needed for the assembly of membrane-bound organelles formed during germination. In conidia germinated in the presence of fungistatic concentrations of sec-butylamine (SBA) the vacuoles enlarged and the phospholipoprotein inclusions decreased in size and appeared to disintegrate and give rise to membrane-bound vesicles. SBA may deprive the conidium of materials normally utilized for membrane formation by the developing organelles.