Abstract
Protoplasts of Pyricularia oryzae, which were isolated from mycelium or germ-tube by 1% Cellulase “Onozuka” R-10 and 1% Driselase, kept spherical shape and sensitivity to osmotic change, and became larger in size when incubated in potato sucrose broth or the synthetic medium containing 0.6M sucrose and also the enzymes. Twenty-four hr after incubation, more than half of the protoplasts became double or more in size. The formation of the giant protoplasts was inhibited by adding IBP or kasugamycin, but not by adding polyoxin D. The incubated protoplasts were fractionated to the giant-rich fraction and the original-size fraction by the two phase system with 0.6M mannitol and 0.6M sucrose. The giant protoplasts kept their viability as well as the original-size did, and had higher metabolic activity in all biosynthesis of protein, DNA, RNA, lipid and cell wall than the original-size had. These results suggest that this protoplast incubation system with the enzymes may be not so poisonous that the protoplasts could keep viability and grow without cell wall, and consequently become giant.
