Age-dependent metabolic differences in peripheral hyphae of Rhizoctonia solani

Peripheral hyphae were separated from the remaining thallus of Rhizoctonia solani in exponential and stationary phases of growth. The QO(2) in whole cells of peripheral hyphae from young fungal colonies was on the average 2.6 times and the protein content 1.6 times greater than in peripheral hyphae from old fungal colonies. The overall rate of amino acid uptake was less in old than in young fungal colonies. In a polyuridylic acid-polyphenylalanine incorporating system, the two kinds of peripheral hyphae required ribosomes, supernatant fraction, polyuridylic acid, soluble ribonucleic acid, adenosine triphosphate, and pyruvate kinase. The rate of polyphenylalanine synthesis in old fungal colonies was slower than in the young fungal colonies. The ribosomes and supernatant fraction of the young and old fungal colonies were interchangeable and active. The factor responsible for deficient protein synthesis in old fungal colonies appears to be in the soluble fraction of the mycelium.