A comparative study of growth regulation in fungi

Abstract

The effect of two plant growth regulating substances(GA(_3) and IAA) has been investigated on growth of Mucor mucedoand SaproLegnia parasitica. No stimulatory effect was observed at low concentrations of both substances on vegetative growth and macromolecular composition of both fungi. Instead a gradual inhibition was found at high concentrations. The only stimulation with both substances was detected on sporangiospore germination of M. mucedo at the range of concentrations between 10 and 100 ppm. Higher concentrations showed a delay of germination Macromolecular composition of these fungi as well asPhycomyces bZakesZeeanus was found to be variable. Results were discussed in terms of relation of these figures to growth rate of the test fungi. Flooding of M. mucedo and P. bZakesZeeanus colonies with their liquid culture medium resulted in unexpected responses (bursting and/or swelling of hyphal tips followed by apicalbranching). Electron microscopy was used as an aid to investigate these phenomena. No observations were obtained directly relating to the bursting of P. bZakesZeeanus hyphal tips. Nevertheless 1 flooding of M. mucedo colonies revealed a high production and accumulation of nearly all cytoplasmic components in the swollen tips which indicated high metabolic activities and thus formation of two or more apical branches. Studies of regeneration of protoplasts produced fromP. blakesZeeanus and S. parasiticav revealed two different patterns. S. parasitica showed unusual regeneration process, protoplast developed an abnormal, very thin hypha(e), sometimes branched with a swollen tip(s) f later on a normal developed from the abnormal one and continued to grow as a normal hypha.Serological methods used to study the relationship between the chitin and cellulose-walled fungi revealed weak antigenic reactivities between representatives of both groups of fungi. Likewise between the members of the chitin-walled fungi, in contrast to the high cross reactivities between the cellulose-walled fungi.