The life cycle and cytology of Brachyallomyces

Abstract

Studies of nuclear and chromosome behavior in the resistant sporangia and hyphae of Brachyallomyces reveal two ways by which the life cycle of this water mold is maintained without a sexual phase. In certain isolates meiosis occurs in the resistant sporangia with subsequent apomixis in the resistant sporangium zoospores, returning the germlings to the sporophytic phase. In other isolates mitosis occurs in the resistant sporangia and meiosis is excluded from the life cycle. Two methods for inducing the gametophytic phase into the life cycle are described. In one method the resistant sporangia were germinated in 0.02 M K2HPO4 solution and gametophytes were obtained from germlings of the resistant sporangia zoospores. The other method was to cut hyphal tips from 4-day-old colonies of sporophytes growing on agar and transfer. By both methods the number of gametophytes obtained was extremely small.