INFLUENCE OF CERTAIN PLANT GROWTH REGULATORS AND CROWN‐GALL RELATED SUBSTANCES ON BUD FORMATION AND GAMETOPHORE DEVELOPMENT OF THE MOSS PYLAISIELLA SELWYNII

Bud formation and gametophore development were studied in the moss Pylaisiella selwynii (Kindb.) Steere and Anderson grown from spores in a liquid medium consisting of inorganic salts. Indoleacetic acid and ethrel increased bud formation within a narrow concentration range. Copious bud formation was obtained with the five cytokinins tested at concentrations varying from 5 X 10 −6 to 5 X 10 −14 M. Except for about 10 % of the buds obtained with 6‐γ, γ‐dimethylallylaminopurine at 5 times 10 −14 m, the cytokinin‐induced buds failed to develop into normal gametophores. Octopine, lysopine, and octopinic acid, substances obtained from crown‐gall tumors, increased bud formation at 10 −3 m. On lysopine‐treated plants these buds developed into typical gametophores. Gemma‐like structures were obtained with octopine but no gametophores. l ‐arginine and l ‐lysine, the amino acids which respectively occur in octopine and lysopine, failed to induce gametophore formation although buds were obtained with 10 −3 m lysine. γ‐Guanidinobutyric acid induced bud formation at 10 −3 m, but these buds developed into highly abnormal gametophores. The failure of buds obtained with many of these treatments to develop into gametophores appeared to result from the formation of new cell walls in other than the normal geometrical relationship during initial divisions of the pro‐bud. The relevance of the findings to the crown‐gall problem is discussed.