Responses of Marchantia in Aseptic Culture to Well-known Auxins and Antiauxins

Responses of young thalli of Marchantia nepalensis to ten well-knownauxins and antiauxins in aseptic culture are described. Effectsof one concentration of an auxin or an antiauxin were studiedin both liquid and solid cultures. The normal growth of inoculated thalli was inhibited but callus-liketissue was produced on them by the highest concentration (I.Omg./I.) of almost all the growth substances except MH, TIBA,and 2, 4^–DNP. At a later period callus-like tissue producedby IAA, IBA, and IPA differentiated into new thalli but thatproduced by NAA, NOA, 2,4^–D, and TCPA only did so on beingtransferred to control medium. At lower concentrations inoculated thalli developed normallybut they were soon overgrown by daughter thalli. No protonemalphase comparable to that of mosses could be observed in thedevelopmental stage of a regenerating thallus. The early stageis characterized by a stable filamentous structure, normallyconsisting of two to three cells. Filamentous structures ofvarying number of cells were however produced in some treatments. Profuse rhizoids were produced by the highest concentrationof NOA, 2,4^–D, TCPA, IBA, and IPA. Certain growth substancesinhibited the formation of tuberculate but not of smooth rhizoidsin liquid but not in solid cultures. Also tuberculate rhizoidswith feebly developed pegs were produced in certain liquid culturesonly and even in control liquid culture. More gemma-cups wereproduced in liquid cultures. Germinated gemmae with rhizoidswere invariably present in solid but not in corresponding liquidcultures. Germinated gemmae within gemma-cups were frequentlyfound. The significance of these results is discussed.