GELRITE AND AGAR DIFFERENTLY INFLUENCE CYTOKININ-SENSITIVITY OF A MOSS

Physcomitrella patens wild-type as well as its cytokinin-sensitive dif ferentiation mutant PC22 exhibit premature as well as enhanced bud for mation when grown on basal medium gelled with Gelrite compared to plan ts grown on basal medium gelled with agar. Thus, cultivation on Gelrit e mimics cytokinin-treatment of mosses. However, plants could only res pond to exogenous cytokinin when grown on agar-media but were inhibite d by the growth regulator when grown on Gelrite. These effects could n ot be mimiced by the addition of inorganic salts, nor by the addition of glucose or rhamnose to agar-gelled basal media.