Genetic, ontogenetic and physiological factors and the development of a broad-spectrum medium for Begonia rex Putz. cultivars

Abstract

The morphogenetic responses of petioles from mature plants of 6 arbitrarily selected cultivars of Begonia rex on a defined medium were investigated. Variation in cultivar response was observed. In an attempt to reduce non-genetic variation due to possible ontogenetic and physiological variation between the stock plants, young axenic leaves from the above cultures were sub-cultured on a defined medium. Again variation in tissue culture responses was observed. To determine the extent of the putative genetic variation between cultivars, and to develop a broad-spectrum medium for all the cultivars, young axenic leaves of each cultivar were set up on auxin/cytokinin factorial media. On the basis of these studies a single medium can be defined, appropriate for the majority but not all of the cultivars. This strategy for the development of broad-spectrum media is discussed but not reached. It is emphasized that it will be necessary to discriminate against cultivars with low morphogenetic potential on the defined medium. The alternative is recurrent medium development.