APPLICATION OF TISSUE AND CELL CULTURES FOR BREEDING MEDICINAL PLANTS
The last method was used in Digitalis lanata breeding to fight against deterioration when applying autopollination, and against reconstitution of the whole glycoside spectrum in case of foreign pollination. Data proved that cloning by tissue culture assured homogenous material for crossing without loosing vitality nor restituting inconvenient glycosidic characters in progenies. Evaluation of effectivity is presented.
The use of cell and tissue cultures in medicinal plant breeding and genetics is a brand new method. Why use this method? The reply can be three fold: to arrive at a higher degree of homogeneity in our plant material, or conversely to raise heterogeneity of heredity, and last but not least to start mutagenesis. To have more homogeneous plant material has long been practically exigent. Cell cultures provide us the most potent alternative because they can produce plants of haploid state.
There are several cases among medicinal plants, where results were published mostly on Solanaceae species. For a different example, I mention the success of Abou-Mandour et al. (1979) with Catharanthus roseus (Apocynaceae) where the plants of progenies contained more active material than their breeding parent.
There can be another aim of breeding to have genetically more heterogenous plant material because this situation may facilitate selections later on. I refer to only one example from medicinal plant breeding accomplished by these techniques producing protoplasts from mesophyllum of leaves and of pollen sacs at Atropa belladonna as well as Nicotiana tabacum (Bajaj et al. 1978). These protoplasts were fusioned and afterwards generated plants. These were various on chromosomal behaviour such as haploids, triploids, and normal diploids, according to the authors investigation. They also found higher variability on morphological and chemical characters, so their trial was judged not only to be successful, but as a valuable one resulting in hybrids between two genera.
The third theoretical purpose of tissue cultures might be the inducement of mutagenesis.
The most interesting results were published by Yoshikawa and