The induction, in vitro, of chromosomal variation in Rosa
The culture in vitro was investigated in 7 clones of roses representing a range of genotypes and ploidy levels. Particular attention was paid to a sterile hybrid, R. persica x xanthina , from which it was hoped to obtain tetraploid clones. It was anticipated that tetraploid clones might be fertile and that this would facilitate introgressive hybridization of R.persica genes into various classes of cultivated roses. Propagation medium was developed based on MS salts and vitamins supplemented with BAP and NAA. Doubling times of 2-4 weeks were obtained on optimum media. Transplantation to soil was achieved with R.wichuraiana had a 99% success rate _____ conditions when a misting system was used whereas transplantation with R.ruRpsa 'Scabrosa' was only 46% successful and no success was achieved with R.persica x xanthina . Success rates were subsequently improved R.persica varying degrees of success, on transfer to in vivo to 80% with 'Scabrosa' and Sorbarod plugs prior to transplantation. Whilst in culture adventitious shoots were induced clones (R.laevigata , R.wichuraiana and R.persica R.persica shoots x xanthina by the use of from leaves of 3 x xanthina ) but only with adventitious callus. The cell established _____ procedure. This was exposure to colchicine gave x xanthina from _____ did it prove possible to induce internodal stem segments, roots, leaves and the cycle time of in vitro as 10.25 hours used in discussing diploid rose R.wichuraiana was using an autoradiographic the optimal duration of solution. It was complete spindle inhibition without a found that reduction 0.05% colchicine mitotic index. in The addition of DMSO was shown to aid the uptake of colchicine into shoot meristems. Terminal buds of R.wichuraiana and R.persica x xanthina were exposed level to colchicine solution in plants derived from these buds was and measuring length of stomata vitro and the determined by ploidy of karyotyping of root cells (LIII layer) (LI layer). X-irradiation was used in vitro to obtain different morphological forms, dose rates of 3, 4 and 5 krads producing 68, 100 and 80% mutant forms respectively. It is suggested that the combined use of drug and X-ray treatments, use of GA^ and protoplast fusion in vitro would be appropriate subjects for further investigation.