Evaluation of image analysis, flow cytometry, and RAPD analysis for the assessment of somaclonal variation and induced mutation in tissue culture-derived Pelargonium plants

Proliferating axillary bud cultures of P x hortorum 'Rio' were established from meristems. These were used to provide control microplants and were sources of root- and petiole-explants for adventitious regeneration. Petiole explants were also irradiated to increase variability. Fifty plants were established in the glasshouse, selected at random, from progeny of each of the treatments and were grown on to flowering. The plants were examined for morphological variation and leaves were taken for image-, flow cytometric-, and RAPD-analysis. Visual examination of the flowering control population showed no morphological variation. No random variation was observed in the root-derived adventitious regenerants. The progeny from root explants, however, appeared to have smaller leaves and were more branched than the controls. Sixteen percent of the adventitious regenerants from non-irradiated petiole explants and 24 % of the plants from irradiated petiole explants, respectively, were random morphological variants. Population means were calculated and distribution data for the image-and flow cytometric-analyses were plotted. The population mean for the root explant progeny was significantly different from the other populations which did not differ from each other or the control. Morphological aberrants, however, with two exceptions in image analysis and one exception in flow cytometry, were not classified as outliers in the respective populations. RAPD-analysis misclassified approximately 50 % of the morphological variants and normal plants screened, as both false positives and false negatives. The results are discussed in the context of the usefulness of the techniques in screening new micropropagation protocols and as an aid to the early detection and selection of off-types in production.