SEQUENTIAL STUDY OF THE GENETIC STABILITY OF CALLUS AND REGENERATED SHOOTS IN CHRYSANTHEMUM

摘要

Callus and adventitious shoots were induced on chrysanthemum 'Red Reagan' leaves following a protocol with different steps in which several factors were studied: callus induction (two variants of MS medium and light/darkness), shoot regeneration (two variants of the medium), and shoot elongation and rooting (three variants of the medium). The influence of the different factors on the response observed and on the genetic stability was studied throughout the process. Genetic stability was assessed using RAPD markers. The identity of the samples was recorded throughout the entire process. The incubation conditions (light/darkness) did have a significant effect on the amount of callus produced. Shoot production in the regeneration phase was not influenced by the incubation conditions or variants of the medium used neither in the previous step (callus induction) nor by the medium used to induce shoot development. Regarding the genetic stability study, all shoots regenerated showed identical RAPD marker profile to those of the pot stock plant (control) and to those of the in vitro shoots from which leaves were used as explants. However, 32% of the calluses sampled after the callus induction step and 23% of those sampled after the shoot induction step were genetically different to the control. From the same explant, stable shoots and variant callus were obtained, which indicates a selection of cells that form organized growth during the process.