Screening of Aster wild germplasm for in vitro response to regeneration.

A screening for in vitro regeneration capacity was performed on sixteen wild species of Aster (A. alpinus, A. amellus, A. caucasicus, A. cordifolius, A. divaricatus, A. ericoides, A. foliaceus, A. greatai, A. lateriflorus, A. novae-angliae, A. ptarmicoides, A. squamatus, A. sedifolius, A. tenellus, A. tongolensis, A. tripolium). Leaf explants were cultured on MS medium in presence of 0.1 mg l*[-1) 2,4 D. After few days of culture, callus induction was obtained in all the species except A. greatai. However, the induction rates and the callus amount differed significantly between the 16 species. After four months, only A. divaricatus regenerated shoots from 32% of the explants with an average of two shoots per leaf explant. Callus induction and plant regeneration were highly genotype-dependent and the callus growth rate may not be adopted in Aster as an indicator for the selection of genotypes with good regeneration potential. Forty-three% of regenerants showed white ligulate flowers, whereas the donor plant was pink. Moreover, variations were detected in the regenerated plants (R1) for quantitative characters such as capitulum and disc diameters, and number of ligulate flowers. Since Aster can be propagated, selection of variants in R1 can provide interesting material for breeding purposes