TDZ, auxin and genotype effects on leaf organogenesis in Fragaria.

The different types oforganogenic (roots and adventitious shoots) and callus formation responses of leaves from 30-day-old proliferating shoots of different Fragaria spp. genotypes were studied in response to MS medium supplemented with 4.54 μM 1-phenyl-3-(1,2,3-thiadiazol- 5-yl) urea (thidiazuron; TDZ) alone and in combination with 0.98 μM indole-3-butyric acid (IBA), 0.84 μM3- benzo[b]selenienyl acetic acid (BSAA) or 0.90 μM2,4- dichlorophenoxy acetic acid (2,4-D). The study included: nine octoploid Fragaria x ananassa cultivars and breeding selections; two octoploid breeding selections from F. virginiana glauca inter-species crosses; two diploid F. vesca cultivars; and one diploid clone of F. nubicola Lindl. TDZ plus IBA promoted the highest shoot regeneration efficiencies from leaves of nearly all of the genotypes, while the TDZ/BSAA and TDZ/2,4-D combinations promoted high regeneration efficiencies for only some of the genotypes (Alpina W.O., Sveva, AN 91.371.53, Onda, Paros and FO93.143.5). For the more efficient regenerating genotypes, IBA induced the highest frequency of regenerating leaves, while BSAA induced the highest number of regenerated shoots from leaves and more callus production for most of the genotypes.