Callus induction and plant regeneration in onion (Allium cepa L.).

MARINANGELI, P.A.; ZAPPACOSTA, D.C; CURVETTO, N.R; GALMARINI, C.R.

ACTA HORTICULTURAE

Año: 2005 p. 301 - 308

0567-7572

Callus induction was tested in explants of A. cepa ‘Valcatorce INTA’ from basal plate, apical meristem with basal plate, immature umbel, mature zygotic embryo (ZE), and fecundated ovule (O). Explants were cultivated on BDS medium with 0.5, 1.0 and 2.0 mg.L-1 2,4-D or Picloram in factorial combinations with 0.0, 0.1 and 1.0 mg.L-1 BAP. Plant regeneration from calli was evaluated on BDS medium with 1 mg.L-1 BAP, 2iP or kinetin. Genotype differences in callus induction and plant regeneration were evaluated on ZE of four genotypes of A. cepa (‘Valcatorce INTA’, ‘Norstar’, ‘T-412’ and ‘Granex 33’) and 2 genotypes of A. fistulosum (‘Nogiwa Negi’ and a wild line). In addition, regeneration from immature zygotic embryos (IE) of A. cepa ‘Valcatorce INTA’ was tested. Callus induction was observed in all explants of A. cepa ‘Valcatorce INTA’ irrespective of the growth regulator compositions and ratios in the media, although it was low in some treatments. Callus induction was more dependent on explant than on auxin type or concentration. 2,4-D-induced calli from ZE and O were more friable and exhibited lower root differentiation following subculture in comparison with those induced by picloram. Callus growth rate showed low variability between treatments, being in the range of 100-150% mass increase per month. A. cepa ‘Valcatorce INTA’ calli showed a low regeneration potential, averaging 6.6% for all explants derived calli. However, regeneration from IE calli was high, 73.1%. Plant regeneration from ZE calli of Allium spp. genotypes was highly variable (6.5-42.8%); this trait together with explant source type are important in order to choose a regeneration protocol involving callus induction.