Genotypic and growth regulator effects on shoot regeneration from hypocotyl and stem segment explants of spring rapeseed (Brassica napus L.)

The aim of the study was to determine the effect of genotype, explant type and growth regulators on shoot regeneration from stem segments and hypocotyls in spring rapeseed. Eleven commercially important spring rapeseed cultivars were tested for the regeneration capacity through direct/indirect shoot regeneration. Significant genotypic variability in adventitious shoots regeneration was evident for both explant sources. Shoot regeneration frequency ranged between 0% and 26.0% and between 38.7% and 100% for hypocotyls and stem segments, respectively. Among genotypes studied, hypocotyls of cultivars Maskot, Terra H and Ability showed the highest capacity to produce shoots, while the highest regeneration frequency from stem segments was obtained for cultivar Sponsor. The comparison between the regeneration ability of different explants showed that the overall regeneration efficiency was four-times ('Griffin') to twelve-times ('Sponsor') higher when using stem segments instead of hypocotyls. Cytokinine BAP induced efficient shoot regeneration from stem segments of ten from eleven tested cultivars. Combination of BAP and NAA significantly improved shoot formation frequency from hypocotyl of 'Mascot' and 'Terra H' and from stem segment of cultivar 'Campino'. Throughout this study shoots with normal appearance and without vitrification were obtained. The regenerated shoots were rooted on MS medium with 0.1 mg l(-1) NAA. The regenerated plants acclimatized in soil were normal in respect to morphology and growth characters. This system of adventitious shoot regeneration from evaluated explants could potentially be useful in genetic transformation or in vitro selection experiments of spring rapeseed.