Rapid shoot regeneration from thin cell layer explants excised from petioles and hypocotyls in four cultivars of Brassica napus L.

The present work describes a procedure that allows for the easy and rapid induction of caulogenesis in four cultivars of Brassica napus L. from transversal Thin Cell Layers (tTCLs). In order to investigate the regeneration ability of this crop, the effects of genotype, explant source and culture medium were examined on shoot regeneration. The tTCL explants were excised from hypocotyl and petiole of 2-week-old seedlings and cultured on a solid basal MS medium supplemented with α-naphthaleneacetic acid (NAA: 0.1–0.4 mg l⁻¹), 6-benzylamino-purine (BAP: 1–4 mg l⁻¹) and sucrose (20–40 g l⁻¹). A significant genotypic effect was observed between the four cvs; Jumbo and Drakkar displayed higher capacities to produce shoots than Pactol and Cossair. Regeneration commenced earlier and the percentage of shoot-producing explants as well as the number of shoots per regenerating explant was greater. The comparison between the regeneration ability of different explants showed that the hypocotyls exhibited a high rate of shoot organogenesis when they were cultured on MS medium supplemented with 3 mg l⁻¹ BAP, 0.3 mg l⁻¹ NAA and 30 g l⁻¹ sucrose. Adventitious shoot buds developed from 46% of the tTCLs, with a mean of 7.5 buds. Furthermore, the method was fast with shoot formation occurring by 7 days culture. Plantlets regenerated from all shoots and developed normally. The regenerated plants were fertile and identical to source plants.