In vitro plant regeneration of the heavy metal tolerant and hyperaccumulator Arabidopsis halleri (Brassicaceae)

Plants were regenerated from root explants of Arabidopsis halleri (L.) O'Kane and Al-Shehbaz via a three-step procedure callus induction, induction of somatic embryos and shoot development. Callus was induced from root segments, leaflets and petiole segments after incubation for 2 weeks in Murashige and Skoog medium (MS) supplemented with 0.5 mg/l -1 (2.26 μM) 2,4-D (2,4-dichlorophenoxyacetic acid) and 0.05 mg/l -1 (0.23 μM) kinetin. Only calli developed from root segments continued to grow when transferred to a regeneration medium containing 2.0 mg/l -1 (9.8 μM) 6-γ-γ-(dimethylallylamino)-purine (2ip) and 0.05 mg/l -1 (2.68 μM) α-naphthalenacetic acid (NAA) and eventually 40 of them developed embryogenic structures. On the same medium 38 of these calli regenerated shoots. Rooting was achieved for 50 of the shoots subcultured in MS medium without hormones. The regeneration ability of callus derived from root cuttings, observed in this study, makes this technique useful for genetic transformation experiments and in vitro culture studies