High frequency somatic embryogenesis and plant regeneration in callus cultures of Astragalus adsurgens gens Pall.

Efficient plant regeneration through somatic embryogenesis was achieved in Astragalus adsurgens. Embryogenic callus was induced from hypocotyl, not root or cotyledon explants, and the maximum induction frequency (62%) was obtained on Murashige and Skoog (1962) basal medium (MS) containing 2.0 mg/l 2,4-dichlorophenoxyacetic acid (2,4-D) and 0.5 mg/l N(6)-benzylaminopurine (BA). Transfer of embryogenic calli to MS medium with 1-2 mg/l BA and 0.1 mg/l alpha-naphthaleneacetic acid (NAA) resulted in somatic embryogenesis at high frequencies (63-74%) with an average of 280 somatic embryos per gram of embryogenic callus. After transfer onto half-strength MS medium without growth regulators, approximately 80% of somatic embryos developed into complete plantlets. Chromosome count of root tips from regenerants revealed a normal diploid, The rooted plantlets were successfuly transferred to soil with 60-80% survival, and the plants showed normal morphological characteristics. On MS medium containing 1.0 mg/l 2,4-D and 0.5 mg/l BA, embryogenic calli have retained morphogenetic potential for 12 months. (C) 1999 Elsevier Science Ireland Ltd, All rights reserved.