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 0.5mg/l N6-benzylaminopurine (BA). Transfer of embryogenic calli to MS medium with 1-2mg/l BA and 0.1mg/l a-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 1.0mg/l 2,4-D and 0.5mg/l BA, embryogenic calli have retained morphogenetic potential for 12 months.

Viable protoplasts of Taxus yunnanensis were isolated from friable, light yellow callus. Protoplast yield was dependent on callus age, with a maximum from 20-day-old callus. Protoplasts were induced to undergo sustained divisions and to form cell colonies when cultured in medium consisting of B5 salts, KM vitamin and organic components, 0.45 M fructose, 3.0mg l-1 2,4-dichlorophenoxyacetic acid and 0.1 mg l-1 kinetin. The planting density was 2.5-3.0

An efficient procedure was developed for inducing callus and plant regeneration using hypocotyls segments of Astragalus adsurgens. The combinations and concentrations of different growth regulators were shown to be critical factors for both the frequency and the type of callus formation as well as for the potential of callus differentiation. Of the four morphologically distinct types of calli that were induced, a friable, yellow callus, i.e. type I, induced on MS medium supplemented with 9.0 mM 2,4-dichlorophenoxyacetic acid and 2.2 mM N6-benzylaminopurine (BA), and then transferred to MS medium containing 0.5 mM a-naphthaleneacetic acid and 8.9 mM BA, exhibited the maximum frequency of shoot regeneration (75%). After regenerated shoots were transferred onto halfstrength MS medium without growth regulators, they rooted and complete plants were obtained. Plantlet regeneration from callus cultures required 7-8 weeks.

A reproducible release of viable protoplasts was obtained from friable calli of Astragalus adsurgens. Protoplasts underwent sustained divisions and formed cell colonies when cultured in either liquid or agarose-solidified Kao and Michayluk (1975) protoplast medium (KM8P) supplemented with 1.5mg/l 2,4-D, 0.5mg/l BA and 0.5 Mglucose. Compared to liquid culture, agarose bead culture improved division frequency effectively, the two culture systems showing a plating efficiency of 0.8