High-frequency plant regeneration from hypocotyl- and leaf-derived tissue cultures of the tropical pasture legume Stylosanthes humilis

Callus cultures were established from seedling hypocotyls of the tropical pasture legume Stylosanthes humilis H.B.K., and from leaves of in vitro-grown regenerated plantlets and glasshouse-grown plants. Callus was induced on Murashige and Skoog medium, supplemented with 1.0 mg/1 each of benzyladenine and naphthaleneacetic acid, and subcultured on the same medium with 0.5 mg/1 each of the same plant growth regulators. Induction of shoot formation occurred with a number of benzyladenine/naphthaleneacetic acid combinations. With 1.0 mg/1 benzyladenine (no auxin) all hypocotyl-derived calli and 78% (in vitro-grown plantlets) and 56% (glasshouse-grown plants) of the leaf-derived calli could be induced to form shoots. Morphogenetic potential was maintained during five subcultures. The process of induction of shoot formation took generally longer in leaf-derived calli than in those derived from hypocotyls. Most regenerated plants survived transfer to soil and all tested plants nodulated if inocculated with Rhizobium . No morphological abnormalities were observed.