Callus induction and de novo regeneration from callus in Guar (Cyamopsis tetragonoloba)

Abstract

Guar (Cyamopsis tetragonoloba L. Taub) is a drought tolerant and multipurpose grain legume cash crop grown primarily under rainfed conditions in several countries. The effect of various growth regulators and their combinations on a variety of explants, namely the embryo, cotyledons, cotyledonary nodes, shoot tip and hypocotyle, has been studied and an efficient system for callus induction and regeneration from callus has been developed. It was established that Murashige and Skoog’s culture medium containing 2,4-dichlorophenoxyacetic acid (10.0μM) in combination with 6-benzylaminopurine (5.0μM) with embryo or cotyledon explants is most suitable for induction of green and friable morphogenic callus, with a range of 82.5–95% of cultured explants responding to callus induction. Efficient de novo shoot regeneration was achieved by culturing the callus obtained on this medium on Murashige and Skoog’s medium containing 1-naphthlenacetic acid (13.0μM) in combination with 6-benzylaminopurine (5.0μM) with a range of 82.1–88.4% of callus clumps producing 20–25 shoots. In vitro rooting of cultured shoots was obtained on half-salt concentration of Murashige and Skoog’s culture medium supplied with indole-3-butyric acid (5.0μM) on which 82–90% of cultured shoots produced healthy roots. The in vitro regenerated plants were grown to pod setting and subsequent maturity under greenhouse conditions.