Rapid and high-frequency in vitro plant regeneration from leaflet and petiole explants of groundnut (Arachis hypogaea L.)

An efficient protocol for regeneration of groundnut plantlets from immature and mature leaflet and petiole explants excised from axenic seedlings has been developed. The highest frequency of callus induction obtained from leaflet explants was on Murashige and Skoog (MS) medium containing 2.0 mg/L of alpha-naphthalene acetic acid (NAA) and 0.5 mg/L of kinetin combination. MS medium containing different auxins in combination with 6-benzylaminopurine (BAP) induced shoot buds. A BAP (2.0 mg/L) and NAA (0.5 mg/L) combination resulted in the highest frequency of shoot-bud regeneration. Subsequent shoot multiplication was obtained on MS medium supplemented with either BAP or kinetin (5.0 mg/L) in combination with NAA (1.0 mg/L). Immature leaflet explants were found to be more responsive to shoot induction than mature leaflet explants. Direct shoot-bud regeneration was also observed from petiole explants on the same regeneration medium used for leaflet callus. Regenerated shoots were rooted on MS medium containing indole-3-butyric acid (2.0 mg/L) and kinetin (0.5 mg/L). Plantlets obtained were successfully established in the field, where they grew to maturity and set viable seeds.