Regeneration of peanut (Arachis hypogaea) plantlets by in vitro culture of immature leaves

Abstract

The in vitro regeneration of buds, shoots, and roots from immature leaves of 3- to 5-day-old peanut (Arachis hypogaea L. cv. Colorado Manfredi) seedlings was studied under defined nutritional, hormonal, and environmental conditions. The first two leaves (2–5 mm in length) removed from aseptically germinated seeds were cultured on Murashige and Skoog medium containing vitamins as in B5 medium and 0.8% agar, supplemented with 12 combinations of naphthaleneacetic acid (NAA) (0.01 to 4 mg/L) and benzyladenine (BA) (1 and 3 mg/L). Bud regeneration occurred in all hormone combinations, but the maximum number of buds was regenerated at a concentration of 1 mg/L each of NAA and BA. Although bud regeneration was maximum with 2- to 5-mm-long leaflets, some success was also obtained with leaflets 8–13 mm long. However, no buds were regenerated when fully expanded leaflets were cultured.Development of buds into shoots was readily achieved by transferring regenerated buds into fresh medium containing 0.01 mg/L NAA and 1 mg/L BA. A few roots were induced to grow when callus with buds was also transferred to medium devoid of hormones. So far, bud regeneration from immature leaves has been induced in vitro in 5 of the 10 cultivars tested.