In vitro plant regeneration in rough lemon (Citrus jambhiri Lush.) through epicotyl segments by direct shoot organogenesis

Abstract

The effect of Murashige and Skoog (MS) medium supplemented with various concentrations and combinations of growth hormones on direct regeneration from one month old epicotyl segments of in vitro grown rough lemon (Citrus jambhiri Lush.) seedlings was studied. The earliest bud induction in 7.5 days, highest bud induction frequency (98.50%), percent regeneration(90.53) were obtained on MS medium supplemented with 6-Benzylaminopurine (BAP) (1mglit-1) with an average number of 12.50 buds per explants. The epicotyls segments with proliferated buds were transferred to elongation media in order to improve the recovery of normal shoots. Maximum number of elongated shoots (8.50) was obtained on MS medium having BAP (0.5mglit-1) + Gibberellic Acid (GA3)(1.0 mglit-1).These elongated shoots were then rooted on MS medium containing Indole-3-butyric acid (IBA) (0.1mglit-1) + Indole-3-aceticacid(IAA)(0.5mglit-1) with highest rooting percentage(96%) and root number(5.0). Early (10.10 days) rooting was observed in MS medium supplemented with NAA1.0 mglit-1 + IBA0.5 mglit-1.The plantlet survival was 98.52%, when plantlets were transferred to plastic pots containing a mixture of garden soil and vermiculite (1:1). The hardened plants were successfully established in the soil. The present study developed protocol which can be reliably used for in vitro regeneration of rough lemon and for gene transfer studies in rough lemon, especially to induce salinity and Phytophthora tolerance.