High frequency induction of multiple shoots and plant regeneration from seedling explants of pigeonpea (Cajanus cajan l.)

An efficient and direct shoot bud differentiation and multiple shoot induction from seedling explants of pigeonpea (Cajanus cajan L.) has been achieved. The frequency of shoot bud regeneration was influenced by the type of explant, genotype and concentrations of cytokinin. Explants, viz. epitocotyl, hypocotyl, leaf, cotyledon and cotyledonary nodal segments from 7-day-old seedlings were cultured on MS medium augmented with different concentrations of BAP/kinetin. Among the various concentrations tested, 2.0 mg/l BAP or kinetin was found to be the best for maximum shoot bud differentiation. Percentage as well as the number of shoots per explant showing differentiation of shoot buds was higher on MS media supplemented with BAP compared to kinetin. Elongation of multiple shoots was obtained on MS medium fortified with BAP in combination with NAA and GA3. The optimal BAP concentration for shoot elongation was 1.0 mg/l. The combination of 1.0 mg/l BAP with 0.1 mg/l NAA increased the number of multiple shoots as well as shoot elongation. Addition of GA3 along with BAP and NAA combination dramatically enhanced both multiple shoot proliferation and shoot elongation in all the explants. The elongated shoots were successfully rooted on MS medium containing different auxins. Among them IBA at 0.2 mg/l induced maximum frequency of rooting followed by NAA and IAA. Regenerated plants were successfully established in soil where 90–95% of them developed into morphologically normal and fertile plants. This method can thus be advantageously applied in the production of transgenic pigenopea plants.