Callus culture and plantlet regeneration in date palm (Phoneix dactylifera L.): an important horticultural cash crop for arid and semi-arid horticulture

Abstract

Phoneix dactylifera L. commonly called date palm is a highly valuable horticultural cash crop for arid and semi-arid regions. The availability of offshoots and their survival during plantation are major concern. Being dioecious tree, seed propagation in date palm do not produce true-to-type offspring and tissue culture propagation is the only viable option to supply quality-planting propagules. Hereby, we report callus culture and plantlet regeneration in female date palm using in vitro-derived adventitious shoot bud tissues as explants. Explants (89.33 ± 2.67%) produced callus culture on 0.8% agar-gelled Murashige and Skoog’s basal medium containing 100.0 mg l−1 each polyvinylpyrrolidone, ascorbic acid and glutamine, 50.0 mg l−1 each citric acid, adenine sulphate and l-arginine as additives, 0.1% activated charcoal (AC), 100 mg l−1 2,4-dichlorophenoxyacetic acid (2,4-D) and 3.0 mg l−1 2-isopentenyladenine (2-iP). Callus culture were amplified on medium containing 3.0 mg l−1 2-iP along with 50 mg l−1 2,4-D for 2 passages and 10 mg l−1 2,4-D for 2 passages. Cultures grew moderately, organized and subsequently regenerated into shoot bud like structures during gradual transfer from medium containing higher concentration of 2,4-D to lower concentration. Plantlets were developed by sub-culturing of differentiated buds on (1) hormone free medium supplied with 10.0% sucrose and (2) medium containing 100.0 mg l−1 each ascorbic acid and glutamine, 50.0 mg l−1 each citric acid, adenine sulphate and l-arginine as additives, 1.0 mg l−1 each 6-benzylaminopurine, kinetin, 2-iP and α-naphthaleneacetic acid. Plantlets were developed on medium containing 0.1% AC, 1.0 mg l−1 each indole-3-acetic acid and indole-3-butyric acid. Rooted plantlets were soil-transplanted and acclimatized through gradual exposure from in vitro to in vivo conditions. Simple adoption, higher culture regeneration and simultaneous production of rooted plantlets in a cyclic manner render the protocol useful for mass scale propagation of elite genotype of female date palm.