Multiple Shoots Induction from Indigenous Nigerian Pumpkin (Cucurbita pepo L.)

Abstract

Aim: The aim of this study was to develop a protocol for in vitro regeneration of a Nigerian indigenous pumpkin (C. pepo L.) via seedling-derived cotelydon, cotyledonary node and hypocotyl explants. Study Design: A combination of 0.00, 1.00, 2.00 and 3.00 mgl-1 of 6-Benzylaminopurine (BAP) and 0.00 or 0.05 mgl-1 of 2,4-Dichlorophenoxy acetic acid (2,4-D) for each explant type were set up in three replicates making a total of 36 culture vessels in the entire experimental set up. Five explants were cultured per combination. Place and Duration of Study: The work was conducted in the Plant Tissue Culture Laboratory of the Department of Biological Sciences, College of Science and Technology, Covenant University, Ota, Ogun State, Nigeria, between January 2017 and July 2017. Methodology: Hypocotyl, cotyledonary node and cotyledon explants derived from 4-week old-seedlings were cultured on MS medium fortified with 0.00, 1.00, 2.00 and 3.00 mgl-1 of BAP in combination with 0.00 or 0.05 mgl-1 of 2,4-D and investigated for callus, shoot and root induction. Results: A combination of 1.00 mgl-1 BAP with 0.05 mgl-1 2,4-D was optimum for callus induction from hypocotyl and cotyledonary node explants, while for cotyledon explants, 2.00 mgl-1 BAP in combination with 0.05 mgl-1 2,4-D was preferred. Cotyledonary node explants and cotyledonary node explant-derived callus responded with multiple shoots (4.50±0.042 and 4.07±0.067 shoots per explant, respectively) on full strength Murashige and Skoog (MS) medium (control) devoid of Plant Growth Regulators (PGRs). When the different explant types were cultured on MS media amended with the different concentrations of BAP in combination with 2,4-D, neither shoot nor root induction was observed. All the explants initiated roots when cultured on full strength PGR-free medium. Only cotyledon explant-derived callus formed roots (2.30±0.56cm) on PGR-free MS medium. Conclusion: Regeneration of indigenous vegetables, such as Cucurbita pepo is achievable through hypocotyl, cotyledonary node and cotyledon explants with or without PGRs.