Callus induction and efficient plant regeneration in Cucumber (Cucumis sativus L.)

A reliable and reproducible protocol is established to get healthy and wellformed callus from juvenile explants of cucumber.The sterilized seeds of cucumber cultivar were cultured on MS basal medium (Murashige and Skoog, 1962).The seeds germinated after 7 days of culture with 24 hours dark photoperiod.Explants from germinated seedlings were cultured on MS medium supplemented with individual treatments of different auxins (2,4-dichloro-phenoxyacetic acid (2,4-D), α naphthalene acetic acid (NAA)) or cytokinins (benzyl aminopurine (BAP)).Plant parts such as leaves, stems and cotyledons were used as source of explants.Callus were initiated from leaves, stems and cotyledons after 4 weeks of culture.The optimum medium for callus induction from leave, stem and cotyledon explants was MS medium supplemented with 0.5 mg/L BAP added with 1.0 mg/L NAA.The highest percentage of callus was obtained from stem explants (89.0 ± 0.75 %) followed by leave (79.05 ± 3.28%) and cotyledon (74.43 ± 1.30 %) explants.Maximum callus induction in stems (73.05 ± 2.1%) was obtained in 1.mg/l concentration of BAP.Incorporating 2,4-D in the callus induction media promoted slow callus growth and low quality callus compared to that produced on media containing NAA and BAP.Callus induced on media containing 2,4-D was friable and yellow in color.This protocol can promote the application of tissue culture technology to facilitate the genetic transformation of this species.