Abstract

Various factors like plant growth regulator combinations, explant type and explant age were examined for establishing a convenient protocol for high frequency plant regeneration of Brassica napus. Cotyledon and hypocotyl explants of B. napus cv. BARI sarisha-8 were cultured on Murashige and Skoog (MS) medium fortified by different strengths of 6-Benzylaminopurine (BA), 2,4-Dichlorophenoxy Acetic Acid (2,4-D) and α-Napthalene Acetic Acid (NAA) to determine the suitable callus induction and shoot regeneration media. MS medium supplemented with 0.5 mg/L NAA and 3.0 mg/L BA was the best combination as regeneration medium because of showing highest frequency for both callus (80% for cotyledon and 53.33% for hypocotyl explants) and shoot initiation (73.33% for cotyledon and 40% for hypocotyl explants). Four days old cotyledon explants showed the highest (73.33%) frequency of shoot regeneration and highest shoot number to each explant (3.13) when 3-7 days old cotyledon cultured. Among the four tested genotypes of B. napus, BARI sarisha-8 showed the highest shoot regeneration frequency (73.33%) with maximum shoot number to each explant (3.13) while the lowest frequency of shoot regeneration was found in BINA sarisha-4 (46.66%) with minimum shoot number per explant (1.66). The ideal rooting medium was MS media comprised with 0.1 mg/L NAA that offered the maximum frequency (100%) of rooting. The regenerated plantlets were shifted to pot soil, acclimatized and grown until maturity in natural conditions. All plants were fertile and morphologically identical with the source plants. This protocol for high frequency regeneration of B. napus could be used for genetic transformation experiments.

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