HIGH FREQUENCY PLANT REGENERATION OF FIELD MUSTARD (Brassica campestris)

Abstract

The experiment was carried out at the Genetic Engineering Laboratory of the Department of Genetics and Plant Breeding, Sylhet Agricultural University, Sylhet to develop a suitable protocol for high frequency plant regeneration of field mustard (Brassica campestris). An efficient system for high frequency plant regeneration system of B. campestris was developed through investigating various factors such as combination of plant growth regulators, explant type, age and ethylene biosynthesis inhibitor AgNO3. To observe the suitable medium for callus initiation and shoot regeneration, cotyledonary and hypocotyl explants were cultured on MS medium supplemented with different concentrations of 6-Benzyl amino purine (BA) and αnaphthalene acetic acid (NAA). The ranges of callus initiation and shoot regeneration frequency

of cotyledonary explants were 33.33% to 94.44% and 13.89% to 63.89%, respectively whereas

hypocotyl

explants showed 11.9% to 47.62% and 2.38% to 19.04% callus initiation and shoot regeneration frequency, respectively. The highest callus initiation (94.44%) and shoot regeneration (63.88%) frequency were observed on MS medium supplemented with 1.0 mg/L BA and 0.5 mg/L NAA in case of cotyledonary explants. To observe the effect of age of explants source material on shoot regeneration 3 to 7 days old cotyledonary explants were cultured on MS medium supplemented with 1.0 mg/L BA and 0.5 mg/L NAA and 4 days old cotyledonary explants showed the highest shoot regeneration frequency (72.22%) and higher number of shoots per explant (3.94). The shoot regeneration frequency and number of shoots per explant were markedly enhanced by the addition of AgNO3. MS medium supplemented with 1.0 mg/L BA, 0.5 mg/L NAA and 2.0 mg/L AgNO3 showed the maximum shoot regeneration frequency (83.33%) and maximum number of shoots per explant (6.86). To observe the genotypic variation for shoot regeneration potentiality 4 days old explants of five B. campestris genotypes namely Tori-7, BARI sarisha-6, BARI sarisha-9, BARI sarisha-12 and BARI sarisha-15 were cultured on MS medium supplemented with 1.0 mg/L BA, 0.5 mg/L NAA and 2.0 mg/L AgNO3. Among the five genotypes BARI sarisha-12 showed the highest shoot regeneration frequency (83.33%) as well as maximum number of shoots per explant (6.86) and BARI sarisha-15 showed the lowest shoot regeneration frequency (52.78%) as well as lower number of shoots per explant (3.23). MS medium supplemented with 0.2 mg/L NAA showed the highest frequency (100%) of rooting. The regenerated plantlets were transferred in pot soil and grow to maturity.