IN VITRO PLANT REGENERATION OF TOMATO (Lycopersicon esculentum)

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 tomato (Lycopersicon esculentum). An efficient system for high frequency plant regeneration system of L. esculentum 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 of L. esculentum cv. BARI Tomato 5 were cultured on MS medium supplemented with different concentrations of 6-benzyl amino purine (BA) and α-naphthalene acetic acid (NAA). The ranges of callus initiation and shoot regeneration frequency of cotyledonary explants were 52.78% to 94.44% and 22.22% to 61.11%, respectively, whereas hypocotyl explants showed 61.11% to 97.22% and 19.44% to 58.33% callus initiation and shoot regeneration frequency, respectively. The highest callus initiation (94.44%) and shoot regeneration (61.11%) frequency were observed on MS medium supplemented with 3.0 mg/L BA and 0.2 mg/L NAA in case of cotyledonary explants. To observe the effect of age of explants source material on shoot regeneration 5 to 9 days old cotyledonary explants were cultured on MS medium supplemented with 3.0 mg/L BA and 0.2 mg/L NAA and 6 days old cotyledonary explants showed the highest shoot regeneration frequency (61.11%). The shoot regeneration frequency was markedly enhanced by the addition of AgNO3. MS medium supplemented with 3.0 mg/L BA, 0.2 mg/L NAA and 2.0 mg/L AgNO3 showed the maximum shoot regeneration frequency (77.78%). To observe the genotypic variation for shoot regeneration potentiality 6 days old explants of six L. esculentum genotypes namely BARI Tomato 2, BARI Tomato 5, BARI Tomato 7, BARI Hybrid Tomato 4, BINA Tomato 3 and BINA Tomato 5 were cultured on MS medium supplemented with 3.0 mg/L BA, 0.2 mg/L NAA and 2.0 mg/L AgNO3. Among the six genotypes BARI Tomato 2 showed the highest shoot regeneration frequency (91.67%) and BINA Tomato 3 showed the lowest shoot regeneration frequency (44.44%). MS medium supplemented with 0.1 mg/L NAA showed the highest frequency (100%) of rooting. The regenerated plantlets were transferred in pot soil and grown to maturity.