Abstract

                                Gibberellins (GAs) are a group of diterpenoid acids with ent-gibberellane skeleton that function as plant growth regulators influencing a range of devel- opmental processes in higher plants including stem elongation, germination, dormancy, flowering, sex expression, enzyme induction, leaf and fruit senes- cence (Graebe and Ropers, 1978). Gibberellic acid is a high value, industrially important biochemical, sell- ing high rate in the international market depending on the purity and potency. Gibberellic acid also has potential application in improving seedling establish- ment and seed production in hybrid rice (Carlson et al., 1992). In India up to 1970’s research on gibberel- lic acid mainly focused on the isolation and identifi- cation of GAs from plant sources. Studies conducted at CFTRI, Mysore in 1970s ended with a GA3 yield of0.40 - 0.45 g per litre in submerged fermentation pro- cess (SmF) even after optimizing the culture condition parameters. The efficient strain selection and usage plays key role to make the gibberellic acid production economically viable. The strain improvement strategy for increased GA production can be achieved by mu- tation and protoplast fusion in filamentous fungi like F.fujikuroi. In the present work, we have screened and developed a procedure to obtain effective F.fujikuroi mutants through physical and chemical mutagenesis for increased gibberellic acid production.

Key words : Gibberellins, Fusarium fujikuroi