Direct organogenesis in some soybean genotypes using cotyledonary segments

Effect of various parameters on direct shoot organogenesis and plantlet regeneration from mature cotyledonary segments of three soybean [Glycine max (L.) Merrill] genotypes, viz., JS 335, Pusa 9814 and Pusa 24, was studied. The seeds of these genotypes were germinated in vitro on Murashige and Skoog medium supplemented with 9.0 mu M BAP (6-benzylamino purine)+1.1 mu M NAA (alpha-naphthalene acetic acid). After 10 d, green cotyledonary segments were excised from the germinating seedlings and used as explant (0.25-0.4 cm). These segments were cultured on B5 medium supplemented with 6.8 mu M BAP+0.73 mu M GA(3) (gibberellic acid)+0-20 mM MES (2-morpholino ethane sulphonic acid). Genotype Pusa 24 was found most responsive (32.23%) for direct shoot organogenesis, followed by Pusa 9814 (22.57%) and JS 335 (7.93%). The regenerated microshoots were elongated on MS medium supplemented with 2.9 mu M GA(3). Medium comprising MS basal salts supplemented with 5.0 mu M IBA (indole-3-butyric acid) and 5.4 mu M NAA was found ideal for root induction on microshoots. Rooted plants were successfully hardened in glass jars with polypropylene cap and established in the greenhouse with 87% survival rate.