PLANT-REGENERATION FROM CULTURED MEDICAGO-TRUNCATULA WITH PARTICULAR REFERENCE TO ABSCISIC-ACID AND LIGHT TREATMENTS

Medicago truncatula (Jemalong 2HA) can be regenerated by somatic embry ogenesis utilising 1-naphthalene acetic acid (NAA) and 6-benzylaminopu rine (BAP). There is a requirement for both NAA and BAP for callus ind uction and embryo formation. There is no requirement for a drop in aux in concentration to induce embryos. Abscisic acid (ABA) when present w ith NAA and BAP during embryo formation at a concentration of 1 mu M, increases the number of embryos per callus. The ABA treatment stimulat es embryo numbers in both light and darkness. The conversion efficienc y of embryo to plant is unchanged irrespective of the presence of ABA during embryo formation, indicating that ABA does not improve the rege neration of the embryos once formed. Importantly, the presence of ligh t in the embryo formation period causes a marked inhibition of embryo conversion.