DIFFERENCES IN FREE STEROLS CONTENT AND COMPOSITION ASSOCIATED WITH SOMATIC EMBRYOGENESIS, SHOOT ORGANOGENESIS AND CALLI GROWTH OF FLAX

A single medium was used for induction of somatic embryogenesis and sh oot organogenesis from flax hypocotyls. With this system, a comparativ e study was performed to determine the free sterols content and compos ition in non-organogenic, shoot organogenic and embryogenic calli as w ell as in regenerated shoots and somatic embryos grown under the same hormonal supplementation. The induction of somatic embryogenesis and s hoot organogenesis of flax was associated with an increase of total st erols in the competent calli and an increased ratio of stigmasterol to beta-sitosterol in derived embryos and shoots. On the contrary, in no n-organogenic calli, the ratio stigmasterol to beta-sitosterol decreas ed during the exponential growth phase due to a drastic rise in the be ta-sitosterol content. This effect as well as the calli growth were hi gher with 0.5 mg/I 2,4-D than with 0.6 mg/l IBA. (C) 1997 Elsevier Sci ence Ireland Ltd.