Ontogenic variations in n-alkanes during somatic embryogenesis of flax (Linum usitatissimum L.)

Abstract

Hypocotyl segments of flax seedlings germinated in vitro, were used to induce indirect somatic embryogenesis on solid medium. The composition and distribution of n-alkanes in flax tissues collected at different developmental stages were studied by GC and GC-MS. During induction and development of callus from hypocotyl tissues a decrease in the percentage of total lipids was observed. In all types of tissue sampled - hypocotyl segments used as primary explants, hypocotyl segments with differentiating calli at the cut ends, embryogenic and non-embryogenic calli and somatic embryos - a skewed-normal distribution of n-alkanes with a low mass range (C13-C21) were found. The highest content of n-alkanes occurred in the primary hypocotyl explants and in the early stages of callus development. Longer carbon chain n-alkanes were observed only in the mature or differentiated tissues of hypocotyls and somatic embryos. Although the n-alkane contents decreased with time, in somatic embryos and calli, a significantly lower n-alkane content was observed in embryogenic calli when compared to non-embryogenic calli independent of the time in culture. These results suggest the utilisation of n-alkanes for heterotrophic cellular growth as well as its mobilisation from embryogenic calli to developing somatic embryos