Light affects in vitro organogenesis of Linum usitatissimum L. and its cyanogenic potential

Abstract

The relationships between organogenesis of oil flax (Linum usitatissimum L., cv. 'Szafir') in vitro, cyanogenic potential (HCN-p) of these tissues and light were investigated. Shoot multiplication obtained on Murashige and Skoog medium containing 0.05 mg L^-1 2,4-dichloro-phenoxyacetic acid and 1 mg L^-1 6-benzyladenine (BA), was about twice higher in light-grown cultures than those in darkness. Light-grown explants showed also higher rate of roots regeneration (in medium containing 1 mg L^-1 α-naphtaleneacetic acid and 0.05 mg L^-1 BA) than dark-grown ones. The cyanogenic potential (expressed both as linamarin and lotaustralin content and linamarase activity) of flax cultured in vitro was tissue-specific and generally was higher under light conditions than in darkness. The highest concentration of linamarin and lotaustralin was detected in light-regenerated shoots, and its amount was twice as high as in roots, and about threefold higher than in callus tissue. The activities of linamarase and β-cyanoalanine synthase in light-regenerated organs were also higher than those in darkness. Thus, higher frequency of regeneration of light-grown cultures than dark-grown ones seems to be correlated with higher HCN-p of these tissues. We suggest that free HCN, released from cyanoglucosides potentially at higher level under light conditions, may be involved in some organogenetic processes which improve regeneration efficiency.

Keywords: Cyanogenesis; Exogenous hormones; Flax; Linamarin; Regeneration.