Cyanogenesis of cassava plantlets in tissue culture

Abstract

Cassava plantlets grown in Murashige and Skoog medium were shown to contain linamarin. The linamarin was found mainly in the leaf and the petiole with small amount in the stem and the root. The linamarin content increased with age reaching a maximum after 5 months. The content was not affected by the level of the minerals in the medium or addition of valine, the known precursor of linamarin, until a very high level of valine was used. Linamarase was found in the plantlets. Its specific activity was highest in the leaf of plantlets at 3 months of age peroxidase was also found in the plantlets. Its specific activity was highest in the root of 5 mohths old plantlets. Radioactive incorporation from U - [(14)C] - L - valine into linamarin by petiole slices was higher than that by leaf slices. The incorporation by the petiole slices increased upon the addition of a linamarase inhibitor, isopropyl - β - D - thioglucopyranoside or δ- gluconolactone, but not by glucos fructose or starch. The finding suggested the potential use of cassava plant tissue culture in studying the control of cyanogenic glucoside metabolism.