Clonal Variation in Growth and Flavour Production in Tissue Cultures of Allium cepa L.

Abstract

Callus cultures of onion were initiated from seedling root tissue of three varieties, Rijnsburger, White Lisbon and Red Italian. Twenty separate clones of each variety were sub-cultured for nine passages and estimates made of growth, friability, sliminess and pigmentation at each sub-culture; measurement of alliinase activity and precursor level was made at the ninth sub-culture. A number of clones showing a uniformity in one or more characters appeared but clonal characteristics could not be correlated with alliinase activity or flavour precursor levels. The alliinase activity was comparable to the normal plant but the precursor level was 2–10 per cent of that in the plant. The work shows that despite the large number of separate cultures established and the development of stable clonal lines, it was not possible to select out a clone able to produce a high level of the onion flavour compounds.