Production of flavour precursors [ S-alk(en)yl- l-cysteine sulphoxides] in photomixotrophic callus of garlic

Abstract

Intact garlic plants contain three flavour precursors, S-allylcysteine sulphoxide, S-propylcysteine sulphoxide and S-methylcysteine sulphoxide. Undifferentiated white callus contains only S-methylcysteine sulphoxide. Full flavour precursor expression, comparable to intact plants can be induced in green undifferentiated callus, in redifferentiated green roots and in redifferentiated green shoots. Redifrerentiated white roots contain S-allyl-, S-propyl- and S-methylcysteine sulphoxides, but at very low levels. It is suggested that S-methylcysteine sulphoxide is constitutively expressed in garlic callus cells, but that the expression of the biosynthetic pathway to S-allyl- and S-propylcysteine sulphoxides requires the presence of differentiated plastids or, optimally, chloroplasts.