Structure and expression of a cDNA encoding a putative neoxanthin cleavage enzyme (NCE), isolated from a wilt-related tomato (Lycopersicon esculentum Mill.) library

Oxidative cleavage of a 9-cis xanthophyll probably represents the key regulatory step in abscisic acid (ABA) biosynthesis. A transposon tagged maize (Zea mays) mutant vp14, provided the original DNA sequence data needed to design a VP14 fusion protein capable of catalysing this reaction in vitro, A cDNA encoding a similar protein has now been isolated from a wilt-related tomato (Lycopersicon esculentum Mill.) library, The tomato cDNA and derived amino acid sequence have been compared to those of maize and of other enzymes catalysing broadly similar oxidative cleavage reactions, The results of Northern analysis in tomato indicated that mRNA levels of this vp14 homologue increased dramatically in response to water stress.