C40-Xanthophylls

Recent studies with the three ABA-deficient tomato mutants have contributed extensively to the clarification of the biosynthesis of ABA. These studies support the so-called indirect pathway of ABA biosynthesis in which the C40 xanthophyll violaxanthin is the likely precursor of ABA, with xanthoxin as an intermediate [22, 26]. It was concluded that the fic and sit mutations are impaired in the conversion of xanthoxin to ABA, and that the lesion in not is at a step between xanthoxin and violaxanthin. 

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