Molecular and biochemical studies were undertaken to characterise pigment composition and biosynthesis in Forsythia, a yellow-flowered ornamental shrub whose petals accumulate large amounts of carotenoids but lack anthocyanins. This work is part of a breeding program at INRA Angers Station, aimed at changing Forsythia flower color by genetic transformation. F. x intermedia cv. 'Spring Glory', a popular variety for which an Agrobacterium-mediated transformation system has already been developed, was taken as model genotype. Gene expression studies enabled to identify a late block in anthocyanin biosynthesis pathway in petals. In order to complement this block and induce de novo anthocyanin formation, several constructs were assembled and transformed plants have been recovered. More recently, transformation experiments with carotenoid gene constructs were also started, in order to modify the pathway toward the synthesis of red compounds. Transformants are expected to flower by spring 2000 and will undergo phenotypic, molecular and biochemical characterisation.

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