A chromoplast-specific protein in Capsicum annuum: characterization and expression of the corresponding gene.

We have isolated cDNA and genomic clones corresponding to a gene highly and specifically expressed at the late stage of fruit-ripening in bell-pepper. Antibodies raised against the expressed protein allowed determination of the cellular localization of the gene product. The encoded protein is present only in chromoplasts from fully-ripe red fruits, as shown by Western analysis and import experiments. The corresponding mRNA accumulates to high levels during ripening at orange and red stages, but is not detected in yellow varieties impaired in the synthesis of ketocarotenoids. Several lines of evidence indicate that the encoded protein is an oxido-reductase involved in the synthesis of capsanthin and capsorubin.