Structural organization and differential expression of carrot beta-fructofuranosidase genes: identification of a gene coding for a flower bud-specific isozyme.

Three genomic clones (InvDc1, InvDc2 and InvDc3) were isolated by using the cDNA for carrot cell wall beta-fructofuranosidase as a probe. The expression patterns of the three genes differed markedly. High levels of InvDc1 transcripts were found in leaves and roots of young carrot, whereas in plants with developing tap roots no transcripts were detected. A high level of mRNA of InvDc1 was also present in suspension-cultured cells. In developing reproductive organs, only low levels of transcripts of InvDc1 were found in flower buds and flowers and none at later stages of development. In contrast, InvDc2 and InvDc3 were not expressed in vegetative plant organs. Invb1Dc1 was exclusively and strongly expressed in flower buds, and InvDc3 at a very low level in suspension-cultured cells.