Cloning, molecular characterization and expression pattern of a strawberry ripening-specific cDNA with sequence homology to pectate lyase from higher plants

A strawberry fruit cDNA showing sequence similarity to higher-plant pectate lyase genes has been isolated by differential screening of a strawberry fruit cDNA subtractive library. The cDNA contains a 396 amino acids open reading frame corresponding to a 44.8 kDa protein. The transcript is predominantly expressed in ripe fruits and was not detected at high levels in any other plant tissues. The removal of the achenes from unripe green fruits induced the expression of this putative pectate lyase gene. In common with other ripening related genes in strawberry, this induction was partially inhibited by treatment of de-achened fruit with the auxin NAA. Southern blot analysis of genomic DNA indicates that in strawberry there is more than one putative pectate lyase gene. We propose that the ripe fruit expression of this strawberry gene with similarity to pectate lyases could be related to cell wall pectin degradation contributing to strawberry fruit softening.