Characterization of a pollen-expressed gene encoding a putative pectin esterase of Petunia inflata

From a pollen tube cDNA library of Petunia inflata, we isolated cDNA clones encoding a protein, PPE1, which exhibits sequence similarity with plant, bacterial, and fungal pectin esterases. Genomic clones containing the PPE1 gene were isolated using cDNA for PPE1 as a probe, and comparison of the cDNA and genomic sequences revealed the presence of a single intron in the PPE1 gene. During pollen development, PPE1 mRNA was first detected in anthers containing uninucleate microspores; it reached the highest level in mature pollen and persisted at a high level in in vitro germinated pollen tubes. The observed expression pattern of the PPE1 gene suggests that its product may play a role in pollen germination and/or tube growth.