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 c lones encoding a protein, PPE1, which exhibits sequence similarity wit h plant, bacterial, and fungal pectin esterases. Genomic clones contai ning the PPE1 gene were isolated using cDNA for PPE1 as a probe, and c omparison 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 r eached the highest level in mature pollen and persisted at a high leve l 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.