PEX1, A POLLEN-SPECIFIC GENE WITH AN EXTENSIN-LIKE DOMAIN

We report here the identification of a pollen-specific gene from Zea m ays that contains multiple Ser-(Pro)(n) repeats, the motif found in th e cell wall-associated extensins. Sequence analysis reveals that the e ncoded protein has a putative globular domain at the N terminus and an extensin-like domain at the C terminus. The Pex1 (pollen extensin-lik e) gene is expressed exclusively in pollen, not in vegetative or femal e tissues, and is not induced in leaves upon wounding. We propose that the encoded protein may have a role in reproduction, either as a stru ctural element deposited in the pollen tube wall during its rapid grow th or as a sexual recognition molecule that interacts with partner mol ecules in the pistil.