STRUCTURE AND SPECIFIC EXPRESSION OF A NICOTIANA-SYLVESTRIS PUTATIVE AMINO-ACID TRANSPORTER GENE IN MATURE AND IN-VITRO GERMINATING POLLEN

We report here the structure and expression analysis of a Nicotiana sy lvestris gene, called nsaap1, coding for a protein which shows signifi cant identity to the members of the Arabidopsis thaliana amino acid pe rmease family. The nsaap1 gene is expressed exclusively in binucleate pollen. Its transcripts begin to accumulate after first pollen mitosis and dramatically increase in mature pollen shortly before anthesis an d during in vitro pollen germination. The nsaap1 5'-flanking region co ntains long regions homologous to the promoter region of the tobacco p ollen specific elF-4A8 translation factor. Our results support the occ urrence of an amino acid remobilization in binucleate pollen. The nsaa p1 gene could play a role in exchanges between the vegetative and the generative pollen cells.