PO149, a new member of pollen pectate lyase-like gene family from alfalfa.

PO149 is a low-copy-number gene expressed in the late stages of pollen development. The promoter region contains no similarities in DNA sequence to those of other pollen-specific genes, except for a tobacco sequence (AAATGA), which occurs four times in this alfalfa gene and much further upstream than in tobacco. Four distinct TATA boxes were detected in the promoter with the distal and proximal TATA boxes being separated by a spacer of 269 nucleotides. Hairpin loop structures were found in the 5'- and 3'-untranslated regions of PO149 mRNA. The coding region of PO149 is interrupted by two introns and encodes a putative prepeptide of 450 amino acids with homology to pollen pectate lyase-like proteins and pollen allergens. The coding region also contains sequences characteristic of both a signal peptide and a nuclear localization signal.