ISOLATION AND CHARACTERIZATION OF A POLYGALACTURONASE GENE HIGHLY EXPRESSED IN BRASSICA-NAPUS POLLEN

A cDNA clone, Sta 44-4, corresponding to a mRNA highly expressed in Br assica napus cv. Westar stamens, was isolated by differential screenin g and characterized. Northern blot and in situ analyses demonstrated t hat Sta 44-4 is synthesized in pollen beginning at the late uninucleat e stage and reaches a maximum in trinucleate microspores. Sta 44-4 dis played significant sequence similarity to known pollen polygalacturona se genes. The B. napus pollen polygalacturonase gene was shown to be p art of a small gene family and to display some polymorphism among diff erent cultivars.