Molecular characterization of a tomato polygalacturonase gene abundantly expressed in the upper third of pistils from opened and unopened flowers

A polygalacturonase (PG) gene, TPG7 (Lyces;Pgal;8), has been cloned from to mato (Lycopersicon esculentum Mill., cv. Rutgers). RNA blot analysis reveal s that TPG7 is highly expressed in pistils (ovary removed) from unopened an d fully open flowers. Dissection of mature pistils demonstrated that TPG7 e xpression is limited to the top third (stigmatic region) of the pistils. Th is is contrasted with another tomato PG, TAPG4, which is also expressed in the same region of the pistil but only in mature pistils from fully open fl owers. Hybridization of the TPG7 probe to anther RNA was nil to none and wa s barely detectable in RNA from leaf and newer abscission zones. The TPG7 p olypeptide shares 39% sequence identity with the tomato fruit PG and betwee n 63% and 73% sequence identities with six other tomato PGs.