Polygalacturonase involved in cell separation in the final stages of pod shatter and in anther dehiscence. Not involved in floral organ abscission. (1,4-alpha-D-galacturonosyl)n+m + H2O = (1,4-alpha-D-galacturonosyl)n + (1,4-alpha-D-galacturonosyl)m. Released to the cell wall during maturation of the dehiscence zone. Expressed in flower buds and siliques, in the dehiscence zone of anthers (stomium cells) and maturing siliques. Expressed in stigma during pollen tube growth. Not expressed in seeds or in the floral part or leaf abscission zone but found at the junction between the seed and the funiculus at the site of seed abscission. Impaired pod shatter. Belongs to the glycosyl hydrolase 28 family.