May function in the depolymerization of the pectin in its walls during pollen tube elongation, or in that of the pistil during pollination. (1,4-alpha-D-galacturonosyl)n+m + H2O = (1,4-alpha-D-galacturonosyl)n + (1,4-alpha-D-galacturonosyl)m. Pollen. Appears 12 days before anthesis and maximum levels are seen in pollen on the day of anthesis. Belongs to the glycosyl hydrolase 28 family.