Could be a pectinolytic enzyme that hydrolyzes the alpha-L-rhamnopyranosyl-(1,4)-alpha-D-galacturonopyranosyl glycosidic linkage by beta-elimination, thereby generating oligosaccharides terminating at the non-reducing end with a hex-4-enopyranosyluronic acid residue. Endotype eliminative cleavage of L-alpha-rhamnopyranosyl-(1->4)-alpha-D-galactopyranosyluronic acid bonds of rhamnogalacturonan I domains in ramified hairy regions of pectin leaving L-rhamnopyranose at the reducing end and 4-deoxy-4,5-unsaturated D-galactopyranosyluronic acid at the non-reducing end. Expressed preferentially during the sexual cycle and essential for normal sexual development. Belongs to the polysaccharide lyase 4 family.