Inhibitor of fungal polygalacturonase. Regulates floral organ number. Highly expressed in calli, immature and mature panicles, and in three inner floral organs: lodicules, stamens and carpels. Expressed at low level in seedling roots and mature stems. Expression increases in the maturing panicle, but is low in developing seed. Increased numbers of floral organs, including the stamen, carpel, palea/lemma, stigma and lodicule. Belongs to the polygalacturonase-inhibiting protein family.