There are two distinct cystatins in rice seeds (Oryzacystatin-1 and -2) with different specificities against cysteine proteinases. May be involved in the control of germination by inhibition of endogenous cysteine proteinases. May play a role in defense by inhibiting exogenous proteases such as those present in digestive tracks of insects and nematodes. Expressed in rice seeds between 2 and 4 weeks after flowering. Introduction by genetic manipulation and expression in potato or banana confers resistance to insects and nematodes. Belongs to the cystatin family. Phytocystatin subfamily.