PROBLEM TO BE SOLVED: To provide a method for exhaustively inhibiting the disulfide bond formation of an intracellular protein and/or a method for inhibiting the oxidation activity of PDI (protein disulfide isomerase), comprising suppressing the expression of endogenous Ero1 gene in plant cells, and to provide a DNA having a function of suppressing the expression of Ero1 gene. SOLUTION: A transformant in which the expression of Ero1 gene of rice plant is endosperm-specifically suppressed is prepared using an RNA interference. As a result of the analysis of the transformant of the RNA interference, the expression of Ero1 gene is suppressed to find the inhibition of protein disulfide bond formation. COPYRIGHT: (C)2008,JPO&INPIT
