A method for preventing mutation of pathogens or pest insects due to exposure to genetically-modified or transgenic plants, comprising: (a) introducing separately a plurality of resistance genes conferring pest and disease resistance to a given recipient plant variety or combinations of the varieties to form a plurality of transgenic plant lines each harboring different resistance genes (b) multiplying the transgenic plant lines separately to obtain separate transgenic plant lines and (c) mixing seeds of the separate transgenic plant lines in a specific weight ratio to form a final transgenic product. Additionally, small number of seeds of the non-transformed plants is incorporated in the transgenic plant lines according to demand. As a result, an excessive selective pressure for targeted insects and pathogens are alleviated considerably, the possibility of auto mutation of the targeted insects and pathogens will be reduced, and the application duration of transgenic crop varieties will be prolonged effectively.
