The polyphenol oxidase activity in rice is controlled by five pairs of minigenes at least. Additive effect is mostly factor within genetic effect, there are also fairly dominant effect, and not exiting epistasis effect. There are strongly genetic correlation between the polyphenol oxidase activity in rice and resistance to bacterial blight ( Xanthomonas campestris PV. Oryzas ). There was four other pairs of actived minigenes at least infected by bacterial blight.