Abstract
The mode of inheritance of whitebacked planthopper resistance in the rice variety CJ-06 was analyzed using two populations of F2 progeny obtained from reciprocal crosses between CJ-06 and the susceptible indica TN1. Two resistance traits, sucking suppression and ovicidal activity, were evaluated based, respectively, on the amount of honeydew excreted and egg mortality. The F2 plants were segregated into 4 phenotypes, which were expressed by the combination of sucking suppression and ovicidal activity. Their segregation ratios fitted statistically the theoretically expected ratio of 45 : 15 : 3 : 1, where sucking suppression and ovicidal activity were assumed to be controlled, respectively, by 2 dominant and 1 recessive gene. Of 35 elite Chinese japonica varieties, 11 (about 30%) displayed ovicidal resistance. In particular, Xiushui 115, Yenjing No. 2 and Bing 97-408-1 showed ovicidal activity as strong as or stronger than that of CJ-06. WBPH females excreted very little honeydew on Xianghu 84, Xiaohuangzhong, Xiushui 04 and Yuenjing No. 2, indicating that these varieties had sucking-suppressive properties. No varieties displayed both ovicidal and sucking-suppressive properties.
