Background The whitebacked planthopper (WBPH) has become a significant threat to rice production. Identification of WBPH-resistant germplasm and genes can drive efforts to develop resistance varieties and effectively limit pest damage.
Methods Fourteen varieties of rice were surveyed for insect resistance using tests that assessed bulk seedling growth rates, insect feeding activity (via measurements of honeydew excretion weight), and insect development (by counting the number of hatched nymphs). Two resistance varieties N22 and OB677 were crossed with susceptible line 9311 to develop mapping populations, which were applied to map the resistance genes/QTLs.
Results The rice variety PTB33 showed high resistance to both brown planthopper (BPH) and WBPH, and varieties N22, RBPH327, and OB677 showed moderate resistance to WBPH. Host choice test and seedling survival rates further verified the WBPH resistance of PTB33, N22, and OB677. By using two F2 mapping populations, two major resistance genes were detected in N22 and OB677. Wbph1 was mapped on chromosome 2 of N22 in a region that harbored the markers RM13650 and RM13478. Its largest logarithm of the odds (LOD) score was 3.94, which explained a 16.6% phenotypic variation. Wbph9 was mapped on chromosome 3 of OB677, where it was flanked by markers RM3513 and RM3525. It had a LOD score of 3.4, explaining a 17.2% phenotypic variation.
Conclusions Four varieties PTB33, N22, RBPH327, and OB677 showed resistance to WBPH, of which OB677 was a novel resistance germplasm; and a novel resistance gene Wbph9 was mapped on chromosome 3.