Genetic analysis of resistance genes for the rice gall midge in two rice genotypes

Asian rice gall midge (Orseolia oryzae Wood-Mason) is the most destructive pest of rice (Oryza sativa L.) in several regions of South and Southeast Asia. Resistance to gall midge is primarily governed by single dominant genes in rice, thus newly evolving biotypes are able to overcome resistance genes rendering these genes ineffective. The objective of this study was to identify the gall midge resistance genes present in BG 380-2 and `Gurmatia' and their relationship to known resistance genes. F-1, F-2, and F-3 populations developed from crosses of BG 380-2 and Gurmatia with susceptible cultivars and differentials, possessing the known resistance genes, were screened for their reactions against gall midge biotype 1. Inheritance studies identified a single dominant gene for gall midge resistance in both BG 380-2 and Gurmatia. Allelic study revealed the gall midge resistance gene present in BG 380-2 was nonallelic to all currently known genes (Gm1, Gm2, gm3, Gm4, Gm5, Gm7, Gm8, and Gm9) that impart resistance against gall midge biotype 1 population and is designated as Gm10. The gall midge resistance gene present in Gurmatia was allelic to the Gm1 gene previously identified. This new resistance gene, Gm10, in BG 380-2 will be useful in breeding new varieties and for pyramiding multiple genes for durable resistance to rice gall midge.