Expression profiles of key genes involved in rice gall midge interactions reveal diversity in resistance pathways

Resistance against the Asian rice gall midge, Orseolia oryzae (Wood-Mason), is conferred by any one of the 11 major genes identified so far. Resistance conferred by these genes may or may not involve a hypersensitive reaction (HR). Three of these gall midge resistance genes have been already cloned. In this study, expression of 20 key genes, identified based on our earlier studies, in 12 rice genotypes was profiled through quantitative real time (RT)-PCR at two time points. Results highlighted diversity in resistance pathways either involving reactive oxygen species (ROS)hypersensitive reaction (HR) salicylic acid-mediated systemic acquired resistance or strong suppression of ROS-HR at initial stage itself. Some of the susceptible test genotypes derived from crosses between gall midge resistant and susceptible parents expressed trace activity of these genes even during compatible interaction.