BARLEY TRANSCRIPT REGULATION AS RHYNCHOSPORIUM SECALIS CHANGES ITS TROPHIC LIFESTYLE
A. Al-Daoude, A. Shoaib, E. Al-Shehadah, M. Jawhar, A.A. Altahan, M.I.E. Arabi
Rhynchosporium secalis, the causal agent of barley scald disease, begins the infection process as a biotroph and switches to necrotrophism after colonization. It is well known that plants require distinct arsenals of genes to successfully respond to either biotrophic or necrotrophic pathogenic stages. To characterize the defense responses initiated by resistant and susceptible barley genotypes when R. secalis changes the trophic lifestyle, a temporal survey of transcript abundance at early points of infection was conducted. A total of 285 gene transcripts, 37 of which exhibited significant (P < 0.0001) differential accumulation in the resistant and susceptible cultivars, compared to non-inoculated controls, with 11 transcripts (4 defense-related) in common. Transcripts were divided into one of six general categories (defense, metabolism, regulatory, transport, miscellaneous, and unknown function), in which defense and metabolism had the greatest number of common transcripts in the resistant cultivar. Quantities of differentially accumulated gene transcripts in both cultivars were identified at 24 h post infection, the approximate time when R. secalis changes trophic lifestyle. Differentially and significantly accumulating transcripts either unique or common between susceptible and resistant barley genotypes suggest distinct defense responses based on the pathogen trophic lifestyle.