Expression Pattern of RNA Interference Genes During Drought Stress and MDMV Infection in Maize

Abstract

When stress factors trigger transcriptional and metabolic changes, RNA interference (RNAi) is associated with gene expression regulation at the transcriptional and post-transcriptional levels. RDR, DCL and AGO proteins contribute to these gene silencing processes during stress reactions and plant development. An entire revision of the maize RDR, DCL and AGO genes was carried out prior to the experiments. In this study, the transcript changes of a total of 4 ZmRDR, 5 ZmDCL and 17 ZmAGO genes were analysed in maize during either drought stress or MDMV infection, with or without salicylic acid pre-treatment or siRNA pre-treatment, respectively. The gene expression profiles showed the early, middle and late activity of these genes. Drought stress caused major changes in the expression profiles, indicating that there were various steps in stress response regulation. Moreover, insights were gained into the fine-tuning mechanisms of SA regulation. In the case of MDMV infection less diverse trends were observed, which were mainly focused on antiviral defence. However, treatment with exogenous siRNA seems to be an appropriate tool for the targeted influencing of RNAi, especially of AGO genes. These results represent the first contribution to the relationship between RNAi and salicylate signalling and between viral infection and siRNA-triggered defence in maize.