A Pelota-like gene regulates root development and defence responses in rice

Pelota (Pelo) are evolutionarily conserved genes reported to be involved in ribosome rescue, cell cycle control and meiotic cell division. However, there is little known about their function in plants. The aim of this study was to elucidate the function of an ethylmethane sulphonate (EMS)-derived mutation of a Pelo-like gene in rice (named Ospelo). A dysfunctional mutant was used to characterize the function of OsPelo. Analyses of its expression and sub-cellular localization were performed. The whole-genome transcriptomic change in leaves of Ospelo was also investigated by RNA sequencing. The Ospelo mutant showed defects in root system development and spotted leaves at early seedling stages. Map-based cloning revealed that the mutation occurred in the putative Pelo gene. OsPelo was found to be expressed in various tissues throughout the plant, and the protein was located in mitochondria. Defence responses were induced in the Ospelo mutant, as shown by enhanced resistance to the bacterial pathogen Xanthomonas oryzae pv. oryzae, coupled with upregulation of three pathogenesis-related marker genes. In addition, whole-genome transcriptome analysis showed that OsPelo was significantly associated with a number of biological processes, including translation, metabolism and biotic stress response. Detailed analysis showed that activation of a number of innate immunity-related genes might be responsible for the enhanced disease resistance in the Ospelo mutant. These results demonstrate that OsPelo positively regulates root development while its loss of function enhances pathogen resistance by pre-activation of defence responses in rice.