OseIF3h Regulates Plant Growth and Pollen Development at Translational Level Presumably through Interaction with OsMTA2

The initiation stage of protein biosynthesis is a sophisticated process tightly regulated by numerous initiation factors and their associated components. However, the mechanism underlying translation initiation has not been completely understood in rice. Here, we showed knock-out mutation of the rice eukaryotic translation initiation factor 3 subunit h (OseIF3h) resulted in plant growth retardation and seed-setting rate reduction as compared to the wild type. Further investigation demonstrated an interaction between OseIF3h and OsMTA2 (mRNA adenosine methylase 2), a rice homolog of METTL3 (methyltransferase-like 3) in mammals, which provided new insight into how N6-methyladenosine (m6A) modification of messenger RNA (mRNA) is engaged in the translation initiation process in monocot species. Moreover, the RIP-seq (RNA immunoprecipitation sequencing) data suggested that OseIF3h was involved in multiple biological processes, including photosynthesis, cellular metabolic process, precursor metabolites, and energy generation. Therefore, we infer that OseIF3h interacts with OsMTA2 to target a particular subset of genes at translational level, regulating plant growth and pollen development.