The ribosomal protein P0A is required for embryo development in rice

Abstract

Abstract The P-stalk is a conserved and vital structural element of ribosome. The eukaryotic P-stalk exists as a P0-(P1-P2)2 pentameric complex, in which P0 function as a base structure for incorporating the stalk onto 60S pre-ribosome. There is only a single copy of P0 gene in yeast and most animal species. Prior studies have suggested that P0 genes are indispensable for survival in yeast and animals. In contrast, each plant species has at least two copies of P0 genes, however, the functions of P0 genes in plants remain elusive. In the present study, we show that rice has three P0 genes predicted to encode highly conserved proteins OsP0A, OsP0B and OsP0C. All of these P0 proteins were localized both in cytoplasm and nucleus, and conversely interacted with OsP1. Intriguingly, the transcripts of OsP0A presented more than 90% of the total P0 transcripts. Moreover, knockout of OsP0A led to embryo lethality, while single or double knockout of OsP0B and OsP0C did not show any comparable phenotypes in rice. The genomic DNA of OsP0A could well complement the phenotypes of osp0a mutant. Finally, sequences and syntenic analyses revealed that OsP0C evolved from OsP0A, and that duplication of genomic fragment harboring OsP0C further gave birth of OsP0B, and both of these duplication events happened prior to the differentiation of Xian and Geng subspecies in rice ancestor. Together, our data indicate that OsP0A functions as the predominant P0 gene, playing an essential role in embryo development in rice.