Ribosome biogenesis factor OLI2 and its interactor BRX1-2 are associated with morphogenesis and lifespan extension in .

Mutations that reduce the expression of ribosomal proteins (RPs) or limit the activity of ribosome biogenesis-related factors frequently cause physiological and morphological changes in Arabidopsis. Arabidopsis /, a homolog of yeast , encodes a nucleolar methyltransferase that is required for the maturation of the 25S ribosomal RNA of the 60S large ribosomal subunit. Mutant plants exhibit pointed leaves and shortened primary roots. In this study, detailed phenotypic analysis of mutant and overexpressor lines revealed a range of phenotypes. Seeds produced by mutant and overexpressor plants were lighter and heavier than wild-type seeds, respectively. Seeds of the mutant also showed delayed germination, whereas seeds from the overexpressor lines germinated earlier than the wild type. The mutant also had fewer and shorter lateral roots than the wild type. The lateral root development phenotype in the mutant was similar to that of auxin-related mutants, but was not enhanced by exogenously supplied auxin. Furthermore, the mutant and overexpressor lines were hypersensitive and less sensitive to high concentrations of sugar, respectively. Split-GFP-based bimolecular fluorescence complementation analysis revealed that OLI2 interacted with a nucleolar protein, BRX1-2, which is involved in rRNA processing for the large ribosomal subunit. Moreover, overexpression of and caused similar morphological changes, including extension of plant lifespans. These results suggest that the functions of OLI2 and its interactor BRX1-2 are intimately associated with a range of developmental events in Arabidopsis.