Involved in ribosome biogenesis, required for normal progression of rRNA processing (PubMed:29375609). Seems to promote cell proliferation in leaves (PubMed:29375609). Strongly expressed in tissues with high cell proliferation activity that have a high demand for ribosome production such as shoot tips, leaves primordia, root tips and floral buds. Reduced leaf cell number associated with pointed leaves shape (PubMed:29375609). Defects in pre-rRNA processing characterized by an increased accumulation of rRNA intermediates containing 50-ETS, ITS1, or ITS2 (PubMed:29375609). Higher levels of 35S, 27SA, 27SB, P-A3, and 18SA3 rRNAs (PubMed:29375609). The double mutant gdp1 oli2 exhibit strong growth defect due to a synergistically impaired cell proliferation in leaves and enlarged cells (PubMed:29375609).