Abstract
Sugars are the prime carbon and energy source and an important signal for growth and development in plants. To elucidate molecular mechanisms of sugar response in plants, we identified evolutionarily conserved and glucose responsive nuclear proteins by proteome analysis of rice nuclear proteins and investigation of the sugar responsiveness of the corresponding genes. There were two WD40 proteins (NuGWD1 and 2) among selected proteins. We confirmed that these transcripts were induced by glucose and sucrose in both rice and Arabidopsis. We isolated T-DNA insertion lines for AtNuGWD1. In the siliques of atnugwd1 heterozygous Arabidopsis, aborted ovules were observed, suggesting either lethality of atnugwd1 homozygous embryo or abnormal female gametogenesis. The result of GST pull down assay using OsNuGWD1 protein revealed that OsNuGWD1 bound a complex containing ribosomal proteins. Homologs of NuGWD1 and 2 are evolutionarily conserved from yeast to human. Taken together with previous reports on function of yeast homologs, these results imply that glucose elevates levels of NuGWD1 and 2, which promote 18S rRNA biogenesis and assembly of 40S small ribosomal subunit in plants.
