Biogenesis of the plant ribosome and its role in plant growth and development

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Arabidopsis is a small plant, in the same family as canola. A ribosome is the natural nano machine, found in all living cells, that is responsible for the conversion of the information stored as DNA in the nucleus, into proteins capable of doing work within the cell, tissue or organism. The two subunits (large: LSU and small: SSU) of a ribosome are themselves comprised of proteins located on an internal scaffold of ribosomal RNA (rRNA) - like the siding, windows and doors on the framing of a house. My research programme is focused on understanding ribosome biogenesis in Arabidopsis, and how it effects overall plant growth & development. The Arabidopsis ribosome is primarily comprised of one copy of each of 81 different ribosomal proteins (rps). Genes for each of the 81 rps are present in the nuclear genome in families of between 2-7 members. Each family member produces a variation (isoform) of the rp that it encodes, such that a family of 7 members can produce 7 isoforms of the same protein, but only one isoform of this protein can be part of any one ribosome. In Arabidopsis, this gene to protein ratio could produce up to 100,000,000,000,000,000,000,000,000,000 variations in ribosome protein composition. Two questions my lab is working to answer are: Why do plants require a level of heterogeneity in ribosome composition that is not present in animals and yeast? What effects does the loss of one rp isoform or the loss of a single rp family have on plant growth & development? The rRNA and rps of the LSU and SSU of the ribosome are assembled in the nucleolus, a small region within the nucleus of the cell, where rRNA is synthesised. However, rps are synthesised in the cytoplasm of the cell and have to be transported across the nuclear membrane into the nucleus and then the nucleolus, where they assemble on the LSU and SSU rRNA. We are in the process of identifying the mechanistic requirements for this rp transport and subsequent LSU and SSU assembly in the nucleolus. Once we understand plant ribosome biogenesis, could we tinker with this natural nano machine and make it do our bidding within the plant cell?