Subcellular localization of a Netrual Invertase from hybrid aspens (Populus tremula x tremuloides)

Abstract: Neutral Invertases are sucrose hydrolyzing enzymes whose role in plants remains to be understood. This thesis focuses on the subcellular localization of a neutral invertase from hybrid aspen (Populus tremula × Populus tremuloides), which shows increased transcript levels during secondary cell wall formation. The study is made with a yellow fluorescent protein (YFP) construct fused to either the C- or N-terminal end of the neutral invertase protein. The constructs were transiently expressed in tobacco (Nicotiana tabacum) leaf epidermis cells. The YFP-signal was mainly seen along the border of the cells, corresponding to the cytoplasm of the epidermal cells. The pattern from the YFP-signal appears aggregated, indicating that the neutral invertase is associated with a compartment located in the cytoplasm. From the interpretation of the pattern and the subcellular prediction of the location based on the peptide sequence, the neutral invertase is plausibly associated with the Golgi-apparatus and the synthesis of hemicellulose and pectin. Experiments that would be able to confirm the results would be: co- localization of the neutral invertase-YFP signal with Golgi compartment markers, ideally in hybrid aspen cells, and Western blots to confirm the correct size of the fusion protein. Hybrid aspen neutral invertase RNAi lines should be characterized for their cell wall properties to investigate the role of neutral invertase during wood biosynthesis.