β-1,3-glucanase class III promotes spread of PVY and improves protein production.

Glucanases are enzymes regulating the size exclusion limit and permeability of plasmodesmata and play a role in biotic stress. In plant genomes, they are encoded as relatively large gene families divided into four classes. Most studies of plant virus interactions have focused on glucanases from classes I and II. In our study, we have evaluated the role of the β-1,3-glucanase class III (Glu-III) gene in the potato-potato virus Y (PVY) interaction and implemented the findings to plant biotechnology application. Potato cultivars Désirée and Santé, which are tolerant and extremely resistant to PVY, respectively, were stably transformed with harbouring constructs for Glu-III overexpression. Localization of Glu-III protein in patches within the cell wall was determined by tagging the Glu-III protein with green fluorescent protein. Transgenic and non-transgenic plants were challenged with PVY and its multiplication and spreading was followed. Differences in viral spread were observed between transgenic lines overexpressing Glu-III and non-transgenic lines, with stronger and faster viral spread in transgenic Désirée, and some multiplication in transgenic Santé. In addition, the ability of Glu-III to improve protein production after agroinfiltration was tested. The results have shown that Glu-III overexpression enables faster spreading of vectors between cells and better protein production, which could be beneficial in improving protein production system using viral vectors.