Proteomic analysis in transgenic hybrid aspen (Populus tremula x tremuloides) trees overexpression of vesicle-associated membrane protein PttVAP27-17

In this study we report on transgenic hybrid aspen (Populus tremula x P. tremuloides) lines that showed potential to increase biomass production both in the greenhouse and after five years of growth in the field. The transgenic lines carried an overexpression construct for Populus tremula x tremuloides vesicle-associated membrane protein (VAMP)-associated protein PttVAP27-17 (Potri.019G116400) that was selected from a gene-mining program for novel regulators of wood formation. A proteomic analysis was performed to characterize the overall effect of the overexpression of PttVAP27-17 on plant metabolic pathways. 20 mg of xylem sample for the selected wild type (WT) and three transgenic lines (lines 1,2 and 3) was collected in the following manner from two-months-old, greenhouse grown trees: The frozen bottom-part of the stem (10-17 cm portion from the base of the stem) was peeled, and the surface of the secondary xylem consisting of living vessels and fibers (into the depth of approximately one mm from the surface) was scraped. The xylem scrapings were ground to fine powder in liquid nitrogen and stored at -80oC. The analyses included 3-5 biological replicates for each of the transgenic lines, and seven replicates for the wild type.