BRC Science Highlight Altering carbon allocation in hybrid poplar impacts cell wall growth and development Objective In this study we test the hypothesis that cell wall attributes and plant development can be altered by augmenting the available pools of soluble sucrose. Approach Overexpression of the Arabidopsis thaliana galactinol synthase (AtGolS3) in hybrid poplar (Populus alba x grandidentata) Characterization of transgenic lines for plant growth, transgene transcript abundance, soluble sugars and starch content in various tissues, cell wall structural carbohydrate and lignin content and composition, xylem properties, wood physical characteristics, and transcript profiling of differentially expressed genes Result/Impacts Several of the transgenic lines had only marginal phenotypes and, in many cases, had improved cell wall characteristics; two transgenic lines possessing the highest transgene abundance in the phloem clearly displayed significant developmental effects. These transgenic lines possessed altered cell wall chemistries and fiber properties, traits characteristic of specialized tension wood (lower total lignin content, higher cellulose content, xylem that often contains small vessels and fibers with a unique inner cell wall layer made primarily of cellulose). This transgenic approach, which yields increased cellulose content, altered hemicellulose composition, and reduced lignin content, is an ideal strategy for poplar and other lignocellulosic-derived feedstocks for improved industrial processing, especially for bioenergy applications. Notes: text Title again: Text 1-2 sentence summary? Calcofluor staining of wild-type (upper panel) and AtGolS3-OE line 6 (lower panel) hybrid poplar. Transgenic lines show an irregular vessel phenotype and increased cellulose staining. Unda, F. et al. “Altering carbon allocation in hybrid poplar (Populus alba x grandidentata) impacts cell wall growth and development.” Plant Biotechnology Journal (2017) [DOI: 10.1111/pbi.12682]. GLBRC March 2017