Overexpression of Human UDP-Galactose Transporter 1 (hUGT1) modulate xylem development via increased arabinogalactan proteins in poplar
Wenbo Lu (Japan)1; Wenbo Shan (Japan)1; Ryosuke Sano (Japan)2 3; Toshihisa Kotake (Japan)4; Taku Demura (Japan)2 5; Misato Ohtani (Japan)1 2 3 5;
1 - Graduate School of Frontier Sciences, The University of Tokyo, Chiba, Japan; 2 - Nara Institute of Science and Technology (NAIST), Nara, Japan; 3 - Graduate School of Science, The University of Tokyo, Tokyo, Japan; 4 - Graduate School of Science and Engineering, Saitama University, Saitama, Japan; 5 - RIKEN Center for Sustainable Resource Science, Kanagawa, Japan;
Keywords: Arabinogalactan proteins (AGPs); Poplar; Secondary cell wall;
Abstract Topics: Theme 4: Arabinogalactan Proteins
Type of Presentation: Poster

Abstract text: Arabinogalactan proteins (AGPs) are highly glycosylated cell wall proteins involved in plant growth and development. Their involvement in woody formation has been elucidated, but it has been not fully understood. In this study, we investigated effects of altered AGP biosynthesis on xylem development in poplar (Populus tremula × tremuloides) by the overexpression of human UDP-galactose transporter gene (hUGT1). Histological analysis revealed that hUGT1 overexpression accelerated the initiation of secondary xylem formation in young stems of one-month-old plantlets, while overall plant growth and mature xylem structure were not significantly changed at later developmental stages. In the hUGT1 overexpressing poplars, the pectin polysaccharide fractions were increased, and β-Yariv assays revealed significant increase in β-1,3-galactan backbone contents. Transcriptome analysis of developing xylem further showed that most AGP genes were downregulated in hUGT1-overexpressing plants, with only a few AGP genes specifically upregulated. These findings indicate that promoting early secondary growth depends on the increase of specific types of AGPs rather than their total contents. Taken together, our findings would reveal a previously underappreciated role of specific AGPs in regulating the timing of secondary cell wall formation in poplar, offering new insights into the strategy of woody biomass improvement through AGP-mediated cell wall regulation.