Current status of the multinational Arabidopsis community

The multinational Arabidopsis research community is highly collaborative and over the past thirty years these activities have been documented by the Multinational Arabidopsis Steering Committee (MASC). Here, we (a) highlight recent research advances made with the reference plant Arabidopsis thaliana; (b) provide summaries from recent reports submitted by MASC subcommittees, projects and resources associated with MASC and from MASC country representatives; and (c) initiate a call for ideas and foci for the “fourth decadal roadmap,” which will advise and coordinate the global activities of the Arabidopsis research community

UDP-Uronic acid transporters are important providing galacturonic acid and arabinose, but not xylose, into the cell wall

International audienc

The three members of the Arabidopsis Glycosyltransferase Family 92 are functional beta-1,4-galactan synthases

Pectin is a major component of primary cell walls and performs a plethora of functions crucial for plant growth, development and plant-defense responses. Despite the importance of pectic polysaccharides their biosynthesis is poorly understood. Several genes have been implicated in pectin biosynthesis by mutant analysis, but biochemical activity has been shown for very few. We used reverse genetics and biochemical analysis to study members of Glycosyltransferase Family 92 (GT92) in Arabidopsis thaliana. Biochemical analysis gave detailed insight into the properties of GALS1 (Galactan synthase 1) and showed galactan synthase activity of GALS2 and GALS3. All proteins are responsible for adding galactose onto existing galactose residues attached to the rhamnogalacturonan-I (RG-I) backbone. Significant GALS activity was observed with galactopentaose as acceptor but longer acceptors are favored. Overexpression of the GALS proteins in Arabidopsis resulted in accumulation of unbranched β-1, 4-galactan. Plants in which all three genes were inactivated had no detectable β-1, 4-galactan, and surprisingly these plants exhibited no obvious developmental phenotypes under standard growth conditions. RG-I in the triple mutants retained branching indicating that the initial Gal substitutions on the RG-I backbone are added by enzymes different from GALS.Berit Ebert, Devon Birdseye, April J.M. Liwanag, Tomas Laursen, Emilie A. Rennie, Xiaoyuan Guo, Michela Catena, Carsten Rautengarten, Solomon H. Stonebloom, Pawel Gluza, Venkataramana R. Pidatala, Mathias C.F. Andersen, Roshan Cheetamun, Jenny C. Mortimer, Joshua L. Heazlewood, Antony Bacic, Mads H. Clausen, William G.T. Willats, and Henrik V. Schelle