Abstract text: The biosynthesis of cell wall polysaccharides requires nucleotide sugars, which are primarily synthesized in the cytosol. For transport into the Golgi apparatus, where polysaccharide biosynthesis occurs, these substrates rely on nucleotide sugar transporters (NSTs). UDP-apiose is a nucleotide sugar present in the pectic fraction of plant cell walls. Apiose plays a crucial role by enabling the borate-mediated cross-linking of two monomers of the branched pectic polysaccharide rhamnogalacturonan II (RG-II), a process essential for cell wall integrity and plant viability. Owing to this central role, understanding UDP-apiose transport and the biosynthesis of apiose-containing polysaccharides is of particular interest. However, the identification of UDP-apiose-specific transporters has long been hindered by the limited availability and inherent instability of UDP-apiose. Here, we characterize two members of the Arabidopsis NST family as UDP-apiose transporters in vitro. Quantitative RT-PCR analysis indicates that both transporters are ubiquitously expressed across A. thaliana tissues and developmental stages. Consistent with their role in RG-II biosynthesis, both proteins localize to the Golgi apparatus.  Studies are currently underway using mutants, for example generated via CRISPR–Cas9, to investigate the functional role of UDP-apiose biosynthesis and transport.