Abstract text: We will present results indicating a direct role of a subset of homogalacturonan (HG) polymers in cell morphogenesis and growth. We will show that HG nanofilaments arranged parallel to cellulose microfibrils are rapidly affected—within as little as 20 minutes—by treatments that disrupt anisotropic growth, such as oryzalin, isoxaben, and DCB. 
We will also present results on cell wall structure and cell growth of constitutive mutants defective in one of the enzymes involved in HG polymerization in the Golgi apparatus (GAUT1). We observed that these mutants develop modified meristems and exhibit altered cell shape and strongly reduced growth in the cotyledons and hypocotyl. Although HG is still present, these mutants lack the HG nanofilaments. 
Finally, we will present results with inducible CRISPR line affecting GAUT1 activity in the epidermis, confirming that GAUT1 alteration leads to strong defects in cell wall morphogenesis and growth in all type of epidermal cells.