The Role of the Golgi ELMO Proteins in Cell Adhesion in Arabidopsis thaliana

Proper growth and development of plant cells is dependent upon successful cell adhesion between cells, and this is mostly mediated by pectin in the plant cell wall. Previously, the Kohorn Laboratory identified a non-enzymatic Golgi protein named ELMO1 as it is required for cell adhesion, likely acting as a scaffold for cell wall polymer synthesis. Plants with mutant ELMO1 demonstrate a weak defective cellular adhesion phenotype as well as reduced mannose content in the cell wall. ELMO1 has homologous proteins in at least 29 different vascular plants. These homologues have 2 possible deletions in their amino acid sequence, but protein modeling determined that these variations will not affect protein structure. There are 5 homologous ELMO1 proteins in Arabidopsis thaliana that have been aptly named ELMO2, ELMO3, ELMO4, ELMO5. elmo2-/-mutants revealed no mutant adhesion phenotypes, while elmo1-/-elmo2-/-double mutants revealed strong defects in adhesion. Confocal microscopy of propidium iodide-stained seedlings confirmed the lack of a phenotype for elmo2-/-mutants and showed disorganized gapping cells for the elmo1-/-elmo2-/-mutant. Additionally, while elmo2-/-did not have any change to root or hypocotyl length, elmo1-/-elmo2-/- mutants were significantly shorter in both regards. Taken together, these data support that ELMO2 and ELMO1 are partially redundant.