Depleting lignin in plant cells makes cellulose easier to break down by enzymes. Researchers used cultured xylem cells from Zinnia elegans to study this. They removed lignin from the cells and found that cellulose became more accessible and digestible. This shows that lignin plays a big role in making cellulose hard to break down. The study used a simple model system to show how reducing lignin levels can improve the digestion of cellulose in plant cell walls.