Cell wall

Plant and animal cells are both eukaryotic because they share this nuclear organisation. They are not identical in every respect: for example, plant cells have a cell wall whereas animal cells do not. The defining point here is that both contain their genetic material in a nucleus.

The cell wall is a rigid layer outside the cell membrane. In plants it is made of cellulose. It supports the cell, helps it retain its shape and contributes to the strength of plant tissues.

If a pathogen gets beyond the leaf surface, it meets the cell walls surrounding plant cells. These strong walls provide support, but they also create another physical obstacle: a pathogen must cross a wall to enter a cell or move directly through the tissue.

Two physical plant defences required for this course are the leaf cuticle and the cell wall. They act at different levels: the cuticle protects the outer surface of the leaf, while cell walls protect individual cells within plant tissues.