Induction of Defensive Barriers in Plants

Several polymers deposited near surface of plants form an effective barrier against invasion or stress. Cuticle (which consists of a structural polymer cutin) is the major barrier between plants and their surroundings. It is often embedded in a complex mixture of soluble lipids collectively called wax.

Cutin is built by esterification of hydroxy-fatty acids and hydroxy-epoxy fatty acids. Another polymer similarly embedded in wax and forming a barrier is called suberin. Wounding triggers suberisation of plant organs even if the natural cover of the injured organ is cutinous. Plants exposed to cold conditions also show an increased deposition of aliphatic polymers. Response of plants to mineral deficiency includes change in the level of suberisation and cutinisation of various plant organs.