A healthy plant cuticle is fundamental for a healthy plant and quality crop.

Diagram of plant cuticle

It may be difficult to comprehend that the marketability of an entire crop can be largely determined by a material that is under 10 microns in size. Yet this is the challenge that must be overcome in the agriculture industry, and it begins with a thorough understanding of that microscopic layer that encompasses the fruit: the cuticle. The cuticle of a plant acts as its armor for protection from outside forces. A healthy cuticle has the ability to defend against excessive water uptake/loss, protect against harmful UV radiation, and decrease the susceptibility of the fruit to attack via fungi, pathogens, and pests.

Made up of two separate layers, the cuticle encompasses the cellular wall of the fruit, as well as the leaves, stems, and trunk of the plant. The first layer is made up of cutin, a variety of waxy polymers, and is embedded with polysaccharides. These polysaccharides, made up of fatty acids, encompass the hydrophilic cell wall and provide a rigidity to the plant with the flexibility to withstand growth. This layer is also essential for gaseous exchange, nutrient transport, and transpiration. The second layer of the cuticle is made up of cuticular waxes. These waxes are hydrophobic and play a primary role in the plant’s permeability to water.

Both layers are produced by the epidermis of the fruit during early growth stages, therefore they must be able to stretch across the fruit as it expands rapidly without developing any imperfections. Imperfections in the cuticle arise from a rapid expansion of the fruit that overcomes the cuticle’s elastic properties. This occurs most commonly during rainfall or times of excess moisture.

Apart from transpiration, the cuticle also protects against fruit sunburn resulting from exposure to UV radiation and excess heat absorption. While the cell wall houses a variety of pigments to screen and absorb UV-B radiation, the cutin layer also possess pigments that provide additional screening and the waxy layer has the ability to reflect UV waves.