What are the roles of anthocyanin?

Anthocyanins, a branch of flavonoids, have many biological functions in higher plants. They provide a variety of colors for plants acting as insect and animal attractants. They also serve as important molecules in defense against UV irradiation, pathogen infection and ROS scavenging. Anthocyanins accumulate in the vacuoles of a wide range of cells and tissues in both vegetative and reproductive organs.

Anthocyanins (from Greek anthos – flower and kyaneos - blue) are plant low molecular weight compounds, defined as secondary metabolites, meaning dyes are not essential for the primary metabolism. The word ‘anthocyanin’ dates back to 1835 when Marquart first coined this term in the paper, “Die Farben der Bluthen,eine chemisch-physiologische Abhandlung”.

The red-to-purple color imparted by anthocyanins to flowers, fruits, and seeds act as visual deterrents to herbivores, and attractants to pollinators and seed dispersers. Anthocyanins and other flavonoids also contribute to stress tolerance in plants.

These compounds are water soluble vacuolar pigments present mostly in fruits and flowers, but also in vegetative organs. They have a strong impact on food sensory properties, as they provide the characteristic red to blue color in fruits and vegetables. In plants, they play a key role in pollination and by absorbing light, protect plants from UV ray-induced damage and from cold stress.

Protection of photosynthetic apparatus: Anthocyanins protect leaves from the stress of photoinhibitory light fluxes by absorbing the excess photons that would otherwise be intercepted by chlorophyll b.

Anthocyanins are excellent scavengers of free radicals. Anthocyanins show antioxidant activity by scavenging free radicals, activating antioxidant enzyme, and chelating metal ions,

There are several different ways anthocyanins might assist plants in their defense against other organisms. These include both direct roles as chemical repellents and more indirect roles as visual signals. In common with other flavonoids, certain anthocyanins have demonstrable antiviral, antibacterial, and fungicidal activities.

If plants lacked anthocyanin, no part of the plant would display purple or blue color. The main function of the anthocyanins, contained in flowers or in fruit epidermis, is to attract animals and pollinating insects to easily disseminate the seeds or to facilitate the spread of pollen. These processes will be affected due to lack of anthocyanin.
What are the roles of anthocyanin?