The antioxidant properties of plant flavonoids: their exploitation by molecular plant breeding

Flavonoids are a large group of plant secondary metabolites that have a high popularity as nutraceuticals. Further, they contribute to food quality, acting as preservatives, pigments and strong antioxidants. Flavonoids also play an important role in plant stress tolerance, with consequent contribution to crop productivity. The enhancement of flavonoid content is an alluring goal that meets the food requirements of an increasing and more demanding world population. After illustrating the relevance of flavonoids for human nutrition, food technology and plant protection, this review covers breeding and molecular strategies used to exploit flavonoid biodiversity present among plant species. Highlighted here are also recent advances in genome sequencing and -omics tools that facilitate the identification of genetic regions influencing flavonoid production in relevant agricultural species. Finally, the review outlines established and new biotechnological techniques which can help to functionalize and use flavonoid genes to improve both the quality and the quantity of these outstanding compounds. The final message of this review is that flavonoids can be an interesting target for molecular plant breeding that can greatly impact both primary agricultural products and food technology.