Production of betalains in plant cell and organ cultures: a review

Betalains are nitrogen-containing natural pigments that are water soluble and they comprise of the red-violet betacyanin and the yellow betaxanthin which are abundant in plants such as red/yellow beet, amaranth, prickly pear, pitaya, and others. They are widely used as food coloring agents for many centuries. Betalains are used in pharmaceuticals, functional foods, and cosmeceuticals, since they have tremendous potential to scavenge free radicals and prevent diseases, such as hypertension, dyslipidemia, cancer, neurological disorders, and vascular stenosis. Betalains are proven to be toxicologically safe and have health benefits, they have been approved as food additives in the United States of America, and European countries. Although betalains can be found in natural resources, there are differences in their composition, amounts, and seasonality. For this reason, researchers have developed alternative methods of producing these valuable compounds using cell and organ culture techniques. In several plants, cell and organ cultures are established, and bioreactor technologies have been used to produce betalains on a wide scale. In this review, we discuss the varied biotechnological methods and approaches applied for the biosynthesis of betalains including metabolic engineering approaches.