Improving color sources by plant breeding and cultivation

Profitable natural pigment production in the form of pure compounds or concentrates requires high-quality plant sources. Plant breeding is a time-consuming process of crop improvement resulting in new plant cultivars of desired characteristics that are suitable for agricultural production. Demands in the pigment industry for high-quality plant materials must be combined with the needs of farmers for high yield. Progress in cultivar development depends on many factors, including plant reproductive biology, trait heritability, existing genetic variation, agrotechnical practices, and environmental conditions. In this chapter, we discuss these and related aspects of breeding plants for improved sources of natural pigments. We have focused our chapter on three separate case studies of vegetable crops: tomato, beetroot, and carrot, representing the most important industrial sources of the three major pigment classes for carotenoids (lycopene), betalain, and anthocyanin production, respectively. These fruit and root crops differ in their life cycle and reproductive biology, and they exhibit diverse biosynthetic pathways for pigment production. The depth of knowledge on genes and biosynthetic pathways involved in pigment production varies for these crops. In addition, the biennial life cycle of carrot and beetroot makes progress in cultivar development more challenging. Advances in new molecular techniques facilitate conventional breeding for pigment production and new avenues of inquiry have been opened from genome sequencing and related approaches.