Betalains and Other Specialized Metabolites of Amaranth spp. Explored using Transcriptomics and Reverse Genetics

Amaranth is valued as a protein-rich, C₄ pseudocereal, and is adaptable to cultivation in a wide range of environments. It is also one of few crops enriched in specialized metabolites such as the triterpenoid squalene, and betalain pigments. We are using the grain amaranth Amaranthus hypochondriacus L., and the ornamental Amaranthus tricolor L., in conjunction with recent genomic and transcriptomic assemblies, to investigate synthesis and function of amaranth metabolites. We have established VIGS (virus-induced gene silencing) as an efficient technique in amaranths, and have used it to dissect the betalain biosynthetic pathway in A. tricolor, converting normally red plants to green. We are currently extending these results using CRISPR/Cas9 mediated gene-silencing. The response of the isogenic green and red plants to various biotic and abiotic stresses will be compared, to better establish the physiological and ecological roles of betalains. We are also investigating the production of modified betalains, to expand the potential biotechnological applications of these pigments.