PRODUCTION OF THE NUTRACEUTICAL CAROTENOID ASTAXANTHIN IN CAMELINA SEEDS

Abstract

The light- harvesting, colorful pigments which are most widely produced by plants are known as carotenoids. These compounds are both high in number and diversity, creating a vast array of bright colors seen in fruits, vegetables, and algae. Carotenoids can only be synthesized de novo by photosynthetic organisms and microbes, but are present in humans through dietary intake. A handful of these compounds display various health benefits. Furthermore, dietary intake of this carotenoid greatly minimizes the risk of Vitamin A deficiency induced blindness. Fortunately, bioengineering of plants provides an avenue to fortify food crops with elevated levels of Vitamin A, which has been a goal of researchers for decades. The Schmidt laboratory has successfully enhanced Camelina sativa seeds with enhanced β-carotene, Vitamin A’s precursor compound. This current multi-year project involved the introduction and subsequent accumulation of a b-carotene derived keto-carotenoid, astaxanthin. This project involves the engineering of Camelina sativa seeds for the production of astaxanthin by extending the b-carotene carotenoid pathway and comparing two separate strategies, the introduction of crtS, a gene isolated from the red yeast Xanthophyllomyces dendrorhous, or the introduction of BKTChamy from the green algae Haematococcus pluvialis. The current project's objectives were to both confirm the presence and expression of the introduced transgenes and detect and quantify the introduced carotenoid astaxanthin in the seeds. This has been completed by genomic PCR using gene- specific primers to verify gene integration as well as RT-PCR to detect transgene transcription. PCR results proved incorporation of the genes, with BKTChamy being produced in higher quantities, evident by the much more noticeable orange seed color. Results of a phenotypic analysis revealed a reddish coloring of seeds with the β-carotene/ β-carotene ketolase cassettes, confirming elevated levels of astaxanthin not found in wild-type seeds