ARS | Publication request: Enhanced carotenoid accumulation as a result of alteration of metabolic sinks in transgenic plants

Submitted to: American Society of Plant Biologists Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: July 7, 2007
Publication Date: July 7, 2007
Citation: Lopez, A.B., Van Eck, J., Conlin, B.J., Paolillo, D., Li, L. Enchanced carotenoid accumulation as a result of alteration of metabolic sinks in transgenic plants. American Society of Plant Biologists Annual Meeting. 2007. M23004, p127.

Technical Abstract: Carotenoids are highly beneficial for human nutrition and health because they provide important nutrients and antioxidants in our diets. We have isolated a novel gene, the Or gene, from an orange cauliflower mutant that confers high levels of B-carotene accumulation (Lu et al., Plant Cell 2006 18:3594). Instead of functioning directly in regulating carotenoid biosynthesis, the Or gene appears to trigger the differentiation of non-colored plastids into chromoplasts for carotenoid accumulation. Expression of the Or gene in transgenic potato tubers resulted in orange-yellow tubers containing 6-fold more total carotenoids than controls, including the production of B-carotene which is present at negligible amounts in control tubers. The Or transgenic effect was stably inherited in a subsequent generation. Interestingly, cold storage greatly enhanced total carotenoid and B-carotene content to a level over 15-fold higher than controls. Carotenoids in the Or potato transgenic lines accumulated in chromoplasts as membranous carotenoid helices, showing similar structures as those found in carrot. Such carotenoid sequestering structures were not observed in control tubers or in the tubers of a potato cultivar that accumulate high levels of zeaxanthin. These results provide strong evidence that induction of the formation of a metabolic sink for carotenoid sequestering and storage is an important mechanism to regulate carotenoid accumulation, and offer a novel example of a very useful strategy for improving the nutritional quality of our food crops.