Lopez, Alex , Van Eck, Joyce , Conlin, Brian , Paolillo Jr, Dominick , Li, Li .
Enhanced carotenoid accumulation as a result of alteration of metabolic sinks in transgenic plants.
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 beta-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 beta-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 beta-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.
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1 - USDA-ARS, Plant, Soil and Nutrition Laboratory
2 - Boyce Thompson Institute for Plant Research
3 - Cornell University, Plant Biology
4 - USDA-ARS, Plant, Soil and Nutrition Laboratory, Cornell University, Ithaca, NY, 14853, USA
Presentation Type: ASPB Minisymposium
Location: Continental A/Hilton
Date: Wednesday, July 11th, 2007
Time: 9:45 AM