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[SANET-MG] there's gold in them thar spuds
The paper below was featured in today's sunday times.
The problem with beta carotene and vitamin D is that if it is too low
it is just public relations as in golden rice, if it is too high you
face human birth defects and resulting lawsuites.
Like Goldylocks porridege, it has to be just right.
Journal of Experimental Botany, doi:10.1093/jxb/eri016 2004
RESEARCH PAPER
Metabolic engineering of high carotenoid potato tubers containing
enhanced levels of -carotene and lutein
Laurence J. M. Ducreux 1, Wayne L. Morris 1, Peter E. Hedley 2, Tom
Shepherd 1, Howard V. Davies 1, Steve Millam 2, and Mark A. Taylor 1*
1 Quality, Health and Nutrition, Scottish Crop Research Institute,
Invergowrie, Dundee, DD2 5DA, UK
2 Gene Expression, Scottish Crop Research Institute, Invergowrie,
Dundee, DD2 5DA, UK
Abstract
In order to enhance the carotenoid content of potato tubers, transgenic
potato plants have been produced expressing an Erwinia uredovora crtB
gene encoding phytoene synthase, specifically in the tuber of Solanum
tuberosum L. cultivar Désirée which normally produces tubers containing
c. 5.6 µg carotenoid g-1 DW and also in Solanum phureja L. cv. Mayan
Gold which has a tuber carotenoid content of typically 20 µg carotenoid
g-1 DW. In developing tubers of transgenic crtB Désirée lines,
carotenoid levels reached 35 µg carotenoid g-1 DW and the balance of
carotenoids changed radically compared with controls: -carotene levels
in the transgenic tubers reached c. 11 µg g-1 DW, whereas control tubers
contained negligible amounts and lutein accumulated to a level 19-fold
higher than empty-vector transformed controls. The crtB gene was also
transformed into S. phureja (cv. Mayan Gold), again resulting in an
increase in total carotenoid content to 78 µg carotenoid g-1 DW in the
most affected transgenic line. In these tubers, the major carotenoids
were violaxanthin, lutein, antheraxanthin, and -carotene. No increases
in expression levels of the major carotenoid biosynthetic genes could be
detected in the transgenic tubers, despite the large increase in
carotenoid accumulation. Microarray analysis was used to identify a
number of genes that were consistently up- or down-regulated in
transgenic crtB tubers compared with empty vector controls. The
implications of these data from a nutritional standpoint and for further
modifications of tuber carotenoid content are discussed.
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