Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 12/14/2004
Publication Date: 3/13/2005
Citation: Mc Cue, K.F., Shepherd, L., Rockhold, D.R., Allen, P.V., Davies, H., Belknap, W.R. 2005. Modification of Potato SGA'S-A Lesson in Applied Metabolmics. American Chemical Society. 229:U83. Interpretive Summary: Potatoes contain naturally occurring compounds called steroidal glycoalkaloids (SGAs) that can make potatoes and food cooked from them excessively bitter. Accumulation of these compounds is undesirable and dependent upon potato variety as well as growing and handling conditions. In excess amounts they can cause a burning sensation in the mouth and throat. We are developing methods to control the accumulation of these compounds using the potato’s own genes to turn off the steps involved in the formation of SGAs. We have successfully identified and turned down the activity of multiple steps in the pathway. These plants have been examined to determine what the effect of turning off one step has on the other products of the pathway as well the potential effects on related and non-related compounds in the resulting potatoes. Results to date indicate that turning off one step usually results in the accumulation of related compounds at other points in the pathway. Using this information we hope to target multiple steps in the pathway to prevent accumulation of these undesirable compounds.
Technical Abstract: Potatoes contain steroidal glycoalkaloids (SGAs), undesirable bitter metabolites whose accumulation is subject to environmental, physical and genetic variation. Two major triglycosylated SGAs alpha-chaconine and alpha-solanine have been the targets of genetic down regulation. Using members of the steroidal alkaloid glycosyl transferase (SGT) gene family we have analyzed the effects of antisense down regulation of the pathway at multiple steps. The resulting transgenic plants have been analyzed for SGA profiles as well as additional non-specific metabolic perturbations and variations as a result of the genetic transformation regeneration process. What we have observed is that feedback regulation between products of the pathway and the biosynthetic enzymes has resulted in compensation of end products or intermediates resulting in a net zero effect on total levels of SGAs in antisense tubers.