Location: Crop Improvement and Genetics ResearchTitle: Modification of potato steroidal glycoalkaloids with silencing RNA constructs
Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/1/2017
Publication Date: 2/1/2018
Citation: McCue, K.F., Breksa III, A.P., Vilches, A.M., Belknap, W.R. 2018. Modification of potato steroidal glycoalkaloids with silencing RNA constructs. American Journal of Potato Research. 95:9-14. https://doi.org/10.1007/s12230-018-9658-9.
Interpretive Summary: Glycoalkaloids are naturally found in potatoes and other plants, including other members of the Solanaceae family such as tomatoes and eggplants. In potatoes, undesirably high amounts of glycoalkaloids can accumulate in response to environmental stresses including exposure to cold or light, raising concerns about the food quality and safety of such potatoes. Breeding efforts to introduce natural diseases resistance or improved nutritional quality into potatoes can be hampered by inadvertent introduction of higher glycoalkaloid levels. We are exploring ways to control the unwanted accumulation of glycoalkaloids by using genes from potatoes to turn off the production of glycoalkaloids. Previous approaches have been successful at reducing the accumulation of specific glycoalkaloids that occur in potatoes, but the methods suffered from low efficiencies. Methods taking advantage of recent discoveries in how plants and animals naturally regulate expression of their own genes has allowed us to design a new approach that increases the efficiency of suppressing accumulation of specific glycoalkaloids in potato. Further research is required to develop strategies to reduce levels of total glycoalkaloids. Application of these methods may help to ensure a safe and healthy food supply while allowing the use of natural biodiversity in the breeding process to develop new potato varieties for the commercial market.
Technical Abstract: Steroidal glycoalkaloids (SGAs), while found in many solanaceous plants, can accumulate to unacceptably high levels in potatoes. The two primary SGAs that occur in potatoes are the tri-glycosylated alkaloids, a-solanine and a-chaconine. The first glycosylation steps in their biosynthetic pathways are performed by the regulated enzymes SGT1, the UDP-galactose:solanidine galactosyltransferase, and SGT2, the UDP-glucose:solanidine glucosyltransferase, respectively. Using fragments of the Sgt1 andSgt2 genes to produce small inhibitory RNAs (siRNA), we have been able to down regulate each branch of the pathway. The use of the siRNA approach increases the efficiency of producing transgenic plant lines with reductions in individual SGAs but further research is required to achieve reductions in levels of total SGA accumulation.