Impact of light-exposure on the metabolite balance of transgenic potato tubers with modified glycoalkaloid biosynthesis

Abstract
Metabolite profiling has been used to assess the impact of light exposure on the composition of potato (Solanum tuberosum L. cv. Desirée) tubers genetically modified (GM) to reduce glycoalkaloid (specifically α-solanine) content via the down-regulation of the SGT1 gene. Using a combination of liquid chromatography-mass spectrometry (LC-MS) and gas chromatography (GC)-MS, the response to light (four and 11 days exposure) of GM line sgt9-2 was compared with its control (BIN+14-3; transformed with an empty vector) for both the outer peel and inner flesh tuber tissues. Metabolomic data were analysed using principal component analysis and analysis of variance. The sgt9-2 line (unlike BIN+14-3) exhibited an almost complete knock-out of α-solanine, and exposing tubers of this line to light had little impact on this metabolite's levels. However, levels of α-chaconine increased significantly in the peel of both lines when exposed to light, and by significantly more in sgt9-2 cf. BIN+14-3. Profiling analyses revealed that the major differences in other metabolite levels significant for a main effect were those driven by differential distributions within tuber tissue types (peel and flesh), and from exposure of tubers to light, and not (in this case) from differences arising from the transgenic event itself. Many of the observed metabolite changes in the light-exposed samples are explicable in terms of pathways known to be affected by stress responses. Only 19 identified metabolites differed significantly between the two lines, and these were, for the most part, explicable in terms of the modification to the glycoalkaloid pathway following down regulation of the SGT1 gene. The fewest number of metabolites observed for a main effect related to temporal differences in light exposure treatment.
Year
2016
Category
Refereed journal
Output Tags
Theme 5 - Food