Color recycling: metabolization of apocarotenoid degradation products suggests carbon regeneration via primary metabolic pathways

• DOI: 10.1007/s00299-022-02831-8
• Publication Date: 2022-01-22T08:02:31Z
• Authors: Julian Koschmieder; Saleh Alseekh; Marzieh Shabani; Raymonde Baltenweck; Veronica G. Maurino; Klaus Palme; Alisdair R. Fernie; Philippe Hugueney; Ralf Welsch
• Keywords: Metabolic pathway; Glyoxal; Metabolome; Lactoylglutathione lyase

Analysis of carotenoid-accumulating roots revealed that oxidative carotenoid degradation yields glyoxal and methylglyoxal. Our data suggest these compounds are detoxified via the glyoxalase system re-enter primary metabolic pathways. Carotenoid levels in plant tissues depend on relative rates synthesis degradation. We recently identified redox enzymes previously known to be involved detoxification fatty acid-derived reactive carbonyl species which were able convert apocarotenoids into corresponding alcohols carboxylic acids. However, their subsequent metabolization pathways remain unresolved. Interestingly, we found have increased glutathione, suggesting apocarotenoid glutathionylation occur. In vitro planta investigations did not, however, support occurrence non-enzymatic or enzymatic β-apocarotenoids. An alternative breakdown pathway is continued derivatives shortest possible oxidation products, namely methylglyoxal, also accumulated roots. fact, combined transcriptome metabolome analysis high glutathione most probably required for detoxifying apocarotenoid-derived methylglyoxal pathway, yielding glycolate D-lactate, respectively. Further suggested reactions involving activities associated with photorespiration peroxisome-specific glycolate/glyoxylate transporter. Finally, products might converted pyruvate possibly re-used biosynthesis precursors. findings allow envision carbon recycling during biosynthesis, re-synthesis consumes energy, but partially maintains initially fixed re-introducing