Hydrogen isotopic fractionations during syntheses of lipid biomarkers in the seeds of broomcorn millet (Panicum miliaceum L.) under controlled environmental conditions

• Broomcorn millet was grown under controlled condition. H/D fractionation during seeds n -alkanes and miliacin synthesis examined. Leaf water δ 2 H value is the primary driver of lipid values. Relative humidity could explain subtle differences in ε bio between -alkanes. Compound specific hydrogen isotopic analyses have potential to reveal biosynthetic pathways biomarkers reconstruct effects stress a plant, or an ecosystem. Although C4 graminoids are great geological interest some world's leading crops, there few experimental studies their biomarker responses hydrological conditions. Here, we study graminoid, broomcorn millet, compare changes environmental conditions on distributions -alkane homologues pentacyclic triterpene, miliacin, which for millet; both were measured graminoid. plants propagated hydroponic solutions with four different values each two growth chambers, differing relative (58 74%). Analyses compounds (miliacin -alkanes) extracted from transpiring non-transpiring organs allowed us quantify apparent (lipids vs. source plant) leaf water) fractionations syntheses. Miliacin linearly related values, permitting credible be calculated (average −149.5‰ ± 11) (−118‰ 5). These within range published respective pathways, although H-enrichment compared remains unexplained. Whereas 16% decrease had no significant impact -C 25 27 alkanes, it led ~25‰ 31 33 alkanes. This consequence contribution more depleted pools atoms cytoplasmic (compared chloroplastic pools) -alkyl elongation process. finding suggests that influences organic may discretely inferred by examining synthesized distinct sources cells. provides clues plant derived but also highlights issues seed lipids require further research.