Premium
Hydrogen isotopic differences between C 3 and C 4 land plant lipids: consequences of compartmentation in C 4 photosynthetic chemistry and C 3 photorespiration
Author(s) -
Zhou Youping,
Grice Kliti,
StuartWilliams Hilary,
Hocart Charles H.,
Gessler Arthur,
Farquhar Graham D.
Publication year - 2016
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/pce.12821
Subject(s) - photorespiration , chloroplast , biochemistry , photosynthesis , crassulacean acid metabolism , chemistry , biosynthesis , metabolism , c4 photosynthesis , mevalonic acid , carbon fixation , metabolic pathway , atp synthase , biology , enzyme , gene
The 2 H/ 1 H ratio of carbon‐bound H in biolipids holds potential for probing plant lipid biosynthesis and metabolism. The biochemical mechanism underlying the isotopic differences between lipids from C 3 and C 4 plants is still poorly understood. GC‐pyrolysis‐IRMS (gas chromatography‐pyrolysis‐isotope ratio mass spectrometry) measurement of the 2 H/ 1 H ratio of leaf lipids from controlled and field grown plants indicates that the biochemical isotopic fractionation (ε 2 H lipid_biochem ) differed between C 3 and C 4 plants in a pathway‐dependent manner: ε 2 H C4 > ε 2 H C3 for the acetogenic pathway, ε 2 H C4 < ε 2 H C3 for the mevalonic acid pathway and the 1‐deoxy‐D‐xylulose 5‐phosphate pathway across all species examined. It is proposed that compartmentation of photosynthetic CO 2 fixation into C 4 mesophyll (M) and bundle sheath (BS) cells and suppression of photorespiration in C 4 M and BS cells both result in C 4 M chloroplastic pyruvate – the precursor for acetogenic pathway – being more depleted in 2 H relative to pyruvate in C 3 cells. In addition, compartmentation in C 4 plants also results in (i) the transferable H of NADPH being enriched in 2 H in C 4 M chloroplasts compared with that in C 3 chloroplasts for the 1‐deoxy‐D‐xylulose 5‐phosphate pathway pathway and (ii) pyruvate relatively 2 H‐enriched being used for the mevalonic acid pathway in the cytosol of BS cells in comparison with that in C 3 cells.