Carbon isotope discrimination as a tool to explore C4 photosynthesis.
Photosynthetic carbon isotope discrimination is a non-destructive tool for investigating C4 metabolism. Tuneable diode laser absorption spectroscopy provides new opportunities for making rapid, concurrent measurements of carbon isotope discrimination and CO2 assimilation over a range of environmental conditions, and this has facilitated the use of carbon isotope discrimination as a probe of C4 metabolism. In spite of the significant progress made in recent years, understanding how photosynthetic carbon isotope discrimination measured concurrently with gas exchange relates to carbon isotope composition of leaf and plant dry matter remains a challenge that requires resolution if this technique is to be successfully applied as a screening tool in crop breeding and phylogenetic research. In this review, we update our understanding of the factors and assumptions that underlie variations in photosynthetic carbon isotope discrimination in C4 leaves. Closing the main gaps in our understanding of carbon isotope discrimination during C4 photosynthesis may help advance research aimed at developing higher productivity and efficiency in key C4 food, feed, and biofuel crops.
Research School of Biology, The Australian National University, Canberra ACT 0200, Australia susanne.caemmerer@anu.edu.au.
Susanne
S
von Caemmerer
Hawkesbury Institute for the Environment, University of Western Sydney, Hawkesbury campus, Locked Bag 1797, Penrith 2751, NSW, Australia.
Oula
O
Ghannoum
Research School of Biology, The Australian National University, Canberra ACT 0200, Australia.
Jasper J L
JJ
Pengelly
School of Biological Sciences, Washington State University, Pullman, WA 99164, USA.
Asaph B
AB
Cousins
D002245:Carbon Dioxide / Q000378:metabolism*; D002247:Carbon Isotopes / Q000032:analysis; D008291:Malate Dehydrogenase / Q000378:metabolism; D010788:Photosynthesis / Q000502:physiology*; D018515:Plant Leaves / Q000502:physiology; D010940:Plant Proteins / Q000378:metabolism; D018526:Plant Transpiration / Q000502:physiology*; D006109:Poaceae / Q000502:physiology*
D002247:Carbon Isotopes; D010940:Plant Proteins; D002245:Carbon Dioxide; D008291:Malate Dehydrogenase; C046446:malate dehydrogenase-(oxaloacetate-decarboxylating) (NAD+); C031917:malate dehydrogenase (oxaloacetate-decarboxylating) (NADP+)
13C discrimination; C4 grasses; C4 photosynthesis; NAD-ME subtype; NADP-ME subtype; carbon isotope discrimination; gas exchange.