Elucidating the biosynthesis of 2-carboxyarabinitol 1-phosphate through reduced expression of chloroplastic fructose 1,6-bisphosphate phosphatase and radiotracer studies with 14CO2.
2-carboxyarabinitol 1-phosphate limits photosynthetic CO2 assimilation at low light because it is a potent, naturally occurring inhibitor of ribulose 1,5-bisphosphate carboxylase/oxygenase. Evidence is presented that this inhibitor is derived from chloroplastic fructose 1,6-bisphosphate. First, transgenic plants containing decreased amounts of chloroplastic fructose 1,6-bisphosphate phosphatase contained increased amounts of fructose 1,6-bisphosphate and 2-carboxyarabinitol 1-phosphate and greatly increased amounts of the putative intermediates hamamelose and 2-carboxyarabinitol, which in some cases were as abundant as sucrose. Second, French bean leaves in the light were shown to incorporate 14C from 14CO2 sequentially into fructose 1,6-bisphosphate, hamamelose bisphosphate, hamamelose monophosphate, hamamelose, and 2-carboxyarabinitol. As shown previously, 14C assimilated by photosynthesis was also incorporated into 2-carboxyarabinitol 1-phosphate during subsequent darkness.
Andralojc
P John
PJ
IACR-Rothamsted, Crop Performance & Improvement Division, West Common, Harpenden, Hertfordshire AL5 2JQ, United Kingdom. john.andralojc@bbsrc.ac.uk
Keys
Alfred J
AJ
Kossmann
Jens
J
Parry
Martin A J
MA
D002245:Carbon Dioxide / Q000032:analysis; D002250:Carbon Radioisotopes; D002736:Chloroplasts / Q000378:metabolism*; D006597:Fructose-Bisphosphatase / Q000096:biosynthesis* / Q000235:genetics; D005635:Fructosediphosphates / Q000378:metabolism; D006601:Hexoses / Q000378:metabolism; D010428:Pentosephosphates / Q000096:biosynthesis*; D010788:Photosynthesis; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000378:metabolism; D011198:Solanum tuberosum / Q000235:genetics / Q000378:metabolism*
D002250:Carbon Radioisotopes; D005635:Fructosediphosphates; D006601:Hexoses; D010428:Pentosephosphates; C054549:2-carboxyarabinitol 1-phosphate; D002245:Carbon Dioxide; C009758:hamamelose; D006597:Fructose-Bisphosphatase; C029063:fructose-1,6-diphosphate