Photosynthetic carbon metabolism of the cool-temperate C4 grass Spartina anglica Hubb.

The aim of this work was to describe the photosynthetic carbon metabolism of the cooltemperate C4 grass Spartina anglica. With the exception of pyruvate, phosphate dikinase and pyruvate kinase, the maximum catalytic activities in leaves of putative enzymes of the C4 cycle of a phosphoenolpyruvate-carboxykinase C4 plant were considerably in excess of the observed, steady-state rate of photosynthesis, and were comparable with the maximum catalytic activities of key enzymes of the reductive pentose-phosphate pathway. Radioactive carbon from (14)CO2 supplied to attached leaves during steady-state photosynthesis appeared first in malate and aspartate from which it moved to intermediates of the reductive pentose-phosphate pathway, and then to sucrose. These experiments show that photosynthetic carbon metabolism in this cool-temperate C4 plant is similar to that of C4 plants of hotter climates.