Further studies on a new pathway of photosynthetic carbon dioxide fixation in sugar-cane and its occurrence in other plant species

Abstract

The pathway of photosynthesis in sugar-cane, which gives most of the radio-activity fixed during short periods in C14O2 in C-4 of oxaloacetate, malate and aspartate, was examined under varied conditions. The pattern of labelling was essentially the same with leaves of different ages and with leaves equilibrated at carbon dioxide concentrations in the range 0-3. 8% (v/v) and light-intensities in the range 1400-9000 ft. -candles before adding C14O2. Radioactive products were examined after exposing leaves of 33 different plant species to C14O2 for 4sec. under standard conditions. A labelling pattern typical of sugar-cane was found in several species of Gramineae but not in others. Of 16 species from other families only a species of Cyperaceae contained a large proportion of the fixed radioactivity in oxaloacetate, malate and aspartate.