Rubisco varies between wheat species and we are seeking to relate different forms of Rubisco to photosynthetic performance in the leaf.

Bread wheat (Triticum aestivum) is a hexaploid that arose from the progressive combination of three diploid species. The primary carbon fixing enzyme of photosynthesis, Rubisco, contains small subunits encoded by nuclear genes and large subunits encoded on the chloroplast genome that is maternally inherited and originated from the B diploid genome donor. Natural variation exists in the amino acid sequence of the Rubisco large subunit. The consequences of this variation for photosynthetic performance is being investigated by generating bioinformatics on DNA sequences, determining Rubisco kinetic parameters and measuring Rubisco performance in planta. We combine gas exchange equipment with tunable diode laser spectroscopy that allows us to measure ¹³CO₂ and C¹⁸O¹⁶O discrimination.