IC4R005-Phenomics-2009-11089458

Project Title

There is now strong evidence that yield potential in rice (Oryza sativa L.) is becoming limited by ‘source’ capacity, i.e. photosynthetic capacity or efficiency, and hence the ability to fill the large number of grain ‘sinks’ produced in modern varieties. One solution to this problem is to introduce a more efficient, higher capacity photosynthetic mechanism to rice, theC4 pathway.Amajor challenge is identifying and engineering the genes necessary to installC4 photosynthesis in rice. Recently, an international research consortium was established to achieve this aim. Central to the aims of this project is phenotyping large populations of rice and sorghum (Sorghum bicolor L.) mutants for ‘C4-ness’ to identifyC3 plants that have acquired C4 characteristics or revertant C4 plants that have lost them. This paper describes a variety of plant phenomics approaches to identify these plants and the genes responsible, based on the detailed physiological knowledge of C4 photosynthesis.

Genetic modification of rice to have C4 traits (functioning as a C3–C4 intermediate or C4 plant) is a challenging goal, requiring both anatomical and biochemical specialisation and compartmentation within chlorenchyma cells (Fig. 1). In C4 plants, spatial separation of the capture of atmospheric CO2 from its delivery to Rubisco is required.

Fig. 1. A simplified scheme of the C4 pathway (adapted from von Caemmerer 2000).

CSIRO Plant Industry and High Resolution Plant Phenomics Centre, GPO Box 1600, Canberra, ACT 2601, Australia.
Research School of Biology, Australian National University, GPO Box 475, Canberra, ACT 2601, Australia.
International Rice Research Institute, DAPO Box 7777, Metro Manila, Philippines.
School of Biological Sciences, Washington State University, Pullman, WA 99164-4236, USA.