More than 25% of the primary terrestrial productivity, and a significant portion of the food consumed by humans, is produced by plants that utilize C4photosynthesis to fix atmospheric CO2. Over decades many scientists have been working toward transferring the C4-abillity to C3 crops, Conservative estimates put the increase in crop yield, that this would give, at 50% and forecast considerable increases in water use efficiency and reduction in fertilizer requirements as a result of such a transfer. These benefits would be especially evident in, hot, dry environments. Crops like maize (Zea mays), sugarcane (Saccharum spp.) and several emerging bioenergy grasses exhibit high productivity levels under those conditions, primarily due to their ability to carry out C4 photosynthesis.
Up to now the ability to induce the more efficient form of photosynthesis in less efficient plants has eluded everyone working in the field. This is all about to change because researchers recently reported in Plant & Cell Physiology that they have pinned down the transcription factor, called SCARECROW, which regulates structural differentiation of the leaf anatomy, conferring the ability to carry out C4 photosynthesis on the plants in which it operates. Once the signal transduction pathway for this process has been completely characterized, researchers believe it will be possible to facilitate the transfer of the C4 trait into C3 crop species, including rice.