I recently joined other botanical illustrators at an IAPI meeting on grasses (Institute for Analytical Plant Illustration), during which Peter Mitchell told us about an important and inspiring project set up by his friend John Sheehy at the International Rice Research Institute.
This is the C4 Rice Project, which aims to boost photosynthesis in rice and thus help to feed the poor in developing areas of the world.
The reasons for wanting to develop a rice plant which has "super-charged" photosynthesis are pretty self-explanatory, and we didn't go into these in our botany meeting. There are an estimated 925 million people who are hungry, many living in areas where rice is a staple crop. If the same area of land could boost rice yield production, then this could help mitigate hunger and provide food security for many people. Developing a new rice plant which could do this might be the answer.
Peter explained that there are two types of grass; C3 and C4 types. C3 types, such as wheat and barley, are cool season grasses.
Barley (Hordeum vulgare), a cool-season C3 grass
In photosynthesis, these fix CO2 into three-carbon compounds. In cross section (very comsumately sliced by Peter) these grasses have blocks of green photosynthetic tissue between vascular bundles (veins) at intervals along the section. This is the typical morphology of a three-carbon compound grass:
Rice, a staple crop in many areas afflicted with poverty and hunger, is a C3 grass.
Rice (Oryza sativa), a C3 grass
The other type of grass is a C4 type. These are warm season grasses, like maize, sorghum and sugar cane.
Sorghum (Sorghum bicolor), a C4 grass species
The leaves of C4 grasses have a different appearance in cross section: dark green rings around lots of small vascular bundles, closely spaced, as seen in the Panicum cross section below. This is called Kranz anatomy, from the German word for a wreath. Carbon dioxide is fixed first into a four-carbon compound, hence C4. This compound moves to the dark green ring where the carbon dioxide is released and refixed by the same mechanism as in C3 plants.
Thus the C4 system acts as a pump, exactly like a supercharger added to an internal combustion engine. The end result is that C4 plants can process more carbon dioxide per unit of sunlight absorbed, and they use less nitrogen and water than C3 plants. In crops, this produces higher yields from the same area of land.
The aim of the C4 rice project is to get rice to photosynthesize like a C4 grass. C4 photosynthesis has evolved over and over again in a wide variety of vascular plants. Surely, with advances in science, and funding from the Bill & Melinda Gates Foundation, it should theoretically be possible to create such a plant?
This is the aim of the C4 Rice project, and is something many botanists and geneticists are working towards. Ultimately, the aim of the C4 Rice Project is to "construct prototypes of crop plants with enhanced photosynthesis that can be used by plant breeders in the developing world to improve yield and recource-use efficiency in a sustainable manner", and "to use science to alleviate hunger in the developing world" (quotes from the C4 Rice Project leaflet).
Rice Paddy landscape
I was deeply moved by the ambition and hope of this project, and feel priviledged to have had one of the founding members of C4 Rice research explain it to me, and the IAPI group. Obviously, this blog is merely a brief introduction to what I see as a very inspiring and important project; for more please do visit the C4 Rice Projects' website.
Many thanks to Peter Mitchell for his input and help with this blog.
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