BY SHAWN KENG
IN a resource-demanding world, humans have developed green technologies which are energy efficient and minimal in carbon footprint. Now, imagine the engineering of energy efficiency is applied in crops. Scientists are programming rice to produce more yield during photosynthesis, by interchanging genetic code found in maize.
Based on University of Oxford press release, a research group [ihc-hide-content ihc_mb_type=”show” ihc_mb_who=”2,3,5″ ihc_mb_template=”1″ ] aims to increase rice productivity and crop yield by design. Scientists are “switching” the rice original C3 photosynthetic pathway to a more efficient C4 photosynthetic pathway found in maize and sorghum. This Oxford-led C4 Rice Project is introducing a single maize gene to rice, to power up crop photosynthetic efficiency.
Maize (a C4 plant) is known to perform photosynthesis much better than rice (a C3 plant) under dry and hot environment. This is because maize has specialised leaf anatomy and biochemistry to capture and concentrate CO2 during photosynthesis to a 4-carbon acid known as oxaloacetic acid.
This C4 photosynthetic pathway offers a competitive advantage for maize to grow despite the environmental condition. Unlike rice in Asian region, maize is the main staple crop for 50 percent of the Sub-Saharan African population.
Beyond Africa, maize is a preferred food for one-third of malnourished kids globally and 900 million poor people worldwide. Based on global crop species, C4 photosynthetic pathway which is being used by only 3% of species, accounts for approximately a quarter of the planet’s primary food production.
Theoretically, if rice could be “switched” to C4 pathway, it has massive potential to grow more yield regardless of climate conditions. The good news is scientists are one-third closer in achieving this switch. A new study published in the journal Current Biology, recreates the first step of likely 3-step evolutionary process to make C3 plants switch to C4 pathway.
The challenge faced by C4 Rice Project today is the limitation in rice leaf anatomy. For most C4 plants, photosynthesis happens in two wreaths of cells arranged closely to veins – a unique C4 plant leaf structure called Kranz anatomy.
To mimic this in C3 plants, a single maize gene called GOLDEN2-LIKE was introduced to the rice plant. Thus, the C3 plants have increased the volume of functional chloroplasts and mitochondria in the cell sheath surrounding the leaf veins, mimicking the traits seen in C4 plants.
According to the release, Professor Langdale who is the Principal Investigator on this phase of the C4 Rice Project said: “This research introduces a single gene to the rice plant to recreate the first step along the evolutionary path from C3 to C4. It’s a really encouraging development, and the challenge now is to build on that and find the right genes to tweak to complete the remaining steps in the process.’
‘The C4 pathway is an extremely complex and remarkable piece of evolution, and we don’t know how the individual evolutionary steps took place – while in terms of leaf anatomy it appears as though there were at least two more steps between proto-Kranz and C4, perhaps these subsequent steps can also each be recapitulated with the introduction of just a single gene.
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