Nick Carne
Australian and US scientists have found a way to increase maize productivity by targeting the enzyme behind photosynthesis.
That’s significant, they say, because they’ve been able to make an already good performer – and an important one – even better.
The research, done by a team led by Coralie Salesse-Smith of the Boyce-Thompson Institute in New York, US, is published in the journal Nature Plants.
All plants use photosynthesis to extract carbon from carbon dioxide, but there are two possible pathways. Maize uses a method known as C4, a more efficient evolutionary improvement of an earlier and more widespread mechanism, known as C3. All plants have the C3 pathway; the additional C4 evolved in species in the wet and dry tropics.
Central to this process is an enzyme called ribulose-1,5-bisphosphate carboxylase/oxygenase, or, more commonly, Rubisco, which is in charge of converting carbon dioxide into organic compounds. Rubisco works much more quickly in C4 plants, which are more water efficient and thus more tolerant to heat and drought.
“We developed a transgenic maize designed to produce more Rubisco … and the result is a plant with improved photosynthesis and hence growth,” says researcher Robert Sharwood from Australia’s ARC Centre of Excellence for Translational Photosynthesis.
“This could potentially increase tolerance to extreme growth conditions.”
In their study, Salesse-Smith and colleagues improved carbon dioxide assimilation and crop biomass by 15%. Sharwood says now they know they can also increase the pool of active Rubisco, things will improve further.
“Our next step is to do field trials to see how our maize behaves in real field conditions. We have tested them in glasshouse and cabinet conditions, but now we need to go into the next phase,” he explains.
Maize, also known as corn, is a staple food for billions of people around the world, with more grown annually than rice or wheat.
Sharwood says expected climate change conditions will increase the threats against global food security and “the only way to prepare for them is through international research collaborations”.
