At the University of York in the United Kingdom, researchers have developed a new, modified wheat variety that increases grain production by up to 12 percent.
Scientists at the university have increased the levels of a protein called expansin, which determines the growth of plants.
“Expansins are conserved in all land plants and play a key role in growth,” said professor Simon McQueen-Mason, chair in materials biology at the university’s Centre for Novel Agricultural Products.
“Growth of plant cells is constrained by the strong cell wall that surrounds them. Expansins loosen the structure of the wall, allowing cells to expand. They are accelerators of growth. They are present in the growing grain, but we just added a bit more, allowing the grain to get bigger. This should work in any plant or crop.”
The team worked with research partners at the Universidad Austral de Chile. They conducted field experiments that demonstrated the effectiveness of the plants with increased expansin levels in agricultural conditions. The plants not only had an increase in grain size but showed that there was no decrease in grain numbers, which resulted in an overall increase in yield.
McQueen-Mason said that there appears to be a developmental tie-in between the two processes of grain expansion and grain number.
“We put the extra expansins into the grain slightly later in development than they usually occur, and presumably after the regulatory process that ties them to one another.”
McQueen-Mason said they knew that extra expansins could make plants bigger, but they targeted the protein so that it was only in developing grain. They wanted to avoid ending up with bigger plants, which would likely have a negative impact on yield because more resources within the plant may end up being put into other plant tissues.
“We inserted a new version of an expansin gene (normally expressed in roots) under the control of a gene promoter that only operates in grain,” he said. “When the gene is expressed, it produces the ‘template’ for the expansin protein, which is then made in the grain.”
The study showed that it was possible to break the negative association between grain weight and grain number using the targeted transgenic approach in Chile. The team wrote in its report that, for many years, grain weight and grain number were believed to be independent of each other. But the study showed that the development of these two central yield components actually overlap in wheat and they are linked, giving rise to the observed trade-off between the two yields before the actual grain filling begins.
The findings were confirmed in a recent study of wheat cultivars across different Australian environments and there seem to be similar overlaps in other crops such as barley, triticale, sorghum and sunflower.
The problem from a practical point of view is that the technology to create the new version of the expansin protein is what is used to create genetically modified wheat, which cannot be grown in the U.K. under existing rules.
“I believe there is some consideration of gene editing being permitted for crops in the U.K., but it will be a big step to see GM being permitted,” he said. “Certainly not any time soon.”
Given that the approach to create a new version of the protein would have wide applicability with other crops, the researchers are looking at alternative applications and at non-GM approaches to get the same effect, at least until there is a change in the regulations to permit GM and gene edited plants into the food chain.
The research was published in New Phytologist.