MANHATTAN, Kan. — Kansas State University researchers continue to unlock the complexity of the wheat genome, recently publishing findings of a study that characterized numerous genes duplicated thousands of years ago to understand how they control wheat yield and other desirable traits.
Wheat geneticist Eduard Akhunov, the director of K-State’s Wheat Genetic Resources Center, said his team’s research may lead to greater opportunities for breeders to perform “targeted breeding” that can increase grain size and number – ultimately increasing yields.
Akhunov said the researchers studied the role of gene copies available from each of the respective genomes in polyploid crops, those that contain more than two sets of chromosomes, in shaping main agronomic traits.
Bread wheat, he added, is polyploid, formed nearly 10,000 years ago from merging the genomes of two wild ancestors: tetraploid wild emmer wheat (which has a genome formula known as AB) and diploid goatgrass (with genome formula D).
“As a result,” Akhunov said, “most genes in wheat exist in three copies, one from each of the A, B and D genomes.”
“This gene redundancy creates a number of possibilities for interactions between genes and has, over time, contributed to new adaptations, making wheat capable of growing and producing grain in more diverse climatic conditions,” he said.
In the current study, K-State researchers tested combinations of the gene copies to see what impact they would have on wheat’s growth and productivity.
“Normally, gene copies from each of (three) respective genomes in wheat are expressed in equal proportions,” Akhunov said. “But we found that there is a relatively small subset of genes where copies from different wheat genomes are expressed at different levels,” referred to as an imbalanced expression of genes.
The imbalanced expression of genes, he added, turned out to have a positive effect on the wheat plant, in many cases increasing grain size, weight and number.
“Our study suggests that over many years, breeders have been selecting combinations of imbalanced genes that positively impacted yield in diverse climatic environments,” Akhunov said.
Important for wheat growers: breeders could use this knowledge to develop new high-yielding wheat varieties capable of growing in a variety of climates.
According to an article from the National Center for Biotechnology Information, polyploidy is a “major force in the evolution of both wild and cultivated plants.” Scientists believe polyploid organisms exhibit increased vigor and — in some cases — outperform their diploid relatives in several aspects.
K-State’s work on this project is summarized in the Feb. 11 issue of Nature Communications.
Akhunov said the research represents a large effort led by his research lab in collaboration with the Wheat Coordinated Agricultural Project, and funded by the USDA National Institute of Food and Agriculture, and the Bill and Melinda Gates Foundation.
The project was part of the International Wheat Yield Partnership in which wheat researchers around the world are cooperating to find solutions to increase wheat yields.
— Pat Melgares, K-State Research and Extension news service