Angelovici awarded NSF grant to uncover genetic basis of amino acids in seeds
June 12, 2018
A significant proportion of the world’s population, particularly those in developing countries, suffer from protein-energy malnutrition, which results when diets lack sufficient protein. Populations whose diets are comprised primarily of staple cereal grains, such as corn, wheat, and rice, are especially vulnerable to this form of malnutrition, as seeds from these plants are deficient in one or more of the nine essential amino acids required for growth and proper development.
Many world organizations recognize the importance of biofortification of staple crops – the breeding and genetic modification of plants to boost their nutritional quality – as an important means of alleviating this world health problem.
Ruthie Angelovici, an assistant professor of biological sciences and an investigator in the Christopher S. Bond Life Sciences Center, has been awarded an $825,000 grant from the National Science Foundation to apply advanced -omic techniques and approaches to pinpoint the genes involved in regulating the composition of amino acids in Arabidopsis thaliana seeds. The research may yield new genetic targets for future biofortification efforts.
When it comes to amino acid content, not all seeds are alike. The specific composition of amino acids in seeds can vary between types of plants –the amino acid content of wheat is somewhat superior to rice, which is slightly better than corn – as well as among strains of the same plant. How is the amount and composition of amino acids in seeds determined? This is the central question being pursued by Angelovici.
The composition of amino acids is important for the growth and development of the plant that seed will eventually become. This fact has made genetically unraveling the mechanism regulating this process challenging. Knocking out, or inactivating, genes to determine their functions in this process leads to sweeping changes to the entire amino acid metabolic network, typically with dire consequences to the growing plant. Introducing genes that bestow an altered amino acid composition also hasn’t worked. Plants respond to such alterations by basically resetting, or rebalancing, the composition of its amino acids back to the original state.
While not the results hoped for, previous efforts to elucidate the genes involved in amino acid content have yielded something else important, says Angelovici.
“Insights into the unique ways a plant regulates its amino acid content in its seeds,” she says. “Specifically, they tell us that the content is very tightly regulated and that any modification to it triggers a rebalancing response from the plant.”
When viewed through the lens of natural variation, Angelovici sees these regulatory mechanisms as a potential key to unlocking this elusive genetic architecture.
“The natural variation in amino acid composition means that the regulation of these compounds is genetically driven and thus should be amenable to manipulation. Since a different amino acid composition cannot be achieved without adjusting the underlying rebalancing response, we can assume that the genes responsible for rebalancing are among the genes selected upon and that enable optimization of amino acid composition to different niches,” she explains.
For the NSF-funded project, Angelovici will take advantage of 800 strains of Arabidopsis thaliana collected from different regions and ecosystems all over the world as part of the 1001 Genomes Project. Using a novel high-throughput protocol developed by her lab, she will measure the seed amino acid content and composition from each strain and then employ an advanced quantitative genetics method called a Genome-Wide Association Study (GWAS), which associates genes with variation in traits of interest.
“With 800 accessions, we are able to measure how much variation in seed amino acid content and composition can be explained by genetic variants,” says Angelovici. “It will give us a much better sense, quantitatively, of the interplay between genetic variation and seed amino acid composition variation.”
In a separate series of experiments, her lab will use a gene expression correlation network analysis to uncover genes associated with the rebalancing mechanism. For the experiment, she will compare gene expression levels between a wildtype strain and two strains that exhibit active rebalancing. The genes of interest generated by this approach will be compared with the genes identified via the first approach.
“Comparing the genetic basis for natural variation in seed amino acid to gene expression that is strongly associated with rebalancing represents a novel approach to revealing the underlying genetic architecture,” Angelovici says.
All genes found in common by both approaches will be tested for involvement in amino acid regulation using traditional genetic approaches. She expects some of these genes will be useful targets for future biofortification efforts.
In addition to being used for research purposes, the new grant will support the development of high school lesson plans on polygenic traits and natural variation and include activities that use advanced technologies, including virtual reality.
An abstract of the project, titled “Unraveling the genetic basis of amino acid composition in dry Arabidopsis seeds,” is available on the NSF Web site.
Written by: Melody Kroll
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