Superfood research: Courtney Leisner receives $281,173 USDA grant to understand natural product biosynthesis in blueberries
Courtney Leisner is the recipient of a $281,173 New Investigator Seed Grant from the United States Department of Agriculture (USDA) National Institute of Food and Agriculture to identify and characterize genes in commercial blueberry cultivars that are responsible for production of iridoid compounds, which are metabolites with known human health benefits.
“I am proud that this grant supports the land-grant mission of Auburn University,” said Courtney Leisner, an assistant professor in the Department of Biological Sciences (DBS). “Not only are blueberries an economically important fruit crop in the southeastern United States, but blueberries are an accessible superfood available year-round to consumers.”
Blueberries provide an array of human health benefits including being rich in antioxidants and vitamins. Additionally, there are many on-going clinical trials to understand the positive health benefits of blueberries when included in the human diet, due to role in promoting cardiovascular and brain health, as well as their role in insulin response and anti-proliferative (antic-cancer) properties.
Leisner will use the two-year grant (2022-2024), “Understanding plant natural product biosynthesis in blueberry through core gene discovery” to collect transcriptomic data from multiple blueberry cultivars and tissues and then perform functional enzyme characterization of core genes involved in iridoid biosynthesis.
“Blueberries make specific types of iridoid compounds,” Leisner explained. “We will identify the genes involved in biosynthesis of these specific compounds to understand more about why some cultivars make these metabolites, and some do not, as well as more fully understand the biosynthetic pathway. Data generated from this work can be used to potentially develop markers to identify additional cultivars of blueberry that make iridoids, as well as pinpoint possible mechanisms to increase iridoid production in blueberries in general.”
Leisner will use long-read RNA sequencing also known as Iso-Seq, to perform full-length transcriptome sequencing on a diverse panel of blueberry cultivars that have been previously identified to either be positive or negative for production of iridoid metabolites.
“By using long-read sequencing, we get a more complete view of the entire mRNA sequence without so heavily relying on computational de novo transcriptome assembly approaches,” Leisner said.
Once Leisner identifies the sequence of the genes involved in biosynthesis of the iridoid metabolite, the data needs to be validated. The native gene can be cloned or synthesized.
“For functional enzyme validation, we will isolate the protein and then have it interact with its known substrate,” Leisner said. “Using mass spectrometry, we can see if the enzyme then produces the next step in the biosynthetic pathway. We know some parts of the iridoid pathway already due to work done in other medicinal plants, but down-stream tailoring enzymes specific to blueberry will need to be identified using both biochemical and computational approaches.”
Leisner is also proud of her research team in DBS.
Emma Peacock, an undergraduate student in DBS began working on this project in 2020 and has since obtained funding for her work through an Undergraduate Research Fellowship. With this funding, she has been able to pilot new work on this project validating new genes and working on expression analysis in additional blueberry cultivars.
In the College of Sciences and Mathematics, Peacock was just named the 2022 Dean's Medalist for Biological Sciences. She was also honored as the 2021 Outstanding Junior for Biological Sciences as well as Outstanding Freshman in Biological Sciences in 2019.
Lovely Mae Lawas is a postdoctoral fellow in DBS working on research for this grant and is currently the President of the Auburn University Postdoctoral Fellow Association (PDA). Lawas was instrumental in developing the methodology needed to perform the protein expression and functional enzyme characterization. “I am sure her early work on this project contributed to the successful award of the proposal by the USDA” says Leisner.
“I am grateful for the hard work my team has put into this research,” Leisner said. “Not only will their contributions advance our basic understanding of natural product biosynthesis, but this work benefits both consumers and producers of blueberries in the region and nationally.”
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