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Xu Li

Associate Professor, Plant Metabolic Pathway Engineer

Plants for Human Health Institute


Dr. Xu “Sirius” Li’s research interests focus on plant secondary metabolism. Plants can produce a large array of diverse specialized metabolites, many of which are known to have beneficial effects on human health. Understanding how these compounds are made and accumulated in plants will enable us to produce crops, vegetables and fruits for enhanced health-promoting properties.

Dr. Li is working to identify novel plant secondary metabolites and to discover the genes and pathways for the biosynthesis of these compounds using natural accessions of Arabidopsis thaliana. This research will not only advance our understanding of plant secondary metabolism in the model plant Arabidopsis, but will also lead to the development of an integrated metabolomics, genetics and genomics discovery platform that can be applied to gain insight in the biochemical pathways and gene networks involved in the accumulation of bioactive compounds in crops, vegetables and fruits.

Metabolic engineering of secondary metabolism holds great promise for plant improvement; however, perturbation of some pathway leads to a detrimental effect on plant growth and development. Another research area of Dr. Li’s is to elucidate the mechanism that underlies such an effect. The knowledge gained from this research is essential to achieve specific metabolic engineering goals while minimizing the negative impact on plant fitness.

Watch a video introduction of Dr. Li and his research.

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Ph.D. Biochemistry Iowa State University 2005

M.S. Plant Physiology Peking University, Bejing, China 2000

B.S. Plant Molecular and Developmental Biology Peking University, Bejing, China 1997

Area(s) of Expertise

Plant Metabolic Pathway Engineer


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Date: 06/01/20 - 5/31/24
Amount: $389,112.00
Funding Agencies: US Dept. of Agriculture - National Institute of Food and Agriculture (USDA NIFA)

Increasing seed oil yield is one of the most important goals for oilseed crop improvement. This project aims to enhancing seed oil content and extractability of oilseed crops by metabolic engineering of phenylpropanoid metabolism. We will manipulate flavonoid and lignin biosynthesis to enhance seed oil accumulation and test the hypothesis that modification of lignin in seed coat will facilitate the extraction of oil from seeds. Two emerging promising biofuel oilseed crops, camelina and pennycress, will be engineered by the CRISPR-Cas9 and RNAi technology. Improvement of these crops will contribute to sustainable biofuel production without competition with food supplies. Oilseeds with high extractability and oil content will enable local seed pressing practice on small and medium-sized farms, fostering rural economic growth. Successful completion of this project will also provide new tools and strategies that can be used to increase the oil production of other oilseed crops. This project addresses Program Area Priorities A1103, Foundational Knowledge of Plant Products; and A1531, Bioprocessing and Bioengineering.

Date: 01/05/20 - 1/04/23
Amount: $40,000.00
Funding Agencies: Vulpes Corp.

Objective: The goal of this project is to examine the effects of functionalized nanocarbon particles (FCNP) on temperature responses in plants, with a particular emphasis on the effects on metabolic traits. Our long-term goal is to try to get at a mechanism for the effects of FCNP on plants. These initial experiments will establish baseline experimental procedures that could drive mechanistic studies.

Date: 06/30/20 - 12/31/21
Amount: $120,000.00
Funding Agencies: Pepsico, Inc.

This project aims to exploit natural variation in stevia cultigens for elucidating the key UGT enzyme functions in steviol glycoside biosynthesis. We will discover UGT genes/alleles involved in steviol glycoside biosynthesis from different stevia cultigens with a specific focus on enzymes utilizing UDPsugars other than UDP-glucose (specifically UDP-rhamnose and UDP-xylose).

Date: 01/01/18 - 12/31/20
Amount: $227,000.00
Funding Agencies: Pepsico, Inc.

Biochemical characterization of key enzymes in steviol glycoside biosynthesis

Date: 08/30/13 - 8/29/17
Amount: $447,740.00
Funding Agencies: Stanford University

Lignin, a major component of plant cell wall, is recalcitrant to degradation and impedes the biofuel production from biomass. Therefore, lignin management is an important research area for the improvement of bioenergy crops. Whereas current lignin modification strategies are able to significantly increase the efficiency of cell wall saccharification, they also impose severe yield penalties to the plants, making them unsuitable for real applications. In this proposal, we aim to understand the molecular mechanism underlying the growth inhibition associated with lignin modification, to discover novel lignin components using a revolutionary ?lignin sequencing? technology, and to generate resources that will be essential for exploiting the new discoveries in bioenergy crops.

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