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.
Ph.D. Biochemistry Purdue 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
- Comparative Phylogenomic Analysis Reveals Evolutionary Genomic Changes and Novel Toxin Families in Endophytic Liberibacter Pathogens , MICROBIOLOGY SPECTRUM (2021)
- Metabolic source isotopic pair labeling and genome-wide association are complementary tools for the identification of metabolite-gene associations in plants , PLANT CELL (2021)
- An Efficient Stevia rebaudiana Transformation System and In vitro Enzyme Assays Reveal Novel Insights into UGT76G1 Function , SCIENTIFIC REPORTS (2020)
- An importin-beta-like protein mediates lignin-modification-induced dwarfism in Arabidopsis , PLANT JOURNAL (2020)
- Overcoming cellulose recalcitrance in woody biomass for the lignin-first biorefinery , Biotechnology for Biofuels (2019)
- Comprehensive transcriptome analyses correlated with untargeted metabolome reveal differentially expressed pathways in response to cell wall alterations , Plant Molecular Biology (2018)
- Discovering variation of secondary metabolite diversity and its relationship with disease resistance in Cornus florida L. , Ecology and Evolution (2018)
- Exploiting natural variation for accelerating discoveries in plant specialized metabolism , Phytochemistry Reviews (2018)
- A A gene encoding maize caffeoyl-CoA O-methyltransferase confers quantitative resistance to multiple pathogens , Nature Genetics (2017)
- Identification of a residue responsible for UPD-sugar donor selectivity of a dihydroxybenzoic acid glycosyltransferase from arabidopsis natural accessions , Plant Journal (2017)
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.
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.
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).
Biochemical characterization of key enzymes in steviol glycoside biosynthesis
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.