In living systems lipids serve multiple and diverse functions; they comprise the building
blocks of biological membranes, in addition to acting as metabolic regulators and cellular
signaling molecules. Storage lipids in the form of triacylglycerols (oils) are one of most
concentrated forms of energy available in eukaryotic cells; having an energy density
equivalent to that of petroleum. It has long been recognized that oils produced by plants
and microalgae are chemically similar to fossil fuel, and thus represent an ideal renewable
feedstock that is carbon neutral with respect to greenhouse gas emission. However, the economic
feasibility of using such oils as renewable resources is critically dependent on their yield and
there is therefore an urgent need to understand the regulation of oil biosynthesis at the molecular
and cellular level in order to improve yield.
Our research group seeks to dissect the regulatory network governing lipid biosynthesis
and storage by a combination of molecular genetic, cell biological and biochemical
approaches. One important facet of such a network concerns the metabolic coordination of
different subcelluar compartments in the dynamic process of lipid metabolism. We use the
seed plant Arabidopsis and the unicellular microalgae Chlamydomonas as complementary
experimental model systems. Specific areas of interest include 1) the regulation of
triacylglycerol assembly and deposition and 2) the molecular basis for interorganelle
lipid transfer. Additional efforts focus on understanding the mechanisms and biochemical
processes that control fatty acid partitioning and channeling with regard to oil
biosynthesis. The long-term goal of our research program is to identify the regulatory
factors and other principles that limit lipid synthesis and storage in plants and
microalgae. This knowledge will be used to overcome bottlenecks in these processes to
enhance oil yield. Successful, transfer of this information to industrial partners
should enable commercially feasible production of biofuels; reducing our dependence on
In the News
Xu C, Shankin J (2016). Triacylglycerol metabolism, function
and accumulation in plant vegetative tissues. Annual Review
of Plant Biology 67: 179-206
Xu C, Andre C, Fan L, Shanklin J (2016). Cellular
organization of triacylglycerol biosynthesis in microalgae.
Subcellular Biochemistry 86:207-21
Li N, Xu C, Li-Beisson Y, Philippar K (2016). Fatty acid and
lipid transport in plant cells. Trends in Plant Science
Fan J, Zhai Z, Yan C, Xu C (2015). Arabidopsis
TRIGALACTOSYLDIACYLGLYCEROL5 interacts with TGD1, TGD2, and TGD4 to
facilitate lipid transfer from the endoplasmic reticulum to
plastids. Plant Cell 27:2941-55
Fan J, Yan C, Roston R, Shanklin J, Xu C. Arabidopsis lipins,
PDAT1 acyltransferase, and SDP1 triacylglycerol lipase
synergistically direct fatty acids toward β-oxidation, thereby
maintaining membrane lipid homeostasis. Plant Cell
Fan J, Yan C, Xu C. Phospholipid:diacylglycerol
acyltransferase-mediated triacylglycerol biosynthesis is crucial for
protection against fatty acid-induced cell death in growing tissues
of Arabidopsis. Plant J. 76: 930-942 (2013).
Fan J, Yan C, Zhang X, C Xu. Dual role for
phospholipid:diacylglycerol acyltransferase: Enhancing fatty acid
synthesis and diverting fatty acids from membrane lipids to
triacylglycerol in Arabidopsis leaves. Plant Cell 25(9):
Yan C, Fan J, C Xu. Analysis of oil droplets in microalgae.
Methods in Cell Biology 116: 71-82 (2013).
Li-Beisson, Y., Shorrosh, B., Beisson, F., Andersson, M. X., Arondel,
V., Bates, P. D., Baud, S., Bird, D., DeBono, A., Durrett, T. P.,
Franke, R. B., Graham, I. A., Katayama, K., Kelly, A. A., Larson,
T., Markham, J. E., Miquel, M., Molina, I., Nishida, I., Rowland,
O., Samuels, L., Schmid, K. M., Wada, H., Welti, R., Xu, C., Zallot,
R., and Ohlrogge, J. Acyl-lipid metabolism. The
Arabidopsis Book, Vol. 11: e0161, The American Society of Plant
Biologists, Rockville, MD (January, 2013).
Fan J., Yan C., Andre C., Shanklin J., Schwender J., and Xu C.
Oil accumulation is controlled by the availability of carbon precursors for fatty acid synthesis in Chlamydomonas reinhardtii.
Plant Cell Physiol., 53(8):1380-1390 (2012).
Wang Z., Xu C., and Benning C.
TGD4 involved in ER-to-chloroplast lipid trafficking is a phosphatidic acid binding protein.
Plant J., 2012 Jan 23. doi: 10.1111/j.1365-313X.2012.04900.x. [Epub ahead of print] (2012).
Boston R., Gao J., Xu C., and Benning C.
Arabidopsis chloroplast lipid transport protein TGD2 disrupt membranes and is part of a large complex.
Plant Journal, 66(5):759-769 (Jun 2011).
Fan J., Andre C. and Xu C.
A chloroplast pathway for the de novo synthesis of triacylglycerol in Chlamydomonas reinhardtii.
FEBS Lett., 585(12):1985-1991 (June 2011).
Fan J. and Xu C.
Genetic analysis of Arabidopsis mutants impaired in plastid lipid import reveals a role of membrane lipids in chloroplast division.
Plant Signaling and Behavior, 6(3):458-460. (Mar 2011).
Lü S., Zhao H., Parsons E.P., Xu C., Kosma D.K., Xu X., Chao D., Lohrey G., Bangarusamy D.K., Wang G., Bressan R.A., and Jenks MA.
The glossyhead1 allele of ACC1 reveals a principal role for multidomain acetyl-coenzyme A carboxylase in the biosynthesis of cuticular waxes by Arabidopsis.
Plant Physiol., 157(3):1079-1092 (Nov 2011).
In “The Arabidopsis Book” 8(1): 1-65 (2010).
Xu C., Moellering E.R., Muthan B., Fan J., and Benning C.
Lipid transport mediated by Arabidopsis TGD proteins is unidirectional from the endoplasmic reticulum to the plastid.
Plant Cell Physiol., 51(6): 1019-1028 (2010).
Gao J., Ajjawi I., Manoli A., Sawin A., Xu C., Froehlich J.E., Last R.L., and Benning C.
FATTY ACID DESATURASE4 of Arabidopsis encodes a protein distinct from characterized fatty acid desaturases.
Plant J., 60(5):832-839 (2009).
Xu C.C., Fan J., Cornish A.J., and Benning C.
Lipid trafficking between the endoplasmic reticulum and the plastid in Arabidopsis requires the extraplastidic TGD4 protein.
Plant Cell, 20(8):2190-2204 (2008).
Xu C.C., Moellering E.R., Fan J., and Benning C.
Mutation of a mitochondrial outer membrane protein affects chloroplast lipid biosynthesis.
Plant J., 54(1):163-175 (2008).
Lu B., Xu C.C., Awai K., Jones A.D., ans Benning C.
A small ATPase protein of Arabidopsis, TGD3, involved in chloroplast lipid import.
J. Biol Chem., 282(49):35945-35953 (2007).
Awai K., Xu C.C., Tamot B., and Benning C.
A phosphatidic acid-binding protein of the chloroplast inner envelope membrane involved in lipid trafficking.
Proc Natl Acad Sci U S A., 103(28):10817-10822 (2006).
Xu C.C., Yu B., Cornish A.J., Froehlich J.E., and Benning C.
Phosphatidylglycerol biosynthesis in chloroplasts of Arabidopsis mutants deficient in acyl-ACP glycerol-3- phosphate acyltransferase.
Plant J., 47(2):296-309 (2006).
Xu C.C., Fan J., Froehlich J.E., Awai K., and Benning C.
Mutation of the TGD1 chloroplast envelope protein affects phosphatidate metabolism in Arabidopsis.
Plant Cell., 17(11):3094-3110 (2005).
Li C., Liu G., Xu C.C., Lee G.I., Bauer P., Ling H.-Q., Ganal M.W., and Howe G.A.
The tomato suppressor of prosystemin-mediated responses2 gene encodes a fatty acid desaturase required for the biosynthesis of jasmonic acid and the production of a systemic wound signal for defense gene expression.
Plant Cell, 15:1646-1661 (2003).
Xu C.C., Fan J.L., Riekhof W., Froehlich J.E., and Benning C.
A permease-like protein involved in ER to thylakoid lipid transfer in Arabidopsis.
EMBO Journal, 22(10):2370-2379 (2003).
Xu C.C., Hartel H., Wada H., Hagio M., Yu B., Eakin C., and Benning C.
The pgp1 mutant locus of Arabidopsis encodes a phosphatidylglycerolphosphate synthase with impaired activity.
Plant Physiology, 129(2):594-604 (2002).
Yu B., Xu C.C., and Benning C.
Arabidopsis disrupted in SQD2 encoding sulfolipid synthase is impaired in phosphate-limited growth.
Proceedings of National Academy of Sciences of the United State of America, 99(8):5732-5737 (2002).