Botany - UBC

Research | Teaching | Team | Publications

e-mail:jetter@interchange.ubc.ca
office phone: (604) 822-2477
lab phone: (604) 822-8124

Associate Professor, Dept. of Botany and Chemistry
Canadian Research Chair in Plants Natural Products Chemistry
Ph.D. Botany (1993) Univ. of Kaiserslautern (Germany);
Postdoctoral Fellow (1994-96) Washington State Univ.;
Research Associate (1996-2003) Univ. of Wuerzburg (Germany).

Research Interests:

The plant surface – a vast stage for interactions…

How do plants create flexible, long-lasting, water-proof skins that grow with their organs?
How do plants seal their vast surface against adverse climatic conditions?
How do insects assess host suitability when they first land on a plant?
How can plants select for partner insects while excluding their unwanted competitors?
How do carnivorous pitcher plants catch their prey?

Leaves, flowers, fruits and parts of plant stems are covered with a waxy skin. The surface of this 'cuticle' forms the interface between plants and their environment, and is therefore extremely important for plant survival and performance. The wax, on the one hand, restricts water loss to the atmosphere and therefore performs a central physiological role. On the other hand, the cuticle also acts as a first barrier against pathogens and herbivores. Characteristic cuticular compounds may act as deterrents against insects (but specialized herbivores can also use them as clues for host-plant recognition). Microscopic structures on the plant surface can reduce the adhesion of insect feet, thereby creating slippery grounds for the animals. Although it is clear that the cuticle must perform all these functions, we don't understand how its chemical composition relates to its material properties. In order to improve our crops, for example to make them more drought-tolerant, we need a fundamental understanding of wax biosynthesis, chemistry, and biological function.

To gain a deeper understanding of this important plant tissue, we are integrating molecular biological, chemical, micro-morphological, eco-physiological and biomechanical methods. The research in our lab focuses on:

• the biosynthesis of selected surface compounds, especially its spatial and temporal regulation,

• the accumulation of surface compounds in the course of organ development,

• the contribution of individual wax layers to the physiological function as a transport barrier for water,

• the role of characteristic surface compounds in creating slippery surfaces and as infochemicals moderating insect behaviour.

Current Projects

1. Identification of polyketides in plant waxes

We are using Gas Chromatography and Mass Spectrometry to separate the complex mixtures of plant waxes and identify their constituents. My group has investigated surfaces of more than 50 plant species and identified more than 500 different wax constituents (fatty acid derivatives, triterpenoids and phenolics). Microscale syntheses of authentic standards were used to confirm structures after they had been assigned by spectroscopy. To date, we have elucidated the structures of more than 200 novel natural products.

Amongst others, homologous series of lactones, hydroxyaldehydes, and alkanediols were identified. These compound classes were found to share the special arrangement of two functional groups in 1,3-, 1,5-, 1,7-, 1,9-, or 1,11-positions. We therefore hypothesize that these compounds are polyketides, and that their biosynthesis proceeds via special elongation pathways. This idea is currently being tested by experiments involving the cloning and characterization of relevant candidate enzymes.

2. Layered structure of plant skin waxes

We could for the first time selectively prepare the outermost portion of surface waxes for quantitative analysis. For several plant species the outer wax layer was less than 1 ?m thick (less than 50 layers of molecules), and its chemical composition differed from that of the underlying wax mixture. The surfaces of some plant species additionally show microscopic crystals with characteristic shapes and arrangements. We developed methods to sample these wax crystals for direct analysis. We then characterized new crystal types based on their major constituents, and confirmed that these constituents can form identical structures in vitro. These methods are currently used to investigate the layered structure of the skin waxes of more plant species.

3. Wax biosynthesis in Arabidopsis thaliana

We are working on a number of projects using the model plant Arabidopsis thaliana to elucidate the pathways leading to the formation of cuticular waxes. In collaboration with the labs of Lacey Samuels and Ljerka Kunst, we have investigated a number of genes and their enzyme products. We performed the wax analyses of mutant plants and of transgenic yeast to help characterize the biochemical function of the enzymes. In a similar way, we were able to find and characterize the first proteins involved in export of waxes from the biosynthesizing cells towards the plant surface.

4. Biosynthesis of cuticular triterpenoids

Characteristic triterpenoids have repeatedly been reported in cuticular wax mixtures of selected plant species, organs or developmental stages. In some instances their role as anti-feedants against insects and vertebrates has been discussed. In other plant species the stem surface is slippery due to the presence of thread-like triterpenoid crystals. The biosynthesis of plant triterpenoids proceeds via a highly stereoselective cyclisation reaction, yielding either cycloartenol (steroid biosynthesis) or triterpenols with characteristic carbon skeletons.

In this project, a PCR-based approach is being used to clone homologous gene products from selected plant systems. The mechanisms of the corresponding enzymes are then assessed by comparison of their product specificities. Finally, we are investigating the expression patterns of the genes to see in how far they are involved in the biosynthesis of cuticular wax.

5. Plant-ant interactions

The stems of many Macaranga ant-plants (Euphorbiaceae) are densely covered with microscopic wax crystals. Symbiotic ant species can adhere to and walk on these vertical surfaces. In contrast, the crystals are slippery for generalist insect species and they are excluded from higher parts of the plants. In this system surface wax crystals consequently function as a mechanical barrier that protects specialist Macaranga partners against competition by other ant species. We currently investigate the mechanisms causing the slipperiness for diverse ant species. For this purpose, the physical properties of the plant surfaces have to be assessed and related to their chemical composition. Based on these data, model surfaces with corresponding characteristics can then be prepared. In a close collaboration, the adhesive organs and the processes of movement both of specialist Macaranga partner ants and their generalist competitors are investigated in the lab of Walter Federle (University of Cambridge) [http://www.zoo.cam.ac.uk/ZOOSTAFF/federle.html].

6. Slippery surfaces on carnivorous plants

	Plants in the carnivorous genus Nepenthes obtain a substantial nutrient supply by trapping insects in highly modified leaves. A broad zone of the inner surface of these pitchers is densely covered with wax crystals on which most insects lose their footing. This slippery wax surface, capturing prey and preventing its escape from the trap, plays a pivotal role in the carnivorous syndrome. To understand the mechanism of slipperiness, we want to characterize the ultrastructure and the physico-chemical properties of the wax crystals in pitchers of various Nepenthes species. Scanning electron microscopy has revealed that characteristic wax platelets protrude perpendicularly from the surface. Methods have been developed that allow the mechanical removal of these wax crystals from the pitcher surface.
	We have shown that the sampling was selective for the outermost part of the wax crystals, relevant for plant-insect-interactions, and can now for the first time directly assess the quantities of all compounds involved in crystal formation.
These chemical results will be combined with data describing the biomechanical properties of the crystals.

Graduate students wanted

I am accepting applications for graduate positions (MSc. or PhD). I am looking for students who have a strong interest in combining chemical and biological methods. Preferably, you will work on one of the projects described above, specializing on suitable plant systems. Basic experience with analytical and/or molecular biological techniques is highly desirable.

Courses Taught:

Research Team:

Current Team:

Christopher Buschhaus (Graduate Student, Botany)
Stephen Greer (Post Doctoral Fellow)
Xiufeng Ji (Graduate Student, Chemistry)
Rui Liu (Graduate Student, Botany)
Clare Scott (Graduate Student, Chemistry)
Zhonghua Wang (Post Doctoral Fellow)
Miao Wen (Graduate Student, Chemistry)

Former group members:

Jason Au
Assad Dharsi
Megan Gao
Ortwin Guhling
Shagha Kayem
Christian Kinzler
Christine Lai
Torsten Vielhaber
Bangjun Wang
Trevor Yeats

Selected Publications:

Markstädter, C.; Federle, W.; Jetter, R.; Riederer, M.; Hölldobler, B. (2000) Chemical composition of the slippery epicuticular wax blooms on Macaranga ant-plants. Chemoecol. 10, 33-40.

Jetter, R.; Schäffer, S.; Riederer, M. (2000) Leaf cuticular waxes are arranged in chemically and mechanically distinct layers: evidence from Prunus laurocerasus L. Plant Cell & Env. 23, 619-628.

Jetter, R.; Schäffer, S. (2001) Chemical composition of the Prunus laurocerasus leaf surface. Dynamic changes of the epicuticular wax film during leaf development. Plant Physiol.126, 1725-1737.

Eigenbrode, S.D.; Jetter, R. (2002) Attachment to plant surface waxes by insect herbivores and predators. Integr. Comp. Biol. 42, 1091-1099.

Jetter, R.; Klinger, A.; Schäffer, S. (2002) Very long-chain phenylpropyl and phenylbutyl esters from Taxus baccata needle cuticular waxes. Phytochemistry 61, 579-587.

Vermeer, C.P.; Nastold, P.; Jetter, R. (2003) Homologous very-long-chain 1,3-alkanediols and 3-hydroxyaldehydes in leaf cuticular waxes of Ricinus communis L. Phytochemistry 62, 433-438.

Riedel, M.; Eichner, A.; Jetter, R. (2003) Slippery surfaces of carnivorous plants: composition of epicuticular wax crystals in Nepenthes alata Blanco pitchers. Planta 218, 87-97.

Vogg, G.; Fischer, S.; Leide, J.; Emmanuel, E.; Jetter, R.; Levy, A.A.; Riederer, M. (2004) Tomato fruit cuticular waxes and their effects on transpiration barrier properties: functional characterisation of a mutant deficient in a very-long-chain fatty acid beta-ketoacyl-CoA synthase. J. Exp. Bot. 55, 1401-1410.

Aharoni, A.; Dixit, S.; Jetter, R.; Thoenes, E.; Van Arkel, G.; Pereira, A. (2004) The SHINE clade of AP2 domain transcription factors activate wax biosynthesis, alter cuticle properties and confer drought tolerance when overexpressed in Arabidopsis. Plant Cell 16, 2463–2480.

Pighin, J.A.; Zheng, H.; Balakshin, L.J.; Goodman, I.P.; Western, T.L.; Jetter, R.; Kunst, L.; Samuels, A.L. (2004) Plant cuticular lipid export requires an ABC transporter. Science 306, 702-704.

Samuels, L.; Jetter, R.; Kunst, L. (2005) First Steps in Understanding the Export of Lipids to the Plant Cuticle. Plant Biosystems 139, 65-68.

Gniwotta, F.; Vogg, G.; Gartmann, V.; Carver, T.L.W.; Riederer, M.; Jetter, R. (2005) What do microbes encounter at the plant surface? Chemical composition of Pisum sativum leaf cuticular waxes. Plant Physiol. 139, 519-530.

Guhling, O.; Kinzler, C.; Dreyer, M.; Bringmann, G.; Jetter, R. (2005) Surface composition of myrmecophilic plants: cuticular wax and glandular trichomes on leaves of Macaranga tanarius (Euphorbiaceae). J. Chem. Ecol. 31, 2325-2343.

Suh, M.C.; Samuels, A.L.; Jetter, R.; Kunst, L.; Pollard, M.; Ohlrogge, J.; Beisson, F. (2005) Cuticular lipid composition, surface structure, and gene expression in Arabidopsis stem epidermis. Plant Physiol. 139, 1649-1665.

Guhling, O.; Hobl, B.; Yeats, T.; Jetter, R. (2006) Cloning and characterization of a lupeol synthase involved in the synthesis of epicuticular wax crystals on stem and hypocotyl surfaces of Ricinus communis. Arch. Biochem. Biophys. 448, 60-72.

Wen, M.; Buschhaus, C.; Jetter, R. (2006) Nanotubules on plant surfaces: Formation and chemical composition of epicuticular wax crystals on needles of Taxus baccata L. Phytochemistry 67, 1808-1817.

Wen, M.; Au, J.; Gniwotta, F.; Jetter, R. (2006) Novel very-long-chain secondary alcohols and alkanediols in cuticular waxes of Pisum sativum leaves. Phytochemistry 67, 2494-2502.

Rowland, O.; Zheng, H.; Hepworth, S.R.; Lam, P.; Jetter, R.; Kunst, L. (2006) CER4 Encodes an Alcohol-Forming Fatty Acyl-CoA Reductase Involved in Cuticular Wax Production in Arabidopsis. Plant Physiol. 142, 866-877.

Riedel, M.; Eichner, A.; Meimberg, H.; Jetter, R. (2007) Chemical composition of epicuticular wax crystals on the slippery zone in pitchers of five Nepenthes species and hybrids. Planta 225, 1517-1534.

Lai, C.; Kunst, L.; Jetter, R. (2007) Composition of alkyl esters in the cuticular wax on inflorescence stems of Arabidopsis thaliana cer mutants. The Plant Journal 50, 189-196.

Yu, M.M.L.; Schulze, G.; Jetter, R.; Blades, M.L.; Turner, R.F.B. (2007) Raman microspectroscopic studies of triterpenoids found in plant cuticles. Appl. Spectr. 61, 32-37.

Bird, D.; Beisson, F.; Brigham, A.; Shin, J.; Greer, S.; Jetter, R.; Kunst, L.; Wu, X.; Yephremov, A.; Samuels, L. (2007) Characterization of Arabidopsis WBC11/ABCG11, an ATP binding cassette (ABC) transporter that is required for cuticular lipid secretion. The Plant Journal 52, 485-498.

Wen, M.; Jetter, R. (2007) Novel very-long-chain hydroxyaldehydes from the cuticular wax of Taxus baccata needles. Phytochemistry 68, 2563-2569.

Buschhaus, C.; Herz, H.; Jetter, R. (2007) Chemical composition of the epicuticular and intracuticular wax layers on the adaxial side of Ligustrum vulgare leaves. New Phytologist 176, 311-316.

Hovav, R.; Chehanovsky, N.; Moy, M.; Jetter, R.; Schaffer, A. (2007) Map-based cloning of a gene (Cwp1), silenced during Solanum evolution, which causes cuticle microfissuring and dehydration when expressed in tomato fruit. The Plant Journal 52, 627-639.

Buschhaus, C.; Herz, H.; Jetter, R. (2007) Chemical composition of the epicuticular and intracuticular wax layers on adaxial sides of Rosa canina L. leaves. Ann. Bot. 100, 1557-1564.

Greer, S.; Wen, M.; Bird, D; Wu, X.; Samuels, L.; Kunst, L.; Jetter, R. (2007) The cytochrome P450 CYP96A15 is the mid-chain alkane hydroxylase responsible for formation of secondary alcohols and ketones in stem cuticular wax of Arabidopsis thaliana, Plant Physiol. 155, 653-667.

Yu, M.M.; Konorov, S.O.; Schulze, H.G.; Blades, M.W.; Turner, R.F.B.; Jetter, R. (2008) In situ analysis by microspectroscopy reveals triterpenoid compositional patterns within leaf cuticles of Prunus laurocerasus. Planta 227, 823–834.

Ji, X.; Jetter, R. (2008) Very long chain alkylresorcinols accumulate in the intracuticular wax of rye (Secale cereale L.) leaves near the tissue surface. Phytochemistry 69, 1197-1207.

Samuels, L.; Kunst, L.; Jetter, R. (2008) Sealing Plant Surfaces: Cuticular Wax Formation by Epidermal Cells, Annual Rev. Plant Biol. 59, 683-707.

Jetter, R.; Kunst, L. (2008) Plant surface lipid biosynthetic pathways and their utility for metabolic engineering of waxes and hydrocarbon biofuels. The Plant Journal 54, 670-683.

Mintz-Oron, S.; Mandel, T.; Rogachev, I.; Feldberg, L.; Lotan, O.; Yativ, M.; Wang, Z.; Jetter,R.; Venger, I.; Adato, A.; Aharoni, A. (2008) Gene expression and metabolite analysis in tomato fruit surface tissues. Plant Physiology 147, 823-851.

Li, F.; Wu, X.; Lam, P.; Bird, D.; Zheng, H; Samuels, L.; Jetter, R.; Kunst L. (2008) Identification of the Wax Ester Synthase/Acyl-CoA:Diacylglycerol Acyltransferase WSD1 Required for stem wax ester biosynthesis in Arabidopsis thaliana. Plant Physiology, 148: 97-107.

van Maarseveen, C.; Han, H.; Jetter, R. (2009) Development of the cuticular wax during growth of Kalanchoe daigremontiana (Hamet et Perr. de la Bathie) leaves. Plant Cell Env., 32, 73–81.


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