Feeding caterpillars make leaves shine Scientists visualize calcium signals in plants which are elicited by wounding and ul-timately regulate defense responses to herbivores. Using a highly sensitive camera system, the researchers were able to track calcium flow in the plants ... p. 4

One simple molecule regulates mating A relatively simple molecule, a fatty acid methyl ester called methyl laurate, is able to regulate complex sexual behavior in Drosophila. This pheromone triggers court-ship behavior in males and is responsible for mating success … p. 3

PULS/CE 26

Deceptive flowers Tobacco plants use their flowers’ scent and nectar to manipulate pollinators and herbivores. Natural variations of scent biosynthesis and nectar secretion in wild tobacco populations ensure that reproductive success is optimized while simultaneously herbivores are kept at bay … p. 5

Newsletter November 2015

Public Understanding of Life Sciences / Chemical Ecology

Phot

o: D

anny

Kes

sler

Dear readers!

The question of how people from different coun-tries, cultures and religions can live together is being discussed publicly in German society today more than ever in light of the challenge of tak-ing care of thousands of refugees who have fled areas of crisis and war and come to our country hoping for a life in peace.

At our institute, internationality is something we take for granted. Science is global, researchers study topics that may change the future of all humans. About half of our scientists come from abroad. There are numerous collaborations with international partners on all continents. In a re-cent survey, our international co-workers were

asked if they felt welcome at our institute and in our town, what they need and what they think contributes to successful integration.

Their positive feedback should make us all very happy, This includes, for example, language. The fact that the institute language is English and that all information is provided in German and English means that nobody is left out. Yet international co-workers are thankful for the opportunity to attend free German classes at the institute. Learning German helps them cope with everyday situations and to communicate with locals. Some research groups even appoint an experienced member to take care of the newcomer: He or she is available for answering all sorts of questions and can thus provide the support needed to famil-iarize new people with Jena’s geography, regu-lations, local culture, etc. When eating together, organizing joint activities or parties, we feel part of the whole institute, whether we are German or from abroad.

Of course, our institute is only a tiny part of the whole society, We have the advantage that we all speak the same language, the language of sci-ence, that we have a common goal, to gain new insights in the field of chemical ecology. However, what is successful on a small scale can also func-tion on a larger scale provided that we take care for others, try to understand each other, offer help and support and discover common interests.

Angela Overmeyer

PULS/CE 26

Newsletter November 2015 | Editorial

2

How integration can succeed

An international MPI-CE football team

participated in a benefit tournament on

September 25, 2015. As a part of an in-

tercultural week, the goal of this event

was to promote exchange between re-

fugees accommodated in Jena and the

citizens of Jena. With the participation

of our team, we wanted to signal

that we support internationality and

openness, especially during a time of

global refugee crisis. The participants:

Tobias Becker, Ran Li, Roman Huber,

Jan Günther, the children Merlin and

Jacob, Shuqing Xu and Guillermo

Jiménez Alemán (in the back), Jens

Preßler and Vinzenz Handrick (in the

front). Photo: Angela Overmeyer

3PULS/CE 22

Above: Common vinegar flies (Droso-

phila melanogaster) during mating on

a kiwi fruit. The pheromone methyl

laurate triggers courtship behavior in

males and is responsible for mating

success. Photo: Anna Schroll

Below left: Markus Knaden and Hany

Dweck prepare a mating experiment

with vinegar flies. Experiments are

performed under a red light, whose

wavelength is not perceived by the

flies. Their behavior is therefore

triggered entirely by odors.

Photo: Anna Schroll

Original Publication:

Dweck, H. K. M., Ebrahim, S. A. M.,

Thoma, M., Mohamed, A. A. M., Kee-

sey, I. W., Trona, F., Lavista Llanos,

S., Svatoš, A., Sachse, S., Knaden,

M., Hansson, B. S. (2015). Novel

pheromones mediate copulation and

attraction in Drosophila. PNAS, 112,

E2829-E2835

PULS/CE 263

Pheromones are signal molecules that pass in-formation from individuals of one species to their conspecifics. In addition to aggregation phero-mones, which prompt insects of the same species to come together, or alarm pheromones, which warn conspecifics about imminent danger, there are sex pheromones, and these are quite well-known. The sexual attractant used by female silkworm moths, bombykol, was the first of many pheromones to be identified, and its effect on males was proven in the late 1950s. Yet the fe-male sex pheromone − the signal molecule which attracts males and triggers mating behavior − of the vinegar fly Drosophila melanogaster remained until recently unidentified.

Researchers from the Department of Evolution-ary Neuroethology now identified methyl laurate as the Drosophila melanogaster sex pheromone. Physiological and genetic data indicated that the flies must have a neuron type that responded to a specific, yet unidentified, compound within odor collections from flies. When this neuron type, which expresses the specific olfactory receptor Or47b, was missing, mating behavior in males was inhibited. Therefore, Hany Dweck, who stud-

ies Drosophila neuroecology, began collecting odors from thousands of vinegar flies. In order to analyze single odor components, he used a new technique known as Thermal Desorption GC-MS. This combination of gas chromatography (GC) and mass spectrometry (MS) also uses thermal desorption, which helps to measure and identify even the tiniest amounts of volatile substances. He then performed electrophysiological measure-ments to test all identified compounds for their ability to activate the pheromone-specific neuron.

From all tested volatile compounds that vinegar flies emit, only one substance triggered a strong response in this neuron: methyl laurate, a sub-stance with a relatively plain molecule structure. The compound is detected by a neuron which expresses the olfactory receptor Or47b, a recep-tor that responds exclusively to methyl laurate. In males, methyl laurate triggers courtship behavior. Methyl laurate is also detected by another sen-sory neuron type that expresses the olfactory receptor Or88a. Flies which lack the olfactory receptor Or47b are still attracted by the odor of other flies; however, their mating behavior is con-siderably reduced. Flies which lack the olfactory receptor Or88a are no longer attracted to fly-specific odors; however, their mating behavior is uninhibited. The novel pheromone activates two different circuits: one is involved in courtship and mating of males and females, the other one in ag-gregation.

In further experiments, the scientists want to find out whether the fly produces the substance by itself or whether symbiotic bacteria may be in-volved. [AO]

Research Highlight | Newsletter November 2015

One simple molecule regulates mating

Calcium is a universal intracellular messenger. In plants, many physiological processes are me-diated by calcium ions, especially responses to abiotic and biotic stresses, such as feeding cat-erpillars. These trigger the activation of a number of defense mechanisms. If a leaf is attacked by an insect, the wound signal which emanates from the affected leaf is transmitted to other, unat-tacked leaves.

In order to visualize this signal, scientists from the Department of Bioorganic Chemistry and the University of Halle performed experiments with transgenic Arabidopsis plants which were geneti-cally modified to express a protein in the cytosol, the liquid inside the cells. This protein breaks down and releases light energy after it has bound to calcium ions. The emitted light energy corre-lates with the respective concentrations of calci-um ions. In this way, intracellular changes of cal-cium levels can be determined directly. Moreover, these processes can be made visible in the plants by applying a highly sensitive camera system which uses charge-coupled devices (CCD). Every bite of a caterpillar made certain leaf areas shine. The immediate reaction of the plants was clearly visible. It was very important for the researchers to show that the calcium signal is a systemic pro-cess, rather than a local one, as it wanders from the attacked leaf to neighboring leaves within a

few minutes to trigger the subsequent defense responses. The scientists succeeded in visualiz-ing this dynamic process.

How calcium signals are elicited in separate ar-eas of plants is not yet fully understood. However, the scientists speculate that the electric signals which are transmitted via the vascular system of plants, so-called vascular bundles, play an im-portant role. There are no significant differences between calcium signals which are elicited by mechanical wounding and those which are trig-gered by feeding caterpillars. Surprisingly, the application of larval oral secretions inhibited the transduction of calcium signals to neighboring leaves in the experiment. Of general importance for systemic calcium signaling is the wounding of the vascular system of the leaf, which is also re-sponsible for the internal transport of water and nutrients in the plant.

This study demonstrates that calcium signals, which are necessary for eliciting plant defense responses, and their spatial and temporal expan-sion can be visualized. Moreover, the scientists showed that calcium signaling can be studied directly in intact plants in different physiological and ecological contexts, which helps us to better understand its role as a secondary messenger in plants. [AO/AM]

PULS/CE 26

Newsletter November 2015 | Research Highlight

4

Above: A Spodoptera littoralis larva

feeds on the leaf of a thale cress

(Arabidopsis thaliana). Photo: Sandra

Scholz/Monika Heyer, MPI-CE.

Below: The temporal sequence of the

larva feeding on the first (below, 0-15

min), then on the second (above, 15-30

min) leaf is clearly visible, as is the

appearance of systemic signals in the

neighboring leaves. Image: Victoria

Kiep, Uni Halle-Wittenberg;

Jyothilakshmi Vadassery, MPI-CE

Original Publication:

Kiep, V., Vadassery, J., Lattke, J.,

Maaß, J.-P., Boland, W., Peiter, E.,

Mithöfer, A. (2015). Systemic cytosolic

Ca2+ elevation is activated upon woun-

ding and herbivory in Arabidopsis.

New Phytologist. 207, 996–1004

Feeding caterpillars make leaves shine

PULS/CE 225

Danny Kessler studies Nicotiana at-

tenuata plants in their natural habitat in

the Southwest of Utah, USA.

Deceptive flowersFlowering plants emit odors in order to attract pollinators. Pollinators are rewarded with sweet nectar for their reproductive assistance. How-ever, some female moths pollinate the flowers and lay their eggs on the leaves of the same plant afterwards. From these eggs, voracious larvae hatch and threaten the survival of the plant. One example is the tobacco hornworm Manduca sex-ta, a moth that visits and pollinates the flowers of Nicotiana attenuata, a wild tobacco species. Its larvae can cause devastating damage. As scien-tists from the Department of Molecular Ecology found out, the concentrations and amounts of flo-ral scent and nectar vary in natural populations of Nicotiana attenuata. Some individual plants do not secrete any nectar at all. These plants cheat floral visitors by initially attracting them and then denying the larvae a reward for pollination ser-vices.

To study both traits, scent and nectar, indepen-dently and simultaneously, the scientists used plants that had been genetically altered to not produce benzylacetone, the main component of the floral scent, or nectar. A third group of plants could synthesize neither benzylacetone nor nec-tar. These plants were modified by using an RNA-interference-based transformation technique (RNAi). The assessment of the experimental data revealed that both scent and nectar ensure that flowers are visited by pollinators more often than plants that lack these traits. Interestingly, scent and nectar had different effects on the pollen transfer service offered by three different pollinators. On the other hand, scent as well as nectar directly influenced oviposition by female

Manduca sexta moths. The amount of nectar more than scent affected the decision of female moths to lay their eggs, and therefore more Man-duca eggs were found on plants that produced large amounts of nectar. Some plants are cheat-ers and only pretend to be offering a reward. They benefit from nectar-producing neighbors and cheated pollinators, thereby substantially reduc-ing herbivory.

Flowers face many challenges. They have to en-sure outcrossing and reproductive success and depend on different pollinating species, all of which have different preferences and behaviors. At the same time, flowers must also make sure that moths won’t lay too many eggs on the leaves of a single plant. The combination of these floral traits, scent biosynthesis and nectar production, requires a certain fine-tuning to maximize the fit-ness of a plant. [AO]

Research Highlight | Newsletter November 2015

Friend or foe: A Manduca sexta moth

pollinates a tobacco plant. Its larvae

feed on tobacco. Photos: Danny Kessler

Original Publication:

Kessler, D., Kallenbach, M., Diezel, C.,

Rothe, E., Murdock, M., Baldwin, I. T.

(2015). How scent and nectar influence

floral antagonists and mutualists.

eLife, 4:e07641

PULS/CE 26

6

Georg Pohnert, Professor for Instru-

mental Analytics at Friedrich Schiller

University. Photo Anne Günther/FSU

Since October 1, 2015, Prof. Dr. Georg Pohnert has been a Max Planck Fellow. This honor allows him to conduct research at the MPI-CE as a guest scientist and to head of his own research group. Georg Pohnert’s research interests focus on the chemical ecology of plankton communities. The term “plankton” includes the numerous, often mi-croscopically small organisms that float in oceans and lakes. He is especially interested in the question of whether unicellular microalgae can be considered individuals. When algal popula-tions “bloom,” they can form huge carpets on the sea surface. The resulting entity comprises many

tiny organisms which interact with each other, is highly complex and changes constantly. Each in-dividual cell seems to have its own “personality.” What is certain is the fact that the algae commu-nicate and interact by using chemical signals, for example, when they use pheromones for sexual reproduction, or in predator-prey relationships or for mediating microbial infection. The new research group wants to find out how heteroge-neous algal populations are and how the chemical properties of individual cells influence the inter-actions between whole populations. [AO/AB]

Newsletter November 2015 | News

PULS/CE 26 6

Prof. Dr. Georg Pohnert from the University of Jena is a new Max Planck Fellow at the Max Planck Institute for Chemical Ecology

With his discovery of several specialized infor-mation channels in the olfactory system of flies, Hany Dweck has contributed to a better under-standing of insect olfaction. For this achieve-ment he has been awarded the Otto Hahn Medal of the Max Planck Society. In his dissertation

on the neuroecology of Drosophila melanogaster olfaction, he successfully demonstrated that vin-egar flies have several highly specialized informa-tion channels and that ecologically relevant odors are recognized and further processed on the fly antenna. [AO]

Hany Dweck received the Otto Hahn Medal

Scientists of the Max Planck Research Group In-sect Symbiosis and the Experimental Ecology and Evolution Group found that acquiring a group of bacterial symbionts that are localized in the gut enabled fire bugs (Pyrrhocoridae) to successfully exploit a previously inaccessible food source, the seeds of Malvales plants, by providing nutrients. The high species diversity observed within the group of firebugs harboring the specialized gut microbiota suggests that the microbial symbionts

have been instrumental in allowing the bugs to diversify into this ecological niche and expand into the large number of species observed today. [AO/SS]

Original Publication: Sudakaran, S., Retz, F., Kikuchi, Y.,

Kost, C., Kaltenpoth, M. (2015). Evolutionary transition in

symbiotic syndromes enabled diversification of phytopha-

gous insects on an imbalanced diet. The ISME Journal.

doi: 10.1038/ismej.2015.75

Microbe-mediated adaptation to a novel diet

Hany Dweck. Photo: Anna Schroll

Cotton stainers (Dysdercus cingula-

tus), are members of the Pyrrhoco-

ridae familie and feed on the seed

of Malvales plants. Photo: Martin

Kaltenpoth

Scientists of the Max Planck Research Group Insect Symbiosis and the Mass Spectrometry Group, in collaboration with Thermo Fisher Sci-entific, succeeded in visualizing the distribution of antibiotics and, simultaneously, their produc-ers in natural samples. Focusing on the defensive alliance between European beewolf wasps, Philanthus triangulum, and bacteria of the genus Streptomyces, they combined mass-spectrometric (MS) imaging with fluorescence in situ hybridiza-tion (FISH). Detecting and visualizing compounds

in nature and identifying their microbial produc-ers constitutes a first step toward being able to monitor complex interactions directly where they occur. [MK/AO]

Original Publication:

Kaltenpoth, M., Strupat, K., Svatoš, A. (2015). Linking me-

tabolite production to taxonomic identity in environmen-

tal samples by (MA)LDI-FISH. The ISME Journal,

doi: 10.1038/ismej.2015.122.

Larvae of butterflies, such as those of the Large White butterfly, can cause severe damage to cab-bage and related plants due to their evolutionarily optimized adaption to glucosinolates. The activity and number of genes that enable these butterflies to feed on cabbage plants vary among species; an optimized detoxification of these insects’ favored cabbage host plant is the result. By sequenc-ing the genomes of both plants and butterflies, an international team of researchers discovered

the genetic basis for this arms race: Advances on both sides were driven by the appearance of new copies of genes, rather than by simple point muta-tions in the plants’ and butterflies’ DNA.

Original Publication:

Edger, P.P., Heidel-Fischer, H. M., et al. (2015). The

butterfly plant arms-race escalated by gene and genome

duplications. PNAS, 112 (27), 8362–8366

PULS/CE 26

News | Newsletter November 2015

7

The secret weapons of cabbages: Overcome by butterfly coevolution

Linking molecules to microbes

Distribution of symbiont cells (white

spots) and the antibiotics they produce

(false-color heatmap) on the surface

of a beewolf cocoon. Image: Martin

Kaltenpoth / Aleš Svatoš, MPI-CE

A community of soil bacteria saves plants from root rot

Root bacteria are known to improve plants’ sup-ply of nutrients. In addition, they also protect plants from infections. During field experiments in Utah, USA, scientists from the Department of Molecular Ecology found that the right mixture of soil microbiota directly influences the survival of wild tobacco plants. Plants that had been unable to establish a protective alliance with the vitally important soil bacteria were susceptible to an infectious wilt disease that in some cases killed

plants overnight. The results of the study reveal the complex ecology of plants, especially with re-spect to the multitude of beneficial and harmful microorganisms that interact with them. [AO] Original Publication:

Santhanam, R., Luu, V. T., Weinhold, A., Goldberg, J., Oh,

Y, Baldwin, I. T. (2015). Native root-associated bacteria

rescue a plant from a sudden-wilt disease that emerged

during continuous cropping. PNAS, 112 (36), E5013–E5020

Tobacco plants that died of root rot.

The disease is probably caused by

fungal pathogens.

Photo: Arne Weinhold, MPI-CE

Hanna Heidel-Fischer from the Ento-

mology Department is one of the first

authors of the study. Photo: A. Schroll

8

www.ice.mpg.dewww.ice.mpg.de

8PULS/CE 26

Newsletter November 2015 | News & Events

Scientists from the Institute of Organic Chemis-try and Biochemistry in Prague and the MPI-CE studied the pheromone chemistry of moths and discovered a new evolutionary mechanism: A single amino acid change in a female moth en-zyme is responsible for the production of new sex pheromones. Divergences in moth pheromone

communication probably led to the evolution of new insect species. [AS/AO]

Original Publication:

Buček, A., et al. (2015). Evolution of moth sex pheromone

composition by a single amino acid substitution in a fatty

acid desaturase. PNAS, 112 (41), 12586–12591

A sex pheromone assembly line in Manduca sexta

Fluorescent light micro-photography

of the pheromone gland of a Manduca

sexta female. Image: A. Svatoš, MPI-CE

Plants produce toxic compounds in order to fend off herbivores. To make sure that these defensive substances will not harm the plants themselves, many plants add a sugar molecule to their toxins. Digestive enzymes cleave this sugar to release the toxin. Scientists from the Department of Mo-lecular Ecology have found a toxic defensive com-pound of the wild tobacco Nicotiana attenuata with sugar molecules bound to it. An enzyme in the gut of the tobacco hornworm Manduca sexta

removes one sugar from this toxin to convert it to a non-toxic form. This is the first time that the role of deglycosylation in detoxification as an insect counter-adaptation has been shown. [AO]

Original Publication:

Poreddy, S., et al. (2015). Detoxification of hostplant’s

chemical defense rather than its anti-predator co-option

drives β-glucosidase-mediated lepidopteran counter-

adaptation. Nature Communications, 6:8525

Reducing the sweetness to survive

Spoorthy Poreddy studies a Manduca

sexta caterpillar feeding on a tobacco

plant in the greenhouse of the

institute. Photo: Anna Schroll

Edible love gifts may influence female behavior

Male crickets offer nuptial gifts to their mating partners, which may alter the females’ reproduc-tive physiology and make them less likely to mate with other males. Researchers from the Univer-sity of Exeter, UK, and the MPI-CE analyzed the proteins in the gift and found a striking resem-blance to growth factor proteins.

This result suggests that the protein in the gift may influence female reproductive behavior.

Original Publication:

Pauchet, Y., et al. (2015). What‘s in the Gift? Towards a

Molecular Dissection of Nuptial Feeding in a Cricket. PLOS

one, 10(10): e0140191

A female decorated cricket (Gryllodes

sigillatus) consuming the nuptial gift.

Photo: David H. Funk

Impressum: PULS/CE is published semi-annually and can be downloaded free of charge on the homepage of the MPI for Chemical Ecology and is distributed electronically as PDF to subscribers. A print version will be sent on request.Editor: MPI-CE, Jena • Managing Director: Prof. Dr. David G. Heckel (viSdP). Editorial Staff: Angela Overmeyer, M.A., Information and Communication • Emily Wheeler, EditingISSN: 2191-7507 (Print), 2191-7639 (Online)

The art exhibition with the title ARCHAISCHE MODERNE - (Archaic Modernity) − Creations of felt and bone with works by artists Ullrich Schmidt and Roland Spieß can be visited until De-cember 17, 2015. The exhibition is open to the public from Monday to Friday, between 9:00 a.m. and 4:00 p.m. Admission to the works exhibited in the entrance hall and the courtyards of the Max Planck Institute for Chemical Ecology is free. http://www.ice.mpg.de/ext/schmidt-spiess2015.html