Quinolizidine and Pyrrolizidine Chemical Ecology – a Mini-Review on Their Similarities and Differences

Michael Wink

Journal of Chemical Ecology

ISSN 0098-0331 Volume 45 Number 2

J Chem Ecol (2019) 45:109-115 DOI 10.1007/s10886-018-1005-6

1 23 Your article is protected by copyright and all rights are held exclusively by Springer Science+Business Media, LLC, part of Springer Nature. This e-offprint is for personal use only and shall not be self-archived in electronic repositories. If you wish to self- archive your article, please use the accepted manuscript version for posting on your own website. You may further deposit the accepted manuscript version in any repository, provided it is only made publicly available 12 months after official publication or later and provided acknowledgement is given to the original source of publication and a link is inserted to the published article on Springer's website. The link must be accompanied by the following text: "The final publication is available at link.springer.com”.

1 23 Author's personal copy

Journal of Chemical Ecology (2019) 45:109–115 https://doi.org/10.1007/s10886-018-1005-6

REVIEW ARTICLE

Quinolizidine and Pyrrolizidine Alkaloid Chemical Ecology – a Mini-Review on Their Similarities and Differences

Michael Wink1

Received: 27 February 2018 /Revised: 13 July 2018 /Accepted: 30 July 2018 /Published online: 6 August 2018 # Springer Science+Business Media, LLC, part of Springer Nature 2018

Abstract This mini-review summarizes over 40 years of research on quinolizidine (QAs) and pyrrolizidine (PAs). Emphasis is on the chemical ecology of both groups of alkaloids, which serve as general defense compounds against herbivores for the plants producing them. For QAs and PAs, a number of (aphids, , beetles) have acquired tolerance. These specialists store the alkaloids and use them as defense chemicals against predators. In some PA sequestering moths, the adaptation is even more intricate and advanced. PAs can function as a morphogen to induce the formation of male coremata, inflatable organs that dissipate pheromones. In these insects, PAs are additionally used as a precursor for male pheromones. Female moths utilize their own PAs and those obtained from males via the spermatophore as nuptial gift, to transfer them to the eggs that thus become chemically protected. Novel genomic technologies will allow deeper insights in the molecular evolution of these two classes of alkaloids in plant- interactions.

Keywords Quinolizidine alkaloids . Pyrrolizidine alkaloids . Chemical ecology . Lupins . Insect herivores . Plant-herbivore interactions

Introduction Flowering plants and insects are closely connected. With the beginning of the Tertiary, we see a phylogenetic It is a trivial observation that plants cannot run away when radiation of flowering plants and concomitantly of in- they are attacked by an herbivore. Neither do they have an sects. Many insects are pollinators, others are herbivo- immune system to defend themselves against invading mi- rous. Within the herbivorous insects, we can distinguish crobes (Wink 1988). However, over the course of more between polyphagous herbivores, which feed on many than 400 million years of evolution, plants evolved com- plant species; oligophagous species, which select a few plex bioactive defence and signalling molecules in order to host plants; and monophagous species, which are closely survive in an environment with a multitude of enemies and adapted to individual hostplants which produce a certain competitors (Wink 2003). The compounds conferring these class of PSM (Ali and Agrawal 2012; Mason and Singer defence functions are often referred to as Plant Secondary 2015). The fact that polyphagous species are not adapted Metabolites (PSM; Hartmann 2007). PSM not only serve as to a single class of PSM, does not mean they do not defence molecules; some of them are used by plants to possess mechanisms to deal with plant toxins. Common attract pollinating and fruit-dispersing . In addition, mechanisms found in many polyphagous insect herbi- some PSM are of direct use for plants as nitrogen storage vores are detoxification by generic detoxification en- compounds, antioxidants and UV protectants (Hartmann zymes, e.g. Cytochrome P450 (CYP) enzymes, or direct 2007; Harborne 2014). elimination of PSM by excretion via so-called ABC- transporters. Some herbivores harbour or even cultivate symbiotic intestinal microorganisms, which can degrade or inactivate toxic PSM (Pennisi 2017). A number of * Michael Wink monophagous insects not only tolerate the toxic PSM [email protected] of their host plant, but actively store them in their bodies (Boppré 1984; Cogni et al. 2012; Hartmann 2004; 1 Heidelberg University, Institute of Pharmacy and Molecular Biotechnology, INF 364, D-69120 Heidelberg, Germany Laurent and Braekman J-C Daloze 2005; Macel 2011; Author's personal copy

110 J Chem Ecol (2019) 45:109–115

Trigo 2011;Wink1992). These specialists use the ac- tigloyl transferase have been identified. Presently, we analyse quired toxins for their own defence against predators transcriptomes from QA producing plants, generated by (Mason and Singer 2015; Petschenka and Agrawal RNASeq, to identify additional genes involved in QA synthe- 2016). Such specialists, often adorned with aposematic sis, storage and transport. warning colours, are known for sequestering toxic cardi- According to our experimental data, the QA biosynthe- ac glycosides, aristolochic acids, cyanogenic glucosides, sis takes place in the chloroplast, which is also the site of iridoid glucosides and several toxic alkaloids, such as lysine formation (Wink and Hartmann 1982b). QA synthe- aconitine, pyrrolizidine, and quinolizidine alkaloids sis is regulated by light and follows a diurnal rhythm. After (Dobler 2001; Kelly and Bowers 2016; Petschenka and synthesis, QAs are exported from the chloroplast into the Agrawal 2016;Wink1992; Zagrobelny and Moller cytoplasm and are actively sequestered in the vacuole. The 2011). The ability to sequester toxins also requires spe- necessary transport across the tonoplast is catalysed by an cific adaptations making the specialist insensitive to the ATP-dependent proton antiporter (Mende and Wink 1987). biological effect of the PSM. For example, insects which Since plants have several hundred of ABC transporter store cardiac glycosides, which target the Na+,K+-ATPase genes it needs to be analysed if our QA transporter is a enzyme, possess a target site modification in the genes true H+ antiporter or an ABC transporter. Apparently, coding for these proteins (Aardema and Andolfatto ABC transporters play a role for the transport of QAs from 2016). This allows them to tolerate high concentrations the phloem to the seeds (Frick et al. 2017). of cardiac glycosides, which would kill any poly- or After synthesis, QAs are exported from the leaves to oligophagous species (Dobler et al. 2012; Holzinger et other organs, such as stems, flowers and fruits. In stems al. 1992; Holzinger and Wink 1996). and leaves, alkaloids are mainly stored in epidermal In this mini -review I will focus on quinolizidine (QA) and cells. The transport takes place in the phloem and not pyrrolizidine alkaloids (PA). These are two main classes of the xylem (review in Wink 1992). We had postulated that alkaloids whose chemical-ecological functions have been the transfer from the phloem into the growing seeds also researched for over 40 years now (Hartmann and Witte requires an alkaloid transporter, which was identified re- 1995). The review will address their biosynthesis, allocation, cently (Frick et al. 2017). If such a transporter would be and, in particular, the similarities and differences in their genetically inactivated, the breeding of lupin varieties chemical ecology in insect-plant interactions. with high alkaloid levels in the green parts, but low levels in the seeds, would be become feasible. Such lu- pins would retain their resistance against herbivores (see Biosynthesis and Accumulation below), but would produce sweet seeds, suitable for an- of Quinolizidine Alkaloids imal and human nutrition. Transport and accumulation occur in a diurnal cycle (Wink Starting with the amino acid lysine, the first step of QA bio- 1992). Alkaloid levels are highest during flowering and fruit synthesis (Fig. 1) is the decarboxylation of lysine (catalysed formation. In annual species, most of the alkaloids are by lysine decarboxylase, LDC) to the diamine cadaverine. The translocated into the seeds whereas the senescent aerial parts next step involves a desamination of cadaverine either by a have very low levels. In wild lupins, seed alkaloid contents transaminase or more like an oxidase into 5-aminopentanal. In can be between 2 and 8% of dry weight (Wink 1992). After a complex reaction, in which the amino group of 5- germination, QA levels drop, because QAs are metabolized aminopentanal forms a Schiff’s base with the aldehyde func- and their nitrogen serves to build amino acids. Therefore, one tion of a second and third molecule of 5-aminopentanal, a additional function of QAs is that of a nitrogen storage. tetracyclic quinolizidine ring skeleton is generated which Alkaloid levels are not static but are regulated by environmen- can be converted into sparteine or lupanine (Wink and tal influences, such as heat, drought, high temperatures and Hartmann 1978;Winketal.1979). After lupanine has been herbivory. Artificial wounding can enhance QA contents by a hydroxylated to 13-hydroxylupanine, ester alkaloids can be factor of four with a couple of hours (Wink 1992). In lupins, generated by a tigloyl-CoA: 13-hydroxylupanine O-tigloyl growing along altitudinal gradients in the Rocky Mountains, transferase (Wink and Hartmann 1982a). An S-adenosyl-L- lupins from high altitudes have lower alkaloid contents than methionine: N-methyltransferase can transfer methyl groups those of lower elevations (Wink et al. 1995). to free nitrogen atoms in some QA, such as cytisine (Wink 1984). At that time, our evidence came from enzyme assays but failed to identify the corresponding genes. Now, 30 years Quinolizidine Alkaloid Diversity in Lupins later, we have genomic and transcriptomic tools to address the old questions again (Frick et al. 2017). So far, genes for LDC, QAs are typical PSM of papilionoid legumes (Wink et al. cadaverine oxidase, and tigloyl-CoA: 13-hydroxylupanine O- 2010), among them the species-rich genus Lupinus. The genus Author's personal copy

J Chem Ecol (2019) 45:109–115 111

Fig. 1 Biosynthesis of quinolizidine alkaloids. A = lysine decarboxylase, B = cadaverine oxidase; C = quinolizidine synthase; D = tigloyl-CoA: 13-hydroxylupanine O-tigloyl transferase; E = S- adenosyl-L-methionine: N- methyltransferase

Lupinus belongs to the tribe Genisteae within the subfamily Using GLC-MS we were able to profile the alkaloid com- Papilionoideae of the family Fabaceae. More than 300 position of more than 70 lupins and several other legumes Lupinus species are known. We have used DNA sequences from Europe, North America, Mexico and South America so of chloroplast genes (rbcL) and nuclear genes (ITSI, ITSII) to far (Wink et al. 1995). It has been argued by chemotaxono- reconstruct the molecular phylogeny of the genus Lupinus mists that the chemical profiles of plants could help to recon- (Käss and Wink 1997). About 13 species occur in southern struct their evolutionary relationships. Knowing the molecular Europe, northern and eastern Africa, where this genus proba- phylogeny of lupins, we could show that similarity of QA bly evolved. From the Old World two emigrations into the profiles are a poor indicator of a common descent. The genes New World took place less than 15 million years ago. About of QA formation appear to be present in all legumes and it 35 species now colonize the eastern lowlands of South seems to be a matter of gene regulation which genes are America whereas more than 250 species evolved after several switched on or off (Wink 2003;Winketal.2010). radiations in the Rocky Mountains and the Andes (Käss and Furthermore, QA profiles often differ more between organs Wink 1997;Nevadoetal.2016). than between species, which would make the profiles an even Lupins employ QAs, saponins, isoflavones and protease more ambiguous taxonomic marker. inhibitors against herbivores and saponins, phenolics and ter- penoids against microbial infections. We developed a solid- liquid extraction procedure using Extrelut columns and di- The Role of Quinolizidine Alkaloids in Plants chloromethane as a solvent to obtain QA extracts suitable for further analyses (Wink 1993). QAs (and PAs) are volatile Lupin alkaloids are toxic to a number of insects, slugs and as free bases, thus the complex mixtures can be separated by vertebrates. Furthermore, they are active against fungi (mil- high resolution capillary gas-liquid chromatography (GLC). dew), bacteria and even viruses and could be used as a natural For the identification of the individual alkaloids, the combi- pesticide (Wink 1992). QAs should thus be important for lu- nation of GLC with mass spectrometry (GLC-MS) is the pins as defence chemicals against herbivorous animals; in method of choice. Kovats retention indexes and mass spectral nature, alkaloid-rich lupins are usually left untouched by gen- data allow the identification of most QAs (details in Wink eral herbivores (Wink 1992). QAs have evolved as neuro- 1993;Winketal.1995). toxins, which target acetylcholine receptors and Na+/K+ ion Author's personal copy

112 J Chem Ecol (2019) 45:109–115 channels (Schmeller et al. 1997). QAs can bind to either the Arctiid moths are known to sequester PAs and cardiac nicotinic acetylcholine receptor or the muscarinic acetylcho- glycosides. I personally came into contact with this topic line receptor, probably as agonists (Wink 2000). Some indi- through Dietrich Schneider, who had discovered the vidual QA interfere with dopamine, GABA, NMDA and strange relationship between Creatonotus moths and PAs alpha-2 neuroreceptors. Sparteine and lupanine are inhibitors (Schneider et al. 1982;Boppré1986). The hairy caterpil- of sodium and potassium channels (Wink et al. 1998). Both lars of Creatonotus gangis and C. transiens prefer plant interactions with neuroreceptors and ion channels qualify material with PAs. They even appear to be ‘addicted’ to these alkaloids as potent neurotoxins. PAs, because they will eat filter paper impregnated with However, a few specialists have evolved counter adapta- pure PAs, when offered. We suggested that PAs induce a tions, such as the lupin aphid, Macrosiphon albifrons, which very strong feeding stimulus, similar to the behaviour of loves alkaloid-rich lupins (Wink 1992). This aphid is appar- humans towards addictive drugs (Wink 2018). ently able to tolerate and to store QA- although we do not For a couple of years, PAs were studied in Braunschweig know the underlying mechanisms. Aphids rich in QA are by the Hartmann lab (Lindigkeit et al. 1997) and our lab in apparently protected against predators (Wink and Römer Munich, Mainz or Heidelberg (von Nickisch-Rosenegk et 1986). Aposematically coloured larvae of the pyralid al. 1990; von Nickisch-Rosenegk and Wink 1993;Winkand Uresiphita reversalis feeds on QA-rich Teline plants. Larvae Schneider 1988, 1990). Studies implied that PAs actively actively take up QAs and store them in their integument. QAs enter the larval body. In most plants, PAs are present as polar are not transferred to pupae and imagines but end up in the PA N-oxides that cannot pass biomembranes by simple dif- cocoon silk of the pupae (Wink et al. 1991). As expected, non- fusion. We discovered that epithelial transporter proteins specialised aphids avoid QA-rich lupins but select alkaloid- can transport the polar PAs into the haemolymph (Wink poor sweet lupin cultivars. Also other animals discriminate and Schneider 1988). An alternative mechanism is also between bitter and sweet lupins and prefer the latter (Wink plausible: In the gut, PAs are reduced to the more lipophilic 1992). This illustrates the role of QAs as defences against a free base, which can pass the membranes by simple diffu- broad range of herbivores. sion. In the haemolymph, however, PAs must be re-oxidised to PA N-oxides to avoid them from diffusing back (Lindigkeit et al. 1997;Wangetal.2012). The PAs do not Occurrence and Biosynthesis of Pyrrolizidine remain in the haemolymph but are sequestered into the lar- Alkaloids val integument (Egelhaaf et al. 1990;vonNickisch- Rosenegk et al. 1990; von Nickisch-Rosenegk and Wink PAs occur in several families and are the main group of alka- 1993), where they apparently serve for chemical defence loids in , in the subtribe Senecioninae against predators (Martins et al. 2015). () and in the tribe Crotalarieae (Fabaceae) The PA story becomes more complex, if we look closer (Hartmann and Witte 1995; El-Shazly and Wink 2014). The into male and female larvae of Creatonotus after metamor- precursors of PAs are the amino acids ornithine and arginine, phosis into adult insects: In female caterpillars, PAs will be which produce the diamine putrescine. One unit of putrescine stored partly in the integument, but a larger proportion is and spermidine are converted to homospermidine by transferred to the eggs, which thus gain chemical defence homospermidine synthase. Homospermidine is deaminated (von Nickisch-Rosenegk et al. 1990). PAs thus function as and via a reactive aldehyde converted to the necine base skel- a nuptial gift for the defense of the eggs; this phenomenon eton. The necine base forms esters with small organic acids has also been described for other arctiids and generates cyclic PAs (retronecine and otonecine type) and and myrodora (Bezzerides and Eisner 2002; open-ringed PAs (heliotridine type) (Fig. 2) (Hartmann and Cogni et al. 2012; Conner et al. 2000; Gonzalez et al. Witte 1995). 1999 ). Male moths of Creatonotus show impressive coremata (hairy, inflatable sacks at the abdomen). They are inflated during courtship to dissipate pheromones Chemical Ecology of Pyrrolizidine Alkaloids attracting female partners. Dietary PAs exhibit morphogen- ic properties, i.e., they induce the formation of coremata. If PAs are among the alkaloids, which are often stored by a male caterpillar is reared on a PA-free diet, it will form specialised insects. The role and fate of PAs have been most only very small coremata as adult male (Boppré 1986; widely explored, thanks to the curiosity of Thomas Hartmann Schneider et al. 1982). The more PAs were ingested by a and Tom Eisner who explored dozens of PA sequestering ar- male caterpillar, the larger the corema become (von thropods (Eisner et al. 2007;Hartmann1999; Hartmann and Nickisch-Rosenegk et al. 1990). Co-evolution was appar- Witte 1995). As compared to QAs, the chemical ecology of ently even more intricate in this system (Schneider et al. PAs is far more intricate and advanced. 1982). As mentioned before, the corema releases Author's personal copy

J Chem Ecol (2019) 45:109–115 113

Fig. 2 Biosynthesis of pyrrolizidine alkaloids pheromones to attract females. The pheromones of PA- react to serotonin receptor agonists (Wink 2018). Possibly, sequestering arctiids consist of hydroxydanadial (and this may explain the ‘addictive’ behaviour of arctiid moths others), which originate from dietary PAs (Boppré 1986; towards PAs, described above. This is an open question, Schulz et al. 1993, 1998;Winketal.1988). Apparently, which needs to be addressed experimentally. female moths are attracted by males with a fragrant PA perfume. And for good reason: the spermatophore of males contains dietary PAs, which were donated as a nuptial gift Conclusion during copulation to the female. These nuptial PAs also end up in the eggs. Males can thus enhance the fitness of their Both QAs and PAs are neurotoxins which are used by the offspringbytransferringchemicaldefences. plants producing them as chemical defense compounds Hydroxydanaidal, occurring in many PA plants is also a against predators. However, a few insects have developed signal for other PA insects (Bogner and Boppré 1989). It resistance to QAs and PAs. In fact, they do not only tolerate was demonstrated that arctiid caterpillars have taste receptor them, but store and utilize them as acquired defence chemicals neurons which are dedicated to the perception of PAs and PA- against predators. In some moths, the interrelationship be- Noxides(Bernaysetal.2002, 2003). In vertebrates, PAs bind tween PAs and insects is more complex and advanced. In to serotonin receptors (Schmeller et al. 1997). We do not these specialist species, PAs serve as morphogens for corema know, if this is also the case of insect serotonin receptors, induction, as precursors for pheromones and as nuptial gifts. which are involved in the regulation of feeding, food choice Despite many years of research by Thomas Hartmann, his and sleep. Serotonin receptors are expressed in the brain but students and colleagues, many details of the biochemistry also in the intestinal tract of animals. Serotonin is involved in and molecular biology of these adaptations need to be ex- the regulation of appetite, mood and emotion, sleep, sexual plored in future studies. New technologies, such as Next activity, pain, learning and memory (Vleugels et al. 2015). As Generation Sequencing of DNA and RNA may open novel serotonin agonist often induce euphoria and hallucinations in possibilities to gain a better understanding of the evolution vertebrates, we can only speculate that maybe also insects and chemical ecology of these alkaloids. Author's personal copy

114 J Chem Ecol (2019) 45:109–115

Acknowledgements Thomas Hartmann was my PhD supervisor at the Harborne JB (2014) Introduction to ecological biochemistry. 4th ed. Technical University of Braunschweig between 1977 and 1980. From Academic Press, London 1980 to 1985 he was a mentor for my Post-Doc studies leading to my Hartmann T (1999) Chemical ecology of pyrrolizidine alkaloids. Planta habilitation in 1985. I am always thankful to Thomas Hartmann that he 207:483–495 had lured me away from zoology into botany and pharmaceutical biology Hartmann T (2004) Plant-derived secondary metabolites as defensive for my PhD studies. What both of us did not know at that time, was that chemicals in herbivorous insects: a case study in chemical ecology. we would develop a serious interest in chemical ecology and the func- Planta 219:1–4 tional aspects of plant alkaloids and various trophic levels. After 40 years Hartmann T (2007) From waste products to ecochemicals: fifty of endeavour, I am happy to say that this deviation was worth it. years research of plant secondary metabolism. Phytochemistry 68:2831–2846 Hartmann T, Witte L (1995) Chemistry, biology and chemoecology of the pyrrolizidine alkaloids. In: Pelletier SW (ed) Alkaloids: Chemical References and Biological Perspectives, vol 9. pp 155–233 Holzinger F, Wink M (1996) Mediation of cardiac glycoside insensitivity Aardema ML, Andolfatto P (2016) Phylogenetic incongruence and evo- + + in the monarch (Danaus plexippus): role of an amino acid substitu- lutionary origins of cardenolide-resistant forms of Na ,K -ATPase tion in the ouabain binding site of Na+,K+ -ATPase. J Chem Ecol 22: – in Danaus . Evolution 70:1913 1921 1921–1937 Ali JG, Agrawal AA (2012) Specialist versus generalist insect herbivores Holzinger F, Frick C, Wink M (1992) Molecular base for the insensitivity – and plant defense. Trends Plant Sci 17:292 302 of the monarch (Danaus plexippus) to cardiac glycosides. FEBS Bernays EA, Chapman RF, Hartmann T (2002) A taste receptor neurone Lett 314:477–480 dedicated to the perception of pyrrolizidine alkaloids in the medial Käss E, Wink M (1997) Molecular phylogeny and phylogeography of the galeal sensillium of two polyphagous arctiid caterpillars. Physiol genus Lupinus (family Leguminosae) inferred from nucleotide se- – Entomol 27:312 321 quences of the RbcL gene and ITS 1+2 sequences of rDNA. Plant Bernays EA, Chapman RF, Lamunyon CW, Hartmann T (2003) Taste Syst Evol 208:139–167 receptors for pyrrolizidine alkaloids in a monophagous caterpillar. J Kelly CA, Bowers MD (2016) Preference and performance of generalist Chem Ecol 29:1709–1722 and specialist herbivores on chemically defended host plants. Ecol Bezzerides A, Eisner T (2002) Apportionment of nuptial alkaloidal gifts Entomol 41:308–316 by a multiply-mated female moth (Utetheisa ornatrix): eggs indi- Laurent P, Braekman J-C Daloze D (2005) Insect chemical defense. Top vidually receive alkaloids from more than one male source. Curr Chem 240:167–229 Chemoecol 12:213–218 Lindigkeit R, Biller A, Buch M, Schiebel HM, Boppré M, Hartmann T Bogner F, Boppré M (1989) Single cell recordings reveal hydroxydanaidal (1997) The two faces of pyrrolizidine alkaloids: the role of the ter- as the volatile compound attracting insects to pyrrolizidine alkaloids. tiary amine and its N-oxide in chemical defense of insects with Entomol Exp Appl 50:171–184 acquired plant alkaloids. Eur J Biochem 245:626–636 Boppré M (1984) Redefining Bpharmacophagy^. J Chem Ecol 10:1151– Macel M (2011) Attract and deter: a dual role for pyrrolizidine alkaloids 1154 in plant-insect interactions. Phytochem Rev 10:75–82 Boppré M (1986) Insects pharmacophagously utilising defensive plant chemicals (pyrrolizidine alkaloids). Naturwissenschaften 73:17–26 Martins CHZ, Cunha BP, Solferini VN, Trigo JR (2015) Feeding on host Cogni R, Trigo JR, Futuyma DJ (2012) A free lunch? No cost for acquir- plants with different concentrations and structures of pyrrolizidine ing defensive plant pyrrolizidine alkaloids in a specialist arctiid alkaloids impacts the chemical defense effectiveness of a specialist moth (Utetheisa ornatrix). Mol Ecol 21:6152–6162 herbivore. PLoS One 10(10):e0141480 Conner WE, Boada R, Schroeder FC, Gonzalez A, Meinwald J, Mason PA, Singer MS (2015) Defensive mixology: combining acquired – Eisner T (2000) Chemical defense: bestowal of a nuptial alka- chemicals towards defence. Funct Ecol 29:441 450 loidal garment by a male moth on its mate. Proc Natl Acad Sci Mende P, Wink M (1987) Uptake of the quinolizidine alkaloid lupanine USA97:14406–14411 by protoplasts and isolated vacuoles of suspension-cultured Lupinus Dobler S (2001) Evolutionary aspects of defense by recycled plant com- polyphyllus cells. Diffusion or carrier-mediated transport? J Plant – pounds in herbivorous insects. Basic Appl Ecol 2:15–26 Physiol 129:229 242 Dobler S, Dalla S, Wagschal V, Agrawal AA (2012) Community-wide Nevado B, Atchison GW, Hughes CE, Filatov DA (2016) Widespread convergent evolution in insect adaptation to toxic cardenolides by adaptive evolution during repeated evolutionary radiations in New substitutions in the Na,K-ATPase. Proc Natl Acad Sci U S A 109: World lupins. Nat Commun. https://doi.org/10.1038/ncomms12384 13040–13045 Pennisi E (2017) How do gut microbes help herbivores? Counting the Egelhaaf A, Cölln K, Schmitz B, Buck M, Wink M, Schneider D (1990) ways. Science 355:236 Organ specific storage of dietary pyrrolizidine alkaloids in the arctiid Petschenka G, Agrawal AA (2016) How herbivores coopt plant defences: moth transiens. J Biosci 45 c:115–120 natural selection, specialization and sequestration. Curr Opin Insect Eisner T, Eisner M, Siegler M (2007) Secret weapons: defenses of insects, Sci 14:17–24 spiders, scorpions, and other many-legged creatures. Harvard Schmeller T, El-Shazly A, Wink M (1997) Allelochemical activities of University Press, Boston pyrrolizidine alkaloids: interactions with neuroreceptors and acetyl- El-Shazly A, Wink M (2014) Structures, distribution, and biological choline related enzymes. J Chem Ecol 23:399–416 properties of pyrrolizidine alkaloids of the Boraginaceae. Diversity Schneider D, Boppré M, Zweig J, Horsley SB, Bell TW, Meinwald J, 6:188–282 Hansen K, Diehl EW (1982) Scent organ development in Frick KM, Kamphuis LG, Siddique KHM, Singh KB, Foley RC (2017) Creatonotos moths: regulation by pyrrolizidine alkaloids. Science Quinolizidine alkaloid biosynthesis in lupins and prospects for grain 215:1264–1265 quality improvement. Front Plant Sci 8:87. https://doi.org/10.3389/ Schulz S (1998) Insect-plant interactions – metabolism of plant com- fpls.2017.00087 pounds to pheromones and allomones by and leaf bee- Gonzalez A, Rossini C, Eisner M, Eisner T (1999) Sexually transmitted tles. Eur J Org Chem 1998:13–20 chemical defense in a moth (Utetheisa ornatrix). Proc Natl Acad Sci Schulz S, Francke W, Boppré M, Eisner T, Meinwald J (1993) Insect pher- USA96:5570–5574 omone biosynthesis: Stereochemical pathway of hydroxydanaidal Author's personal copy

J Chem Ecol (2019) 45:109–115 115

production from alkaloidal precursors in Creatonotos transiens Wink M, Hartmann T (1982a) Enzymatic synthesis of alkaloid esters: a (Lepidoptera, Arctiidae). Proc Natl Acad Sci U S A 90:6834–6838 tigloyl-CoA: 13-hydroxylupanine O-tigloyl transferase from Trigo JR (2011) Effects of pyrrolizidine alkaloids through different tro- Lupinus albus. Planta 156:560–565 phic levels. Phytochem Rev 10:83–98 Wink M, Hartmann T (1982b) Localization of the enzymes of Vleugels R, Verlinden H, van den Broeck J (2015) Serotonin, serotonin quinolizidine alkaloid biosynthesis in leaf chloroplasts of Lupinus receptors and their action in insects. Neurotransmitter 2:e314 polyphyllus. Plant Physiol 70:74–77 von Nickisch-Rosenegk E, Wink M (1993) Sequestration of pyrrolizidine Wink M, Römer P (1986) Acquired toxicity- the advantages of special- alkaloids in several arctiid moths (Lepidoptera: Arctiidae). J Chem izingonalkaloid-richlupinstoMacrosiphum albifrons (Aphidae). Ecol 19:1889–1903 Naturwissenschaften 73:210–212 von Nickisch-Rosenegk E, Schneider D, Wink M (1990) Time-course of Wink M, Schneider D (1988) Carrier-mediated uptake of pyrrolizidine pyrrolizidine alkaloid processing in the alkaloid exploiting arctiid alkaloids in larvae of the aposematic and alkaloid exploiting moth, – moth, Creatonotos transiens. J Biosci 45(c):881 894 Creatonotos. Naturwissenschaften 75:524–525 Wang L, Beuerle T, Timbilla J, Ober D (2012) Independent recruitment of Wink M, Schneider D (1990) Fate of plant-derived secondary metabolites a flavin-dependent monooxygenase for safe accumulation of se- in three moth species (Syntomis mogadorensis, Syntomeida epilais, questered pyrrolizidine alkaloids in grasshoppers and moths. PLoS and Creatonotos transiens). J Comp Physiol B 160:389–400 One 7(2):e31796 Wink M, Hartmann T, Schiebel HM (1979) A model mechanism for the Wink M (1984) N-methylation of quinolizidine alkaloids: an S-adenosyl- enzymatic synthesis of lupin alkaloids. Z Naturforsch 34c:704–708 L-methionine: cytisine N-methyltransferase from Laburnum Wink M, Schneider D, Witte L (1988) Biosynthesis of pyrrolizidine anagyroides plants and cell cultures of L. alpinum and Cytisus alkaloid-derived pheromones in the arctiid moth, Creatonotos canariensis. Planta 161:339–344 transiens: Stereochemical conversion of heliotrine. J Biosci 43c: Wink M (1988) Plant breeding: importance of plant secondary metabo- 737–741 lites for protection against pathogens and herbivores. Theor Appl Genet 75:225–233 Wink M, Monttlor C, Bernays EA, Witte L (1991) Uresiphita reversalis Wink M (1992) The role of quinolizidine alkaloids in plant insect inter- (Lepidoptera: Pyralidae): carrier-mediated uptake and sequestration actions. In: Bernays EA (ed) Insect- plant interactions, vol IV.CRC- of quinolizidine alkaloids obtained from the host plant Teline – Press, Boca Raton, pp 133–169 monspessulana. Z Naturforsch 46c:1080 1088 Wink M (1993) In: Waterman P (ed) Quinolizidine alkaloids: In methods Wink M, Meißner C, Witte L (1995) Patterns of quinolizidine alkaloids in – in plant biochemistry, vol 8. Academic Press, London, pp 197–239 56 species of the genus Lupinus. Phytochemistry 38:139 153 Wink M (2000) Interference of alkaloids with neuroreceptors and ion Wink M, Schmeller T, Latz-Brüning B (1998) Modes of action of channels. Bioactive Nat Prod 21:3–129 allelochemical alkaloids: interaction with neuroreceptors, DNA Wink M (2003) Evolution of secondary metabolites from an ecological and other molecular targets. J Chem Ecol 24:1881–1937 and molecular phylogenetic perspective. Phytochemistry 64:3–19 Wink M, Botschen F, Gosmann C, Schäfer H, Waterman PG (2010) Wink M (2018) Plant secondary metabolites modulate insect behaviour- Chemotaxonomy seen from a phylogenetic perspective and evolu- steps towards addiction? Front Physiol 9:364. https://doi.org/10. tion of secondary metabolism. In: Wink M (ed) Biochemistry of 3389/fphys.2018.00364 plant secondary metabolism. Blackwell, Oxford, Annual Plant Wink M, Hartmann T (1978) Cadaverine-pyruvate transamination: Reviews, vol 40. pp 364–433 the pricipal step of enzymatic quinolizidine alkaloid biosynthe- Zagrobelny M, Moller BL (2011) Cyanogenic glucosides in the biologi- sis in Lupinus polyphyllus cell suspension cultures. FEBS Lett cal warfare between plants and insects: the Burnet moth- Birdsfoot 101:343–346 trefoil model system. Phytochemistry 72:1585–1592