Phenolic Metabolites in Leaves of the Invasive Shrub, Lonicera maackii, and Their Potential Phytotoxic and Anti-Herbivore Effects

Abstract

Lonicera maackii is an invasive shrub in North America for which allelopathic effects toward other plants or herbivores have been suspected. We characterized the major phenolic metabolites present in methanol extracts of L. maackii leaves. In addition, we examined the effects of methanol-water extracts of L. maackii leaves on seed germination of a target plant species and on feeding preference and growth rate of a generalist insect herbivore. A total of 13 individual major and minor compounds were detected in crude leaf extracts by high-performance liquid chromatography coupled to electronspray ionization-tandem mass spectrometry (ESI-MS/MS). Extracts were dominated by two major flavones, apigenin and luteolin, and their glucoside derivatives, apigenin-7-glucoside and luteolin-7-glucoside. Quantities of these compounds, along with chlorogenic acid, varied between two sampling points. Leaf extracts that contained these compounds were inhibitory to seed germination of Arabidopsis thaliana. In addition, treatment of artificial diet with leaf extracts deterred feeding of the generalist herbivore, Spodoptera exigua, in choice experiments but had no effect on growth rate in short-term no-choice bioassays. Purified apigenin tended to deter feeding by S. exigua and inhibited seed germination of A. thaliana. We conclude that leaves of L. maackii contain phenolic compounds, including apigenin and chlorogenic acid, capable of having biological effects on other plants and insects.

Prospecção química de compostos produzidos por Senna alata com atividade alelopática

“…Nesse contexto, a alelopatia tem sido sugerida como um dos mecanismos que dirigem a invasão dessas plantas. Algumas espécies invasoras podem ter um impacto alelopático mais forte sobre as outras espécies do local onde foram introduzidas, talvez devido ao fato de que em seus locais de origem as espécies, ao redor, estão mais bem adaptadas aos compostos bioquímicos inerentes (Inderjit et al, 2008 Flavonoides glicosilados, entre outros 13 constituintes detectados por cromatografia líquida de alta eficiência acoplada a espectrômetro de massa (electronspray ionization ESI-MS/MS), também parecem ter sido responsáveis pelos efeitos alelopáticos de extratos metanólicos de folhas de Lonicera maackii sobre Arabdopsis thaliana (Cipollini et al, 2008).…”

Higher Allocation to Low Cost Chemical Defenses in Invasive Species of Hawaii

“…The capacity to produce carbon based secondary compounds (CBSC) such as phenolics, tannins, and terpenes, can be involved in the competition between alien and native plant species by conferring chemical defenses against herbivores, allelochemical defenses against neighboring competing plants ( Peñuelas et al, 1996;Peñuelas and Estiarte, 1998;Kursar and Coley, 2003;Mote et al, 2007;Cipollini et al, 2008;Khanh et al, 2008), or/and greater anti stress capacity Llusià, 2003, 2004;Filella and Peñuelas, 1999).…”

“…Phenolics, including low molecular mass phenolics and condensed polyphenolics such as tannins act by reducing digestibility rather than through direct toxicity (Eichhorn et al, 2007), but many of them also have toxic effects, and may be more toxic for some herbivores than for others (Mole et al, 1990;Cipollini et al, 2008). They are effective mainly against specialist herbivores (Beck and Schoonhoven, 1980;Coley et al, 1985;Bernays and Chapman, 1994;Bennet and Wallsgrove, 1994).…”

Chemical interaction between undamaged plants – Effects on herbivores and natural enemies

“…There are examples of compounds known to be allelopathic agents in plant-plant interactions that directly repel or deter herbivores (Bouda et al, 2001), a classic example being caffeine (Kim et al, 2006). Allelopathic phenolics in the leaves of the invasive shrub Lonicera maackii deterred feeding by lepidopteran larvae, with the flavone apigenin as the potential active compound (Cipollini et al, 2008).…”