Autotoxic effects of essential oils on photosynthesis in parsley, parsnip, and rough lemon

Abstract

Many plant species contain essential oils with allelochemical properties, yet the extent to which these same chemicals can be autotoxic is unclear. In this study, we tested the toxicity of several essential oil components to three species that produce them-Pastinaca sativa and Petroselinum crispum (Apiaceae), and Citrus jambhiri (Rutaceae). The effects of exogenous application of small amounts of essential oil components to the surface of foliage, followed by a pinprick to allow entry into the leaf, were monitored by chlorophyll fluorescence imaging. Rapid and spatially extensive declines in photosynthetic capacity were detected within 200 s. The most toxic constituents were monoterpenes. Two sesquiterpenes, caryophyllene and farnesene, and the phenylpropanoid myristicin, by comparison, were not toxic. Autotoxicity of endogenous essential oil was investigated by slicing through containment structures (glands or tubes); significant toxicity, manifested by reduced photosynthetic activity, was observed in all three species but was most pronounced in P. sativa and P. crispum, both of which possess oil tubes.

Chemistry and Bioactivity of Essential Oils

“…Myristicin and dillapiole are two other phenylpropanoids that occur commonly in essential oils when phenylpropanoids are present [87,[91][92][93][94].…”

Facing the Future of Plant-Insect Interaction Research: Le Retour à la “Raison d'Être”

“…Unleashed from their typical confines in the plant, many plant secondary substances (e.g. nicotine and terpenes) are toxic to their producers (Baldwin and Callahan, 1993;Gog et al, 2005). Consequently, plants that synthesize these toxic materials must also have the means to handle them, which among other things involves transporting them into and sometimes, as during leaf senescence, out of containment structures (such as glands, oil tubes, or laticifers) brimming with highly nonpolar, densely concentrated, secondary compound soups.…”

Elevated CO2 interacts with herbivory to alter chlorophyll fluorescence and leaf temperature in Betula papyrifera and Populus tremuloides

“…As arthropod herbivores feed, tissue damage may suppress photosynthesis in remaining tissues by severing vasculature (Aldea et al 2006;Tang et al 2006), altering sink/source relationships (Dorchin et al 2006), autotoxicity (Gog et al 2005), and defense-induced downregulation of photosynthetic genes (Bilgin et al 2010). Remaining tissues also may respond to the type of damage with varying degrees of physiological impairment; a 5% reduction in leaf area by a chewing herbivore resulted in a 20% reduction in the photosynthetic capacity of remaining parsnip leaf tissue (Zangerl et al 2002), whereas gall damage to understory hardwood trees reduced photosynthesis in remaining tissues equal to the area removed (Aldea et al 2006).…”