A unified mechanism of action for volatile isoprenoids in plant abiotic stress

Abstract

The sessile nature of plants has resulted in the evolution of an extraordinarily diverse suite of protective mechanisms against biotic and abiotic stresses. Though volatile isoprenoids are known to be involved in many types of biotic interactions, they also play important but relatively unappreciated roles in abiotic stress responses. We review those roles, discuss the proposed mechanistic explanations and examine the evolutionary significance of volatile isoprenoid emission. We note that abiotic stress responses generically involve production of reactive oxygen species in plant cells, and volatile isoprenoids mitigate the effects of oxidative stress by mediating the oxidative status of the plant. On the basis of these observations, we propose a 'single biochemical mechanism for multiple physiological stressors' model, whereby the protective effect against abiotic stress is exerted through direct or indirect improvement in resistance to damage by reactive oxygen species.

Increased Thermostability of Thylakoid Membranes in Isoprene-Emitting Leaves Probed with Three Biophysical Techniques

“…Experimental evidence shows that isoprene protects photosynthesis under thermal and oxidative stress conditions (for review, see Vickers et al, 2009a;Loreto and Schnitzler, 2010). It was demonstrated that leaves in which isoprene biosynthesis was blocked by the methyl erythritol pathway inhibitor fosmidomycin, were more sensitive to high temperature and ozone exposure, and developed stronger oxidative damage, compared to isoprene-emitting leaves (Loreto and Velikova, 2001;Velikova and Loreto, 2005).…”

An ecological implication of glandular trichome-sequestered artemisinin: as a sink of biotic/abiotic stress-triggered singlet oxygen

“…We thought that dihydroartemisinic acid/artemisinic acid is chosen as a quencher of 1 O2 in A. annua may be an evolutionary consequence of random mutation and beneficial selection. As discussed below, 1 O2 originated within chloroplasts can be scavenged by β-carotene and α-tocopherol, but overdosed 1 O2 emitting to the cytosol must be depleted by other isoprenoids (Vickers et al 2009). …”

“…According to the 'single biochemical mechanism for multiple physiological stressor's model (Vickers et al 2009), abiotic stress signals such as intense light, extreme temperature, drought, and ozone can cause oxidative stress via triggering ROS including 1 O2, superoxide (O2 -), hydroxy radical (OH -), and hydrogen peroxide (H2O2). On the other hand, there are also reactive nitrogen species (RNS) including nitric oxide (NO) and peroxynitrite (ONOO -).…”

“…Why does A. annua accumulate artemisinin? Although artemisinin exists in A. annua with or without ecological implications is unknown, plant volatile isoprenoids have been suggested to play protective roles against damage from abiotic stress-triggered ROS (Vickers et al 2009). Indeed, the emission of volatile isoprenoids frequently increments under abiotic stress conditions at least including intense light, extreme heat, and drought stress (Brilli et al 2007;Loreto and Sharkey 1990;Loreto et al 1998;Loreto et al 2006;Sharkey and Loreto 1993;Sharkey and Yeh 2001;Tingy et al 1981).…”

Resistance to pathogens in terpene down-regulated orange fruits inversely correlates with the accumulation of D-limonene in peel oil glands

“…[1][2][3][4][5] These secondary metabolites, including terpenoids, offer great potential for biotechnological applications, mainly with the aim of achieving resistance to pest and pathogens in crops. An improvement of our knowledge beyond general phytochemical cataloging of these compounds is needed, by performing specific experiments raised to identify their mode of action within the plant and on plant interactions with other organisms.…”