Poplar volatiles – biosynthesis, regulation and (eco)physiology of isoprene and stress‐induced isoprenoids

Abstract

Plants interact with their environment through a wide variety of biogenic volatile organic compounds (BVOCs), with isoprenoids ( identical with terpenes), i.e. isoprene, mono- and sesquiterpenes, playing an important role. Isoprene, a hemiterpene, is the simplest isoprenoid compound mainly emitted by tree species like poplars, oaks and willows. Woody plants alone comprise 75% of the global isoprene emitted to the atmosphere. Due to its significant influence on atmospheric chemistry, research has been focused on this C5 compound, with poplar being the most prominent model system. Recent studies indicate that isoprene can enhance thermotolerance or quench oxidative stress, while also interfering with the attraction of herbivores and parasitoids to plants. In this paper, we report on biosynthesis, regulation and function of isoprene and other stress-induced volatile isoprenoids in poplar, and discuss the future scientific challenges in this genus with respect to the importance of plant volatiles in high-density poplar biomass plantations.

Monoterpene and sesquiterpene emissions from <i>Quercus coccifera</i> exhibit interacting responses to light and temperature

“…It is generally recognized that monoterpenes in BVOC non-storing plants are produced in the methylerythritol-phosphate (MEP) pathway located in chloroplasts, where photosynthetic processes provide the major bulk of primary carbon substrate and co-factors for the biosynthesis of isoprenoid precursors thus shaping the light responses of emissions (Loreto et al, 1996;Niinemets et al, 2002;Rasulov et al, 2009). Light activation of some enzymes in the MEP pathway might further contribute to positive light effects on emissions especially in the longer term control (Rasulov et al, 2009;Rivasseau et al, 2009;Schnitzler et al, 2010). Light dependency is more uncertain for SQT emissions, whose biosynthesis are thought to proceed in the cytosol.…”

“…Since then, light and temperature responses of BVOC emissions have been measured on at least 60 different plant species and many other studies have been conducted to gain more insight into the controls over emissions (see reviews by Loreto and Schnitzler, 2010;Monson et al, 2007;Schnitzler et al, 2010;Sharkey et al, 2008). Despite this, our understanding of the variability and correctness of these responses is still insufficient especially for BVOCs other than isoprene .…”

Metabolic Flux Analysis of Plastidic Isoprenoid Biosynthesis in Poplar Leaves Emitting and Nonemitting Isoprene

“…Poplar leaves invest a significant amount of recently fixed carbon in isoprene biosynthesis (Delwiche and Sharkey, 1993;Schnitzler et al, 2010;Ghirardo et al, 2011) to cope with abiotic stresses (Sharkey, 1995;Velikova and Loreto, 2005;Behnke et al, 2007Behnke et al, , 2010bBehnke et al, , 2013Vickers et al, 2009;Loreto and Schnitzler, 2010;Sun et al, 2013b), although there are indications that other protective mechanisms can partially compensate the lack of isoprene emission in genetically transformed poplars Way et al, 2013). It has been suggested that in isoprene-emitting (IE) species, most of the carbon that passes through the MEP pathway is used for isoprene biosynthesis (Sharkey and Yeh, 2001).…”

Biotic stress: a significant contributor to organic aerosol in Europe?

“…MeSA is emitted by many different plant species, in response to various types of stress, not only the ones considered here (e.g. Vuorinen et al, 2007;Blande et al, 2010;Schnitzler et al, 2010). Assuming Case 2 SIE, model calculated MeSA concentrations in the gas-phase are relatively high; depending on the assumptions regarding MeSA-deposition and NO 3 -reactivity, the average MeSA concentrations for the period Mar-Oct at Hyytiälä are from 110 to 260 ppt(v); see trations are of the same order of magnitude as observed by Karl et al (2008).…”