The diversification of terpene emissions in Mediterranean oaks: lessons from a study of Quercus suber, Quercus canariensis and its hybrid Quercus afares

Abstract

Interspecific gene flow is common in oaks. In the Mediterranean, this process produced geographical differentiations and new species, which may have contributed to the diversification of the production of volatile terpenes in the oak species of this region. The endemic North African deciduous oak Quercus afares (Pomel) is considered to be a stabilized hybrid between the evergreen Quercus suber (L.) and the deciduous Quercus canariensis (Willd.), presumably being monoterpene and isoprene emitters, respectively. In a common garden experiment, we examined the terpene emission capacities, terpene synthase (TPS) activities and nuclear genetic markers in 52 trees of these three oak species. All but one of the Q. suber and Q. canariensis trees were found to be genetically pure, whereas most Q. afares trees possessed a mixed genotype with a predominance of Q. suber alleles. Analysis of the foliar terpene emissions and TPS activities revealed that all the Q. canariensis trees strongly produced isoprene while all the Q. suber trees were strong monoterpene producers. Quercus afares trees produced monoterpenes as well but at more variable and significantly lower rates, and with a monoterpene pattern different than that observed in Q. suber. Among 17 individuals tested, one Q. afares tree emitted only an insignificant amount of terpenes. No mixed isoprene/monoterpene emitter was detected. Our results suggest that the capacity and pattern of volatile terpene production in Algerian Q. afares populations have strongly diverged from those of its parental species and became quantitatively and qualitatively reduced, including the complete suppression of isoprene production.

Leaf level emissions of volatile organic compounds (VOC) from some Amazonian and Mediterranean plants

“…But we estimated an emission factor of 35.6 ± 5.5 µg g −1 h −1 , confirming more recent literature showing typical summertime values of 10-43 µg g −1 h −1 (Staudt et al, 2004;Pio et al, 2005;Staudt et al, 2008). A further oak species, Quercus afares, was found to emit high quantities of monoterpenes and low amounts of isoprene (see also Welter et al, 2012). Furthermore, we classified Ficus carica and Spartium junceum as non-monoterpene emitters contrasting earlier reports (Benjamin and Winer, 1998;Pio et al, 1993).…”

Variation in short-term and long-term responses of photosynthesis and isoprenoid-mediated photoprotection to soil water availability in four Douglas-fir provenances

“…Compared to carotenoids, which are essential and conserved in higher plants49, non-essential isoprenoids are highly variable across species50 and within species5152. This variability was reflected by the observed provenance-specific differences in monoterpene pool sizes, which exceeded the observed variations in essential isoprenoids by far (Figs 3F and 8A).…”

Urban stress-induced biogenic VOC emissions and SOA-forming potentials in Beijing

“…This procedure is commonly used when accessibility to large and tall natural trees with the cuvette system without branch disturbance is difficult or impossible (e.g., Affek and Yakir, 2002;Geron et al, 2006;Harley et al, 1998;Helmig et al, 1999;Klinger et al, 1998;Monson et al, 2007). On the basis of our experiences, measuring cut branches does not alter terpene emissions (Ghirardo et al, 2011;Welter et al, 2012) and lipoxygenase-derived compound emissions in distant foliage (e.g., Ghirardo et al, 2011) considerably for several hours. This agrees with Loreto et al (2006), who showed that except for a small amount of acetaldehyde, no other BVOCs were emitted from broadleaf plant species when the mechanical wounding (cutting) is remotely located.…”