Emission Timetable and Quantitative Patterns of Wound-Induced Volatiles Across Different Leaf Damage Treatments in Aspen (Populus Tremula)

Abstract

Plant-feeding herbivores can generate complex patterns of foliar wounding, but it is unclear how wounding-elicited volatile emissions scale with the severity of different wounding types, and there is no common protocol for wounding experiments. We investigated the rapid initial response to wounding damage generated by different numbers of straight cuts and punctures through leaf lamina as well as varying area of lamina squeezing in the temperate deciduous tree Populus tremula Wounding-induced volatile emission time-courses were continuously recorded by a proton-transfer-reaction time-of-flight mass-spectrometer. After the mechanical wounding, an emission cascade was rapidly elicited resulting in sequential emissions of key stress volatiles methanol, acetaldehyde, and volatiles of the lipoxygenase pathway, collectively constituting more than 97% of the total emission. The maximum emission rates, reached after one to three minutes after wounding, and integrated emissions during the burst were strongly correlated with the severity in all damage treatments. For straight cuts and punch hole treatments, the emissions per cut edge length were constant, indicating a direct proportionality. Our results are useful for screening wounding-dependent emission capacities.

Glandular trichomes as a barrier against atmospheric oxidative stress: Relationships with ozone uptake, leaf damage, and emission of LOX products across a diverse set of species

“…In order to minimize the influence of leaf damage on VOC emissions, at least 2 days were allowed for recovery before conducting measurements. According to previous measurements, the effect of lamina wounding is short‐lived with the bulk of the stress volatiles released within first 5–10 min after wounding (Portillo‐Estrada, Kazantsev, Talts, Tosens, & Niinemets, ). We also did not observe any subsequent induction of stress volatiles and volatile isoprenoids after wounding, and leaf photosynthesis measurements with a clip‐on type gas‐exchange system (GFS‐3000, Walz GmbH, Effeltrich, Germany) demonstrated that the wounding also did not alter foliage photosynthesis rate and stomatal conductance at 48 hr since wounding stress (data not shown).…”

“…The main advantages of PTR‐TOF‐MS are simultaneous detection of all masses rather than predetermined masses, higher sensitivity, higher mass resolution, and improved accuracy over the traditional quadrupole PTR (PTR‐QMS); this allows quantification of a larger number of organic compounds at trace levels in real time (Graus, Müller, & Hansel, ; Jordan et al, ). The PTR‐TOF‐MS was operated according to the method described in detail in Graus et al (), Brilli et al () and Portillo‐Estrada et al (). The drift tube voltage was kept at 600 V at 2.3 mbar drift pressure and 60°C temperature, corresponding to an E/N ≈ 130 Td in H 3 O + reagent ion mode.…”

“…The PTR‐TOF‐MS system was calibrated with a calibration standard mixture containing key volatiles from different compound families (Ionimed Analytic GmbH, Austria). The data acquisition software TofDaq (Tofwerk AG, Switzerland) was used to acquire the raw data, and the data were further post‐processed by PTR‐MS Viewer software (PTR‐MS Viewer v3.1, Tofwerk AG, Switzerland; Jordan et al, ; S. Li et al, ; Portillo‐Estrada et al, ).…”

“…The total amount of LOX pathway products (LOX products) presented in this study is the sum of the dominant compounds with mass signals m/z 81.070 [hexenal (fragment)], m/z 83.085 [hexenol + hexanal (fragments)], m/z 85.101 [hexanol (fragment)], m/z 99.080 [( Z )‐3‐hexenal + ( E )‐3‐hexenal (main)], m/z 101.096 [( Z )‐3‐hexenol + ( E )‐3 hexenol + ( E )‐2‐hexenol + hexanal (main)] (Brilli et al, ; S. Li et al, ; Portillo‐Estrada et al, ).…”

Small‐scale indirect plant responses to insect herbivory could have major impacts on canopy photosynthesis and isoprene emission

“…Because the effect was not visible in the surrounding intact leaves, the damage‐triggered change in isoprene emission seems to be a leaf‐level response. Contrary to our results, previous studies have found a reduction in isoprene emission immediately after leaf damage (Loreto & Sharkey, ; Portillo‐Estrada et al ., ; Copolovici et al ., ; but see Ferrieri et al ., ). VOC emission profile emitted immediately after damage can substantially differ from longer‐term emissions (Maja et al ., ).…”