Pinus halepensis, Pinus pinaster, Pinus pinea and Pinus sylvestris Essential Oils Chemotypes and Monoterpene Hydrocarbon Enantiomers, before and after Inoculation with the Pinewood Nematode Bursaphelenchus xylophilus

Abstract

Pinewood nematode (PWN), Bursaphelenchus xylophilus, is the causal agent of pine wilt disease, a serious threat to global forest populations of conifers, especially Pinus spp. A time-course study of the essential oils (EOs) of 2-year-old Pinus halepensis, Pinus pinaster, Pinus pinea and Pinus sylvestris following inoculation with the PWN was performed. The constitutive and nematode inoculation induced EOs components were analyzed at both the wounding or inoculation areas and at the whole plant level. The enantiomeric ratio of optically active main EOs components was also evaluated. External symptoms of infection were observed only in P. pinaster and P. sylvestris 21 and 15 days after inoculation, respectively. The EO composition analysis of uninoculated and unwounded plants revealed the occurrence of chemotypes for P. pinaster, P. halepensis and P. sylvestris, whereas P. pinea showed a homogenous EO composition. When whole plants were evaluated for EO and monoterpene hydrocarbon enantiomeric chemical composition, no relevant qualitative and quantitative differences were found. Instead, EO analysis of inoculated and uninoculated wounded areas revealed an increase of sesquiterpenes and diterpenic compounds, especially in P. pinea and P. halepensis, comparatively to healthy whole plants EOs.

The Effect of Nanocoatings Enriched with Essential Oils on ‘Rocha’ Pear Long Storage

“…LG was analysed by gas chromatography (GC) and gas chromatography coupled to mass spectrometry (GC-MS), for compound quantification and identification, respectively, as described by Rodrigues et al [16].…”

Experimental Design and Sample Preparation in Forest Tree Metabolomics

“…VOCs are commonly collected with headspace techniques (e.g., SPME), while EOs are obtained exclusively with hydro-, steam-or dry-distillation, or in the case of citrus fruits, mechanically without heating [80]. EO screening studies are popular among forest tree species, namely Eucalyptus and Pinus spp., mainly due to the occurrence of EO chemotypes [81][82][83][84]. The non-destructive nature of headspace techniques, such as SPME, allow for time-course evaluation of VOCs emission and have been widely applied in forest tree research not only for plant chemotype classification but also for plant-pathogen interactions or plant-insect communication [85,86].…”

Mass spectrometry‐based forest tree metabolomics

“…The essential oil (EO) profile of Pinus spp. in response to PWN infection has been characterized with GC‐MS to reveal no major differences in EO composition between control and inoculated tree hosts, apart from the occurrence of EO chemotypes (Faria et al, 2015; Rodrigues et al, 2017). The profile of volatile organic compound (VOCs) emission with GC‐MS (further details in Section IV.B) has also revealed no difference between control and infected pine hosts (Santos & Vasconcelos, 2011).…”

“…The profile of volatile organic compound (VOCs) emission with GC‐MS (further details in Section IV.B) has also revealed no difference between control and infected pine hosts (Santos & Vasconcelos, 2011). Interestingly, some differences were found in yield and EO composition when one analyzed the nematode inoculation area separately (Rodrigues et al, 2017). The role of constitutive defenses (e.g., phenolic compounds, condensed tannins, and lignin) on the phloem of pine tree species has also been studied, and a positive correlation between a lower level of these secondary metabolites and tree susceptibility to PWN infection was observed (Pimentel et al, 2017).…”