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Comparison of headspace-oxylipin-volatilomes of some Eastern Himalayan mosses extracted by sample enrichment probe and analysed by gas chromatography-mass spectrometry

Mitra, Souvik, Burger, Barend V., Poddar-Sarkar, Mousumi
Protoplasma 2017 v.254 no.2 pp. 1115-1126
abiotic stress, alcohols, aldehydes, alkanes, alkenes, biodiversity, chemical defenses, gas chromatography-mass spectrometry, headspace analysis, ketones, metabolites, mosses and liverworts, oxylipins, phospholipids, phylogeny, polyunsaturated fatty acids, surveys
Mosses have an inherent adaptability against different biotic and abiotic stresses. Oxylipins, the volatile metabolites derived from polyunsaturated fatty acids (PUFAs), play a key role in the chemical defence strategy of mosses. In the present study, a comparative survey of these compounds, including an investigation into their precursor fatty acids (FAs), was carried out for the first time on the mosses Brachymenium capitulatum (Mitt.) Paris, Hydrogonium consanguineum (Thwaites & Mitt.) Hilp., Barbula hastata Mitt., and Octoblepharum albidum Hedw. collected from the Eastern Himalayan Biodiversity hotspot. Their headspace volatiles were sampled using a high-efficiency sample enrichment probe (SEP) and were characterized by gas chromatography-mass spectrometric analysis. FAs from neutral lipid (NL) and phospholipid (PL) fractions were also evaluated. Analysis of the oxylipin volatilome revealed the generation of diverse metabolites from C₅ to C₁₈, dominated by alkanes, alkenes, saturated and unsaturated alcohols, aldehydes, ketones and cyclic compounds, with pronounced structural variations. The C₆ and C₈ compounds dominated the total volatilome of all the samples. Analyses of FAs from membrane PL and storage NL highlighted the involvement of C₁₈ and C₂₀ PUFAs in oxylipin generation. The volatilome of each moss is characterized by a ‘signature oxylipin mixture’. Quantitative differences in the C₆ and C₈ metabolites indicate their phylogenetic significance.