Interspecific variation in bulk tissue, fatty acid and monosaccharide d 13 C values of leaves from a mesotrophic grassland plant community Jennifer A.J. Dungait a , Gordon Docherty a , Vanessa Straker b , Richard P. Evershed a, * a Organic Geochemistry Unit, Bristol Biogeochemistry Research Centre, School of Chemistry, Cantocks Close, Bristol BS8 1TS, UK b English Heritage South West Regional Office, 29 Queen Square, Bristol BS1 4ND, UK article info Article history: Received 5 November 2007 Received in revised form 15 March 2008 Available online 6 June 2008 Keywords: Mesotrophic grassland Leaves Gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS) Bulk d 13 C values Compound-specific d 13 C values Monosaccharides Fatty acids abstract The leaves of 37 grass, herb, shrub and tree species were collected from a mesotrophic grassland to assess natural variability in bulk, fatty acid and monosaccharide d 13 C values of leaves from one plant commu- nity. The leaf tissue mean bulk d 13 C value was 29.3‰. No significant differences between tissue bulk d 13 C values with life form were determined (P = 0.40). On average, C 16:0 ,C 18:2 and C 18:3 constituted 89% of leaf tissue total fatty acids, whose d 13 C values were depleted compared to whole leaf tissues. A general interspecific (between different species) trend for fatty acids d 13 C values was observed, i.e. d 13 C 16:0 < d 13 C 18:2 < d 13 C 18:3 , although these values ranged widely between species, e.g. C 16:0 (34.7‰, Alisma plantago-aquatica; 44.0‰, Leucanthemum vulgare), C 18:2 (33.3‰, Acer campestre; 44.2‰, L. vulgare;) and C 18:3 (34.3‰, Bellis perennis; 41.8‰, Plantago lanceolata). Average relative abundances of leaf monosaccharides arabinose, xylose, mannose, galactose and glucose were 12%, 13%, 5%, 12% and 54%, respectively. Mean d 13 C values of these monosaccharides were 26.6‰ (arabinose), 27.2‰ (xylose), 30.9‰ (mannose), 30.0‰ (galactose) and 29.0‰ (glucose). The general relationship between individual monosaccharide d 13 C values, d 13 C arabinose > d 13 C xylose > d 13 C glucose > d 13 C galactose , was consistently observed. Therefore, we have shown (i) diversity in compound-specific d 13 C values contrib- uting to leaf bulk d 13 C values; (ii) interspecific variability between bulk and compound-specific d 13 C val- ues of leaves of individual grassland species, and (iii) trends between individual fatty acid and monosaccharide d 13 C values common to leaves of all species within one plant community. Ó 2008 Published by Elsevier Ltd. 1. Introduction Stable isotope methods have emerged as one of the more pow- erful tools for advancing understanding of relationships between plants and their environments (Dawson et al., 2002). Bulk d 13 C val- ues have been are used to investigate routing of photosynthate C in plants tissues and organs (Behboudian et al., 2000; Damesin and Lelarge, 2003; Badeck et al., 2005), bulk organic matter turnover in soils (Balesdent and Marriotti, 1996; Boutton et al., 1998; Glaser, 2005) and sediments (Macko et al., 1984; Yoshii et al., 1997; Mar- tinelli et al., 2003), and routing of C in modern (Coates et al., 1991; Dungait et al., 2005) and palaeodiets (Heaton, 1999). However, bulk isotopic determinations provide average values of a wide range of individual biochemical components, each of which have different isotope compositions and abundances (Schweizer et al., 1999; Grice, 2001; Yeh and Wang, 2001) due to (i) the C source uti- lized in biosynthesis, (ii) isotope effects associated with assimila- tion of C by the producing organism, (iii) isotope effects associated with metabolism and biosynthesis, and (iv) cellular C budgets (Hayes, 1993). The difference in natural abundance of 13 C between C 3 (d 13 C= 20 to 32‰) and C 4 (d 13 C= 9 to 17‰) detrital vegetation input to ecosystem C pools is routinely exploited to determine C provenance (Boutton, 1991), however, C 3 and C 4 photosynthetic pathways also differ in shifts in 13 C between different specific plant tissues, between specific compounds and at the intramolecular level (Hobbie and Werner, 2004). Therefore, information on (i) the contributions of biomolecular components to bulk d 13 C values and (ii) the variation between d 13 C values of key biochemical components within specific plant communities would enhance understanding of the constraints on C cycling be- tween pools at organism to field scales. Many investigations have used bulk d 13 C values of foliar tissues to investigate C turnover in plants (Lockheart et al., 1998; Hobbie et al., 2002; Jumpponen et al., 2005; Li et al., 2007; Zheng and Shangguan, 2007) and have revealed genotypic and spatiotemporal variation due to differences in C isotope fractionation during car- bon fixation, i.e. discrimination against the heavier 13 C isotope by Rubisco. In C 3 plants, isotopic fractionation is linked to photosyn- thesis via c i /c a , the ratio of intercellular to atmospheric CO 2 concen- trations (Farquhar et al., 1989). Thus, variation in isotopic 0031-9422/$ - see front matter Ó 2008 Published by Elsevier Ltd. doi:10.1016/j.phytochem.2008.03.009 * Corresponding author. Tel.: +44 (0) 117 928 7671; fax: +44 (0) 117 925 1295. E-mail address: r.p.evershed@bristol.ac.uk (R.P. Evershed). Phytochemistry 69 (2008) 2041–2051 Contents lists available at ScienceDirect Phytochemistry journal homepage: www.elsevier.com/locate/phytochem