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Marsh KJ, Wallis IR, Kulheim C, Clark R, Nicolle D, Foley WJ, Salminen J. New approaches to tannin analysis of leaves can be used to explain in vitro biological activities associated with herbivore defence. THE NEW PHYTOLOGIST 2020; 225:488-498. [PMID: 31412143 PMCID: PMC6916633 DOI: 10.1111/nph.16117] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Accepted: 08/05/2019] [Indexed: 05/08/2023]
Abstract
Although tannins have been an important focus of studies of plant-animal interactions, traditional tannin analyses cannot differentiate between the diversity of structures present in plants. This has limited our understanding of how different mixtures of these widespread secondary metabolites contribute to variation in biological activity. We used UPLC-MS/MS to determine the concentration and broad composition of tannins and polyphenols in 628 eucalypt (Eucalyptus, Corymbia and Angophora) samples, and related these to three in vitro functional measures believed to influence herbivore defence: protein precipitation capacity, oxidative activity at high pH and capacity to reduce in vitro nitrogen (N) digestibility. Protein precipitation capacity was most strongly correlated with concentrations of procyanidin subunits in proanthocyanidins (PAs), and late-eluting ellagitannins. Capacity to reduce in vitro N digestibility was affected most by the subunit composition and mean degree of polymerisation (mDP) of PAs. Finally, concentrations of ellagitannins and prodelphinidin subunits of PAs were the strongest determinants of oxidative activity. The results illustrate why measures of total tannins rarely correlate with animal feeding responses. However, they also confirm that the analytical techniques utilised here could allow researchers to understand how variation in tannins influence the ecology of individuals and populations of herbivores, and, ultimately, other ecosystem processes.
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Affiliation(s)
- Karen J. Marsh
- Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
| | - Ian R. Wallis
- Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
| | - Carsten Kulheim
- Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
| | - Robert Clark
- Research School of FinanceActuarial Studies and StatisticsThe Australian National UniversityCanberraACT2601Australia
| | - Dean Nicolle
- Currency Creek ArboretumPO Box 808Melrose ParkSA5039Australia
| | - William J. Foley
- Research School of BiologyThe Australian National UniversityCanberraACT2601Australia
| | - Juha‐Pekka Salminen
- Natural Chemistry Research GroupDepartment of ChemistryUniversity of TurkuTurkuFI‐20500Finland
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Marsh KJ, Saraf I, Hocart CH, Youngentob K, Singh IP, Foley WJ. Occurrence and distribution of unsubstituted B-ring flavanones in Eucalyptus foliage. PHYTOCHEMISTRY 2019; 160:31-39. [PMID: 30682682 DOI: 10.1016/j.phytochem.2019.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 01/08/2019] [Accepted: 01/10/2019] [Indexed: 06/09/2023]
Abstract
A group of plant specialised metabolites (PSMs) collectively known as unsubstituted B-ring flavanones (UBFs) have previously been found in the foliage of some species from the genus Eucalyptus L'Hér. (Myrtaceae), specifically from the subgenus Eucalyptus (monocalypts). Captive feeding studies using artificial diets suggest that these compounds may potentially influence the feeding preferences of marsupial folivores, such as koalas. Understanding natural variation in the composition and concentration of UBFs in eucalypt foliage is a first step to deciding whether, through their effects on herbivory, they might have broader effects on ecosystem dynamics. We used ESI-LCMS/MS and HPLC to characterise and quantify UBFs in 351 individual trees from 25 monocalypt species. We found large variation in the total UBF concentration both between and within species. For example, the mean concentration of UBFs in Eucalyptus muelleriana was 0.2 mg g-1 dry wt, whereas it was 105.7 mg g-1 dry wt, with a range of 78.2-141.3 mg g-1 dry wt, in Eucalyptus mediocris. Different eucalypt species contained different subsets of ten UBFs, and three species showed potential chemotypic variation between individuals within species. Our results suggest that UBFs naturally vary between monocalypt species and individuals at concentrations that could realistically be expected to affect the feeding dynamics of marsupial eucalypt folivores. UBFs could be measured relatively rapidly and cheaply in future studies using near-infrared reflectance (NIR) spectroscopy, as we were able to successfully predict the total UBF concentration of samples from their NIR spectra, with an r2 value of 0.98 and a standard error of prediction (SEP) of 6.07. This work further solidifies NIR spectroscopy as a powerful tool enabling ecologists to analyse the chemical composition of large numbers of samples.
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Affiliation(s)
- Karen J Marsh
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia.
| | - Isha Saraf
- Department of Natural Products, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, 160062 Punjab, India
| | - Charles H Hocart
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia; School of Chemistry and Chemical Engineering, Shaanxi University of Science and Technology, Long Shuo Rd, Wei Yang District, Xi'an, Shaanxi 710021, People's Republic of China
| | - Kara Youngentob
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
| | - Inder-Pal Singh
- Department of Natural Products, National Institute of Pharmaceutical Education and Research (NIPER), Sector 67, S.A.S. Nagar, 160062 Punjab, India
| | - William J Foley
- Research School of Biology, The Australian National University, Canberra, ACT 2601, Australia
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Marsh KJ, Kulheim C, Blomberg SP, Thornhill AH, Miller JT, Wallis IR, Nicolle D, Salminen JP, Foley WJ. Genus-wide variation in foliar polyphenolics in eucalypts. PHYTOCHEMISTRY 2017; 144:197-207. [PMID: 28957714 DOI: 10.1016/j.phytochem.2017.09.014] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 09/18/2017] [Accepted: 09/20/2017] [Indexed: 05/11/2023]
Abstract
Many studies quantify total phenolics or total tannins, but understanding the ecological role of polyphenolic secondary metabolites requires at least an understanding of the diversity of phenolic groups present. We used UPLC-MS/MS to measure concentrations of different polyphenol groups - including the four most common tannin groups, the three most common flavonoid groups, and quinic acid derivatives - in foliage from 628 eucalypts from the genera Eucalyptus, Angophora and Corymbia. We also tested for phylogenetic signal in each of the phenolic groups. Many eucalypts contained high concentrations of polyphenols, particularly ellagitannins, which have been relatively poorly studied, but may possess strong oxidative activity. Because the biosynthetic pathways of many phenolic compounds share either precursors or enzymes, we found negative correlations between the concentrations of several of the constituents that we measured, including proanthocyanidins (PAs) and hydrolysable tannins (HTs), HTs and flavonol derivatives, and HTs and quinic acid derivatives. We observed moderate phylogenetic signal in all polyphenol constituents, apart from the concentration of the prodelphinidin subunit of PAs and the mean degree of polymerisation of PAs. These two traits, which have previously been shown to be important in determining plants' protein precipitation capacity, may have evolved under selection, perhaps in response to climate or herbivore pressure. Hence, the signature of evolutionary history appears to have been erased for these traits. This study is an important step in moving away from analysing "totals" to a better understanding of how phylogenetic effects influence phenolic composition, and how this in turn influences ecological processes.
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Affiliation(s)
- Karen J Marsh
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia.
| | - Carsten Kulheim
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Simon P Blomberg
- School of Biological Sciences, University of Queensland, St Lucia, 4072, Australia
| | - Andrew H Thornhill
- Centre for Australian National Biodiversity Research, CSIRO National Research Collections, GPO Box 1600, Canberra, ACT, 2601, Australia; Australian Tropical Herbarium, James Cook University, Cairns, QLD, 4870, Australia
| | - Joseph T Miller
- Centre for Australian National Biodiversity Research, CSIRO National Research Collections, GPO Box 1600, Canberra, ACT, 2601, Australia; Office of International Science and Engineering, National Science Foundation, Arlington, VA, 22230, USA
| | - Ian R Wallis
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
| | - Dean Nicolle
- Currency Creek Arboretum, PO Box 808, Melrose Park, SA, 5039, Australia
| | - Juha-Pekka Salminen
- Natural Chemistry Research Group, Department of Chemistry, University of Turku, FI-20500, Turku, Finland
| | - William J Foley
- Research School of Biology, The Australian National University, Canberra, ACT, 2601, Australia
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