The quantification of condensed tannins in African savanna tree species

Hattas, Dawood; Julkunen‐Tiitto, Riitta

doi:10.1016/j.phytol.2012.02.013

Cited by 32 publications

(24 citation statements)

References 25 publications

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“…leaf N (mg g −1 ) × proportion available N). We measured the concentration of total condensed tannins (CT) in each leaf sample following Hattas and Julkunen‐Tiitto () and the concentration of total polyphenolic compounds (TP) following Hattas, Stock, Mabusela, and Green (). We used an Ankom fibre analyser to measure acid detergent fibre (ADF) content of all leaf samples which provides an index of the unpalatable fibre component of leaf material and includes the cell‐wall components of cellulose and lignin (Cooper, Owen‐Smith, & Bryant, ).…”

Section: Methodsmentioning

confidence: 99%

A thorny issue: Woody plant defence and growth in an East African savanna

et al. 2019

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Recent work suggests that savanna woody plant species utilise two different strategies based on their defences against herbivory; a low nutrient/high chemical defence strategy and a nutrition paired with mostly architectural defences strategy. The concept that chemical and structural defences can augment each other and do not necessarily trade‐off has emanated from this work. In this study, we examine woody plant defence strategies, how these respond to herbivore removal and how they affect plant growth in an East African savanna. At three paired long‐term exclosure sites with high browser and mixed‐feeder densities at Mpala Ranch, Kenya, we investigated: (a) whether defences employed by the dominant fine‐ and broad‐leaved woody savanna species form defence strategies and if these align with previously proposed strategies, (b) how nine key plant defence traits respond to herbivore removal and (c) how effective the different defence strategies are at protecting against intense herbivory (by measuring plant growth with and without herbivores present). We identified three defence strategies. We found a group (a) with high N, short spines and high N‐free secondary metabolites, a group (b) with high N, long spines and low N‐free secondary metabolites and a group (c) with moderate N, no spines and low N‐free secondary metabolites (most likely defended by unmeasured chemical defences). Structural defences (spine length, branching) were generally found to be induced by herbivory, leaf available N increased or did not respond, and N‐free secondary metabolites decreased or did not respond to herbivory. Species with long spines combined with increased “caginess” (dense canopy architecture arising from complex arrangement of numerous woody and spiny axis categories) of branches, maintained the highest growth under intense browsing, compared to species with short spines and high N‐free secondary metabolites and species with no spines and low N‐free secondary metabolites. Synthesis. At our study site, structural traits (i.e. spines, increased caginess) were the most inducible and effective defences against intense mammalian herbivory. We propose that high levels of variability in the way that nutrient and defence traits combine may contribute to the coexistence of closely related species comprising savanna woody communities.

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Section: Methodsmentioning

confidence: 99%

A thorny issue: Woody plant defence and growth in an East African savanna

et al. 2019

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“…In addition, to obtain an accurate CT content determination of dried material from the HCl-butanol-iron assay, it is highly recommended that purified CTs from the source undergoing analysis be used as a reference standard (Giner-Chavez et al, 1997;Schofield et al, 2001;Kraus et al, 2003;Waghorn, G., 2008;Hattas and Julkunen-Tiitto, 2012;Grabber et al, 2013), as color yields in this assay are greatly dependent on the source of the CT (del Pino et al, 2005). In addition, to obtain an accurate CT content determination of dried material from the HCl-butanol-iron assay, it is highly recommended that purified CTs from the source undergoing analysis be used as a reference standard (Giner-Chavez et al, 1997;Schofield et al, 2001;Kraus et al, 2003;Waghorn, G., 2008;Hattas and Julkunen-Tiitto, 2012;Grabber et al, 2013), as color yields in this assay are greatly dependent on the source of the CT (del Pino et al, 2005).…”

Section: Purification Of Condensed Tanninsmentioning

confidence: 99%

Activity, Purification, and Analysis of Condensed Tannins: Current State of Affairs and Future Endeavors

Zeller

2019

Crop Science

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As a class of plant polyphenolic compounds contained in some forages (i.e., sainfoin [Onobrychis viciifolia Scop.], big trefoil [Lotus pedunculatus Cav.], birdsfoot trefoil [Lotus corniculatus L.]), condensed tannins (CTs), also referred to as proanthocyanidins (PAs or PACs), exhibit a variety of biological effects on ruminants. The potential positive impact of CTs on the agricultural industry stems from their ability to modulate proteolysis during forage conservation and ruminal digestion, to prevent bloat, to reduce intestinal parasite burdens, to abate methane and ammonia emissions from ruminants, and to inhibit the activity of soil‐nitrifying bacteria. How CTs exert these effects on ruminants focuses on the interaction of CTs with proteins. The structure‐activity relationship in CT–protein interaction is not well understood but is known to be dependent on the structure and properties of both the CT and the protein. The purpose of this perspective is fivefold. First, we provide the reader with a better understanding of the structural diversity of CTs present in plant material and enable the reader to appreciate that not all CTs are the same. Second, we provide examples of how CT structural diversity affects the interaction of CTs with the protein, which, in turn, dictates the biological response from the animal. Third, we describe the hurdles in obtaining highly pure and well‐characterized CTs from natural sources for use in studies to attempt to elucidate how CTs impart each biological effect. We then describe improved and emerging techniques for CT analysis and, finally, we conclude this perspective with questions to address in future investigations and forward a list of recommendations for CT researchers to follow.

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“…Sorghum tannin (ST) was used as the standard and results were expressed as mg ST equivalents g −1 dry matter. The use of Sorghum tannin as a standard may under-estimate CT concentrations compared with other standards, but Sorghum tannin is generally better than other commercially available tannins (Hattas and Julkunen-Tiitto 2012).…”

Section: Research Notementioning

confidence: 99%

Calibration of a hand-held instrument for measuring condensed tannin concentration based on UV- and red-excited fluorescence

Scogings

Siko

Taylor

2014

African Journal of Range & Forage Science

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Condensed tannins are ecologically important compounds in plants for several reasons, e.g. as herbivore deterrents or protecting photosynthetic tissues against ultraviolet radiation. The hand-held Dualex Series 4 instrument was originally developed for indirect determination of flavonol concentrations in crops. Flavonols are low-molecular-weight phenolics from which condensed tannins are synthesised. Therefore, it was expected that the Dualex's 'flavonol index' (range 0.00-3.00) could be used to predict condensed tannin concentrations, providing a rapid, cost-effective, non-destructive method to sample more species and more plants per treatment than destructive methods used for wet-chemistry tannin assays. Thirteen broad-leaved woody species were sampled at the Nkuhlu and Letaba exclosures in Kruger National Park during December 2011. Four plants were sampled per species by collecting 100 leaves per plant, measuring the flavonol index of each leaf and pooling them in classes of 0.10 flavonol units. Condensed tannin concentrations were determined according to the acid-butanol assay with Sorghum tannin as standard. Regression models (condensed tannin = a*flavonol index -b) were significant for only four species: Acacia nigrescens (Senegalia nigrescens), Euclea divinorum, Spirostachys africana and Combretum zeyheri. Other than high variation in chemistry among plants, poor calibration results were likely caused by high chemical variation within leaves.

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The quantification of condensed tannins in African savanna tree species

Cited by 32 publications

References 25 publications

A thorny issue: Woody plant defence and growth in an East African savanna

A thorny issue: Woody plant defence and growth in an East African savanna

Activity, Purification, and Analysis of Condensed Tannins: Current State of Affairs and Future Endeavors

Calibration of a hand-held instrument for measuring condensed tannin concentration based on UV- and red-excited fluorescence

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