Rethinking the role of many plant phenolics - protection from photodamage not herbivores?

By D. Close, C. Mcarthur. 2002

537 citations recorded by the source corpus.

Phenolics have been considered classic defence compounds for protecting plants from herbivores, ever since plant secondary metabolites were suggested to have evolved for that reason. The resource availability and carbon-nutrient balance hypotheses proposed that variation in phenolic levels between and within plant species reflects environmental availability of nutrients and light, and represents a trade-off in allocation by plants to growth and defence against herbivores. In contrast to these concepts, we suggest that (1) the main role of many plant phenolics may be to protect leaves from photodamage, not herbivores; (2) they can achieve this by acting as antioxidants; and (3) their levels may vary with environmental conditions in order to counteract this potential photodamage. We therefore suggest that patterns in phenolic levels, often used to support the concept of trade-off between growth and herbivore defence in relation to resource availability, may actually reflect different risks of photodamage. We suggest that the level of many phenolics is low under some environmental conditions, not because resources to produce them are limited, but simply because the risk of photodamage is low and they are not required. If our photodamage hypothesis is correct, a reassessment of the ecological and evolutionary role of many phenolics in plant defence theory is required.

Subfields: Ecology, Ecology, Evolution, Behavior and Systematics, Nature and Landscape Conservation

View Paper: https://www.semanticscholar.org/paper/c04282ba6424a3099f8a12431c9bd0dd08f71f4d

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In Ecology

1. K. Heck
2. R. Lindroth
3. H. Jactel
4. J. Valentine
5. A. Solovchenko
6. J. Wood
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8. S. Hart

In Ecology, Evolution, Behavior and Systematics

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2. A. Solovchenko
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In Nature and Landscape Conservation

1. T. Whitham
2. J. Schweitzer
3. J. Bailey
4. R. Lindroth
5. S. Hart
6. S. Wooley
7. C. LeRoy
8. J. Wood

Citations in the corpus

• Induction of glandular and non-glandular trichomes by damage in leaves of Madia sativa under contrasting water regimes (2008, background): “…environments, the selection of increased expression of resistance traits may be the result of both direct selection from herbivores and the benefits conferred by these resistance traits in other functional roles for the plant (Langenheim, 1994; Press, 1999; Close and McArthur, 2002).”
• Assessing the evidence for latitudinal gradients in plant defence and herbivory (2011, background): “For example, flavonoids may protect plants from photodamage (Close & McArthur 2002), and phenolics in general can have a role in frost-tolerance (Teklemariam & Blake 2004).”
• Effects of nitrogen concentrations in turtlegrass Thalassia testudinum on consumption by the bucktooth parrotfish Sparisoma radians (2005, background): “Phenolic compounds have been shown to play numerous roles in plants such as providing protection from photodamage (Close & McArthur 2002) and serving as antimicrobial agents (Vergeer & Develi 1997), but for the most part, phenolic compounds are considered to be herbivore deterrents.”
• Significance of Flavonoids in Plant Resistance and Enhancement of Their Biosynthesis (2005, unknown): “Reviewing the existing hypotheses in order to explain the evolution of flavonoids Close and McArthur (2002) formulated the “Oxidative pressure hypothesis” (Fig.”
• Climate‐driven change in plant–insect interactions along elevation gradients (2014, background): “This division was based on the assumption that flavonoid-based compounds can be involved in pigmentation, UV protection and freezing tolerance in plants (Close & McArthur 2002).”
• From Genes to Ecosystems: The Genetic Basis of Condensed Tannins and Their Role in Nutrient Regulation in a Populus Model System (2008, background): “These inhibitory and nutrient binding properties as well as other possible roles of CT, such as protection of leaves from photo-oxidation (Close and McArthur 2002), argue several possible adaptive roles for the production of this polymer in plants.”
• Feeny revisited: condensed tannins as anti‐herbivore defences in leaf‐chewing herbivore communities of Quercus (2004, background): “Although the raison d’être for polyphenolics may have been their antioxidant capacity (Grace & Logan, 2000; Close & McArthur, 2002), this does not preclude a contemporary role for tannins as antiherbivore compounds (Hagerman & Butler, 1991).”
• FOLIAR NUTRITION, SITE QUALITY, AND TEMPERATURE INFLUENCE FOLIAR CHEMISTRY OF TALLOWWOOD (EUCALYPTUS MICROCORYS) (2004, background): “Close and McArthur (2002) have suggested that the main role of phenolics may be to act as antioxidants, which can quench these reactive species.”