In Defense of Roots: A Research Agenda for Studying Plant Resistance to Belowground Herbivory

Rasmann, Sergio; Agrawal, Anurag A.

doi:10.1104/pp.107.112045

Cited by 132 publications

(124 citation statements)

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“…Despite the importance of roots for plant fitness, the function and evolution of these metabolites is often unknown [11]. We previously showed that the latex-derived sesquiterpene lactone TA-G is a major defensive compound in T. officinale roots that protects plants against M. melolontha attack [32].…”

Section: Discussionmentioning

confidence: 99%

“…In contrast with the ecological and evolutionary dynamics of above-ground plant-herbivore interactions, below-ground interactions have received little attention, despite the importance of roots for plant fitness and the high concentrations of secondary metabolites in below-ground organs [11][12][13][14]. The rhizosphere differs from the phyllosphere in both biotic and abiotic conditions [15], and the selective forces shaping variation in secondary metabolites may therefore differ between the two environments.…”

Section: Introductionmentioning

confidence: 99%

“…Recent studies demonstrate that herbivore abundance can covary with the expression of plant defence metabolites [7], that the exclusion of phytophagous insects can lead to a relaxation of defences within a few generations [8] and that defence genes are under differential selection across environments [9,10]. Together, these studies show that the temporal and spatial variation in above-ground herbivore communities can shape plant defensive chemistry.In contrast with the ecological and evolutionary dynamics of above-ground plant-herbivore interactions, below-ground interactions have received little attention, despite the importance of roots for plant fitness and the high concentrations of secondary metabolites in below-ground organs [11][12][13][14]. The rhizosphere differs from the phyllosphere in both biotic and abiotic conditions [15], and the selective forces shaping variation in secondary metabolites may therefore differ between the two environments.…”

mentioning

confidence: 99%

“…The rhizosphere differs from the phyllosphere in both biotic and abiotic conditions [15], and the selective forces shaping variation in secondary metabolites may therefore differ between the two environments. The evolution of root secondary metabolites may for instance be driven by herbivores [11,12,16], pathogens [17] and symbionts [18], as well as nutrient availability [19], salt, drought and cold stress [20]. By comparing one mainland and two island populations, Watts et al [21] showed that geographical isolation, including the escape from pocket gophers (Geomyidae), resulted in the evolutionary decline of root alkaloid concentrations of the host plant Eschscholzia californica (Papaveraceae).…”

Section: Introductionmentioning

confidence: 99%

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A below-ground herbivore shapes root defensive chemistry in natural plant populations

et al. 2016

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Plants display extensive intraspecific variation in secondary metabolites. However, the selective forces shaping this diversity remain often unknown, especially below ground. Using Taraxacum officinale and its major native insect root herbivore Melolontha melolontha, we tested whether below-ground herbivores drive intraspecific variation in root secondary metabolites. We found that high M. melolontha infestation levels over recent decades are associated with high concentrations of major root latex secondary metabolites across 21 central European T. officinale field populations. By cultivating offspring of these populations, we show that both heritable variation and phenotypic plasticity contribute to the observed differences. Furthermore, we demonstrate that the production of the sesquiterpene lactone taraxinic acid b-D-glucopyranosyl ester (TA-G) is costly in the absence, but beneficial in the presence of M. melolontha, resulting in divergent selection of TA-G. Our results highlight the role of soil-dwelling insects for the evolution of plant defences in nature. BackgroundHeritable intraspecific variation is a common feature of many biological traits. Genetic variation results from heterogeneous selection pressures in relation to genetic architecture, population substructures and gene flow [1 -4]. In plants, local differences in both abiotic and biotic factors may drive trait evolution [5]. Insect herbivores, the most abundant and diverse plant consumers, have long been suspected to play an important role in this context [6]. Recent studies demonstrate that herbivore abundance can covary with the expression of plant defence metabolites [7], that the exclusion of phytophagous insects can lead to a relaxation of defences within a few generations [8] and that defence genes are under differential selection across environments [9,10]. Together, these studies show that the temporal and spatial variation in above-ground herbivore communities can shape plant defensive chemistry.In contrast with the ecological and evolutionary dynamics of above-ground plant-herbivore interactions, below-ground interactions have received little attention, despite the importance of roots for plant fitness and the high concentrations of secondary metabolites in below-ground organs [11][12][13][14]. The rhizosphere differs from the phyllosphere in both biotic and abiotic conditions [15], and the selective forces shaping variation in secondary metabolites may therefore differ between the two environments. The evolution of root secondary metabolites may for instance be driven by herbivores [11,12,16], pathogens [17] and symbionts [18], as well as nutrient availability [19], salt, drought and cold stress [20]. By comparing one mainland and two island populations, Watts et al. [21] showed that geographical isolation, including the escape from pocket gophers (Geomyidae), resulted in the evolutionary decline of root alkaloid concentrations of the host plant Eschscholzia californica (Papaveraceae). The specific potential of root herbivores to shap...

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A below-ground herbivore shapes root defensive chemistry in natural plant populations

et al. 2016

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“…It will also be important to learn more about the interaction of arthropod attackers with belowground plant tissues. Two Updates, one by Erb et al (2008) and the other by Rasmann and Agrawal (2008), are devoted to the theme of belowground herbivory.…”

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confidence: 99%