Variation in the Defense Strategies of Plants: Are Resistance and Tolerance Mutually Exclusive?

Abstract

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The eco-physiological complexity of plant responses to insect herbivores

“…Tolerance is operationally de®ned by quantitative geneticists as the ratio of the ®tness of a plant lineage which has been attacked by herbivores to that of plants from the same lineage grown under identical conditions but without the herbivores (Simms and Rausher 1987;Rausher 1992). While this operational de®nition has done little to identify traits responsible for tolerance, it has established that these traits can be heritable (Mauricio et al 1997) and hence are as likely to evolve as any trait conferring resistance against herbivores. Physiological studies have implicated a large suite of morphological ± the number and dormancy of meristems (Haukioja 1991;Tuomi et al 1994) and sectoriality (Marquis 1996) ± and physiological traits, such as intrinsic rates of growth, storage of reserves, changes in resource acquisition (compensatory photosynthesis and increases in mineral nutrient uptake) and alterations in patterns of senescence, as contributing to the buering of plant reproductive performance against tissue loss to herbivores (Fig.…”

“…In addition to the physiological costs of resistance,`e cological'' tradeos, such as those between resistance and susceptibility to dierent natural enemies (Simms 1992;Adler and Karban 1994;Rausher 1996), mutualists (Euler and Baldwin 1996;Strauss 1997) or between resistance and tolerance to herbivory (van der Meijden et al 1988;Rosenthal and Kotanen 1994;Fineblum and Rausher 1995;Mauricio et al 1997), may result in signi®cant ®tness reductions for a well-defended plant, independent of the resource demands of the resistance traits. These``ecological'' costs may be particularly important for some indirect defenses, such as the release of volatile``alarm'' signals which are likely to make only small demands on a plant's metabolism (Dicke and Sabelis 1992).…”

Ontogenetic changes in tolerance to herbivory in Arabidopsis

“…In an exploratory approach, we used three accessions that span a wide range in resistance levels with the intention of sampling from a wide range of tolerance levels. We expected such variation in tolerance because of the negative correlation between resistance and tolerance proposed to occur as a consequence of a tradeoff in resource allocation between two sets of costly traits with a high degree of redundancy in their function (Mauricio et al 1997). However, detecting this tradeoff was not a main goal of this study.…”

Protein storage and root:shoot reallocation provide tolerance to damage in a hybrid willow system

“…Studies on annuals and short-lived, monocarpic herbs provide better estimates of lifetime fitness, so research on plant tolerance to damage has focused on these plants (Fineblum and Rausher 1995;Rosenthal and Welter 1995;Lennartsson et al 1998;Mauricio et al 1997;Juenger and Bergelson 2000;van der Meijden et al 2000;Fornoni et al 2003Fornoni et al , 2004Weinig et al 2003). Even though some studies have examined tolerance in perennial herbs and in woody plants (Hochwender et al 2000b; Rogers and Siemann 2002;Myers and Kitajima 2007;Stevens et al 2007Stevens et al , 2008Eyles et al 2009), studies of woody plants have usually not incorporated reproductive fitness into their evaluation of tolerance (but see Kaitaniemi et al 1999;Pratt et al 2005).…”