The Experts below are selected from a list of 35031 Experts worldwide ranked by ideXlab platform
Jon Ågren - One of the best experts on this subject based on the ideXlab platform.
-
no trade off between trichome production and tolerance to Leaf and inflorescence Damage in a natural population of arabidopsis lyrata
Journal of Plant Ecology, 2014Co-Authors: Adriana Puentes, Jon ÅgrenAbstract:Aims Early models of plant defense conceived resistance and tolerance to herbivore Damage as mutually exclusive strategies. Support for this idea has been equivocal and studies on these two strategies are still needed to understand the evolution of defenses in natural populations. In Arabidopsis lyrata, the production of trichomes, a documented resistance trait, has been associated with a fitness cost in the absence of herbivores. We examined whether trichome production is also associated with reduced tolerance to simulated herbivore Damage. Methods We conducted a field experiment in a natural Swedish population of A. lyrata where we inflicted Leaf (0 vs. 50% of the area of each Leaf removed) and inflorescence Damage (0 vs. 50% of inflorescences removed) to trichome-producing and glabrous plants in a factorial design. We examined the response (survival, growth and reproduction) of the plants to the imposed Damage over 2 years. Important Findings Trichome-producing plants were not less tolerant than glabrous plants to simulated herbivore Damage (no significant morph × Leaf Damage or morph × inflorescence Damage interactions). Inflorescence and Leaf Damage had independent negative effects on the performance of Damaged plants. Leaf Damage reduced rosette size the year of Damage, but effects on reproductive output in the year of Damage, and on survival and reproductive performance the following year were weak and not statistically significant. Inflorescence Damage significantly reduced the number of flowers, fruits and seeds the year of Damage, but not in the following year. Irrespective of morph, the study population was more tolerant to Leaf than to inflorescence Damage. The results indicated no trade-off between trichome production and tolerance, suggesting that these two defense mechanisms have the potential to evolve independently in this A. lyrata population.
-
additive and non additive effects of simulated Leaf and inflorescence Damage on survival growth and reproduction of the perennial herb arabidopsis lyrata
Oecologia, 2012Co-Authors: Adriana Puentes, Jon ÅgrenAbstract:Herbivores may Damage both leaves and reproductive structures, and although such combined Damage may affect plant fitness non-additively, this has received little attention. We conducted a 2-year field experiment with a factorial design to examine the effects of simulated Leaf (0, 12.5, 25, or 50% of Leaf area removed) and inflorescence Damage (0 vs. 50% of inflorescences removed) on survival, growth and reproduction in the perennial herb Arabidopsis lyrata. Leaf and inflorescence Damage negatively and independently reduced flower, fruit and seed production in the year of Damage; Leaf Damage also reduced rosette size by the end of the first season and flower production in the second year. Leaf Damage alone reduced the proportion of flowers forming a fruit and fruit production per plant the second year, but when combined with inflorescence Damage no such effect was observed (significant Leaf × inflorescence Damage interaction). Damage to leaves (sources) caused a greater reduction in future reproduction than did simultaneous Damage to leaves and inflorescences (sinks). This demonstrates that a full understanding of the effects of herbivore Damage on plant fitness requires that consequences of Damage to vegetative and reproductive structures are evaluated over more than 1 year and that non-additive effects are considered.
-
magnitude and timing of Leaf Damage affect seed production in a natural population of arabidopsis thaliana brassicaceae
PLOS ONE, 2012Co-Authors: Reiko Akiyama, Jon ÅgrenAbstract:Background: The effect of herbivory on plant fitness varies widely. Understanding the causes of this variation is of considerable interest because of its implications for plant population dynamics and trait evolution. We experimentally defoliated the annual herb Arabidopsis thaliana in a natural population in Sweden to test the hypotheses that (a) plant fitness decreases with increasing Damage, (b) tolerance to defoliation is lower before flowering than during flowering, and (c) defoliation before flowering reduces number of seeds more strongly than defoliation during flowering, but the opposite is true for effects on seed size. Methodology/Principal Findings: In a first experiment, between 0 and 75% of the Leaf area was removed in May from plants that flowered or were about to start flowering. In a second experiment, 0, 25%, or 50% of the Leaf area was removed from plants on one of two occasions, in mid April when plants were either in the vegetative rosette or bolting stage, or in mid May when plants were flowering. In the first experiment, seed production was negatively related to Leaf area removed, and at the highest Damage level, also mean seed size was reduced. In the second experiment, removal of 50% of the Leaf area reduced seed production by 60% among plants defoliated early in the season at the vegetative rosettes, and by 22% among plants defoliated early in the season at the bolting stage, but did not reduce seed output of plants defoliated one month later. No seasonal shift in the effect of defoliation on seed size was detected. Conclusions/Significance: The results show that Leaf Damage may reduce the fitness of A. thaliana, and suggest that in this population Leaf herbivores feeding on plants before flowering should exert stronger selection on defence traits than those feeding on plants during flowering, given similar Damage levels.
-
Cost of trichome production and resistance to a specialist insect herbivore in Arabidopsis lyrata
Evolutionary Ecology, 2010Co-Authors: Nina Sletvold, Katri Kärkkäinen, Piritta Huttunen, Richard Handley, Jon ÅgrenAbstract:Theory predicts that trade-offs between resistance to herbivory and other traits positively affecting fitness can maintain genetic variation in resistance within plant populations. In the perennial herb Arabidopsis lyrata , trichome production is a resistance trait that exhibits both qualitative and quantitative variation. Using a paternal half-sib design, we conducted two greenhouse experiments to ask whether trichomes confer resistance to oviposition and Leaf herbivory by the specialist moth Plutella xylostella , and to examine potential genetic constraints on evolution of increased resistance and trichome density. In addition, we examined whether trichome production is induced by insect herbivory. We found strong positive genetic and phenotypic correlations between Leaf trichome density and resistance to Leaf herbivory, demonstrating that the production of Leaf trichomes increases resistance to Leaf Damage by P. xylostella. Also resistance to oviposition tended to increase with increasing Leaf trichome density, but genetic and phenotypic correlations were not statistically significant. Trichome density and resistance to Leaf herbivory were negatively correlated genetically with plant size in the absence of herbivores, but not in the presence of herbivores. There was no evidence of increased trichome production after Leaf Damage by P. xylostella . The results suggest that trichome production and resistance to Leaf herbivory are associated with a cost and that the direction of selection on resistance and trichome density depends on the intensity of herbivory.
Wilhelm Boland - One of the best experts on this subject based on the ideXlab platform.
-
evolutionary change from induced to constitutive expression of an indirect plant resistance
Nature, 2004Co-Authors: Martin Heil, Eduard K Linsenmair, Sabine Greiner, Harald Meimberg, Ralf Kruger, Jeanlouis Noyer, Gunther Heubl, Wilhelm BolandAbstract:Induced plant resistance traits are expressed in response to attack and occur throughout the plant kingdom1,2. Despite their general occurrence, the evolution of such resistances has rarely been investigated3. Here we report that extrafloral nectar, a usually inducible trait, is constitutively secreted by Central American Acacia species that are obligately inhabited by ants. Extrafloral nectar is secreted as an indirect resistance4, attracting ants that defend plants against herbivores5. Leaf Damage induces extrafloral nectar secretion in several plant species6,7,8; among these are various Acacia species and other Fabaceae investigated here. In contrast, Acacia species obligately inhabited by symbiotic ants9 nourish these ants by secreting extrafloral nectar constitutively at high rates that are not affected by Leaf Damage. The phylogeny of the genus Acacia and closely related genera indicate that the inducibility of extrafloral nectar is the plesiomorphic or ‘original’ state, whereas the constitutive extrafloral nectar flow is derived within Acacia. A constitutive resistance trait has evolved from an inducible one, obviously in response to particular functional demands.
-
adaptations to biotic and abiotic stress macaranga ant plants optimize investment in biotic defence
Journal of Experimental Botany, 2001Co-Authors: Eduard K Linsenmair, M Heil, Werner M Kaiser, Brigitte Fiala, Thomas Koch, Wilhelm BolandAbstract:Obligate ant plants (myrmecophytes) in the genus Macaranga produce energy- and nutrient-rich food bodies (FBs) to nourish mutualistic ants which live inside the plants. These defend their host against biotic stress caused by herbivores and pathogens. Facultative, 'myrmecophilic' interactions are based on the provision of FBs and/or extrafloral nectar (EFN) to defending insects that are attracted from the vicinity. FB production by the myrmecophyte, M. triloba, was limited by soil nutrient content under field conditions and was regulated according to the presence or absence of an ant colony. However, increased FB production promoted growth of the ant colonies living in the plants. Ant colony size is an important defensive trait and is negatively correlated to a plant's Leaf Damage. Similar regulatory patterns occurred in the EFN production of the myrmecophilic M. tanarius. Nectar accumulation resulting from the absence of consumers strongly decreased nectar flow, which increased again when consumers had access to the plant. EFN flow could be induced via the octadecanoid pathway. Leaf Damage increased levels of endogenous jasmonic acid (JA), and both Leaf Damage and exogenous JA application increased EFN flow. Higher numbers of nectary visiting insects and lower numbers of herbivores were present on JA-treated plants. In the long run, this decreased Leaf Damage significantly. Ant food production is controlled by different regulatory mechanisms which ensure that costs are only incurred when counterbalanced by defensive effects of mutualistic insects.
-
extrafloral nectar production of the ant associated plant macaranga tanarius is an induced indirect defensive response elicited by jasmonic acid
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: M Heil, Andrea Hilpert, Brigitte Fiala, Thomas Koch, Wilhelm Boland, Karl Eduard LinsenmairAbstract:Plant species in at least 66 families produce extrafloral nectar (EFN) on their leaves or shoots and therewith attract predators and parasitoids, such as ants and wasps, which in turn defend them against herbivores. We investigated whether EFN secretion is induced by herbivory and/or artificial Damage, and thus can be regarded as an induced defensive response. In addition, we studied the underlying signaling pathway. EFN secretion by field-grown Macaranga tanarius increased after herbivory, artificial Leaf Damage, and exogenous jasmonic acid (JA) application. Artificial Damage strongly enhanced endogenous JA concentrations. The response in EFN production to artificial Damage was much less pronounced in those leaves that were treated with phenidone to inhibit endogenous JA synthesis. Quantitative dose-response relations were found between the increase in nectar production and both the intensity of Leaf Damage and the amounts of exogenously applied JA. The amount of endogenously produced JA was positively correlated with the intensity of Leaf Damage. Increased numbers of defending insects and decreased numbers of herbivores were observed on leaves after inducing EFN production by exogenous JA treatment. Over 6 weeks, repeatedly applied JA or artificial Damage resulted in a ten-fold reduction in herbivory. These results demonstrate that EFN production represents an alternative mechanism for induced, indirect defensive plant responses that are mediated via the octadecanoid signal transduction cascade.
Jenny Klingberg - One of the best experts on this subject based on the ideXlab platform.
-
Predation by avian insectivores on caterpillars is linked to Leaf Damage on oak (Quercus robur)
Oecologia, 2018Co-Authors: Bengt Gunnarsson, Jonas Wallin, Jenny KlingbergAbstract:Birds that are foraging in tree canopies can cause a substantial decrease in arthropod numbers. Trees may benefit from avian insectivores attacking insect herbivores. In a field study, we tested whether the intensity of bird predation on caterpillars is linked quantitatively to Leaf Damage caused by insect herbivores, a hypothesized relationship that previously was poorly investigated. Artificial caterpillars were placed in the lower part of oak trees ( Quercus robur ) in urban and suburban sites across the city of Gothenburg, Sweden. Two days later, we recorded the survival: the pooled predation rate was 11.5% (5.7% day^−1). Mean predation rate per tree was 10.4%. Mean Leaf Damage, i.e. Leaf area eaten by insect herbivores, per tree was 5.7% but there was large variation between trees. We found a significant negative relationship between survival probability of caterpillars and Leaf Damage in an analysis using a mixed model logistic regression. This suggests that caterpillars are at high risk of bird attacks in trees with a high degree of Leaf Damage and avian insectivores may increase the foraging effort in the foliage of such oak trees. Our findings concerning the quantitative relationship between the predator–prey interactions and plant Damage suggested tentatively that the survival probability of caterpillars decreases rapidly at 15–20% Leaf Damage in lower part of oak canopies. Furthermore, our findings add credence to the idea of using artificial caterpillars as a means to obtain standardized comparisons of predation rates in various habitats.
Vaughan V Symonds - One of the best experts on this subject based on the ideXlab platform.
-
the genetic architecture of constitutive and induced trichome density in two new recombinant inbred line populations of arabidopsis thaliana phenotypic plasticity epistasis and bidirectional Leaf Damage response
BMC Plant Biology, 2014Co-Authors: Rebecca H Bloomer, Alan M Lloyd, Vaughan V SymondsAbstract:Herbivory imposes an important selective pressure on plants. In Arabidopsis thaliana Leaf trichomes provide a key defense against insect herbivory; however, trichome production incurs a fitness cost in the absence of herbivory. Previous work on A. thaliana has shown an increase in trichome density in response to Leaf Damage, suggesting a mechanism by which the cost associated with constitutively high trichome density might be mitigated; however, the genetic basis of trichome density induction has not been studied. Here, we describe the mapping of quantitative trait loci (QTL) for constitutive and Damage induced trichome density in two new recombinant inbred line populations of A. thaliana; mapping for constitutive and induced trichome density also allowed for the investigation of Damage response (plasticity) QTL. Both novel and previously identified QTL for constitutive trichome density and the first QTL for induced trichome density and response are identified. Interestingly, two of the four parental accessions and multiple RILs in each population exhibited lower trichome density following Leaf Damage, a response not previously described in A. thaliana. Importantly, a single QTL was mapped for the response phenotype and allelic variation at this locus appears to determine response trajectory in RILs. The data also show that epistatic interactions are a significant component of the genetic architecture of trichome density. Together, our results provide further insights into the genetic architecture of constitutive trichome density and new insights into induced trichome density in A. thaliana specifically and to our understanding of the genetic underpinnings of natural variation generally.
Evan H Delucia - One of the best experts on this subject based on the ideXlab platform.
-
foliage of oaks grown under elevated co2 reduces performance of antheraea polyphemus lepidoptera saturniidae
Environmental Entomology, 2007Co-Authors: Rachel G Knepp, Jason G Hamilton, Arthur R Zangerl, May R Berenbaum, Evan H DeluciaAbstract:To understand how the increase in atmospheric CO2 from human activity may affect Leaf Damage by forest insects, we examined host plant preference and larval performance of a generalist herbivore, Antheraea polyphemus Cram., that consumed foliage developed under ambient or elevated CO2. Larvae were fed leaves from Quercus alba L. and Quercus velutina Lam. grown under ambient or plus 200 μl/liter CO2 using free air carbon dioxide enrichment (FACE). Lower digestibility of foliage, greater protein precipitation capacity in frass, and lower nitrogen concentration of larvae indicate that growth under elevated CO2 reduced the food quality of oak leaves for caterpillars. Consuming leaves of either oak species grown under elevated CO2 slowed the rate of development of A. polyphemus larvae. When given a choice, A. polyphemus larvae preferred Q. velutina leaves grown under ambient CO2; feeding on foliage of this species grown under elevated CO2 led to reduced consumption, slower growth, and greater mortality. Larvae compensated for the lower digestibility of Q. alba leaves grown under elevated CO2 by increasing the efficiency of conversion of ingested food into larval mass. Despite equivalent consumption rates, larvae grew larger when they consumed Q. alba leaves grown under elevated compared with ambient CO2. Reduced consumption, slower growth rates, and increased mortality of insect larvae may explain lower total Leaf Damage observed previously in plots in this forest exposed to elevated CO2. By subtly altering aspects of Leaf chemistry, the ever-increasing concentration of CO2 in the atmosphere will change the trophic dynamics in forest ecosystems.
-
elevated co2 reduces Leaf Damage by insect herbivores in a forest community
New Phytologist, 2005Co-Authors: Rachel G Knepp, Jason G Hamilton, Arthur R Zangerl, May R Berenbaum, Jacqueline E Mohan, Evan H DeluciaAbstract:Summary • By altering foliage quality, exposure to elevated levels of atmospheric CO 2 potentially affects the amount of herbivore Damage experienced by plants. • Here, we quantified foliar carbon (C) and nitrogen (N) content, C : N ratio, phenolic levels, specific Leaf area (SLA) and the amount of Leaf tissue Damaged by chewing insects for 12 hardwood tree species grown in plots exposed to elevated CO 2 (ambient plus 200 µl l − 1 ) using free-air CO 2 enrichment (FACE) over 3 yr. • The effects of elevated CO 2 varied considerably by year and across species. Elevated CO 2 decreased herbivore Damage across 12 species in 1 yr but had no detectable effect in others. Decreased Damage may have been related to lower average foliar N concentration and SLA and increased C : N ratio and phenolic content for some species under elevated compared with ambient CO 2 . It remains unclear how these changes in Leaf properties affect herbivory. • Damage to the leaves of hardwood trees by herbivorous insects may be reduced in the future as the concentration of CO 2 continues to increase, perhaps altering the trophic structure of forest ecosystems.