To defend themselves against herbivore attack, plants produce secondary metabolites, which are variously inducible and constitutively deployed, presumably to optimize their fitness benefits in light of their fitness c...To defend themselves against herbivore attack, plants produce secondary metabolites, which are variously inducible and constitutively deployed, presumably to optimize their fitness benefits in light of their fitness costs. Three phytohormones, jasmonates （JA） and their active forms, the JA-isoleucine （JA-Ile） and ethylene （ET）, are known to play central roles in the elicitation of induced defenses, but little is known about how this mediation changes over ontogeny. The Optimal Defense Theory （ODT） predicts changes in the costs and benefits of the different types of defenses and has been usefully extrapolated to their modes of deployment. Here we studied whether the herbivore-induced accumulation of JA, JA-Ile and ET changed over ontogeny in Nicotiana attenuata, a native tobacco in which inducible defenses are particularly well studied. Herbivore-elicited ET production changed dramatically during six developmental stages, from rosette through flowering, decreasing with the elongation of the first corollas during flower development. This decrease was largely recovered within a day after flower removal by decapitation. A similar pattern was found for the herbivore-induced accumulation of JA and JA-Ile. These results are consistent with ODT predictions and suggest that the last steps in floral development control the inducibility of at least three plant hormones, optimizing defense-growth tradeoffs.展开更多
Plants have evolved complex physical and chemical defense systems that allow them to withstand herbivory infestation.Composed of a complex mixture of very-long-chain fatty acids(VLCFAs)and their derivatives,cuticular ...Plants have evolved complex physical and chemical defense systems that allow them to withstand herbivory infestation.Composed of a complex mixture of very-long-chain fatty acids(VLCFAs)and their derivatives,cuticular wax constitutes the first physical line of defense against herbivores.Here,we report the function of Glossy 8(ZmGL8),which encodes a 3-ketoacyl reductase belonging to the fatty acid elongase complex,in orchestrating wax production and jasmonic acid(JA)-mediated defenses against herbivores in maize(Zea mays).The mutation of GL8 enhanced chemical defenses by activating the JA-dependent pathway.We observed a trade-off between wax accumulation and JA levels across maize glossy mutants and 24 globally collected maize inbred lines.In addition,we demonstrated that mutants defective in cuticular wax biosynthesis in Arabidopsis thaliana and maize exhibit enhanced chemical defenses.Comprehensive transcriptomic and lipidomic analyses indicated that the gl8 mutant confers chemical resistance to herbivores by remodeling VLCFA-related lipid metabolism and subsequent JA biosynthesis and signaling.These results suggest that VLCFA-related lipid metabolism has a critical role in regulating the trade-offs between cuticular wax and JA-mediated chemical defenses.展开更多
Alien plant invasion success can be inhibited by two key biotic factors:native herbivores and plant diversity.However,few studies have experimentally tested whether these factors interact to synergistically resist inv...Alien plant invasion success can be inhibited by two key biotic factors:native herbivores and plant diversity.However,few studies have experimentally tested whether these factors interact to synergistically resist invasion success,especially factoring in changing global environments(e.g.nutrient enrichment).Here we tested how the synergy between native herbivores and plant diversity affects alien plant invasion success in various nutrient conditions.For this purpose,we exposed alien plant species in potmesocosms to different levels of native plant diversity(4 vs.8 species),native generalist herbivores,and high and low soil nutrient levels.We found that generalist herbivores preferred alien plants to native plants,inhibiting invasion success in a native community.This inhibition was amplified by highly diverse native communities.Further,the amplified effect between herbivory and native plant diversity was independent of nutrient conditions.Our results suggest that a higher diversity of native communities can strengthen the resistance of native generalist herbivores to alien plant invasions by enhancing herbivory tolerance.The synergistic effect remains in force in nutrient-enriched habitats that are always invaded by alien plant species.Our results shed light on the effective control of plant invasions using multi-trophic means,even in the face of future global changes.展开更多
The influence of phlorotannins and bromophenols on the feeding behavior of marine herbivores was determined using bioassay of Turbo cornutus. It was found that phloroglucinol and its oligomers isolated from the brown ...The influence of phlorotannins and bromophenols on the feeding behavior of marine herbivores was determined using bioassay of Turbo cornutus. It was found that phloroglucinol and its oligomers isolated from the brown alga Eisenia bicyclis (eckol, fucofuroeckol A, phlorofucofuroeckol A, dieckol, and 8,8’-bieckol) had a deterrent effect against feeding behavior of T. cornutus in the concentration of algal body, respectively. In the case of the examination of 0.1 mM concentration, although fucofuroeckol A and phlorofucofuroeckol A significantly reduced feeding by T. cornutus, phloroglucinol and 8,8’-bieckol did not show any significant influence on feeding behavior, and eckol and dieckol had stimulating activity. 2,4-Dibromophenol and 2,4,6-tribromophenol, which are major components of extracellular secretions from Eisenia and Ecklonia species, caused the death, the torpidity, and the decreased appetite of T. cornutus at the concentration of 0.1 mM. In addition, 2,4-dibromophenol had strong feeding deterrent activity at the concentration of 1 μM. These results indicate that phlorotannins and bromophenols act as chemical defense agents of brown algae against environmental stresses such as the herbivore attack.展开更多
Arabidopsis thaliana plants are less resistant to attack by the generalist lepidopteran herbivore Trichoplusia ni when plants and herbivores are entrained to opposite, versus identical diurnal cycles and tested under ...Arabidopsis thaliana plants are less resistant to attack by the generalist lepidopteran herbivore Trichoplusia ni when plants and herbivores are entrained to opposite, versus identical diurnal cycles and tested under constant conditions. This effect is associated with circadian fluctuations in levels of jasmonic acid, the transcription factor MYC2, and glucosinolate contents in leaves. We tested whether a similar effect could be observed in a different plant-herbivore system： the wild tobacco Nicotiana attenuata and its co-evolved specialist herbivore, Manduca sexta. We measured larval growth on plants under both constant and diurnal conditions following identical or opposite entrainment, profiled the metabolome of attacked leaf tissue, quantified specific metabolites known to reduce M. sexta growth, and monitored A/I. sexta feeding activity under all experimental conditions. Entrainment did not consistently affect NI. sexta growth or plant defense induction. However, both were reduced under constant dark conditions,as was M. sexta feeding activity. Our data indicate that the response induced by NI. sexta in N. attenuata is robust to diurnal cues and independent of plant or herbivore entrain- ment. We propose that while the patterns of constitutive or general damage-induced defense may undergo circadian fluctuation, the orchestration of specific induced responses is more complex.展开更多
Global warming is predicted to strengthen marine plant-herbivore interactions. However, little is known about the effect of temperature on palatability and the associated chemical composition of marine macroalgae. To ...Global warming is predicted to strengthen marine plant-herbivore interactions. However, little is known about the effect of temperature on palatability and the associated chemical composition of marine macroalgae. To study the effects of physiological stress caused by the warm water temperatures and nutrient-poor conditions that occur during summer, we cultured the brown alga Sargassum yezoense at three different temperatures (16°C, 22°C, and 28°C) in both nutrient-enriched and non-enriched media. We then compared phlorotannin (i.e., defensive compounds) and nitrogen concentrations of S. yezoense as well as consumption rate by the sea urchin Hemicetrotus pulcherrimus among the treatment groups. No effect of culture temperature on phlorotannin and ni-trogen concentrations or consumption rate was detected. Nutrient enrichment resulted in decreased phlorotannin concentration and increased nitrogen concentration. Although nutrient enrichment did not affect consumption rate, a positive correlation between nitrogen concentration and consumption rate was detected. In contrast, there was no correlation between phlorotannin concentration and consumption rate. These results suggested that palatability of S. yezoense to H. pulcherrimus might not be affected by elevated temperature but that it could increase with nutrient enrichment.展开更多
It is well known that herbivore-induced plant defenses alter host plant quality and can affect the behavior and performance of later arriving herbivores.Effects of sequential attacks by herbivores that either suppress...It is well known that herbivore-induced plant defenses alter host plant quality and can affect the behavior and performance of later arriving herbivores.Effects of sequential attacks by herbivores that either suppress or induce plant defenses are less well studied.We sequentially infested leaves of tomato plants with a strain of the phytophagous spider mite Tetranychus urticae that induces plant defenses and the closely related Tetranychus evansi, which suppresses plant defenses.Plant quality was quantified through oviposifion of both spider mite species and by measuring proteinase inhibitor activity using plant material that had been sequentially attacked by both herbivore species.Spider-mite oviposifion data show that T.evansi could suppress an earlier induction of plant defenses by T.urticae,and T.urticae could induce defenses in plants previously attacked by T.evansi in 1 day.Longer attacks by the second species did not result in further changes in oviposifion.Proteinase inhibitor activity levels showed that T.evansi suppressed the high activity levels induced by T.urticae to constitutive levels in 1 day,and further suppressed activity to levels similar to those in plants attacked by T.evansi alone.Attacks by T.urticae induced proteinase inhibitor activity in plants previously attacked by T.evansi,eventually to similar levels as induced by T.urticae alone.Hence,plant quality and plant defenses were significantly affected by sequential attacks and the order of attack does not affect subsequent performance,but does affect proteinase inhibitor activity levels.Based on our results,we discuss the evolution of suppression of plant defenses.展开更多
Novel interactions between introduced oaks and their natural enemies across different continents provide an opportunity to test the enemy release hypothesis(ERH)at local and global scales.Based on the ERH,we assessed ...Novel interactions between introduced oaks and their natural enemies across different continents provide an opportunity to test the enemy release hypothesis(ERH)at local and global scales.Based on the ERH,we assessed the impacts of native seed-feeding insects on introduced and native oaks within and among continents.We combined a common-garden experiment in China and biogeographic literature surveys to measure seed predation by insects and the proportion of acorn embryos surviving after insect infestation among 4 oak species with different geographical origins:Quercus mongolica origin from China,Q.robur and Q.petraea from Europe,and Q.rubra from North America.Mostly supporting the ERH,oaks in introduced continents escaped seed predation compared to those in native continents and compared to other native oaks in introduced continents.Common-garden comparisons showed that total acorn infestation rate of introduced Q.rubra(section Lobatae)was considerably lower than that of native oaks(section Quercus)in China and Europe,likely because of the differences in seed traits associated with different oak sections.Literature surveys showed that seed predation of introduced oaks was lower in the introduced continent than in the native continent.Embryo survival was higher in introduced Q.rubra than native oaks in China and Poland.However,insect seed predation of recently introduced Q.rubra in China was similar to that in Europe,which is not consistent with the ERH.Our results suggest that reduced acorn attack by native insects and higher embryo survival after acorn damage could increase the establishment success or invasion risk of introduced oaks in non-native continents.展开更多
Aims We aimed to test the hypothesis that plants that grow at lower lati-tudes will be better structurally defended than plants from higher latitudes.Methods We collated binary spinescence data for 5145 species across...Aims We aimed to test the hypothesis that plants that grow at lower lati-tudes will be better structurally defended than plants from higher latitudes.Methods We collated binary spinescence data for 5145 species across Australia and New Zealand.Our dataset spanned 35°of latitude,and included over 1 million observations,making it the larg-est empirical study ever conducted for a single physical defence trait.A weighted logistic regression was applied first within Australia and New Zealand separately,and then across the com-bined dataset.Important Findings There was no significant latitudinal gradient in the proportion of spe-cies with spinescence in Australia or New Zealand,or in the overall dataset.That is,plant species are no more likely to be defended by spines at low latitudes than at high latitudes.This finding is counter to the idea that plant defences increase with latitude due to increased selective pressure from higher levels of herbivory.We suggest that future studies should investigate the relationship between herbivory and defence directly,without using latitude as a proxy.展开更多
In this paper, we consider a diffusive plant-herbivore system with the toxin-determined functional response and subject to the homogeneous Neumann boundary conditions on the bounded one-dimensional spatial domain. The...In this paper, we consider a diffusive plant-herbivore system with the toxin-determined functional response and subject to the homogeneous Neumann boundary conditions on the bounded one-dimensional spatial domain. The impacts of diffusion on the dynamical behaviors are investigated and it is found that although the appearance of diffusion does not affect the stability of constant steady states, it can lead to the occurrence of Hopf bifurcation of spatially inhomogeneous periodic solutions at the constant positive steady state. The conclusions show that the occurrence of spatial diffusion can induce more complex dynamical behaviors.展开更多
Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation.However,less is known about the effects of nutrient levels on tolerance and induced resistance,...Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation.However,less is known about the effects of nutrient levels on tolerance and induced resistance,and whether the effects differ between native and introduced populations of invasive plants.We performed a greenhouse experiment with introduced(the USA)and native(Argentina)genotypes of Alternanthera philoxeroides in order to study the effects of soil nitrogen levels on plant growth,constitutive and herbivore(Agasicles hygrophila)-induced chemical defense,and herbivory tolerance.We measured total biomass,elongation rate(as proxy of growth rate),carbon and nitrogen,and the concentration of triterpenoid saponins(defensive chemicals)in leaves and roots.Constitutive resistance(+33%higher leaf triterpenoid saponins in control treatment at low nitrogen level)and tolerance[less decreased total biomass after herbivory treatment(−24%and−15%for high and low nitrogen levels)]were favored at lower nitrogen level,while induced resistance was favored at higher nitrogen level(+24%increased leaf triterpenoid saponins after herbivory treatment at high nitrogen level).Constitutive resistance and tolerance exhibited trade-offs with growth rate,while induced resistance positively correlated with growth rate.Additionally,the introduced genotypes had−6%lower content of leaf carbon in the presence of herbivores than the native genotypes at low nitrogen level,but such difference was absent at high nitrogen level.Our results indicate that soil nitrogen levels influence the preference of different defensive strategies of plant,and interweave with herbivory to determine the performance of introduced genotypes.展开更多
The submerged plant species Carolina fanwort(Cabomba caroliniana)has become a dominant invasive aquatic plant in the Lake Taihu Basin(LTB)in China.Introduced species may escape their original specialist enemies and en...The submerged plant species Carolina fanwort(Cabomba caroliniana)has become a dominant invasive aquatic plant in the Lake Taihu Basin(LTB)in China.Introduced species may escape their original specialist enemies and encounter fewer enemies in their new environment.They were assumed to have suffered less herbivory than native species as they are relatively unpalatable(the enemy release hypothesis[ERH]).The objective of this study was to compare the responses of C.caroliniana with those of co-occurring native species to herbivory from native herbivores.We conducted a mesocosm experiment to record the responses of C.caroliniana and two commonly co-occurring native submerged plant counterparts,water thyme(Hydrilla verticillata)and Eurasian watermilfoil(Myriophyllum spicatum),to herbivory by two native generalist gastropod snails,Radix swinhoei and Sinotaia quadrata.Plant morphological traits(total biomass,shoot/root[S/R]biomass ratio and relative growth rate[RGR])and physiological traits(leaf total nonstructural carbohydrate[TNC],lignin,and cellulose)were recorded.The snail S.quadrata rarely influenced the plant traits of the three submerged plants.With the increasing numbers of R.swinhoei treatments,most of the plant traits of H.verticillata and M.spicatum changed,while those of C.caroliniana showed a relatively stable fluctuation.This result indicates that C.caroliniana is more resistant to herbivory by the snail R.swinhoei,which is consistent with the ERH hypothesis.This finding indicates that herbivorous snail species contributes to the invasion of C.caroliniana,which potentially alters the species composition of submerged plants in the plant community.展开更多
文摘To defend themselves against herbivore attack, plants produce secondary metabolites, which are variously inducible and constitutively deployed, presumably to optimize their fitness benefits in light of their fitness costs. Three phytohormones, jasmonates （JA） and their active forms, the JA-isoleucine （JA-Ile） and ethylene （ET）, are known to play central roles in the elicitation of induced defenses, but little is known about how this mediation changes over ontogeny. The Optimal Defense Theory （ODT） predicts changes in the costs and benefits of the different types of defenses and has been usefully extrapolated to their modes of deployment. Here we studied whether the herbivore-induced accumulation of JA, JA-Ile and ET changed over ontogeny in Nicotiana attenuata, a native tobacco in which inducible defenses are particularly well studied. Herbivore-elicited ET production changed dramatically during six developmental stages, from rosette through flowering, decreasing with the elongation of the first corollas during flower development. This decrease was largely recovered within a day after flower removal by decapitation. A similar pattern was found for the herbivore-induced accumulation of JA and JA-Ile. These results are consistent with ODT predictions and suggest that the last steps in floral development control the inducibility of at least three plant hormones, optimizing defense-growth tradeoffs.
基金supported by the National Science Foundation of China to Chun-Peng Song (U21A20206)the National Natural Science Foundation of China (32102187)+4 种基金Hainan Province Joint Cultivation Project (2021JJLH0014)to Xi Zhangthe Project of Sanya Yazhou Bay Science and Technology City (SCKJ-JYRC-2022-78) to Bao Zhu Lithe Program for Innovative Research Team (in Science and Technology) in the University of Henan Province (21IRTSTHN019) to Siyi Guothe Program of Introducing Talents of Discipline to Universities (111 Project, number D16014)Henan Province Key Research and Development Project (221111112200) to Shutang Zhou and Xi Zhang
文摘Plants have evolved complex physical and chemical defense systems that allow them to withstand herbivory infestation.Composed of a complex mixture of very-long-chain fatty acids(VLCFAs)and their derivatives,cuticular wax constitutes the first physical line of defense against herbivores.Here,we report the function of Glossy 8(ZmGL8),which encodes a 3-ketoacyl reductase belonging to the fatty acid elongase complex,in orchestrating wax production and jasmonic acid(JA)-mediated defenses against herbivores in maize(Zea mays).The mutation of GL8 enhanced chemical defenses by activating the JA-dependent pathway.We observed a trade-off between wax accumulation and JA levels across maize glossy mutants and 24 globally collected maize inbred lines.In addition,we demonstrated that mutants defective in cuticular wax biosynthesis in Arabidopsis thaliana and maize exhibit enhanced chemical defenses.Comprehensive transcriptomic and lipidomic analyses indicated that the gl8 mutant confers chemical resistance to herbivores by remodeling VLCFA-related lipid metabolism and subsequent JA biosynthesis and signaling.These results suggest that VLCFA-related lipid metabolism has a critical role in regulating the trade-offs between cuticular wax and JA-mediated chemical defenses.
基金supported by Postdoctoral Funding from Jilin Province to Liping Shan(2020000147).
文摘Alien plant invasion success can be inhibited by two key biotic factors:native herbivores and plant diversity.However,few studies have experimentally tested whether these factors interact to synergistically resist invasion success,especially factoring in changing global environments(e.g.nutrient enrichment).Here we tested how the synergy between native herbivores and plant diversity affects alien plant invasion success in various nutrient conditions.For this purpose,we exposed alien plant species in potmesocosms to different levels of native plant diversity(4 vs.8 species),native generalist herbivores,and high and low soil nutrient levels.We found that generalist herbivores preferred alien plants to native plants,inhibiting invasion success in a native community.This inhibition was amplified by highly diverse native communities.Further,the amplified effect between herbivory and native plant diversity was independent of nutrient conditions.Our results suggest that a higher diversity of native communities can strengthen the resistance of native generalist herbivores to alien plant invasions by enhancing herbivory tolerance.The synergistic effect remains in force in nutrient-enriched habitats that are always invaded by alien plant species.Our results shed light on the effective control of plant invasions using multi-trophic means,even in the face of future global changes.
文摘The influence of phlorotannins and bromophenols on the feeding behavior of marine herbivores was determined using bioassay of Turbo cornutus. It was found that phloroglucinol and its oligomers isolated from the brown alga Eisenia bicyclis (eckol, fucofuroeckol A, phlorofucofuroeckol A, dieckol, and 8,8’-bieckol) had a deterrent effect against feeding behavior of T. cornutus in the concentration of algal body, respectively. In the case of the examination of 0.1 mM concentration, although fucofuroeckol A and phlorofucofuroeckol A significantly reduced feeding by T. cornutus, phloroglucinol and 8,8’-bieckol did not show any significant influence on feeding behavior, and eckol and dieckol had stimulating activity. 2,4-Dibromophenol and 2,4,6-tribromophenol, which are major components of extracellular secretions from Eisenia and Ecklonia species, caused the death, the torpidity, and the decreased appetite of T. cornutus at the concentration of 0.1 mM. In addition, 2,4-dibromophenol had strong feeding deterrent activity at the concentration of 1 μM. These results indicate that phlorotannins and bromophenols act as chemical defense agents of brown algae against environmental stresses such as the herbivore attack.
基金supported by funding from the Max Planck Society(all)the German Centre for Integrative Biodiversity Research(iDiv)Halle-Jena-Leipzig,funded by the German Research Foundation(FZT 118,M.C.S.)+2 种基金the Global Research Lab program(2012055546)from the National Research Foundation of Korea(Y.J.)a European Research Council advanced grant to I.T.B.(number 293926I.T.B.,M.C.S.,S.-G.K.,and S.M.)
文摘Arabidopsis thaliana plants are less resistant to attack by the generalist lepidopteran herbivore Trichoplusia ni when plants and herbivores are entrained to opposite, versus identical diurnal cycles and tested under constant conditions. This effect is associated with circadian fluctuations in levels of jasmonic acid, the transcription factor MYC2, and glucosinolate contents in leaves. We tested whether a similar effect could be observed in a different plant-herbivore system： the wild tobacco Nicotiana attenuata and its co-evolved specialist herbivore, Manduca sexta. We measured larval growth on plants under both constant and diurnal conditions following identical or opposite entrainment, profiled the metabolome of attacked leaf tissue, quantified specific metabolites known to reduce M. sexta growth, and monitored A/I. sexta feeding activity under all experimental conditions. Entrainment did not consistently affect NI. sexta growth or plant defense induction. However, both were reduced under constant dark conditions,as was M. sexta feeding activity. Our data indicate that the response induced by NI. sexta in N. attenuata is robust to diurnal cues and independent of plant or herbivore entrain- ment. We propose that while the patterns of constitutive or general damage-induced defense may undergo circadian fluctuation, the orchestration of specific induced responses is more complex.
文摘Global warming is predicted to strengthen marine plant-herbivore interactions. However, little is known about the effect of temperature on palatability and the associated chemical composition of marine macroalgae. To study the effects of physiological stress caused by the warm water temperatures and nutrient-poor conditions that occur during summer, we cultured the brown alga Sargassum yezoense at three different temperatures (16°C, 22°C, and 28°C) in both nutrient-enriched and non-enriched media. We then compared phlorotannin (i.e., defensive compounds) and nitrogen concentrations of S. yezoense as well as consumption rate by the sea urchin Hemicetrotus pulcherrimus among the treatment groups. No effect of culture temperature on phlorotannin and ni-trogen concentrations or consumption rate was detected. Nutrient enrichment resulted in decreased phlorotannin concentration and increased nitrogen concentration. Although nutrient enrichment did not affect consumption rate, a positive correlation between nitrogen concentration and consumption rate was detected. In contrast, there was no correlation between phlorotannin concentration and consumption rate. These results suggested that palatability of S. yezoense to H. pulcherrimus might not be affected by elevated temperature but that it could increase with nutrient enrichment.
文摘It is well known that herbivore-induced plant defenses alter host plant quality and can affect the behavior and performance of later arriving herbivores.Effects of sequential attacks by herbivores that either suppress or induce plant defenses are less well studied.We sequentially infested leaves of tomato plants with a strain of the phytophagous spider mite Tetranychus urticae that induces plant defenses and the closely related Tetranychus evansi, which suppresses plant defenses.Plant quality was quantified through oviposifion of both spider mite species and by measuring proteinase inhibitor activity using plant material that had been sequentially attacked by both herbivore species.Spider-mite oviposifion data show that T.evansi could suppress an earlier induction of plant defenses by T.urticae,and T.urticae could induce defenses in plants previously attacked by T.evansi in 1 day.Longer attacks by the second species did not result in further changes in oviposifion.Proteinase inhibitor activity levels showed that T.evansi suppressed the high activity levels induced by T.urticae to constitutive levels in 1 day,and further suppressed activity to levels similar to those in plants attacked by T.evansi alone.Attacks by T.urticae induced proteinase inhibitor activity in plants previously attacked by T.evansi,eventually to similar levels as induced by T.urticae alone.Hence,plant quality and plant defenses were significantly affected by sequential attacks and the order of attack does not affect subsequent performance,but does affect proteinase inhibitor activity levels.Based on our results,we discuss the evolution of suppression of plant defenses.
基金This research was supported by the National Natural Science Foundation of China(31770565)the National Key Research and Development Program of China(2017YFC0503802)the State Key Laboratory of Integrated Management of Pest Insects and Rodents(IPM1911).
文摘Novel interactions between introduced oaks and their natural enemies across different continents provide an opportunity to test the enemy release hypothesis(ERH)at local and global scales.Based on the ERH,we assessed the impacts of native seed-feeding insects on introduced and native oaks within and among continents.We combined a common-garden experiment in China and biogeographic literature surveys to measure seed predation by insects and the proportion of acorn embryos surviving after insect infestation among 4 oak species with different geographical origins:Quercus mongolica origin from China,Q.robur and Q.petraea from Europe,and Q.rubra from North America.Mostly supporting the ERH,oaks in introduced continents escaped seed predation compared to those in native continents and compared to other native oaks in introduced continents.Common-garden comparisons showed that total acorn infestation rate of introduced Q.rubra(section Lobatae)was considerably lower than that of native oaks(section Quercus)in China and Europe,likely because of the differences in seed traits associated with different oak sections.Literature surveys showed that seed predation of introduced oaks was lower in the introduced continent than in the native continent.Embryo survival was higher in introduced Q.rubra than native oaks in China and Poland.However,insect seed predation of recently introduced Q.rubra in China was similar to that in Europe,which is not consistent with the ERH.Our results suggest that reduced acorn attack by native insects and higher embryo survival after acorn damage could increase the establishment success or invasion risk of introduced oaks in non-native continents.
基金Australian Research Council(DP 0984222 and DP140102861)to A.T.M.
文摘Aims We aimed to test the hypothesis that plants that grow at lower lati-tudes will be better structurally defended than plants from higher latitudes.Methods We collated binary spinescence data for 5145 species across Australia and New Zealand.Our dataset spanned 35°of latitude,and included over 1 million observations,making it the larg-est empirical study ever conducted for a single physical defence trait.A weighted logistic regression was applied first within Australia and New Zealand separately,and then across the com-bined dataset.Important Findings There was no significant latitudinal gradient in the proportion of spe-cies with spinescence in Australia or New Zealand,or in the overall dataset.That is,plant species are no more likely to be defended by spines at low latitudes than at high latitudes.This finding is counter to the idea that plant defences increase with latitude due to increased selective pressure from higher levels of herbivory.We suggest that future studies should investigate the relationship between herbivory and defence directly,without using latitude as a proxy.
基金Acknowledgments The first author was supported by the Natural Science Foundation of Gansu Province （1212RJZA065）. The second author was supported by the National Natural Science Foundation of China （11261028） and Gansu Province National Natural Science Foundation （145RJZA216） and China Scholarship Council.
文摘In this paper, we consider a diffusive plant-herbivore system with the toxin-determined functional response and subject to the homogeneous Neumann boundary conditions on the bounded one-dimensional spatial domain. The impacts of diffusion on the dynamical behaviors are investigated and it is found that although the appearance of diffusion does not affect the stability of constant steady states, it can lead to the occurrence of Hopf bifurcation of spatially inhomogeneous periodic solutions at the constant positive steady state. The conclusions show that the occurrence of spatial diffusion can induce more complex dynamical behaviors.
基金supported by the National Natural Science Foundation of China(grant no.41771053,32071659,31961133028 and 32030067).
文摘Plants growing in nutrient-rich environment are predicted to be less defended than conspecifics under nutrient limitation.However,less is known about the effects of nutrient levels on tolerance and induced resistance,and whether the effects differ between native and introduced populations of invasive plants.We performed a greenhouse experiment with introduced(the USA)and native(Argentina)genotypes of Alternanthera philoxeroides in order to study the effects of soil nitrogen levels on plant growth,constitutive and herbivore(Agasicles hygrophila)-induced chemical defense,and herbivory tolerance.We measured total biomass,elongation rate(as proxy of growth rate),carbon and nitrogen,and the concentration of triterpenoid saponins(defensive chemicals)in leaves and roots.Constitutive resistance(+33%higher leaf triterpenoid saponins in control treatment at low nitrogen level)and tolerance[less decreased total biomass after herbivory treatment(−24%and−15%for high and low nitrogen levels)]were favored at lower nitrogen level,while induced resistance was favored at higher nitrogen level(+24%increased leaf triterpenoid saponins after herbivory treatment at high nitrogen level).Constitutive resistance and tolerance exhibited trade-offs with growth rate,while induced resistance positively correlated with growth rate.Additionally,the introduced genotypes had−6%lower content of leaf carbon in the presence of herbivores than the native genotypes at low nitrogen level,but such difference was absent at high nitrogen level.Our results indicate that soil nitrogen levels influence the preference of different defensive strategies of plant,and interweave with herbivory to determine the performance of introduced genotypes.
基金supported by the National Science Foundation of China(NSFC)(31930074,41877415 and 32001157)the Science and Technology Service Network Initiative(KFJ-STS-QYZD-156)+2 种基金the Chinese Academy of Sciences(CAS)the Project of the Young Scientist Group(2021NIGLAS-CJH01)Nanjing Institute of Geography and Limnology(NIGLAS),CAS.
文摘The submerged plant species Carolina fanwort(Cabomba caroliniana)has become a dominant invasive aquatic plant in the Lake Taihu Basin(LTB)in China.Introduced species may escape their original specialist enemies and encounter fewer enemies in their new environment.They were assumed to have suffered less herbivory than native species as they are relatively unpalatable(the enemy release hypothesis[ERH]).The objective of this study was to compare the responses of C.caroliniana with those of co-occurring native species to herbivory from native herbivores.We conducted a mesocosm experiment to record the responses of C.caroliniana and two commonly co-occurring native submerged plant counterparts,water thyme(Hydrilla verticillata)and Eurasian watermilfoil(Myriophyllum spicatum),to herbivory by two native generalist gastropod snails,Radix swinhoei and Sinotaia quadrata.Plant morphological traits(total biomass,shoot/root[S/R]biomass ratio and relative growth rate[RGR])and physiological traits(leaf total nonstructural carbohydrate[TNC],lignin,and cellulose)were recorded.The snail S.quadrata rarely influenced the plant traits of the three submerged plants.With the increasing numbers of R.swinhoei treatments,most of the plant traits of H.verticillata and M.spicatum changed,while those of C.caroliniana showed a relatively stable fluctuation.This result indicates that C.caroliniana is more resistant to herbivory by the snail R.swinhoei,which is consistent with the ERH hypothesis.This finding indicates that herbivorous snail species contributes to the invasion of C.caroliniana,which potentially alters the species composition of submerged plants in the plant community.
