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
To study the local and systemic effects of arbuscular mycorrhizal fungal （AMF） colonization, Nicotiana attenuata plants impaired in their interactions with AMF due to silencing of a calcium- and calmodulin dependent...To study the local and systemic effects of arbuscular mycorrhizal fungal （AMF） colonization, Nicotiana attenuata plants impaired in their interactions with AMF due to silencing of a calcium- and calmodulin dependent protein kinase （inverted repreat （ir）CCaMK） were grown competitively in pairs with empty vector （EV） plants, with and without two different types of inoculum. When inoculated, EV plants strongly outperformed irCCaMK plants. Foliar transcript profiling revealed that AMF colonization significantly changed gene expression of P-starvation and -transporter genes in irCCaMK plants. The Phtl family phosphate transporter NaPT5 was not only specifically induced in roots after AMF colonization, but also in leaves of AMF-colonized irCCaMK plants, and in plants grown under low Pi conditions in the absence of AMF. The P-starvation signature of inoculated irCCaMK plants corresponded with increases in selected amino acids and phenolic compounds in leaves. We also found a strong AMF-induced increase in amino acids and phenolic metabolites in roots. Plants impaired in their interactions with AMF clearly have a fitness disadvantage when competing for limited soil nutrients with a fully functional isogenic line. The additional role of the AMF-induced Phtl family transporter NaPT5 in leaves under P-starvation conditions will require further experiments to fully resolve.展开更多
Nicotiana attenuata flowers, diurnally open,emit scents and move vertically to interact with nocturnal hawkmoth and day-active hummingbird pollinators. To examine the fitness consequences of these floral rhythms, we c...Nicotiana attenuata flowers, diurnally open,emit scents and move vertically to interact with nocturnal hawkmoth and day-active hummingbird pollinators. To examine the fitness consequences of these floral rhythms, we conducted pollination trials in the plant’s native habitat with phase-shifted flowers of plants silenced in circadian clock genes. The results revealed that some pollination benefits observed under glasshouse conditions were not reproduced under natural field conditions. Floral arrhythmicity increased pollination success by hummingbirds, while reducing those by hawkmoths in the field. Thus, floral circadian rhythms may influence a plant’s fitness by filtering pollinators leading to altered seed set from outcrossed pollen.展开更多
The plant circadian clock regulates the rhythms of plant metabolism.Many herbivore-induced plant volatiles(HIPVs)fluctuate,diurnally,but the role of the circadian clock in the emission of HIPVs and their ecological co...The plant circadian clock regulates the rhythms of plant metabolism.Many herbivore-induced plant volatiles(HIPVs)fluctuate,diurnally,but the role of the circadian clock in the emission of HIPVs and their ecological consequences remains largely unknown.Here,we show that the timing of herbivore attack can alter the outcome of tri-trophic interactions,and this is mediated by the circadian clock,under both field and glasshouse conditions.Although most HIPV emissions did not have a circadian rhythm,the circadian clock modulated HIPV emissions in a time-dependent manner.HIPVs mediate tri-trophic interactions,and the circadian clock may affect these interactions by modulating HIPV emission in nature.展开更多
Being shaded is a common environmental stress for plants, especial y for densely planted crops. Shade de-creases red: far-red (R:FR) ratios that inactivate phyto-chrome B (PHYB) and subsequently release phytochrome in...Being shaded is a common environmental stress for plants, especial y for densely planted crops. Shade de-creases red: far-red (R:FR) ratios that inactivate phyto-chrome B (PHYB) and subsequently release phytochrome interaction factors (PIFs). Shaded plants display elongated hypocotyls, internodes, and petioles, hyponastic leaves, early flowering and are inhibited in branching: traits col ectively cal ed the shade avoidance syndrome (SAS). ZEITLUPE (ZTL) is a circadian clock component and blue light photoreceptor, which is also involved in floral rhythms and plant defense in Nicotiana attenuata. ztl mutants are hypersensitive to red light and ZTL physical y interacts with PHYB, suggesting the involvement of ZTL in R:FR light signaling. Here, we show that N. attenuata ZTL-silenced plants display a phenotype op-posite to that of the SAS under normal light. After simulated shade, the normal y induced transcript levels of the SAS mar-ker gene, ATHB2 are attenuated in ZTL-silenced plants. The auxin signaling pathway, known to be involved in SAS, was also significantly attenuated. Furthermore, NaZTL directly in-teracts with NaPHYBs, and regulates the transcript levels of PHYBs, PIF3a, PIF7 and PIF8 under shade. Our results suggest that ZTL may regulate PHYB- and the auxin-mediated sig-naling pathway, which functions in the SAS of N. attenuata.展开更多
Flowers are required for the Darwinian fitness of flowering plants, but flowers＇ advertisements for pollination services can attract florivores. Previous glasshouse work with Nicotiana attenuata revealed the role of ...Flowers are required for the Darwinian fitness of flowering plants, but flowers＇ advertisements for pollination services can attract florivores. Previous glasshouse work with Nicotiana attenuata revealed the role of jasmonate （JA） signaling in flower development, advertisement and defense. However, whether JA signaling mediates flowers＇ filtering of floral visitors in nature remained unknown. This field study revealed that silencing JA signaling resulted in flowers that produce less nectar and benzyl acetone, two pollinatorattractive traits. Meanwhile, flowers of defenseless plants were highly attacked by a suite of native herbivores, and damage to buds in native plants correlated negatively with their JA-lle levels.展开更多
Olive fly（Bactrocera oleae R.） is the most harmful insect pest of olive（Olea europaea L.） which strongly affects fruits and oil production. Despite the expanding economic importance of olive cultivation, up to now...Olive fly（Bactrocera oleae R.） is the most harmful insect pest of olive（Olea europaea L.） which strongly affects fruits and oil production. Despite the expanding economic importance of olive cultivation, up to now, only limited information on plant responses to B. oleae is available. Here,we demonstrate that olive fruits respond to B. oleae attack by producing changes in an array of different defensive compounds including phytohormones, volatile organic compounds（VOCs）, and defense proteins. Bactrocera oleaeinfested fruits induced a strong ethylene burst and transcript levels of several putative ethylene-responsive transcription factors became significantly upregulated. Moreover, infested fruits induced significant changes in the levels of 12-oxophytodienoic acid and C12 derivatives of the hydroperoxide lyase. The emission of VOCs was also changed quantitatively and qualitatively in insect-damaged fruits, indicating that B.oleae larval feeding can specifically affect the volatile blend offruits. Finally, we show that larval infestation maintained high levels of trypsin protease inhibitors in ripe fruits, probably by affecting post-transcriptional mechanisms. Our results provide novel and important information to understand the response of the olive fruit to B. oleae attack; information that can shed light onto potential new strategies to combat this pest.展开更多
Herbivore species sharing a host plant often compete. In this study, we show that host plant-mediated interaction between two insect herbivores-a generalist and a specialist-results in a sex ratio shift of the special...Herbivore species sharing a host plant often compete. In this study, we show that host plant-mediated interaction between two insect herbivores-a generalist and a specialist-results in a sex ratio shift of the specialist＇s offspring. We studied demographic parameters of the specialist Tupiocoris notatus（Hemiptera： Miridae）when co-infesting the host plant Nicotiana attenuata（Solanaceae） with the generalist leafhopper Empoasca sp.（Hemiptera： Cicadellidae）. We show that the usually female-biased sex ratio of T. notatus shifts toward a higher male proportion in the offspring on plants coinfested by Empoasca sp. This sex ratio change did not occur after oviposition, nor is it due differential mortality of female and male nymphs. Based on pyrosequencing and PCR of bacterial 16 S rRNA amplicons, we concluded that sex ratio shifts were unlikely to be due to infection with Wolbachia or other known sex ratio-distorting endosymbionts. Finally, we used transgenic lines of N.attenuata to evaluate if the sex ratio shift could be mediated by changes in general or specialized host plant metabolites. We found that the sex ratio shift occurred on plants deficient in two cytokinin receptors（irCHK2/3）.Thus, cytokinin-regulated traits can alter the offspring sex ratio of the specialist T.notatus.展开更多
The ubiquitous volatile linalool is metabolized in plants to nonvolatile derivatives.We studied Nicotiana attenuata plants which naturally vary in(S)-(+)-linalool contents,and lines engineered to produce either(R)-(-)...The ubiquitous volatile linalool is metabolized in plants to nonvolatile derivatives.We studied Nicotiana attenuata plants which naturally vary in(S)-(+)-linalool contents,and lines engineered to produce either(R)-(-)-or(S)-(+)-linalool.Only(S)-(+)-linalool production was associated with slower growth of a generalist herbivore,and a large fraction was present as nonvolatile derivatives.We found that variation in volatile linalool and its nonvolatile glycosides mapped to the same genetic locus which harbored the biosynthetic gene,NaLIS,but that free linalool varied more in environmental responses.This study reveals how(S)-(+)-linalool and conjugates differ in their regulation and possible functions in resistance.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funded by the Max Planck Societyby Advanced Grant 293926 from the European Research Council to I.T.B.by a JSMC grant to J.W.and by the Collaborative Research Centre“Chemical Mediators in Complex Biosystems-ChemBioSys”(SFB 531 1127).
文摘To study the local and systemic effects of arbuscular mycorrhizal fungal （AMF） colonization, Nicotiana attenuata plants impaired in their interactions with AMF due to silencing of a calcium- and calmodulin dependent protein kinase （inverted repreat （ir）CCaMK） were grown competitively in pairs with empty vector （EV） plants, with and without two different types of inoculum. When inoculated, EV plants strongly outperformed irCCaMK plants. Foliar transcript profiling revealed that AMF colonization significantly changed gene expression of P-starvation and -transporter genes in irCCaMK plants. The Phtl family phosphate transporter NaPT5 was not only specifically induced in roots after AMF colonization, but also in leaves of AMF-colonized irCCaMK plants, and in plants grown under low Pi conditions in the absence of AMF. The P-starvation signature of inoculated irCCaMK plants corresponded with increases in selected amino acids and phenolic compounds in leaves. We also found a strong AMF-induced increase in amino acids and phenolic metabolites in roots. Plants impaired in their interactions with AMF clearly have a fitness disadvantage when competing for limited soil nutrients with a fully functional isogenic line. The additional role of the AMF-induced Phtl family transporter NaPT5 in leaves under P-starvation conditions will require further experiments to fully resolve.
基金supported by European Research Council advanced grant Clockwork Green(No.293926)to I.T.B.the Global Research Lab program(2012055546)from South Koreathe Max Planck Society
文摘Nicotiana attenuata flowers, diurnally open,emit scents and move vertically to interact with nocturnal hawkmoth and day-active hummingbird pollinators. To examine the fitness consequences of these floral rhythms, we conducted pollination trials in the plant’s native habitat with phase-shifted flowers of plants silenced in circadian clock genes. The results revealed that some pollination benefits observed under glasshouse conditions were not reproduced under natural field conditions. Floral arrhythmicity increased pollination success by hummingbirds, while reducing those by hawkmoths in the field. Thus, floral circadian rhythms may influence a plant’s fitness by filtering pollinators leading to altered seed set from outcrossed pollen.
基金supported by theEcole Normale Superieure de Lyon (ENS L) to LTSCEuropean Research Council advanced grant Clockwork Green (No. 293926) to ITB+1 种基金the Collaborative Research Centre “Chemical Mediators in Complex Biosystems à ChemBioSys” (SFB 1127) to ITBthe Max Planck Society
文摘The plant circadian clock regulates the rhythms of plant metabolism.Many herbivore-induced plant volatiles(HIPVs)fluctuate,diurnally,but the role of the circadian clock in the emission of HIPVs and their ecological consequences remains largely unknown.Here,we show that the timing of herbivore attack can alter the outcome of tri-trophic interactions,and this is mediated by the circadian clock,under both field and glasshouse conditions.Although most HIPV emissions did not have a circadian rhythm,the circadian clock modulated HIPV emissions in a time-dependent manner.HIPVs mediate tri-trophic interactions,and the circadian clock may affect these interactions by modulating HIPV emission in nature.
文摘Being shaded is a common environmental stress for plants, especial y for densely planted crops. Shade de-creases red: far-red (R:FR) ratios that inactivate phyto-chrome B (PHYB) and subsequently release phytochrome interaction factors (PIFs). Shaded plants display elongated hypocotyls, internodes, and petioles, hyponastic leaves, early flowering and are inhibited in branching: traits col ectively cal ed the shade avoidance syndrome (SAS). ZEITLUPE (ZTL) is a circadian clock component and blue light photoreceptor, which is also involved in floral rhythms and plant defense in Nicotiana attenuata. ztl mutants are hypersensitive to red light and ZTL physical y interacts with PHYB, suggesting the involvement of ZTL in R:FR light signaling. Here, we show that N. attenuata ZTL-silenced plants display a phenotype op-posite to that of the SAS under normal light. After simulated shade, the normal y induced transcript levels of the SAS mar-ker gene, ATHB2 are attenuated in ZTL-silenced plants. The auxin signaling pathway, known to be involved in SAS, was also significantly attenuated. Furthermore, NaZTL directly in-teracts with NaPHYBs, and regulates the transcript levels of PHYBs, PIF3a, PIF7 and PIF8 under shade. Our results suggest that ZTL may regulate PHYB- and the auxin-mediated sig-naling pathway, which functions in the SAS of N. attenuata.
基金supported by the Max Planck Society,the European Research Council advanced grant Clockwork Green(293926)to I.T.B.by a Humboldt Postdoctoral Research Fellowship to R.L
文摘Flowers are required for the Darwinian fitness of flowering plants, but flowers＇ advertisements for pollination services can attract florivores. Previous glasshouse work with Nicotiana attenuata revealed the role of jasmonate （JA） signaling in flower development, advertisement and defense. However, whether JA signaling mediates flowers＇ filtering of floral visitors in nature remained unknown. This field study revealed that silencing JA signaling resulted in flowers that produce less nectar and benzyl acetone, two pollinatorattractive traits. Meanwhile, flowers of defenseless plants were highly attacked by a suite of native herbivores, and damage to buds in native plants correlated negatively with their JA-lle levels.
基金financially supported by the OLEA Project-Genomics and Breeding of Olivefunded by MIPAF,Italyby the Max Plank Society
文摘Olive fly（Bactrocera oleae R.） is the most harmful insect pest of olive（Olea europaea L.） which strongly affects fruits and oil production. Despite the expanding economic importance of olive cultivation, up to now, only limited information on plant responses to B. oleae is available. Here,we demonstrate that olive fruits respond to B. oleae attack by producing changes in an array of different defensive compounds including phytohormones, volatile organic compounds（VOCs）, and defense proteins. Bactrocera oleaeinfested fruits induced a strong ethylene burst and transcript levels of several putative ethylene-responsive transcription factors became significantly upregulated. Moreover, infested fruits induced significant changes in the levels of 12-oxophytodienoic acid and C12 derivatives of the hydroperoxide lyase. The emission of VOCs was also changed quantitatively and qualitatively in insect-damaged fruits, indicating that B.oleae larval feeding can specifically affect the volatile blend offruits. Finally, we show that larval infestation maintained high levels of trypsin protease inhibitors in ripe fruits, probably by affecting post-transcriptional mechanisms. Our results provide novel and important information to understand the response of the olive fruit to B. oleae attack; information that can shed light onto potential new strategies to combat this pest.
基金supported by the Max Planck Society(all)the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig,funded by the German Research Foundation(FZT 118+3 种基金N.A.,I.T.B.,M.C.S.)European Research Council advanced grant Clockwork Green to I.T.B.(number 293926I.T.B.,M.C.S.)in part by the Collaborative Research Centre Chemical Mediators in Complex Biosystems - ChemBioSys(CRC 1127) funded by the German Research Foundation(I.T. B.,M.C.S.)
文摘Herbivore species sharing a host plant often compete. In this study, we show that host plant-mediated interaction between two insect herbivores-a generalist and a specialist-results in a sex ratio shift of the specialist＇s offspring. We studied demographic parameters of the specialist Tupiocoris notatus（Hemiptera： Miridae）when co-infesting the host plant Nicotiana attenuata（Solanaceae） with the generalist leafhopper Empoasca sp.（Hemiptera： Cicadellidae）. We show that the usually female-biased sex ratio of T. notatus shifts toward a higher male proportion in the offspring on plants coinfested by Empoasca sp. This sex ratio change did not occur after oviposition, nor is it due differential mortality of female and male nymphs. Based on pyrosequencing and PCR of bacterial 16 S rRNA amplicons, we concluded that sex ratio shifts were unlikely to be due to infection with Wolbachia or other known sex ratio-distorting endosymbionts. Finally, we used transgenic lines of N.attenuata to evaluate if the sex ratio shift could be mediated by changes in general or specialized host plant metabolites. We found that the sex ratio shift occurred on plants deficient in two cytokinin receptors（irCHK2/3）.Thus, cytokinin-regulated traits can alter the offspring sex ratio of the specialist T.notatus.
基金This work was funded by the Max Planck Society and advanced Grant No.293926 of the European Research Council(to I.T.B.)in part supported by the Collaborative Research Centre ChemBioSys(CRC 1127)funded by the Deutsche Forschungsgemeinschaft,and the Venture&Innovation Support Program for Chongqing Overseas Returnees(7820100514).
文摘The ubiquitous volatile linalool is metabolized in plants to nonvolatile derivatives.We studied Nicotiana attenuata plants which naturally vary in(S)-(+)-linalool contents,and lines engineered to produce either(R)-(-)-or(S)-(+)-linalool.Only(S)-(+)-linalool production was associated with slower growth of a generalist herbivore,and a large fraction was present as nonvolatile derivatives.We found that variation in volatile linalool and its nonvolatile glycosides mapped to the same genetic locus which harbored the biosynthetic gene,NaLIS,but that free linalool varied more in environmental responses.This study reveals how(S)-(+)-linalool and conjugates differ in their regulation and possible functions in resistance.
