The plant hormone jasmonic acid （JA） plays a central role in plant defense against herbivores. Herbivore damage elicits a rapid and transient JA burst in the wounded leaves and JA functions as a signal to mediate th...The plant hormone jasmonic acid （JA） plays a central role in plant defense against herbivores. Herbivore damage elicits a rapid and transient JA burst in the wounded leaves and JA functions as a signal to mediate the accumulation of various secondary metabolites that confer resistance to herbivores. Nicotiana attenuata is a wild tobacco species that inhabits western North America. More than fifteen years of study and its unique interaction with the specialist herbivore insect Manduca sexta have made this plant one of the best models for studying plant-herbivore interactions. Here we review the recent progress in understanding the elicitation of JA accumulation by herbivore-specific elicitors, the regulation of JA biosynthesis, JA signaling, and the herbivore-defense traits in N. attenuata.展开更多
Jasmonic acid(JA)plays important roles in plant resistance to insect herbivores.One important derivative of JA is 12-OH-JA,which is produced by two independent pathways:direct hydroxylation of JA by jasmonate-induced ...Jasmonic acid(JA)plays important roles in plant resistance to insect herbivores.One important derivative of JA is 12-OH-JA,which is produced by two independent pathways:direct hydroxylation of JA by jasmonate-induced oxygenases(JOXs)or hydrolyzation of 12-OH-JA-Ile.Yet the function of 12-OH-JA in plant-herbivore interactions remains largely unknown.In this study,we silenced four JOX homologs independently in the wild tobacco Nicotiana attenuata by virus-induced gene silencing(VIGS),and found that all four JOX homologs are involved in JA hydroxylation.Simultaneously silencing the four JA hydroxylases in VIGS-NaJOXs plants decreased herbivory-induced 12-OH-JA by 33%,but JA and JA-Ile levels increased by 45%and 30%,respectively,compared to those in control plants.Compared to direct hydroxylation from JA,hydrolyzation from 12-OH-JA-Ile is equally important for herbivory-induced 12-OHJA accumulation:in the 12-OH-JA-Ile deficient irJAR4/6 plants,12-OH-JA decreased 34%.Moreover,VIGSNaJOXs plants exhibited enhanced resistance to the generalist herbivore Spodoptera litura.The poor larval performance was strongly correlated with high levels of several JA-Ile-dependent direct defense metabolites in the VIGS-NaJOXs plants.When we simultaneously silenced all four JA hydroxylases in the JAIle-deficient irJAR4/6 background,the enhanced herbivore resistance diminished,demonstrating that enhanced herbivore resistance resulted from elevated JA-Ile levels.Given that silencing these NaJOX-like genes did not detectably alter plant growth but highly increased plant defense levels,we propose that JOX genes are potential targets for genetic improvement of herbivore-resistant crops.展开更多
We performed desiccation and storage trials to better understand storage behavior of Knema attenuata seeds. Mature seeds with moisture content （MC） of 31% exhibited 73% germination. During the period of desiccation ...We performed desiccation and storage trials to better understand storage behavior of Knema attenuata seeds. Mature seeds with moisture content （MC） of 31% exhibited 73% germination. During the period of desiccation （open lab condition） seeds with MC 23% showed 40% germination. After further drying to MC 21% germination was reduced to 16%. Complete loss in viability resulted when seed moisture was reduced to 18%. The seeds stored at -10℃, 0℃, 10℃ and 28±2℃ （open lab condition） lost their viability within 10 days. Seeds stored in sealed polythene hags and moist sand retained viability for more days than did seeds stored under all other storage conditions. Sensitivity of seeds to lower temperature and desiccation suggest that the storage behavior of K. attenuata seeds is recalcitrant. Seeds stored in moist conditions can, at best, be stored for a period of two months.展开更多
We studied effect of desiccation on Knema attenuata seeds in the laboratory conditions （28 ± 2℃） for 8 days. We also monitored biochemical changes during germination by following standard procedures. Seeds los...We studied effect of desiccation on Knema attenuata seeds in the laboratory conditions （28 ± 2℃） for 8 days. We also monitored biochemical changes during germination by following standard procedures. Seeds lost their viability in 8 days by decreasing to 18% of moisture content from its original value of 31%. The total sugar, protein and lipid contents decreased during seed ageing. An increase was noticed in the protease activity during desiccation. The phenolic content in seed exudates was increased during ageing. The result confirms the degradation of stored biomolecules in seeds during ageing. Desiccation sensitiv- ity and biochemical changes during dehydration confirm its recalcitrant nature.展开更多
On October 1, 2009, sixteen dolphins were obtained from fishermen by incidental catching in the Yellow Sea, China. As the dolphins＇ skin color was ambiguous, morphological parameters were measured, and mitochondrial ...On October 1, 2009, sixteen dolphins were obtained from fishermen by incidental catching in the Yellow Sea, China. As the dolphins＇ skin color was ambiguous, morphological parameters were measured, and mitochondrial DNA cytochrome b （Cyt b） gene sequence was studied to identify the species. Morphological characteristics were consistent with Pantropical spotted dolphins, Stenella attenuata. Furthermore, a partial mitochondrial DNA eytoehrome b （Cyt b） gene sequence as long as 328-bp was studied by extracting genomic DNA from the skins, and six haplotypes were detected in the sixteen dolphins. By comparing homologous sequences available in GenBank （www.ncbi.nlm.nih.gov）, all the six haplotypes had maximal genetic similarity with Pantropical spotted dolphin. Eight species of cetacean （whales and dolphins） are now recognised in the Yellow Sea. To the best of our knowledge, this is the first record of Pantropical spotted dolphins from this region. Despite this species being listed as a Grade II National Key Protected Animal since 1988, little is known of its biology in Chinese waters. We recommend remedial research be undertaken to ensure appropriate management.展开更多
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
DICER-like （DCL） proteins produce small RNAs that silence genes involved in development and defenses against viruses and pathogens. Which DCLs participate in plant-herbivore interactions remains unstudied. We identi...DICER-like （DCL） proteins produce small RNAs that silence genes involved in development and defenses against viruses and pathogens. Which DCLs participate in plant-herbivore interactions remains unstudied. We identified and stably silenced four distinct DCL genes by RNAi in Nicotiana attenuata （Torrey ex. Watson）, a model for the study of plant-herbivore interactions. Silencing DCL1 expression was lethal. Manduca sexta larvae performed significantly better on ir-dcl3 and ir-dcl4 plants, but not on ir-dcl2 plants compared to wild type plants. Phytohormones, defense metabolites and microarray analyses revealed that when DCL3 and DCL4 were silenced separately, herbivore resistance traits were regulated in distinctly different ways. Crossing of the lines revealed complex interactions in the patterns of regulation. Single ir-dcl4 and double ir-dcl2 ir-dcl3 plants were impaired in JA accumulation, while JA- Ile was increased in ir-dcl3 plants. Ir-dcl3 and ir-dcl4 plants were impaired in nicotine accumulation; silencing DCL2 in combination with either DCL3 or DCL4 restored nicotine levels to those of WT. Trypsin proteinase inhibitor activity and transcripts were only silenced in ir-dcl3 plants. We conclude that DCL2/3/4 interact in a complex manner to regulate anti-herbivore defenses and that these interactions significantly complicate the already challenging task of understanding smRNA function in the regulation of biotic interactions.展开更多
The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores....The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores. The transcripts of the respiratory burst NADPH oxidase homolog Narboh D in Nicotiana attenuate are rapidly and transiently elicited by wounding, and are amplified when Manduca sexta oral secretions （OS） are added to the wounds. The fatty-acid-amino-acid-conjugates （FACs）, demonstrably the major elicitors in M. sexta OS, are responsible for the increase in Narboh D transcripts. Silencing Narboh D significantly reduced reactive oxygen species （ROS） levels after OS elicitation, but neither OS-elicited jasmonic acid （JA） or JA-isoleucine （JA-Ile） bursts, pivotal hormones that regulates plant resistance to herbivores, nor early transcripts of herbivore defense-related genes （NaJAR4 and NaPAL1）, were influenced. However, late OS-elicited increases in trypsin proteinase inhibitors （TPIs）, as well as the transcript levels of defense genes such as polyphenol oxidase, TPI and Thionin were significantly reduced, in addition, Narboh D-silenced plants were more vulnerable to insect herbivores, especially the larvae of the generalist Spodoptera fittoralis. We thus conclude that Narboh D-based defenses play an important role in late herbivore-elicited responses.展开更多
The brassinosteroid （BR） receptor, BR insensitive 1 （BRI1）, plays a critical role in plant development, but whether BRI1-mediated BR signaling is involved in plant defense responses to herbivores was largely unkno...The brassinosteroid （BR） receptor, BR insensitive 1 （BRI1）, plays a critical role in plant development, but whether BRI1-mediated BR signaling is involved in plant defense responses to herbivores was largely unknown. Here, we examined the function of BRI1 in the resistance of Nicotiana attenuata （Solanaceae） to its specialist insect herbivore Manduca sexta. Jasmonic acid （JA） and JA-isoleucine conjugate （JA-Ile） are important hormones that mediate resistance to herbivores and we found that after wounding or simulated herbivory NaBRI1 had little effect on JA levels, but was important for the induction of JA-Ile. Further experiments revealed that decreased JAR （the enzyme for JA-Ile production） activity and availability of Ile in NaBRI1-silenced plants were likely responsible for the low JA-Ile levels. Consistently, M. sexta larvae gained more weight on NaBRI1-silenced plants than on the control plants. Quantification of insect feeding-induced secondary metabolites revealed that silencing NaBRI1 resulted in decreased levels of carbon-rich defensive secondary metabolites （hydroxygeranyllinalool diterpene glycosides, chlorogenic acid, and rutin）, but had little effect on the nitrogen-rich ones （nicotine and trypsin proteinase inhibitors）. Thus, NaBRI1-mediated BR signaling is likely involved in plant defense responses to M. sexta, including maintaining JA-Ile levels and the accumulation of several carbon-rich defensive secondary metabolites.展开更多
Nearly half a century ago insect herbivores were found to induce the formation of green islands by manipulating cytokinin （CK） levels. However, the response of the CK pathway to attack by chewing insect herbivores r...Nearly half a century ago insect herbivores were found to induce the formation of green islands by manipulating cytokinin （CK） levels. However, the response of the CK pathway to attack by chewing insect herbivores remains unclear. Here, we characterize the CK pathway of Nicotiana attenuata （Torr. ex S. Wats.） and its response to wounding and perception of herbivoreassociated molecular patterns （HAMPs）. We identified 44 genes involved in CK biosynthesis, inactivation, degradation, and signaling. Leaf wounding rapidly induced transcriptional changes in multiple genes throughout the pathway, as well as in the levels of CKs, including isopentenyladenosine and cis-zeatin riboside; perception of HAMPs present in the oral secretions （OS） of the specialist herbivore Manduca sexta amplified these responses. The jasmonate pathway, which triggers many herbivore-induced processes, was not required for these HAMP-triggered changes, but rather suppressed the CK responses. Interestingly CK pathway changes were observed also in systemic leaves in response to wounding and OS application indicating a role of CKs in mediating long distance systemic processes in response to herbivory. Since wounding and grasshopper OS elicited similar accumulations of CKs in Arabidopsis thaliana L., we propose that CKs are integral components of wounding and HAMP-triggered responses in many plant species.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
Despite the growing awareness on the importance of gut microbiomes,understanding marine mammal gut microbiomes remains limited due to difficulties in sampling.Spotted dolphins(Stenella attenuata)are widely spread ocea...Despite the growing awareness on the importance of gut microbiomes,understanding marine mammal gut microbiomes remains limited due to difficulties in sampling.Spotted dolphins(Stenella attenuata)are widely spread oceanic cetaceans,and there is a gap in knowledge regarding their gut microbiology.In this study,we opportunistically collected samples from both wild and human-cared spotted dolphins in the southern waters of Hainan Island,China.This provided the opportunity to examine the composition and diversity of the gut microbial communities of this cetacean species.Since these dolphins inhabit a similar water environment,different food sources might be the primary factor distinguishing the gut microbiomes of wild and human-cared populations,offering valuable experimental material to investigate potential differences in gut microbial community structure among marine mammals in similar environments but with varying food sources.We found that the gastrointestinal microbial community structure of wild and human-cared dolphins demonstrated significant differences,both overall and at specific locations.However,no significant difference was observed in the microbial diversity of their gastrointestinal tracts,indicating that the disparities primarily lie in microbiota composition.Additionally,we detected numerous potentially pathogenic bacteria,suggesting a comprehensive future study of marine mammal gut microbiology.Such a study might involve determining health indicator factors associated with these microbiomes.Our study not only supplements information on the gut microbiology of spotted dolphins but also delves into the similarities and differences in gastrointestinal microbial communities within the same marine mammal species when food source variations play a significant role in their lives.展开更多
Nutrients are distributed unevenly in the soil.Phenotypic plasticity in root growth and proliferation may enable plants to cope with this variation and effectively forage for essential nutrients. However, how micronut...Nutrients are distributed unevenly in the soil.Phenotypic plasticity in root growth and proliferation may enable plants to cope with this variation and effectively forage for essential nutrients. However, how micronutrients shape root architecture of plants in their natural environments is poorly understood. We used a combination of field and laboratory-based assays to determine the capacity of Nicotiana attenuata to direct root growth towards localized nutrient patches in its native environment. Plants growing in nature displayed a particular root phenotype consisting of a single primary root and a few long, shallow lateral roots. Analysis of bulk soil surrounding the lateral roots revealed a strong positive correlation between lateral root placement and micronutrient gradients, including copper, iron and zinc. In laboratory assays, the application of localized micronutrient salts close to lateral root tips led to roots bending in the direction of copper and iron. This form of chemotropism was absent in ethylene and jasmonic acid deficient lines,suggesting that it is controlled in part by these two hormones. This work demonstrates that directed root growth underlies foraging behavior, and suggests that chemotropism and micronutrient-guided root placement are important factors that shape root architecture in nature.展开更多
基金the Max Planck Society for financing the projects during our work at the Max Planck Institute for Chemical Ecologypart supported by the National Natural Science Foundation of China(Grant No.31201527) to L.Wang
文摘The plant hormone jasmonic acid （JA） plays a central role in plant defense against herbivores. Herbivore damage elicits a rapid and transient JA burst in the wounded leaves and JA functions as a signal to mediate the accumulation of various secondary metabolites that confer resistance to herbivores. Nicotiana attenuata is a wild tobacco species that inhabits western North America. More than fifteen years of study and its unique interaction with the specialist herbivore insect Manduca sexta have made this plant one of the best models for studying plant-herbivore interactions. Here we review the recent progress in understanding the elicitation of JA accumulation by herbivore-specific elicitors, the regulation of JA biosynthesis, JA signaling, and the herbivore-defense traits in N. attenuata.
基金supported by the Key Project of Applied Basic Research Program of Yunnan(2017FA015)the Young Academic and Technical Leader Raising Foundation of Yunnan Province(no. 2017HB063)+1 种基金the Yunnan Academy of Tobacco Agricultural Sciences(2018530000241002 and 2019530000241003)the Biotechnology Experimental Center at the Kunming Institute of Botany,CAS,for supporting plant cultivation.
文摘Jasmonic acid(JA)plays important roles in plant resistance to insect herbivores.One important derivative of JA is 12-OH-JA,which is produced by two independent pathways:direct hydroxylation of JA by jasmonate-induced oxygenases(JOXs)or hydrolyzation of 12-OH-JA-Ile.Yet the function of 12-OH-JA in plant-herbivore interactions remains largely unknown.In this study,we silenced four JOX homologs independently in the wild tobacco Nicotiana attenuata by virus-induced gene silencing(VIGS),and found that all four JOX homologs are involved in JA hydroxylation.Simultaneously silencing the four JA hydroxylases in VIGS-NaJOXs plants decreased herbivory-induced 12-OH-JA by 33%,but JA and JA-Ile levels increased by 45%and 30%,respectively,compared to those in control plants.Compared to direct hydroxylation from JA,hydrolyzation from 12-OH-JA-Ile is equally important for herbivory-induced 12-OHJA accumulation:in the 12-OH-JA-Ile deficient irJAR4/6 plants,12-OH-JA decreased 34%.Moreover,VIGSNaJOXs plants exhibited enhanced resistance to the generalist herbivore Spodoptera litura.The poor larval performance was strongly correlated with high levels of several JA-Ile-dependent direct defense metabolites in the VIGS-NaJOXs plants.When we simultaneously silenced all four JA hydroxylases in the JAIle-deficient irJAR4/6 background,the enhanced herbivore resistance diminished,demonstrating that enhanced herbivore resistance resulted from elevated JA-Ile levels.Given that silencing these NaJOX-like genes did not detectably alter plant growth but highly increased plant defense levels,we propose that JOX genes are potential targets for genetic improvement of herbivore-resistant crops.
文摘We performed desiccation and storage trials to better understand storage behavior of Knema attenuata seeds. Mature seeds with moisture content （MC） of 31% exhibited 73% germination. During the period of desiccation （open lab condition） seeds with MC 23% showed 40% germination. After further drying to MC 21% germination was reduced to 16%. Complete loss in viability resulted when seed moisture was reduced to 18%. The seeds stored at -10℃, 0℃, 10℃ and 28±2℃ （open lab condition） lost their viability within 10 days. Seeds stored in sealed polythene hags and moist sand retained viability for more days than did seeds stored under all other storage conditions. Sensitivity of seeds to lower temperature and desiccation suggest that the storage behavior of K. attenuata seeds is recalcitrant. Seeds stored in moist conditions can, at best, be stored for a period of two months.
文摘We studied effect of desiccation on Knema attenuata seeds in the laboratory conditions （28 ± 2℃） for 8 days. We also monitored biochemical changes during germination by following standard procedures. Seeds lost their viability in 8 days by decreasing to 18% of moisture content from its original value of 31%. The total sugar, protein and lipid contents decreased during seed ageing. An increase was noticed in the protease activity during desiccation. The phenolic content in seed exudates was increased during ageing. The result confirms the degradation of stored biomolecules in seeds during ageing. Desiccation sensitiv- ity and biochemical changes during dehydration confirm its recalcitrant nature.
基金Supported by the International Cooperation Department,State Oceanic Administration(No.HC10701-10(1))the National Special Research Fund for Non-Profit Marine Sector(No.201105011)+1 种基金the National Natural Science Foundation of China(No.41206159)the Natural Science Foundation of Shandong Province,China(No.Y2007D75)
文摘On October 1, 2009, sixteen dolphins were obtained from fishermen by incidental catching in the Yellow Sea, China. As the dolphins＇ skin color was ambiguous, morphological parameters were measured, and mitochondrial DNA cytochrome b （Cyt b） gene sequence was studied to identify the species. Morphological characteristics were consistent with Pantropical spotted dolphins, Stenella attenuata. Furthermore, a partial mitochondrial DNA eytoehrome b （Cyt b） gene sequence as long as 328-bp was studied by extracting genomic DNA from the skins, and six haplotypes were detected in the sixteen dolphins. By comparing homologous sequences available in GenBank （www.ncbi.nlm.nih.gov）, all the six haplotypes had maximal genetic similarity with Pantropical spotted dolphin. Eight species of cetacean （whales and dolphins） are now recognised in the Yellow Sea. To the best of our knowledge, this is the first record of Pantropical spotted dolphins from this region. Despite this species being listed as a Grade II National Key Protected Animal since 1988, little is known of its biology in Chinese waters. We recommend remedial research be undertaken to ensure appropriate management.
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the Max Planck Society for fundingSPP acknowledges support from MPG-DST India partner program
文摘DICER-like （DCL） proteins produce small RNAs that silence genes involved in development and defenses against viruses and pathogens. Which DCLs participate in plant-herbivore interactions remains unstudied. We identified and stably silenced four distinct DCL genes by RNAi in Nicotiana attenuata （Torrey ex. Watson）, a model for the study of plant-herbivore interactions. Silencing DCL1 expression was lethal. Manduca sexta larvae performed significantly better on ir-dcl3 and ir-dcl4 plants, but not on ir-dcl2 plants compared to wild type plants. Phytohormones, defense metabolites and microarray analyses revealed that when DCL3 and DCL4 were silenced separately, herbivore resistance traits were regulated in distinctly different ways. Crossing of the lines revealed complex interactions in the patterns of regulation. Single ir-dcl4 and double ir-dcl2 ir-dcl3 plants were impaired in JA accumulation, while JA- Ile was increased in ir-dcl3 plants. Ir-dcl3 and ir-dcl4 plants were impaired in nicotine accumulation; silencing DCL2 in combination with either DCL3 or DCL4 restored nicotine levels to those of WT. Trypsin proteinase inhibitor activity and transcripts were only silenced in ir-dcl3 plants. We conclude that DCL2/3/4 interact in a complex manner to regulate anti-herbivore defenses and that these interactions significantly complicate the already challenging task of understanding smRNA function in the regulation of biotic interactions.
文摘The superoxide （O^2-）-generating NADPH oxidases are crucial for the defense of plants against attack from pathogens; however, it remains unknown whether they also mediate responses against chewing insect herbivores. The transcripts of the respiratory burst NADPH oxidase homolog Narboh D in Nicotiana attenuate are rapidly and transiently elicited by wounding, and are amplified when Manduca sexta oral secretions （OS） are added to the wounds. The fatty-acid-amino-acid-conjugates （FACs）, demonstrably the major elicitors in M. sexta OS, are responsible for the increase in Narboh D transcripts. Silencing Narboh D significantly reduced reactive oxygen species （ROS） levels after OS elicitation, but neither OS-elicited jasmonic acid （JA） or JA-isoleucine （JA-Ile） bursts, pivotal hormones that regulates plant resistance to herbivores, nor early transcripts of herbivore defense-related genes （NaJAR4 and NaPAL1）, were influenced. However, late OS-elicited increases in trypsin proteinase inhibitors （TPIs）, as well as the transcript levels of defense genes such as polyphenol oxidase, TPI and Thionin were significantly reduced, in addition, Narboh D-silenced plants were more vulnerable to insect herbivores, especially the larvae of the generalist Spodoptera fittoralis. We thus conclude that Narboh D-based defenses play an important role in late herbivore-elicited responses.
文摘The brassinosteroid （BR） receptor, BR insensitive 1 （BRI1）, plays a critical role in plant development, but whether BRI1-mediated BR signaling is involved in plant defense responses to herbivores was largely unknown. Here, we examined the function of BRI1 in the resistance of Nicotiana attenuata （Solanaceae） to its specialist insect herbivore Manduca sexta. Jasmonic acid （JA） and JA-isoleucine conjugate （JA-Ile） are important hormones that mediate resistance to herbivores and we found that after wounding or simulated herbivory NaBRI1 had little effect on JA levels, but was important for the induction of JA-Ile. Further experiments revealed that decreased JAR （the enzyme for JA-Ile production） activity and availability of Ile in NaBRI1-silenced plants were likely responsible for the low JA-Ile levels. Consistently, M. sexta larvae gained more weight on NaBRI1-silenced plants than on the control plants. Quantification of insect feeding-induced secondary metabolites revealed that silencing NaBRI1 resulted in decreased levels of carbon-rich defensive secondary metabolites （hydroxygeranyllinalool diterpene glycosides, chlorogenic acid, and rutin）, but had little effect on the nitrogen-rich ones （nicotine and trypsin proteinase inhibitors）. Thus, NaBRI1-mediated BR signaling is likely involved in plant defense responses to M. sexta, including maintaining JA-Ile levels and the accumulation of several carbon-rich defensive secondary metabolites.
基金funded by the Max-Planck-Society, Meza-Canales by the DAADVanková by the Czech Science Foundation, project no. 206/09/2062Meldau and Brütting are funded by Advanced Grant no. 293926 of the European Research Council to Baldwin
文摘Nearly half a century ago insect herbivores were found to induce the formation of green islands by manipulating cytokinin （CK） levels. However, the response of the CK pathway to attack by chewing insect herbivores remains unclear. Here, we characterize the CK pathway of Nicotiana attenuata （Torr. ex S. Wats.） and its response to wounding and perception of herbivoreassociated molecular patterns （HAMPs）. We identified 44 genes involved in CK biosynthesis, inactivation, degradation, and signaling. Leaf wounding rapidly induced transcriptional changes in multiple genes throughout the pathway, as well as in the levels of CKs, including isopentenyladenosine and cis-zeatin riboside; perception of HAMPs present in the oral secretions （OS） of the specialist herbivore Manduca sexta amplified these responses. The jasmonate pathway, which triggers many herbivore-induced processes, was not required for these HAMP-triggered changes, but rather suppressed the CK responses. Interestingly CK pathway changes were observed also in systemic leaves in response to wounding and OS application indicating a role of CKs in mediating long distance systemic processes in response to herbivory. Since wounding and grasshopper OS elicited similar accumulations of CKs in Arabidopsis thaliana L., we propose that CKs are integral components of wounding and HAMP-triggered responses in many plant species.
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funded by the Hainan Provincial Natural Science Foundation of China(422RC744)Youth Innovation Promotion Association of Chinese Academy of Sciences(2020363)the“One Belt and One Road”Science and Technology Cooperation Special Program of the International Partnership Program of the Chinese Academy of Sciences(Grant No.183446KYSB20200016).
文摘Despite the growing awareness on the importance of gut microbiomes,understanding marine mammal gut microbiomes remains limited due to difficulties in sampling.Spotted dolphins(Stenella attenuata)are widely spread oceanic cetaceans,and there is a gap in knowledge regarding their gut microbiology.In this study,we opportunistically collected samples from both wild and human-cared spotted dolphins in the southern waters of Hainan Island,China.This provided the opportunity to examine the composition and diversity of the gut microbial communities of this cetacean species.Since these dolphins inhabit a similar water environment,different food sources might be the primary factor distinguishing the gut microbiomes of wild and human-cared populations,offering valuable experimental material to investigate potential differences in gut microbial community structure among marine mammals in similar environments but with varying food sources.We found that the gastrointestinal microbial community structure of wild and human-cared dolphins demonstrated significant differences,both overall and at specific locations.However,no significant difference was observed in the microbial diversity of their gastrointestinal tracts,indicating that the disparities primarily lie in microbiota composition.Additionally,we detected numerous potentially pathogenic bacteria,suggesting a comprehensive future study of marine mammal gut microbiology.Such a study might involve determining health indicator factors associated with these microbiomes.Our study not only supplements information on the gut microbiology of spotted dolphins but also delves into the similarities and differences in gastrointestinal microbial communities within the same marine mammal species when food source variations play a significant role in their lives.
基金the Max Planck Society,European Research Council Advanced Grant(No.293926 to ITB)Alexander von Humboldt Postdoctoral Research Fellowship (to APF)+1 种基金Brazilian National Council for Research (CNPq grant no.237929/2012-0 to CCMA) for financial support
文摘Nutrients are distributed unevenly in the soil.Phenotypic plasticity in root growth and proliferation may enable plants to cope with this variation and effectively forage for essential nutrients. However, how micronutrients shape root architecture of plants in their natural environments is poorly understood. We used a combination of field and laboratory-based assays to determine the capacity of Nicotiana attenuata to direct root growth towards localized nutrient patches in its native environment. Plants growing in nature displayed a particular root phenotype consisting of a single primary root and a few long, shallow lateral roots. Analysis of bulk soil surrounding the lateral roots revealed a strong positive correlation between lateral root placement and micronutrient gradients, including copper, iron and zinc. In laboratory assays, the application of localized micronutrient salts close to lateral root tips led to roots bending in the direction of copper and iron. This form of chemotropism was absent in ethylene and jasmonic acid deficient lines,suggesting that it is controlled in part by these two hormones. This work demonstrates that directed root growth underlies foraging behavior, and suggests that chemotropism and micronutrient-guided root placement are important factors that shape root architecture in nature.
基金National Natural Science Foundation of China(Grant Nos.39899400 and 30499340)the Knowledge Innovation Project of Chinese Academy of Sciences(Grant No.KSCX-SW-122)
