functional interactions in the use of direct and indirect defences in native nicotiana plants.nicotiana attenuata has both direct (induced nicotine production) and indirect (induced release of mono- and sesquiterpenes) defences induced by herbivore attack; both are activated by the jasmonate cascade, albeit in different tissues (roots and shoots, respectively). the fact that both types of defences are induced suggests that their benefits are conditional. indeed, jasmonate treatment of roots to induce nicotine production increases plant fitness correlates (lifetime viable seed production) ...199910549549
herbivore-induced allene oxide synthase transcripts and jasmonic acid in nicotiana attenuata.exogenous jasmonate treatment of nicotiana attenuata torr. ex wats. plants elicits durable resistance against herbivores and attack from its specialist herbivore, manduca sexta, results in an amplification of the transient wound-induced increase in endogenous jasmonic acid levels (ja). to understand whether this "ja burst" is under transcriptional control, we cloned allene oxide synthase (aos; ec, the enzyme that catalyzes the dehydration of 13(s)-hydroperoxy octadecatrienoic acid to a ...200111672737
gene expression of 5-epi-aristolochene synthase and formation of capsidiol in roots of nicotiana attenuata and n. sylvestris.three new copies of a sesquiterpenoid synthase gene encoding 5-epi-aristolochene synthase (eas) were cloned as cdnas from nicotiana attenuata and functionally characterized after expression of the recombinant enzymes in e. coli. differential patterns of eas gene expression and formation of the antimicrobial sesquiterpenoid capsidiol were found in roots and shoots of two species of nicotiana. eas is expressed constitutively in roots of n. attenuata and n. sylvestris corresponding with constitutiv ...200212009313
methyl jasmonate and cis-jasmone do not dispose of the herbivore-induced jasmonate burst in nicotiana attenuata.the oxylipin pathway mediates wound- and herbivore-induced defense reactions in nicotiana attenuata as evidenced by a transient jasmonic acid (ja)-burst that precedes these defense responses. the fate of this induced ja-burst remains unknown. two derivatives of ja, its methylester, methyl jasmonate (meja) and cis-jasmone (cisj), are thought to be a means of disposing of ja through volatilization at the plant surface. in n. attenuata, the headspace quantities of these compounds did not change ove ...200415032845
nicotine's defensive function in nature.plants produce metabolites that directly decrease herbivore performance, and as a consequence, herbivores are selected for resistance to these metabolites. to determine whether these metabolites actually function as defenses requires measuring the performance of plants that are altered only in the production of a certain metabolite. to date, the defensive value of most plant resistance traits has not been demonstrated in nature. we transformed native tobacco(nicotiana attenuata) with a consensus ...200415314646
issr and aflp analysis of the temporal and spatial population structure of the post-fire annual, nicotiana attenuata, in sw utah.the native annual tobacco, nicotiana attenuata, is found primarily in large ephemeral populations (typically for less than 3 growing seasons) after fires in sagebrush and pinyon-juniper ecosystems and in small persistent populations (for many growing seasons) in isolated washes typically along roadsides throughout the great basin desert of the sw usa. this distribution pattern is due to its unusual germination behavior. ephemeral populations are produced by the germination of dormant seeds from ...200415350209
silencing the jasmonate cascade: induced plant defenses and insect populations.we transformed the native tobacco, nicotiana attenuata, to silence its lipoxygenase, hydroperoxide lyase, and allene oxide synthase genes in order to inhibit oxylipin signaling, known to mediate the plant's direct and indirect defenses. when planted into native habitats, lipoxygenase-deficient plants were more vulnerable to n. attenuata's adapted herbivores but also attracted novel herbivore species, which fed and reproduced successfully. in addition to highlighting the value of genetically sile ...200415232071
nitrogen supply influences herbivore-induced direct and indirect defenses and transcriptional responses in nicotiana attenuata.although nitrogen (n) availability is known to alter constitutive resistance against herbivores, its influence on herbivore-induced responses, including signaling pathways, transcriptional signatures, and the subsequently elicited chemical defenses is poorly understood. we used the native tobacco, nicotiana attenuata, which germinates in the postfire environment and copes with large changes in soil n during postfire succession, to compare a suite of manduca sexta- and elicitor-induced responses ...200415133153
consistency of nicotiana attenuata's herbivore- and jasmonate-induced transcriptional responses in the allotetraploid species nicotiana quadrivalvis and nicotiana clevelandii.we examined the consistency of the native diploid nicotiana attenuata (na)'s herbivore-induced transcriptional changes in the two allotetraploid natives, nicotiana clevelandii (nc) and nicotiana quadrivalvis (nq), which are thought to be derived from hybridizations with an ancestral na. an analysis of nuclear-encoded chloroplast-expressed gln synthetase gene (ncpgs) sequences found strong similarity between nc and na and between n. trigonophylla and the two allopolyploids. all species were elici ...200415133150
specificity in ecological interactions: attack from the same lepidopteran herbivore results in species-specific transcriptional responses in two solanaceous host plants.model systems have proven enormously useful in elucidating the biochemical function of plant genes. however their ecological function, having been sculpted by evolutionary forces specific to a species, may be less conserved across taxa. responses to wounding and herbivore attack differ among plant families and are known to be mediated by oxylipin, ethylene, and systemin-signaling networks. we analyzed transcriptional responses of two native solanaceous species to the attack of an herbivore whose ...200515980198
herbivore-induced plant vaccination. part ii. array-studies reveal the transience of herbivore-specific transcriptional imprints and a distinct imprint from stress combinations.summary microarray technology has given plant biologists the ability to simultaneously monitor changes in the expression of hundreds of genes, and yet, to date, this technology has not been applied to ecological phenomena. in native tobacco (nicotiana attenuata), prior attack of sap-feeding mirids (tupiocoris notatus) results in vaccination of the plant against subsequent attacks by chewing hornworms (manduca sexta). this vaccination is mediated by a combination of direct and indirect defenses a ...200415125771
herbivore-induced plant vaccination. part i. the orchestration of plant defenses in nature and their fitness consequences in the wild tobacco nicotiana attenuata.a plant's responses to attack from particular pathogens and herbivores may result in resistance to subsequent attack from the same species, but may also affect different species. such a cross-resistance, called immunization or vaccination, can benefit the plant, if the fitness consequences of attack from the initial attacker are less than those from subsequent attackers. here, we report an example of naturally occurring vaccination of the native tobacco plant, nicotiana attenuata, against manduc ...200415125770
silencing of a germin-like gene in nicotiana attenuata improves performance of native herbivores.germins and germin-like proteins (glps) are known to function in pathogen resistance, but their involvement in defense against insect herbivores is poorly understood. in the native tobacco nicotiana attenuata, attack from the specialist herbivore manduca sexta or elicitation by adding larval oral secretions (os) to wounds up-regulates transcripts of a glp. to understand the function of this gene, which occurs as a single copy, we cloned the full-length naglp and silenced its expression in n. att ...200616461381
manipulation of endogenous trypsin proteinase inhibitor production in nicotiana attenuata demonstrates their function as antiherbivore defenses.evidence for the in planta defensive function of trypsin protease inhibitors (tpis) comes from observations of enhanced herbivore resistance after heterologous tpi expression or the manipulation of signal cascades that activate numerous defense responses, including tpi production; no studies have altered the expression of an endogenous pi gene to examine defensive function. we isolated two genes with seven- and six-repeat tpi domains from nicotiana attenuata from the potato (solanum tuberosum) p ...200414976235
virus-induced gene silencing of jasmonate-induced direct defences, nicotine and trypsin proteinase-inhibitors in nicotiana attenuata.research into the molecular basis of plant-insect interactions is hampered by the inability to alter the expression of individual genes in plants growing under natural conditions. the ability of virus-induced gene silencing (vigs) to silence the expression of two jasmonate-induced genes known to mediate the expression of two potent direct defences (nicotine and proteinase inhibitors) that are produced in different tissues (roots and shoots, respectively) in nicotiana attenuata is documented here ...200414623900
manduca sexta recognition and resistance among allopolyploid nicotiana host plants.allopolyploid speciation occurs instantly when the genomes of different species combine to produce self-fertile offspring and has played a central role in the evolution of higher plants, but its consequences for adaptive responses are unknown. we compare herbivore-recognition and -resistance responses of the diploid species and putative ancestral parent nicotiana attenuata with those of the two derived allopolyploid species nicotiana clevelandii and nicotiana bigelovii. manduca sexta larvae atta ...200314530394
constraints to herbivore-induced systemic responses: bidirectional signaling along orthostichies in nicotiana attenuata.we investigated the impact of leaf vascular connections on systemically transmitted herbivore-induced gene expression in nicotiana attenuata. although systemic signaling is clearly associated with the plant vascular system, few studies consider vascular architecture when measuring systemically induced defenses. n. attenuata is a plant with dispersed phyllotaxis approximating 3/8 in the rosette stage of growth. we mimicked manduca sexta herbivory by introducing larval regurgitant to wounds produc ...200312757332
molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphingidae) and its natural host nicotiana attenuata. vi. microarray analysis reveals that most herbivore-specific transcriptional changes are mediated by fatty acid-amino acid conjugates.evidence is accumulating that insect-specific plant responses are mediated by constituents in the oral secretions and regurgitants (r) of herbivores, however the relative importance of the different potentially active constituents remains unclear. fatty acid-amino acid conjugates (facs) are found in the r of many insect herbivores and have been shown to be necessary and sufficient to elicit a set of herbivore-specific responses when the native tobacco plant nicotiana attenuata is attacked by the ...200312692348
molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphingidae) and its natural host nicotiana attenuata. vii. changes in the plant's proteome.when manduca sexta attacks nicotiana attenuata, fatty acid-amino acid conjugates (facs) in the larvae's oral secretions (os) are introduced into feeding wounds. these facs trigger a transcriptional response that is similar to the response induced by insect damage. using two-dimensional gel electrophoresis, matrix-assisted laser desorption ionization-time of flight, and liquid chromatography-tandem mass spectrometry, we characterized the proteins in phenolic extracts and in a nuclear fraction of ...200617028148
molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphingidae) and its natural host nicotiana attenuata: v. microarray analysis and further characterization of large-scale changes in herbivore-induced mrnas.we extend our analysis of the transcriptional reorganization that occurs when the native tobacco, nicotiana attenuata, is attacked by manduca sexta larvae by cloning 115 transcripts by mrna differential display reverse transcription-polymerase chain reaction and subtractive hybridization using magnetic beads (shmb) from the m. sexta-responsive transcriptome. these transcripts were spotted as cdna with eight others, previously confirmed to be differentially regulated by northern analysis on glass ...200312692347
methyl jasmonate as an allelopathic agent: sagebrush inhibits germination of a neighboring tobacco, nicotiana attenuata.artemisia tridentata ssp. tridentata is the dominant and defining shrub in the great basin desert, with well-documented allelopathic tendencies that have generally been ascribed to its most abundantly released secondary metabolites. however, as a minor component, sagebrush releases a highly biologically active substance, methyljasmonate (meja), which is known to function as both a germination inhibitor and promoter in laboratory studies. nicotiana attenuata is a tobacco species native to the gre ...200212523573
rapid hplc screening of jasmonate-induced increases in tobacco alkaloids, phenolics, and diterpene glycosides in nicotiana attenuata.a rapid, hplc-based screening procedure for the main classes of secondary metabolites in nicotiana attenuata leaves (alkaloids, phenolics, and diterpene glycosides) is reported. in a single step, leaves are extracted in aqueous acidified (0.5% acetic acid) methanol, and the extracted compounds are separated by reversed-phase hplc with an acidic water/acetonitrile gradient in <30 min. the utility of the method in quantifying changes in the secondary metabolites after methyl jasmonate treatment of ...200111513627
molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphingidae) and its natural host nicotiana attenuata. iii. fatty acid-amino acid conjugates in herbivore oral secretions are necessary and sufficient for herbivore-specific plant responses.feeding by the tobacco specialist manduca sexta (lepidoptera, sphingidae) and application of larval oral secretions and regurgitant (r) to mechanical wounds are known to elicit: (a) a systemic release of mono- and sesquiterpenes, (b) a jasmonate burst, and (c) r-specific changes in transcript accumulation of putatively growth- and defense-related mrnas in nicotiana attenuata torr. ex wats. we identified several fatty acid-amino acid conjugates (facs) in the r of m. sexta and the closely related ...200111161028
rna-directed rna polymerase 1 (rdr1) mediates the resistance of nicotiana attenuata to herbivore attack in nature.small rnas are important regulators of plant development and resistance to viruses. to determine whether small rnas mediate defense responses to herbivore attack, we silenced the expression of three rna-directed rna polymerases (rdrs) in the native tobacco nicotiana attenuata by virus-induced gene silencing. larvae of the leaf-chewing solanaceous specialist manduca sexta grew faster on the rdr1-silenced plants than on empty vector (ev) controls; silencing rdr3 and 2 had little to no effect on la ...200717346266
herbivory rapidly activates mapk signaling in attacked and unattacked leaf regions but not between leaves of nicotiana attenuata.mitogen-activated protein kinase (mapk) signaling plays a central role in transducing extracellular stimuli into intracellular responses, but its role in mediating plant responses to herbivore attack remains largely unexplored. when manduca sexta larvae attack their host plant, nicotiana attenuata, the plant's wound response is reconfigured at transcriptional, phytohormonal, and defensive levels due to the introduction of oral secretions (os) into wounds during feeding. we show that os dramatica ...200717400894
molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphingidae) and its natural host nicotiana attenuata. ii. accumulation of plant mrnas in response to insect-derived cues.the transcriptional changes in nicotiana attenuata torr. ex wats. elicited by attack from manduca sexta larvae were previously characterized by mrna differential display (d. hermsmeier, u. schittko, i.t. baldwin [2001] plant physiol 125: 683-700). because herbivore attack causes wounding, we disentangled wound-induced changes from those elicited by m. sexta oral secretions and regurgitant (r) with a northern analysis of a subset of the differentially expressed transcripts encoding threonine deam ...200111161027
molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphingidae) and its natural host nicotiana attenuata. i. large-scale changes in the accumulation of growth- and defense-related plant mrnas.plants respond to herbivore attack with a dramatic functional reorganization that involves the activation of direct and indirect defenses and tolerance, which in turn make large demands on primary metabolism. here we provide the first characterization of the transcriptional reorganization that occurs after insect attack in a model plant-herbivore system: nicotiana attenuata torr. ex wats.-manduca sexta. we used mrna differential display to characterize one-twentieth of the insect-responsive tran ...200111161026
antisense lox expression increases herbivore performance by decreasing defense responses and inhibiting growth-related transcriptional reorganization in nicotiana attenuata.inhibition of jasmonic acid (ja) signaling has been shown to decrease herbivore resistance, but the responsible mechanisms are largely unknown because insect resistance is poorly understood in most model plant systems. we characterize three members of the lipoxygenase (lox) gene family in the native tobacco plant nicotiana attenuata and manipulate, by antisense expression, a specific, wound- and herbivory-induced isoform (lox3) involved in ja biosynthesis. in three independent lines, antisense e ...200314675445
opportunistic out-crossing in nicotiana attenuata (solanaceae), a predominantly self-fertilizing native tobacco.although nicotiana attenuata is entirely self-compatible, chemical and other floral traits suggest selection for the maintenance of advertisement for moth pollinators.200312866951
allometric analysis of the induced flavonols on the leaf surface of wild tobacco (nicotiana attenuata).trichomes excrete secondary metabolites that may alter the chemical composition of the leaf surface, reducing damage caused by herbivores, pathogens and abiotic stresses. we examined the surface exudates produced by nicotiana attenuata torr. ex wats., a plant known to contain and secrete a number of secondary metabolites that are toxic or a deterrent to herbivorous insects. extractions specific to the leaf surface, the trichomes, and the laminar components demonstrated the localization of partic ...200312620365
naralf, a peptide signal essential for the regulation of root hair tip apoplastic ph in nicotiana attenuata, is required for root hair development and plant growth in native soils.rapid alkalinization factor (ralf) is a 49-amino-acid peptide that rapidly alkalinizes cultivated tobacco cell cultures. in the native tobacco nicotiana attenuata, naralf occurs as a single-copy gene and is highly expressed in roots and petioles. silencing the naralf transcript by transforming n. attenuata with an inverted-repeat construct generated plants (irralf) with normal wild-type (wt) above-ground parts, but with roots that grew longer and produced trichoblasts that developed into abnorma ...200717916115
ontogeny constrains systemic protease inhibitor response in nicotiana attenuata.protease inhibitors (pis) are plant compounds that can inhibit proteases of mammal, insect, or pathogen origin and are frequently induced by mechanical wounding, insect feeding, or pathogen infection. nicotiana attenuata is a species that induces nicotine, volatiles, and phenolics in response to damage. here we examine the distribution of pis in n. attenuata to determine if they are part of the induced response in this species and if this response is ontogenetically constrained. we found that n. ...200111441445
molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphingidae) and its natural host nicotiana attenuata. iv. insect-induced ethylene reduces jasmonate-induced nicotine accumulation by regulating putrescine n-methyltransferase transcripts.attack by the specialist herbivore, manduca sexta, on its native host nicotiana attenuata torr. ex wats. produces a dramatic ethylene release, a jasmonate burst, and a suppression of the nicotine accumulation that results from careful simulations of the herbivore's damage. methyl-jasmonate (meja) treatment induces nicotine biosynthesis. however, this induction can be suppressed by ethylene as pretreatment of plants with 1-methylcyclopropene (1-mcp), a competitive inhibitor of ethylene receptors, ...200111299398
eating the evidence? manduca sexta larvae can not disrupt specific jasmonate induction in nicotiana attenuata by rapid feeding by the tobacco specialist manduca sexta l. is known to result in significantly higher jasmonate (ja) concentrations in nicotiana plants than do mechanical simulations of the larval damage, we investigated whether m. sexta, which is known to rapidly consume large quantities of leaf material, can impair this "recognition" response by consuming the leaf tissue before it can respond with amplified ja levels. we report that oral secretions (os) from m. sexta, but not from the cabbage speci ...200010664142
herbivore-induced ethylene suppresses a direct defense but not a putative indirect defense against an adapted herbivore.herbivory induces both direct and indirect defenses in plants; however, some combinations of these defenses may not be compatible. the jasmonate signal cascade activated both direct (nicotine accumulations) and indirect (mono- and sesquiterpene emissions) whole-plant defense responses in the native tobacco nicotiana attenuata torr. ex wats. nicotine accumulations were proportional to the amount of leaf wounding and the resulting increases in jasmonic acid (ja) concentrations. however, when larva ...200010664141
silencing of hydroperoxide lyase and allene oxide synthase reveals substrate and defense signaling crosstalk in nicotiana attenuata.the fatty acid hydroperoxide (hp) substrates required for the biosynthesis of jasmonic acid (ja) and green leaf volatiles (glvs) are supplied by separate lipoxygenases (lox). we silenced the expression of two genes downstream of the lox: allene oxide synthase (aos) and hp lyase (hpl) by antisense expression of endogenous genes (naaos, nahpl) in nicotiana attenuata, in which the biosynthesis of ja is amplified by herbivore-specific elicitors. we report that these elicitors also amplify wound-indu ...200415361139
individual variability in herbivore-specific elicitors from the plant's perspective.lepidopteran larvae oral secretions and regurgitant (r), which contain a plethora of potential elicitors, are known to dramatically change a plant's wound response. we demonstrate, with a detailed microarray and secondary metabolite analysis, that the two most abundant fatty acid-amino acid conjugates (facs) in the r of the specialist herbivore manduca sexta (lepidoptera, sphingidae) can account for all measured direct (trypsin proteinase inhibitor: tpi) and indirect (cis-alpha-bergamotene) defe ...200415245414
jasmonic acid signalling and herbivore resistance traits constrain regrowth after herbivore attack in nicotiana attenuata.because traits conferring resistance on herbivores can reduce fitness-associated traits, trade-offs may occur between tolerance and resistance responses. we examined these trade-offs in genotypes of nicotiana attenuata that were transformed to silence trypsin proteinase inhibitor (tpi) production (as-natpi), an antiherbivore defense associated with (14%) reductions in seed production, and the jasmonate signal cascade that elicits these defenses (as-nalox3), by measuring stalk and axillary branch ...200616913864
digestive duet: midgut digestive proteinases of manduca sexta ingesting nicotiana attenuata with manipulated trypsin proteinase inhibitor expression.background: the defensive effect of endogenous trypsin proteinase inhibitors (natpis) on the herbivore manduca sexta was demonstrated by genetically altering natpi production in m. sexta's host plant, nicotiana attenuata. to understand how this defense works, we studied the effects of natpi on m. sexta gut proteinase activity levels in different larval instars of caterpillars feeding freely on untransformed and transformed plants. methodology/ principal findings: second and third instars larvae ...200818431489
an analysis of plant-aphid interactions by different microarray hybridization strategies.aphids have long been considered 'stealthy' herbivores that subvert a plant's induced defenses and manipulate its source-sink signaling, but these hypotheses are largely untested at a transcriptional level. we analysed gene expression in native tobacco plants (nicotiana attenuata) infested with myzus nicotianae aphids, without resorting to the use of clip-cages, with a cdna microarray containing 240 defense-related n. attenuata genes. using a hybridization scheme ('ratio analysis' and 'state ana ...200415367131
plant-plant signaling: application of trans- or cis-methyl jasmonate equivalent to sagebrush releases does not elicit direct defenses in native tobacco.nicotiana attenuata plants growing in close proximity to damaged sagebrush (artemisia tridentata ssp. tridentata) suffer less herbivory than plants near undamaged sagebrush. sagebrush constitutively releases methyl jasmonate (meja), a compound that when applied directly to n. attenuata, elicits herbivore resistance and the direct defense traits [protease inhibitors (pis), nicotine]. damage increases the release of volatile meja, primarily in the cis epimer, suggesting that cis-meja may mediate t ...200415672665
independently silencing two photosynthetic proteins in nicotiana attenuata has different effects on herbivore resistance.insect attack frequently down-regulates photosynthetic proteins. to understand how this influences the plant-insect interaction, we transformed nicotiana attenuata to independently silence ribulose-1,5-bisphosphate carboxylase/oxygenase (rubpcase) activase (rca) and rubpcase and selected lines whose photosynthetic capacity was similarly reduced. decreases in plant growth mirrored the decreases in photosynthesis, but the effects on herbivore performance differed. both generalist (spodoptera litto ...200818723666
piriformospora indica and sebacina vermifera increase growth performance at the expense of herbivore resistance in nicotiana attenuata.a sebacinales species was recovered from a clone library made from a pooled rhizosphere sample of nicotiana attenuata plants from 14 native populations. axenic cultures of the related species, piriformospora indica and sebacina vermifera, were used to examine their effects on plant performance. inoculation of n. attenuata seeds with either fungus species stimulated seed germination and increased growth and stalk elongation. s. vermifera inoculated plants flowered earlier, produced more flowers a ...200516032437
priming of plant defense responses in nature by airborne signaling between artemisia tridentata and nicotiana attenuata.plants release volatile organic compounds (vocs) in response to wounding and herbivore attack, some of which trigger responses in neighboring unattacked plants in the laboratory under conditions that are not likely to occur in the real world. whether plants 'eavesdrop' on the volatile emissions of their neighbors in nature is not known. the best documented field study of between-species signaling via above-ground vocs involves increases in fitness parameters of native tobacco (nicotiana attenuat ...200616463175
root growth dynamics of nicotiana attenuata seedlings are affected by simulated herbivore attack.many studies demonstrate resource-based trade-offs between growth and defence on a large timescale. yet, the short-term dynamics of this growth reaction are still completely unclear, making it difficult to explain growth-defence trade-offs mechanistically. in this study, image-based non-destructive methods were used to quantify root growth reactions happening within hours following simulated herbivore attack. the induction of wound reactions in nicotiana attenuata in the seedling stage led to tr ...200717727422
the hydroxyproline-rich glycopeptide systemin precursor napreprohypsys does not play a central role in nicotiana attenuata's anti-herbivore defense determine whether the nicotiana tabacum preprohypsys homolog in nicotiana attenuata (napreprohypsys) mediates anti-herbivore responses, we silenced (irsys) and ectopically over-expressed (ovsys) napreprohypsys in n. attenuata. neither herbivore simulation nor methyl jasmonate (meja) application increased transcripts in wild-type (wt) or transformed lines. compared to wt plants, ovsys plants had marginally higher constitutive levels but normally induced levels of trypsin proteinase inhibitors ...200717897415
silencing threonine deaminase and jar4 in nicotiana attenuata impairs jasmonic acid-isoleucine-mediated defenses against manduca sexta.threonine deaminase (td) catalyzes the conversion of thr to alpha-keto butyrate in ile biosynthesis; however, its dramatic upregulation in leaves after herbivore attack suggests a role in defense. in nicotiana attenuata, strongly silenced td transgenic plants were stunted, whereas mildly silenced td transgenic plants had normal growth but were highly susceptible to manduca sexta attack. the herbivore susceptibility was associated with the reduced levels of jasmonic acid-isoleucine (ja-ile), tryp ...200617085687
solar ultraviolet-b radiation and insect herbivory trigger partially overlapping phenolic responses in nicotiana attenuata and nicotiana longiflora.plants exposed to solar ultraviolet-b radiation (uv-b, 280-315 nm) frequently suffer less insect herbivory than do plants that receive attenuated levels of uv-b. this anti-herbivore effect of solar uv-b exposure, which has been documented in several ecosystems, is in part mediated by changes in plant tissue quality. exposure to uv-b can modify the abundance of a number of secondary metabolites, including phenolic compounds with potential impacts on insect herbivores. the aim of this study is to ...200717210605
pectin methylesterase napme1 contributes to the emission of methanol during insect herbivory and to the elicitation of defence responses in nicotiana attenuata.pectin methylesterases (pmes) catalyse the demethylation of pectin within plant cell walls, releasing methanol (meoh) in the process. thus far, pmes have been found to be involved in diverse processes such as plant growth and development and defence responses against pathogens. herbivore attack increases pme expression and activity and meoh emissions in several plant species. to gain further insights into the role of pmes in defence responses against herbivores, the expression of a manduca sexta ...200919380422
silencing geranylgeranyl diphosphate synthase in nicotiana attenuata dramatically impairs resistance to tobacco bioassays with artificial diets, the 17-hydroxygeranyllinalool diterpenoid glycosides (hgl-dtgs) of nicotiana attenuata function as antifeedants for the plant's adapted herbivore, tobacco hornworm (manduca sexta). to determine whether hgl-dtgs have a defensive function in planta, we suppressed hgl-dtg production by silencing the source of the geranylgeranyl diphosphates (ggpps) required for geranyllinalool biosynthesis, a key intermediate. we used virus-induced gene silencing to suppress tran ...200817965175
a comparison of two nicotiana attenuata accessions reveals large differences in signaling induced by oral secretions of the specialist herbivore manduca sexta.genetic variation within and among populations provides the raw material for evolution. although many studies describe inter- and intraspecific variation of defensive metabolites, little is known about variation among plant populations within early signaling responses elicited by herbivory or by herbivore oral secretions (os) introduced into wounds during feeding. in this study, we compare the os-elicited early responses as well as the antiherbivore defensive metabolites in two accessions of the ...200818218965
co(i)-ordinating defenses: nacoi1 mediates herbivore- induced resistance in nicotiana attenuata and reveals the role of herbivore movement in avoiding defenses.arabidopsis and tomato plants mutated in the f-box protein coi1 mediating jasmonate (ja) responses are more susceptible to herbivores in laboratory trials, but the exact mechanisms of coi1-mediated resistance are not known. we silenced coi1 by transformation with an inverted repeat construct (ir-coi1) in nicotiana attenuata, a plant the direct and indirect defenses of which against various herbivores have been well studied. ir-coi1 plants are male sterile and impaired in ja-elicited direct [nico ...200717561925
reverse genetics in ecological precisely manipulating the expression of individual genetic elements thought to be important for ecological performance, reverse genetics has the potential to revolutionize plant ecology. however, untested concerns about possible side-effects of the transformation technique, caused by agrobacterium infection and tissue culture, on plant performance have stymied research by requiring onerous sample sizes. we compare 5 independently transformed nicotiana attenuata lines harboring empty vector c ...200818253491
silencing rna-directed rna polymerase 2 increases the susceptibility of nicotiana attenuata to uv in the field and in the glasshouse.rna-directed rna-polymerases (rdrs) are essential in small interfering rna (sirna) biogenesis and appear to be functionally specialized. we examined the consequences of silencing rdr2 in nicotiana attenuata with a field release, and transcriptional, two-dimensional proteomic and metabolite analyses. nardr2-silenced plants (irrdr2) had large reductions (46% of wild type) in 22-24-nt small rnas (smrnas), and smaller reductions (35, 23 and 26% of wild type) in the 19-21, 25-27 and 28-30-nt smrnas, ...200818298673
pr-13/thionin but not pr-1 mediates bacterial resistance in nicotiana attenuata in nature, and neither influences herbivore resistance.increases in pathogenesis-related (pr) transcripts are commonly interpreted as evidence of plants' resistance responses to pathogens; however, few studies have examined whether increases in pr proteins protect plants growing under natural conditions. pseudomonas syringae pv. tomato dc3,000, which is virulent and causes disease in arabidopsis, is also pathogenic to the native tobacco nicotiana attenuata. n. attenuata responds to p. syringae pv. tomato dc3,000's challenges with increases in salicy ...200818533839
induced defense in nicotiana attenuata (solanaceae) fruit and flowers.plants protect themselves against herbivory using a continuum of strategies, ranging from constitutive defenses to intermittent induced responses. induced defenses may not provide immediate and maximum protection, but could be advantageous when continuous defense is either energetically or ecologically costly. as such, induced defenses in flowers could help defend relatively valuable tissue while keeping reproductive structures accessible and attractive to pollinators. thus far, no one has demon ...200616328552
r2r3-namyb8 regulates the accumulation of phenylpropanoid-polyamine conjugates, which are essential for local and systemic defense against insect herbivores in nicotiana attenuata.although phenylpropanoid-polyamine conjugates (ppcs) occur ubiquitously in plants, their biological roles remain largely unexplored. the two major ppcs of nicotiana attenuata plants, caffeoylputrescine (cp) and dicaffeoylspermidine, increase dramatically in local and systemic tissues after herbivore attack and simulations thereof. we identified namyb8, a homolog of ntmybjs1, which in by-2 cells regulates ppc biosynthesis, and silenced its expression by rna interference in n. attenuata (ir-myb8), ...201020089770
occurrence of tetraploidy in nicotiana attenuata plants after agrobacterium-mediated transformation is genotype specific but independent of polysomaty of explant tissue.genotypes of nicotiana attenuata collected from utah and arizona were transformed with 17 different vectors (14 unpublished vectors based on 3 new backbone vectors) using an agrobacterium-mediated procedure to functionally analyze genes important for plant-insect interactions. none of the 51 t1-t3 transgenic utah lines analyzed by the flow cytometry were tetraploid, as opposed to 18 of 33 transgenic arizona lines (55%). analysis of t0 regenerants transformed with the same vector carrying an inve ...200616518637
jasmonate perception regulates jasmonate biosynthesis and ja-ile metabolism: the case of coi1 in nicotiana attenuata.coronatine insensitive 1 (coi1) is a well-known key player in processes downstream of jasmonic acid (ja) biosynthesis: silencing coi1 in nicotiana attenuata (ir-coi1) makes plants insensitive to ja, prevents the up-regulation of ja-mediated defenses and decreases the plant's resistance to herbivores and pathogens. in agreement with previous studies, we observed that regulation of several ja biosynthesis genes elicited by manduca sexta oral secretions (os) is coi1 dependent. in response to woundi ...200818559356
methyl jasmonate-elicited herbivore resistance: does meja function as a signal without being hydrolyzed to ja?treatment with methyl jasmonate (meja) elicits herbivore resistance in many plant species and over-expression of ja carboxyl methyltransferase (jmt) constitutively increases ja-induced responses in arabidopsis. when wild-type (wt) nicotiana attenuata plants are treated with meja, a rapid transient endogenous ja burst is elicited, which in turn increases levels of nicotine and trypsin proteinase inhibitors (tpis) and resistance to larvae of the specialist herbivore, manduca sexta. all of these re ...200818214527
sebacina vermifera promotes the growth and fitness of nicotiana attenuata by inhibiting ethylene signaling.sebacina vermifera, a growth-promoting endophytic fungus, significantly increases nicotiana attenuata's growth but impairs both its herbivore resistance and its accumulation of the costly, jasmonic acid (ja)-regulated defense protein, trypsin proteinase inhibitor (tpi). to determine if the fungi's growth-promoting effects can be attributed to lower tpi-related defense costs, we inoculated transformed n. attenuata plants silenced in their ability to synthesize ja, ja-isoleucine, and tpi by antise ...200717416638
tuning the herbivore-induced ethylene burst: the role of transcript accumulation and ethylene perception in nicotiana attenuata.caterpillar-induced ethylene emissions play an important role in plant-herbivore interactions. the ethylene burst that ensues after attack exceeds wound-induced ethylene emissions, but the mechanisms responsible remain unknown. adding larval oral secretions (os) to wounds mimics this ethylene burst. we demonstrate that fatty acid-amino acid conjugates are the responsible elicitors in manduca sexta os, and identify genes that are important in os-elicited ethylene biosynthesis and perception in th ...200717559506
independently silencing two jar family members impairs levels of trypsin proteinase inhibitors but not nicotine.jasmonic acid (ja)-amino acid conjugates are important ja metabolites that activate ja responses. however, our understanding of their involvement in herbivore defenses is limited. we identified a new arabidopsis jasmonate resistant 1 (jar1) homologue in nicotiana attenuata (n. attenuata) and named it jasmonate resistant 6 (jar6). jar6 clustered closely with arabidopsis jar1 and the recently reported jasmonate resistant 4 (jar4), another jar1 homologue in n. attenuata, in a phylogenic analysis. t ...200717273867
induced plant defenses in the natural environment: nicotiana attenuata wrky3 and wrky6 coordinate responses to herbivory.a plant-specific family of wrky transcription factors regulates plant responses to pathogens and abiotic stresses. here, we identify two insect-responsive wrky genes in the native tobacco nicotiana attenuata: wrky3, whose transcripts accumulate in response to wounding, and wrky6, whose wound responses are significantly amplified when fatty acid-amino acid conjugates (facs) in larval oral secretions are introduced into wounds during feeding. wrky3 is required for wrky6 elicitation, yet neither is ...200818641266
silencing jasmonate signalling and jasmonate-mediated defences reveals different survival strategies between two nicotiana attenuata determine the impact of genotypic variation in secondary metabolite production on antiherbivore resistance and plant fitness, we genetically silenced biosynthetic genes for nicotine, trypsin proteinase inhibitors (tpi), and jasmonate (ja) production in two accessions of nicotiana attenuata: one from utah (ut) which responds to herbivory with ja-induced nicotine and tpi production, and one from arizona (az) which is tpi-deficient but also produces ja-induced nicotine. transient silencing of ja ...200818662222
oxylipin channelling in nicotiana attenuata: lipoxygenase 2 supplies substrates for green leaf volatile production.lipoxygenases (loxs) are key enzymes in the biosynthesis of oxylipins, and catalyse the formation of fatty acid hydroperoxides (hps), which represent the first committed step in the synthesis of metabolites that function as signals and defences in plants. hps are the initial substrates for different branches of the oxylipin pathway, and some plant species may express different lox isoforms that supply specific branches. here, we compare isogenic lines of the wild tobacco nicotiana attenuata with ...201020584148
field experiments with transformed plants reveal the sense of floral scents.plants use many means to attract pollinators, including visual cues and odor. we investigated how nonpigment floral chemistry influences nectar removal, floral visitation, florivory, rates of outcrossing, and fitness through both male and female functions. we blocked expression of biosynthetic genes of the dominant floral attractant [benzyl acetone (nachal1)] and nectar repellent [nicotine (napmt1/2)] in all combinations in the native tobacco nicotiana attenuata and measured their effects on pla ...200818755975
host-plant-mediated effects of nadefensin on herbivore and pathogen resistance in nicotiana attenuata.the adage from shakespeare, "troubles, not as single spies, but in battalions come," holds true for nicotiana attenuata, which is commonly attacked by both pathogens (pseudomonas spp.) and herbivores (manduca sexta) in its native habitats. defense responses targeted against the pathogens can directly or indirectly influence the responses against the herbivores. nadefensin is an effective induced defense gene against the bacterial pathogen pseudomonas syringae pv tomato (pst dc3000), which is als ...200818950524
unbiased transcriptional comparisons of generalist and specialist herbivores feeding on progressively defenseless nicotiana attenuata plants.herbivore feeding elicits dramatic increases in defenses, most of which require jasmonate (ja) signaling, and against which specialist herbivores are thought to be better adapted than generalist herbivores. unbiased transcriptional analyses of how neonate larvae cope with these induced plant defenses are lacking.201020090945
herbivore-induced jasmonic acid bursts in leaves of nicotiana attenuata mediate short-term reductions in root growth.root growth in nicotiana attenuata is transiently reduced after application of oral secretions (os) of manduca sexta larvae to wounds in leaves. feeding of m. sexta or os elicitation is known to result in jasmonic acid (ja) and ethylene bursts, and activates a suite of defence responses. because both plant hormones are known to strongly reduce root growth, their activation might account for the observed reduction of root growth following herbivory. to test this hypothesis, we measured primary ro ...200919054344
silencing two herbivory-activated map kinases, sipk and wipk, does not increase nicotiana attenuata's susceptibility to herbivores in the glasshouse and in nature.salicylic acid-induced protein kinase (sipk) and wound-induced protein kinase (wipk) are activated by manduca sexta attack and elicitors to mediate defense signaling in nicotiana attenuata. here, the ecological consequences of sipk and wipk silencing for n. attenuata's resistance to m. sexta and its other native herbivores were analyzed. stably transformed plants with reduced expression of nasipk (irnasipk) and nawipk(irnawipk) were generated and characterized in field and glasshouse experiments ...200919076722
caterpillar-elicited methanol emission: a new signal in plant-herbivore interactions?plants release into the atmosphere large quantities of volatile organic compounds (vocs), of which methanol (meoh), a putative waste product, is the second most abundant. using online proton-transfer-reaction mass spectrometry (ptr-ms), we demonstrate that when manduca sexta larvae attack nicotiana attenuata plants, the wound-induced release of meoh dramatically increases. the sustained meoh emission 24 h after herbivore feeding is already substantially greater than the release of the well-chara ...200616805729
using nutritional indices to study lox3-dependent insect resistance.induced resistance to biotic attackers is thought to be mediated by responses elicited by jasmonic acid (ja), a subset of which are lipoxygenase 3 (lox3) dependent. to understand the importance of lox3-mediated insect resistance, we analysed the performance of manduca sexta larvae on wild-type (wt) and on isogenic nicotiana attenuata plants silenced in nalox3 expression and ja signalling, and we used waldbauer nutritional indices to measure the pre- and post-ingestive effects. lox3-mediated defe ...200616898019
lipoxygenase-mediated modification of insect elicitors: generating chemical diversity on the leaf wound surface.plants can distinguish mechanical damage from larval folivory through the recognition of specific constituents of larval oral secretions (os) which are deposited on the surface of leaf wounds during feeding. fatty acid-amino acid conjugates (facs) are major constituents of the os of lepidopteran larvae and they are strong elicitors of herbivore-induced defense responses in several plant species, including the wild tobacco nicotiana attenuata. when os from manduca sexta larvae is deposited on n. ...201021150262
molecular interactions between the specialist herbivore manduca sexta (lepidoptera, sphigidae) and its natural host nicotiana attenuata. viii. an unbiased gcxgc-tofms analysis of the plant's elicited volatile emissions.treating wounds in nicotiana attenuata leaves with manduca sexta oral secretions (w+os) mimics most changes elicited by m. sexta herbivory, but an unbiased analysis of the effect of the different os constituents on volatile emissions is lacking. we used two-dimensional gas chromatography/time-of-flight (gcxgc-tof) mass spectrometry combined with multivariate statistics to parse volatiles into regulatory patterns. volatiles released by wounding alone and by the alkalinity of os were assessed by a ...200919136568
herbivore-associated elicitors: fac signaling and metabolism.the recognition of insect and pathogen attack requires the plant's ability to perceive chemical cues generated by the attacker. in contrast to the recognition of microbe-associated molecular patterns and effectors, little is known about the molecular recognition of herbivore-associated elicitors (haes) and the signaling mechanisms operating in plants after their perception. hae perception depends strongly on the natural history of both plants and insects and it is therefore expected that many of ...201121354852
enhanced fluorescence imaging in chlorophyll-suppressed tobacco tissues using virus-induced gene silencing of the phytoene desaturase gene.fluorescence imaging in plants is unusually challenging because of the large amounts of photosynthetic pigments contained in green plant tissues. for example, chlorophyll can obstruct the penetration of light and has high levels of autofluorescence at wavelengths that are often used for fluorescence imaging. until now, mostly confocal laser scanning microscopy or the use of non-green parts of the plants, typically roots, have been used to overcome these limitations. we constructed tobacco (nicot ...201020359296
an ecological analysis of the herbivory-elicited ja burst and its metabolism: plant memory processes and predictions of the moving target model.rapid herbivore-induced jasmonic acid (ja) accumulation is known to mediate many induced defense responses in vascular plants, but little is known about how ja bursts are metabolized and modified in response to repeated elicitations, are propagated throughout elicited leaves, or how they directly influence herbivores.200919277115
root growth of nicotiana attenuata is decreased immediately after simulated leaf herbivore attack.image-based non-destructive methods were used to quantify root growth reactions happening within hours following simulated leaf herbivore attack.1 the induction of wound reactions in leaves of seedlings of nicotiana attenuata led to transiently decreased root growth rates: upon application of the oral secretions and regurgitants of the specialist herbivore manduca sexta, a transient decrease in root growth was observed that was more pronounced than if a mere mechanical wounding was imposed. root ...200819704639
17-hydroxygeranyllinalool glycosides are major resistance traits of nicotiana obtusifolia against attack from tobacco hornworm the great basin desert, nicotiana obtusifolia (synonymous with nicotiana trigonophylla) and nicotiana attenuata co-occur, but the former is frequently less attacked by larvae of the tobacco hornworm than the latter, despite having lower nicotine and trypsin protease inhibitor defenses. glycosides of the diterpene, 17-hydroxygeranyllinalool (hgl-dtgs) have recently been found to be important defenses of n. attenuata. total hgl-dtg levels are 5-fold higher in n. obtusifolia than in n. attenuata ...201020452633
making sense of nectar scents: the effects of nectar secondary metabolites on floral visitors of nicotiana produce a plethora of secondary metabolites but only nectar sugars, floral pigments and headspace volatiles have been examined in the context of pollinator behavior. we identify secondary metabolites in the headspace and nectar of glasshouse- and field-grown nicotiana attenuata plants, infer within-flower origins by analyzing six flower parts, and compare the attractiveness of 16 constituents in standardized choice tests with two guilds of natural pollinators (manducasexta moths and arch ...200717316174
new insights into mechanisms regulating differential accumulation of phenylpropanoid-polyamine conjugates (ppcs) in herbivore-attacked nicotiana attenuata plants.ubiquitously occurring phenylpropanoid-polyamine conjugates (ppcs) in plants show both developmental and stress inducible patterns of accumulation. the presence of high ppc levels in reproductive organs of plants resulted in a long lasting controversy whether ppcs could play important roles in the development of reproductive tissues; their accumulation in response to stresses suggested a potential defensive function. the discovery and use of a key regulator, myb8 in jasmonic acid signal transduc ...201020436280
root growth is affected differently by mechanical wounding in seedlings of the ecological model species nicotiana attenuata and the molecular model species arabidopsis the ecological model plant nicotiana attenuata, leaf wounding or herbivory lead to a reduction of root growth via jasmonic acid (ja) signaling. a single wounding treatment is sufficient to induce this response; multiple wounding does not increase the plant growth reaction. in a recent study, in which ja bursts were elicited in leaves of the molecular model species arabidopsis thaliana in different ways,(1) we tested whether ja induces the same response there. root growth reduction was neither ...201020037470
new insights into the early biochemical activation of jasmonic acid biosynthesis in plants, herbivore attack elicits the rapid accumulation of jasmonic acid (ja) which results from the activation of constitutively expressed biosynthetic enzymes. the molecular mechanisms controlling the activation of ja biosynthesis remain largely unknown however new research has elucidated some of the early regulatory components involved in this process. nicotiana attenuata plants, a wild tobacco species, responds to fatty acid amino acid conjuguates (fac) elicitors in the oral secretion of ...201020037473
variation in antiherbivore defense responses in synthetic nicotiana allopolyploids correlates with changes in uniparental patterns of gene expression.we examined the expression of nicotiana attenuata (na) and nicotiana obtusifolia (no) herbivore-induced genes in synthetic autopolyploids (nat and not) and five independent allopolyploid nicotiana x obtusiata (nxo) lines to understand how the expression of genes regulating complex polygenetic defense traits is altered in the early stages of allopolyploid hybridization. in na, applying manduca sexta oral secretions (os) to wounds rapidly increased the transcript accumulation of wound-induced prot ...201020525855
changing pollinators as a means of escaping herbivores.all animal-pollinated plants must solve the problem of attracting pollinators while remaining inconspicuous to herbivores, a dilemma exacerbated when voracious larval-stage herbivores mature into important pollinators for a plant [1]. herbivory is known to alter pollination rates, by altering flower number [2], size [3, 4], nectar production [5], seasonal timing of flowering [6], or pollinator behavior [7]. nicotiana attenuata, a night-flowering tobacco that germinates after fires in the southwe ...201020096581
different lepidopteran elicitors account for cross-talk in herbivory-induced phytohormone signaling.salicylic acid (sa), jasmonic acid (ja), ethylene (et), and their interactions mediate plant responses to pathogen and herbivore attack. ja-sa and ja-et cross-signaling are well studied, but little is known about sa-et cross-signaling in plant-herbivore interactions. when the specialist herbivore tobacco hornworm (manduca sexta) attacks nicotiana attenuata, rapid and transient ja and et bursts are elicited without significantly altering wound-induced sa levels. in contrast, attack from the gener ...200919458114
jasmonic acid and ethylene modulate local responses to wounding and simulated herbivory in nicotiana attenuata leaves.jasmonic acid (ja) and ethylene (et) are known to play important roles in mediating plant defense against herbivores, but how they affect development in herbivore-attacked plants is unknown. we used ja-deficient (silenced in lipoxygenase3 [aslox3]) and et-insensitive (expressing a mutated dominant negative form of ethylene response1 [metr1]) nicotiana attenuata plants, and their genetic cross (metr1aslox3), to examine growth and development of these plants under simulated herbivory conditions. a ...201020382894
jasmonic acid does not mediate root growth responses to wounding in arabidopsis thaliana.jasmonic acid (ja) is a crucial plant defence signalling substance that has recently been shown to mediate herbivory-induced root growth reduction in the ecological model species nicotiana attenuata. to clarify whether ja-induced reduction of root growth might be a general response increasing plant fitness under biotic stress, a suite of experiments was performed with the model plant arabidopsis thaliana. ja bursts were elicited in leaves of a. thaliana in different ways. root growth reduction w ...201019895400
supersage analysis of the nicotiana attenuata transcriptome after fatty acid-amino acid elicitation (fac): identification of early mediators of insect responses.plants trigger and tailor defense responses after perception of the oral secretions (os) of attacking specialist lepidopteran larvae. fatty acid-amino acid conjugates (facs) in the os of the manduca sexta larvae are necessary and sufficient to elicit the herbivory-specific responses in nicotiana attenuata, an annual wild tobacco species. how facs are perceived and activate signal transduction mechanisms is unknown.201020398280
jasmonate and pphsystemin regulate key malonylation steps in the biosynthesis of 17-hydroxygeranyllinalool diterpene glycosides, an abundant and effective direct defense against herbivores in nicotiana attenuata.we identified 11 17-hydroxygeranyllinalool diterpene glycosides (hgl-dtgs) that occur in concentrations equivalent to starch (mg/g fresh mass) in aboveground tissues of coyote tobacco (nicotiana attenuata) and differ in their sugar moieties and malonyl sugar esters (0-2). concentrations of hgl-dtgs, particularly malonylated compounds, are highest in young and reproductive tissues. within a tissue, herbivore elicitation changes concentrations and biosynthetic kinetics of individual compounds. usi ...201020081114
from the cover: trichome-derived o-acyl sugars are a first meal for caterpillars that tags them for predation.plant glandular trichomes exude secondary metabolites with defensive functions, but these epidermal protuberances are surprisingly the first meal of lepidopteran herbivores on nicotiana attenuata. o-acyl sugars, the most abundant metabolite of glandular trichomes, impart a distinct volatile profile to the body and frass of larvae that feed on them. the headspace composition of manduca sexta larvae is dominated by the branched chain aliphatic acids hydrolyzed from ingested o-acyl sugars, which wa ...201121518882
nicotiana tabacum agglutinin is active against lepidopteran pest insects.a jasmonate-inducible lectin called nicotiana tabacum agglutinin or nictaba was found in tobacco (nicotiana tabacum cv samsun) leaves. since nictaba expression is also induced after insect herbivory, a role in the defence response of tobacco was suggested. in this report, a detailed analysis was made of the entomotoxic properties of nictaba using different transgenic approaches. first, purified nictaba was shown to be strongly resistant to proteolytic degradation by enzymes present in the lepido ...201020018900
trichomes as dangerous lollipops: do lizards also use caterpillar body and frass odor to optimize their foraging?when attacked by herbivores, plants produce toxic secondary metabolites that function as direct defenses, as well as indirect defenses that attract and reward predators of the offending herbivores. these indirect defenses include both nutritive rewards such as extra floral nectar, as well as informational rewards, such as the production and release of volatile compounds that betray the location of feeding herbivores to predators. herbivory of nicotiana attenuata by the tobacco hornworm (manduca ...201122095147
native bacterial endophytes promote host growth in a species-specific manner; phytohormone manipulations do not result in common growth responses.all plants in nature harbor a diverse community of endophytic bacteria which can positively affect host plant growth. changes in plant growth frequently reflect alterations in phytohormone homoeostasis by plant-growth-promoting (pgp) rhizobacteria which can decrease ethylene (et) levels enzymatically by 1-aminocyclopropane-1-carboxylate (acc) deaminase or produce indole acetic acid (iaa). whether these common pgp mechanisms work similarly for different plant species has not been rigorously teste ...200818628963
phaseoloidin, a homogentisic acid glucoside from nicotiana attenuata trichomes, contributes to the plant's resistance against lepidopteran herbivores.plant trichomes are known for their capability to produce and store secondary metabolites that protect plants from biotic and abiotic stresses. (1)h nmr studies on intact individual trichomes located on the leaf surface of nicotiana attenuata revealed the presence of two major secondary metabolites: nicotine, the signature metabolite of the genus, and phaseoloidin, a homogentisic acid glucoside. this glucoside was reported originally from the seeds of entada phaseoloides, and this is the first r ...201121904938
a native plant growth promoting bacterium, bacillus sp. b55, rescues growth performance of an ethylene-insensitive plant genotype in nature.many plants have intimate relationships with soil microbes, which improve the plant's growth and fitness through a variety of mechanisms. bacillus sp. isolates are natural root-associated bacteria, isolated from nicotiana attenuata plant roots growing in native soils. a particular isolate b55, was found to have dramatic plant growth promotion (pgp) effects on wild type (wt) and transgenic plants impaired in ethylene (et) perception (35s-etr1), the genotype from which this bacterium was first iso ...201222701461
rapid modification of the insect elicitor n-linolenoyl-glutamate via a lipoxygenase-mediated mechanism on nicotiana attenuata leaves.some plants distinguish mechanical wounding from herbivore attack by recognizing specific constituents of larval oral secretions (os) which are introduced into plant wounds during feeding. fatty acid-amino acid conjugates (facs) are major constituents of manduca sexta os and strong elicitors of herbivore-induced defense responses in nicotiana attenuata plants.201020696061
constitutive and inducible trypsin proteinase inhibitor production incurs large fitness costs in nicotiana attenuata.plant trypsin proteinase inhibitors (tpis) are potent herbivore- and jasmonate (ja)-induced defenses, but support for the commonly invoked explanation for their inducible expression, namely their associated fitness costs, has been elusive. to determine whether the expression of tpis incurs fitness costs, we expressed 175 bp of the seven-domain pi from nicotiana attenuata in an antisense orientation in a tpi-producing genotype (wt) of n. attenuata to reduce tpi expression. moreover, we expressed ...200414757829
development and validation of a liquid chromatography-electrospray ionization-time-of-flight mass spectrometry method for induced changes in nicotiana attenuata leaves during simulated herbivory.a liquid chromatography-electrospray ionization-time-of-flight mass spectrometry (hplc/esi-tof-ms) procedure was developed to characterize changes induced in nicotiana attenuata leaves 1 h and 5 days after wounding and application of manduca sexta elicitors. the constancy of the measurement conditions was first confirmed for 22 selected analytes spanning the entire chromatogram. using the profile analysis software, we extracted 367 buckets, which were analyzed by principal component analysis and ...201020701244
Displaying items 1 - 100 of 164