Understanding the systemic burden of disease in hidradenitis suppurativa from plasma lipidomic analysis.

BACKGROUND: Hidradenitis suppurativa (HS) is an inflammatory skin condition that is often considered a systemic disease due to its association with metabolic comorbidity. OBJECTIVE: In this study, we aimed to identify differences in plasma lipidomic profiles between HS patients and control subjects. METHODS: HS patients were recruited from a tertiary dermatological centre and demographic and comorbidity matched controls from the general population. A targeted lipidomic approach was performed to characterize over 700 lipid species representing 35 lipid classes/sub-classes. Linear regression models adjusted for confounding factors were used to compare the plasma lipidomic profiles of HS patients to controls. Ordinal regression models were used to study the association of lipids with disease activity and severity scores. RESULTS: 60 HS patients and 73 control subjects were recruited. Differential levels (p < 0.05) of 32 lipid species in HS patients compared to controls were observed, including a decrease in the long chain base d19:1 containing ceramides, and elevation of hydroxyeicosatetraenoic acid (HETE) and dihydroxyeicosatrienoic acid (DHET) oxylipins. These lipids along with several other molecules showed associations with Hurley, HS-PGA and disease activity scores. CONCLUSION: This study found mild changes in plasma lipidomic profiles, consistent with previous studies showing attenuated metabolomic changes in plasma as opposed to lesional skin. However, a number of lipid species were associated with increasing activity and severity of the disease. Further, the significant lipid species within the same class showed consistent trends of increase or decrease in HS as compared to controls.

Impact of Age, Menopause, and Obesity on Oxylipins Linked to Vascular Health.

OBJECTIVE: Cardiovascular disease, a major cause of mortality and morbidity, exhibits sexual dimorphism since the onset of cardiovascular disease occurs later in women than in men. The loss of cardioprotection in older women may be due to an increase in arterial stiffness after menopause. Free fatty acid metabolites of polyunsaturated fatty acids, called oxylipins, are known to impact vessel function and may be responsible for the vascular benefits of polyunsaturated fatty acids. The objectives of this study were to compare the plasma oxylipin profiles of young females (20-55 years), older females (55+), and older males (55+) and to identify associations between oxylipins and cardiovascular disease risk factors, such as obesity and arterial stiffness. Approach and Results: We quantified plasma oxylipins by high-performance liquid chromatography-tandem mass spectrometry in archived samples taken from completed clinical trials. We identified 3 major 12-lipoxygenase products, 12-hydroxy-eicosatetraenoic acid, 12-hydroxy-eicosapentaenoic acid, and 14-hydroxy-docosahexaenoic acid, that are present at high levels in young females compared with older females and males. These oxylipins also decreased with obesity and displayed robust negative associations with arterial stiffness as assessed by brachial-ankle pulse wave velocity. According to multiple linear regression modeling, these associations were maintained even after correcting for body mass index category combined with either age, menopausal status, or estradiol levels. Using linear discriminant analysis, the combination of these 3 oxylipins effectively distinguished participants according to both brachial-ankle pulse wave velocity risk group and age. CONCLUSIONS: Higher 12-lipoxygenase oxylipin plasma concentrations associated with lower arterial stiffness in premenopausal females may be an important contributing factor to sex differences in cardiovascular disease. Registration: URL: https://www.clinicaltrials.gov; Unique identifiers: NCT01661543, NCT01562171, NCT01890330, NCT02571114 and NCT02317588.

TOC1 in Nicotiana attenuata regulates efficient allocation of nitrogen to defense metabolites under herbivory stress.

The circadian clock contextualizes plant responses to environmental signals. Plants use temporal information to respond to herbivory, but many of the functional roles of circadian clock components in these responses, and their contribution to fitness, remain unknown. We investigate the role of the central clock regulator TIMING OF CAB EXPRESSION 1 (TOC1) in Nicotiana attenuata's defense responses to the specialist herbivore Manduca sexta under both field and glasshouse conditions. We utilize 15 N pulse-labeling to quantify nitrogen incorporation into pools of three defense compounds: caffeoylputrescine (CP), dicaffeoyl spermidine (DCS) and nicotine. Nitrogen incorporation was decreased in CP and DCS and increased in nicotine pools in irTOC1 plants compared to empty vector (EV) under control conditions, but these differences were abolished after simulated herbivory. Differences between EV and irTOC1 plants in nicotine, but not phenolamide production, were abolished by treatment with the ethylene agonist 1-methylcyclopropene. Using micrografting, TOC1's effect on nicotine was isolated to the root and did not affect the fitness of heterografts under field conditions. These results suggest that the circadian clock contributes to plant fitness by balancing production of metabolically expensive nitrogen-rich defense compounds and mediating the allocation of resources between vegetative biomass and reproduction.

The Presence of Active Brown Adipose Tissue Determines Cold-Induced Energy Expenditure and Oxylipin Profiles in Humans.

BACKGROUND: Accumulating evidence links brown adipose tissue (BAT) to increased cold-induced energy expenditure (CIEE) and regulation of lipid metabolism in humans. BAT has also been proposed as a novel source for biologically active lipid mediators including polyunsaturated fatty acids (PUFAs) and oxylipins. However, little is known about cold-mediated differences in energy expenditure and various lipid species between individuals with detectable BAT positive (BATpos) and those without BAT negative (BATneg). METHODS: Here we investigated a unique cohort of matched BATpos and BATneg individuals identified by 18F-fluorodeoxyglucose positron emission tomography combined with computed tomography ([18F]-FDG PET/CT). BAT function, CIEE, and circulating oxylipins, were analyzed before and after short-term cold exposure using [18F]-FDG PET/CT, indirect calorimetry, and high-resolution mass spectrometry, respectively. RESULTS: We found that active BAT is the major determinant of CIEE since only BATpos individuals experienced significantly increased energy expenditure in response to cold. A single bout of moderate cold exposure resulted in the dissipation of an additional 20 kcal excess energy in BATpos but not in BATneg individuals. The presence of BAT was associated with a unique systemic PUFA and oxylipin profile characterized by increased levels of anti-inflammatory omega-3 fatty acids as well as cytochrome P450 products but decreased concentrations of some proinflammatory hydroxyeicosatetraenoic acids when compared with BATneg individuals. Notably, cold exposure raised circulating levels of various lipids, including the recently identified BAT-derived circulating factors (BATokines) DiHOME and 12-HEPE, only in BATpos individuals. CONCLUSIONS: In summary, our data emphasize that BAT in humans is a major contributor toward cold-mediated energy dissipation and a critical organ in the regulation of the systemic lipid pool.

Assessment of soluble epoxide hydrolase activity in vivo: A metabolomic approach.

Soluble epoxide hydrolase (sEH) converts several FFA epoxides to corresponding diols. As many as 15 FFA epoxide-diol ratios are measured to infer sEH activity from their ratios. Using previous data, we assessed if individual epoxide-diol ratios all behave similarly to reflect changes in sEH activity, and whether analyzing these ratios together increases the power to detect changes in in-vivo sEH activity. We demonstrated that epoxide-diol ratios correlated strongly with each other (P < 0.05), suggesting these ratios all reflect changes in sEH activity. Furthermore, we developed a modeling approach to analyze all epoxide-diol ratios simultaneously to infer global sEH activity, named SAMI (Simultaneous Analysis of Multiple Indices). SAMI improved power in detecting changes in sEH activity in animals and humans when compared to individual ratio estimates. Thus, we introduce a new powerful method to infer sEH activity by combining metabolomic determination and simultaneous analysis of all measurable epoxide-diol pairs.

Increased Leaf Nicotine Content by Targeting Transcription Factor Gene Expression in Commercial Flue-Cured Tobacco (Nicotiana tabacum L.).

Nicotine, the most abundant pyridine alkaloid in cultivated tobacco (Nicotiana tabacum L.), is a potent inhibitor of insect and animal herbivory and a neurostimulator of human brain function. Nicotine biosynthesis is controlled developmentally and can be induced by abiotic and biotic stressors via a jasmonic acid (JA)-mediated signal transduction mechanism involving members of the APETALA 2/ethylene-responsive factor (AP2/ERF) and basic helix-loop-helix (bHLH) transcription factor (TF) families. AP2/ERF and bHLH TFs work combinatorically to control nicotine biosynthesis and its subsequent accumulation in tobacco leaves. Here, we demonstrate that overexpression of the tobacco NtERF32, NtERF221/ORC1, and NtMYC2a TFs leads to significant increases in nicotine accumulation in T2 transgenic K326 tobacco plants before topping. Up to 9-fold higher nicotine production was achieved in transgenics overexpressing NtERF221/ORC1 under the control of a constitutive GmUBI3 gene promoter compared to wild-type plants. The constitutive 2XCaMV35S promoter and a novel JA-inducible 4XGAG promoter were less effective in driving high-level nicotine formation. Methyljasmonic acid (MeJA) treatment further elevated nicotine production in all transgenic lines. Our results show that targeted manipulation of NtERF221/ORC1 is an effective strategy for elevating leaf nicotine levels in commercial tobacco for use in the preparation of reduced risk tobacco products for smoking replacement therapeutics.

Tobacco transcription repressors NtJAZ: Potential involvement in abiotic stress response and glandular trichome induction.

Members of the Jasmonate ZIM domain (JAZ) proteins act as transcriptional repressors in the jasmonate (JA) hormonal response. To characterize the potential roles of JAZ gene family in plant development and abiotic stress response, fifteen JAZs were identified based on the genome of Nicotiana tabacum. Structural analysis confirmed the presence of single Jas and TIFY motif. Tissue expression pattern analysis indicated that NtJAZ-2, -3, -5, and -10 were highly expressed in roots and NtJAZ-11 was expressed only in the cotyledons. The transcript level of NtJAZ-3, -5, -9, and -10 in the stem epidermis was higher than that in the stem without epidermis. Dynamic expression of NtJAZs exposed to abiotic stress and phytohormone indicated that the expression of most NtJAZs was activated by salicylic acid, methyl jasmonate, gibberellic acid, cold, salt, and heat stresses. With abscisic acid treatment, NtJAZ-1, -2, and -3 were not activated; NtJAZ-4, -5, and -6 were up-regulated; and the remaining NtJAZ genes were inhibited. With drought stress, the expression of NtJAZ-1, -2, -3, -4, -5, -6, -7, and -8 was up-regulated, whereas the transcript of the remaining genes was inhibited. Moreover, high concentration MeJA (more than 1 mM MeJA) had an effect on secreting trichome induction, but inhabited the plant growth. Nine NtJAZs may play important role in secreting trichome induction. These results indicate that the JAZ proteins are convergence points for various phytohormone signal networks, which are involved in abiotic stress responses.

Assessment of the Efficacy and Mode of Action of Benzo(1,2,3)-Thiadiazole-7-Carbothioic Acid S-Methyl Ester (BTH) and Its Derivatives in Plant Protection Against Viral Disease.

Systemic acquired resistance (SAR) induction is one of the primary defence mechanisms of plants against a broad range of pathogens. It can be induced by infectious agents or by synthetic molecules, such as benzo(1,2,3)-thiadiazole-7-carbothioic acid S-methyl ester (BTH). SAR induction is associated with increases in salicylic acid (SA) accumulation and expression of defence marker genes (e.g., phenylalanine ammonia-lyase (PAL), the pathogenesis-related (PR) protein family, and non-expressor of PR genes (NPR1)). Various types of pathogens and pests induce plant responses by activating signalling pathways associated with SA, jasmonic acid (JA) and ethylene (ET). This work presents an analysis of the influence of BTH and its derivatives as resistance inducers in healthy and virus-infected plants by determining the expression levels of selected resistance markers associated with the SA, JA, and ET pathways. The phytotoxic effects of these compounds and their influence on the course of viral infection were also studied. Based on the results obtained, the best-performing BTH derivatives and their optimal concentration for plant performance were selected, and their mode of action was suggested. It was shown that application of BTH and its derivatives induces increased expression of marker genes of both the SA- and JA-mediated pathways.

Potential of Physalis peruviana calyces as a low-cost valuable resource of phytoprostanes and phenolic compounds.

BACKGROUND: In Colombia, agro-industrial residues represent an enormous economic and environmental problem, which could be reduced if different techniques for the addition of value to such residues were implemented by this industrial sector. One of the fruits with the highest export rates is Physalis peruviana (goldenberry); however, this fruit is generally marketed without its calyx, generating a large amount of residues. To develop a strategy to add value to these residues, it is essential to know their chemical composition. RESULTS: In the present work, phytoprostanes (PhytoPs) - new active oxylipins - have been detected for the first time in Physalis peruviana calyces by ultra-high performance liquid chromatography triple quadrupole tandem mass spectrometry (UHPLC-QqQ-MS/MS), F1t -phytoprostanes and D1t -phytoprostanes being the predominant and minor classes, respectively. In addition, we were able to characterize the phenolic compounds profile of this matrix using LC-IT-DAD-MS/MS, describing six phenolic derivatives for the first time therein. CONCLUSIONS: This study increases our knowledge of the chemical composition of the calyces of this fruit and thereby supports the recycling of this class of residue. Consequently, goldenberry calyces could be used as phytotherapeutic, nutraceutic, or cosmetic ingredients for the development of diverse natural products. © 2018 Society of Chemical Industry.

Cry1Ac production is costly for native plants attacked by non-Cry1Ac-targeted herbivores in the field.

Plants are the primary producers in most terrestrial ecosystems and have complex defense systems to protect their produce. Defense-deficient, high-yielding agricultural monocultures attract abundant nonhuman consumers, but are alternatively defended through pesticide application and genetic engineering to produce insecticidal proteins such as Cry1Ac (Bacillus thuringiensis). These approaches alter the balance between yield protection and maximization but have been poorly contextualized to known yield-defense trade-offs in wild plants. The native plant Nicotiana attenuata was used to compare yield benefits of plants transformed to be defenseless to those with a full suite of naturally evolved defenses, or additionally transformed to ectopically produce Cry1Ac. An insecticide treatment allowed us to examine yield under different herbivore loads in N. attenuata's native habitat. Cry1Ac, herbivore damage, and growth parameters were monitored throughout the season. Biomass and reproductive correlates were measured at season end. Non-Cry1Ac-targeted herbivores dominated on noninsecticide-treated plants, and increased the yield drag of Cry1Ac-producing plants in comparison with endogenously defended or undefended plants. Insecticide-sprayed Cry1Ac-producing plants lagged less in stalk height, shoot biomass, and flower production. In direct comparison with the endogenous defenses of a native plant, Cry1Ac production did not provide yield benefits for plants under observed herbivore loads in a field study.

Rhizosphere-associated Pseudomonas induce systemic resistance to herbivores at the cost of susceptibility to bacterial pathogens.

Plant-associated soil microbes are important mediators of plant defence responses to diverse above-ground pathogen and insect challengers. For example, closely related strains of beneficial rhizosphere Pseudomonas spp. can induce systemic resistance (ISR), systemic susceptibility (ISS) or neither against the bacterial foliar pathogen Pseudomonas syringae pv. tomato DC3000 (Pto DC3000). Using a model system composed of root-associated Pseudomonas spp. strains, the foliar pathogen Pto DC3000 and the herbivore Trichoplusia ni (cabbage looper), we found that rhizosphere-associated Pseudomonas spp. that induce either ISS and ISR against Pto DC3000 all increased resistance to herbivory by T. ni. We found that resistance to T. ni and resistance to Pto DC3000 are quantitative metrics of the jasmonic acid (JA)/salicylic acid (SA) trade-off and distinct strains of rhizosphere-associated Pseudomonas spp. have distinct effects on the JA/SA trade-off. Using genetic analysis and transcriptional profiling, we provide evidence that treatment of Arabidopsis with Pseudomonas sp. CH267, which induces ISS against bacterial pathogens, tips the JA/SA trade-off towards JA-dependent defences against herbivores at the cost of a subset of SA-mediated defences against bacterial pathogens. In contrast, treatment of Arabidopsis with the ISR strain Pseudomonas sp. WCS417 disrupts JA/SA antagonism and simultaneously primes plants for both JA- and SA-mediated defences. Our findings show that ISS against the bacterial foliar pathogens triggered by Pseudomonas sp. CH267, which is a seemingly deleterious phenotype, may in fact be an adaptive consequence of increased resistance to herbivory. Our work shows that pleiotropic effects of microbiome modulation of plant defences are important to consider when using microbes to modify plant traits in agriculture.

The phenotypic and molecular assessment of the non-conserved Arabidopsis MICRORNA163/S-ADENOSYL-METHYLTRANSFERASE regulatory module during biotic stress.

In plants, microRNAs (miRNAs) have evolved in parallel to the protein-coding genes that they target for expression regulation, and miRNA-directed gene expression regulation is central to almost every cellular process. MicroRNA, miR163, is unique to the Arabidopsis genus and is processed into a 24-nucleotide (nt) mature small regulatory RNA (sRNA) from a single precursor transcript transcribed from a single locus, the MIR163 gene. The MIR163 locus is a result of a recent inverted duplication event of one of the five closely related S-ADENOSYL-METHYLTRANSFERASE genes that the mature miR163 sRNA targets for expression regulation. Currently, however, little is known about the role of the miR163/S-ADENOSYL-METHYLTRANSFERASE regulatory module in response to biotic stress. Here, we document the expression domains of MIR163 and the S-ADENOSYL-METHYLTRANSFERASE target genes following fusion of their putative promoter sequences to the ß-glucuronidase (GUS) reporter gene and subsequent in planta expression. Further, we report on our phenotypic and molecular assessment of Arabidopsis thaliana plants with altered miR163 accumulation, namely the mir163-1 and mir163-2 insertion knockout mutants and the miR163 overexpression line, the MIR163-OE plant. Finally, we reveal miR163 accumulation and S-ADENOSYL-METHYLTRANSFERASE target gene expression post treatment with the defence elicitors, salicylic acid and jasmonic acid, and following Fusarium oxysporum infection, wounding, and herbivory attack. Together, the work presented here provides a comprehensive new biological insight into the role played by the Arabidopsis genus-specific miR163/S-ADENOSYL-METHYLTRANSFERASE regulatory module in normal A. thaliana development and during the exposure of A. thaliana plants to biotic stress.

Clinical Assessment of a Novel Jasmonate Cosmeceutical, LR2412-Cx, for the Treatment of Skin Aging.

BACKGROUND: The jasmonates are a novel class of plant-derived anti-aging compounds. Among these, LR2412-Cx (tetrahydrojasmonic acid, Visionnaire) has been demonstrated to reduce photoaging and the appearance of wrinkles, as well as to upregulate collagens, hyaluronic acid and fibrillin. OBJECTIVE: To clinically study the cosmetic effects of a novel jasmonate complex LR2412-Cx in the treatment of visible skin aging. METHODS: LR2412-Cx was evaluated in a 15-subject open-label prospective clinical trial for the treatment of fine wrinkle appearance, texture, and pores. Subjects were evaluated by an investigator at baseline, day 1, day 3, and week 6 with the Alexiades comprehensive grading scale of skin aging, and introducing a novel pore-grading scale and subject quality of life assessments. RESULTS: The mean (SEM) at baseline and at week 6 following twice-daily application were: for the appearance of wrinkles 2.91 (0.12) and 2.70 (0.10); for texture 2.91 (0.10) and 2.55 (0.10); and for pores 3.29 (0.08) and 2.46 (0.09), respectively. The differences in all 3 categories at all follow-up intervals were statistically significant (P<.005). The percentage improvement in investigator-assessed grades relative to baseline at day 1, day 3, and week 6 were: 2.3%, 4.9%, and 7.4% for the appearance of wrinkles, 5.7%, 9.4%, and 12.4% for texture, and 14.2%, 21.6% and 25.2% for pores, respectively. No significant untoward effects were reported. CONCLUSION: Visionnaire LR2412-Cx is a novel jasmonate-containing compound that is safe and effective for the cosmetic treatment of fine wrinkle appearance, texture, and pores of the facial skin.

Differential Costs of Two Distinct Resistance Mechanisms Induced by Different Herbivore Species in Arabidopsis.

Plants respond to herbivory with the induction of resistance, mediated by distinct phytohormonal signaling pathways and their interactions. Phloem feeders are known to induce plant resistance via the salicylic acid pathway, whereas biting-chewing herbivores induce plant resistance mainly via the jasmonate pathway. Here, we show that a specialist caterpillar (biting-chewing herbivore) and a specialist aphid (phloem feeder) differentially induce resistance against Pieris brassicae caterpillars in Arabidopsis (Arabidopsis thaliana) plants. Caterpillar feeding induces resistance through the jasmonate signaling pathway that is associated with the induction of kaempferol 3,7-dirhamnoside, whereas aphid feeding induces resistance via a novel mechanism involving sinapoyl malate. The role of sinapoyl malate is confirmed through the use of a mutant compromised in the biosynthesis of this compound. Caterpillar-induced resistance is associated with a lower cost in terms of plant growth reduction than aphid-induced resistance. A strong constitutive resistance against P. brassicae caterpillars in combination with a strong growth attenuation in plants of a transfer DNA (T-DNA) insertion mutant of WRKY70 (wrky70) suggest that the WRKY70 transcription factor, a regulator of downstream responses mediated by jasmonate-salicylic acid signaling cross talk, is involved in the negative regulation of caterpillar resistance and in the tradeoff between growth and defense. In conclusion, different mechanisms of herbivore-induced resistance come with different costs, and a functional WRKY70 transcription factor is required for the induction of low-cost resistance.

Assessment of inflammatory resilience in healthy subjects using dietary lipid and glucose challenges.

BACKGROUND: Resilience or the ability of our body to cope with daily-life challenges has been proposed as a new definition of health, with restoration of homeostasis as target resultant of various physiological stress responses. Challenge models may thus be a sensitive measure to study the body's health. The objective of this study was to select a dietary challenge model for the assessment of inflammatory resilience. Meals are a challenge to metabolic homeostasis and are suggested to affect inflammatory pathways, yet data in literature are limited and inconsistent. METHOD: The kinetic responses of three different dietary challenges and a water control challenge were assessed on various metabolic and inflammatory markers in 14 healthy males and females using a full cross-over study design. The dietary challenges included glucose (75 g glucose in 300 ml water), lipids (200 ml whipping cream) and a mix of glucose and lipids (same amounts as above), respectively. Blood samples were collected at baseline and at 0.5, 1, 2, 4, 6, 8 and 10 h after consumption of the treatment products. Inflammation (IFNγ, IL-1ß, IL-6, IL-8, IL-10, IL-12p70, TNF-α CRP, ICAM-1, VCAM-1, SAA, E-selectin, P-selectin, thrombomodulin, leukocytes, neutrophils, lymphocytes) and clinical (e.g. glucose, insulin, triglycerides) markers as well as gene expression in blood cells and plasma oxylipin profiles were measured. RESULTS: All three dietary challenges induced changes related to metabolic control such as increases in glucose and insulin after the glucose challenge and increases in triglycerides after the lipid challenge. In addition, differences between the challenges were observed for precursor oxylipins and some downstream metabolites including DiHETrE's and HODE's. However, none of the dietary challenges induced an acute inflammatory response, except for a modest increase in circulating leukocyte numbers after the glucose and mix challenges. Furthermore, subtle, yet statistically significant increases in vascular inflammatory markers (sICAM-1 and sVCAM-1) were found after the mix challenge, when compared to the water control challenge. CONCLUSIONS: This study shows that dietary glucose and lipid challenges did not induce a strong acute inflammatory response in healthy subjects, as quantified by an accurate and broad panel of parameters.

Abiotic induction affects the costs and benefits of inducible herbivore defenses in Datura wrightii.

We evaluated the costs and benefits of continuous high-level expression of defenses relative to naturally-induced defenses in field-grown Datura wrightii in the presence and absence of herbivores. We induced D. wrightii plants with monthly applications of the plant hormone methyl jasmonate (MeJA) and assessed levels of inducible proteinase inhibitors (Pins). MeJA application increased Pin production by 124 %, whereas the increase in Pins due to herbivory was more modest (36 %). Pin induction was costly and significantly reduced plant fitness compared to unmanipulated plants both in the presence and absence of herbivores. Although MeJA-treated plants exposed to herbivory suffered significantly less herbivore damage than unmanipulated plants exposed to herbivory, this was not accompanied by a corresponding fitness benefit. In contrast to glasshouse studies in which protected plants never expressed Pins, Pin induction occurred in field-grown plants not treated with MeJA and completely protected from herbivory. Subsequent experiments confirmed that putative herbivore defenses can be induced abiotically in D. wrightii as: 1) Pin levels did not differ significantly between field-grown plants protected from herbivory and plants exposed to chronic herbivory over the full season; and 2) plants exposed to ambient UV-B light in the absence of herbivory expressed low levels of Pins after two wk of exposure, whereas plants protected from UV-B remained uninduced. The costs of induced responses may be relatively easily determined under field conditions, but there may be many inducing agents in the field, and the benefits of induction may be difficult to associate with any single inducing agent.

Stem transcriptome reveals mechanisms to reduce the energetic cost of shade-avoidance responses in tomato.

While the most conspicuous response to low red/far-red ratios (R:FR) of shade light perceived by phytochrome is the promotion of stem growth, additional, less obvious effects may be discovered by studying changes in the stem transcriptome. Here, we report rapid and reversible stem transcriptome responses to R:FR in tomato (Solanum lycopersicum). As expected, low R:FR promoted the expression of growth-related genes, including those involved in the metabolism of cell wall carbohydrates and in auxin responses. In addition, genes involved in flavonoid synthesis, isoprenoid metabolism, and photosynthesis (dark reactions) were overrepresented in clusters showing reduced expression in the stem of low R:FR-treated plants. Consistent with these responses, low R:FR decreased the levels of flavonoids (anthocyanin, quercetin, kaempferol) and selected isoprenoid derivatives (chlorophyll, carotenoids) in the stem and severely reduced the photosynthetic capacity of this organ. However, lignin contents were unaffected. Low R:FR reduced the stem levels of jasmonate, which is a known inducer of flavonoid synthesis. The rate of stem respiration was also reduced in low R:FR-treated plants, indicating that by downsizing the stem photosynthetic apparatus and the levels of photoprotective pigments under low R:FR, tomato plants reduce the energetic cost of shade-avoidance responses.

Costs of jasmonic acid induced defense in aboveground and belowground parts of corn (Zea mays L.).

Costs of jasmonic acid (JA) induced plant defense have gained increasing attention. In this study, JA was applied continuously to the aboveground (AG) or belowground (BG) parts, or AG plus BG parts of corn (Zea mays L.) to investigate whether JA exposure in one part of the plant would affect defense responses in another part, and whether or not JA induced defense would incur allocation costs. The results indicated that continuous JA application to AG parts systemically affected the quantities of defense chemicals in the roots, and vice versa. Quantities of DIMBOA and total amounts of phenolic compounds in leaves or roots generally increased 2 or 4 wk after the JA treatment to different plant parts. In the first 2 wk after application, the increase of defense chemicals in leaves and roots was accompanied by a significant decrease of root length, root surface area, and root biomass. Four weeks after the JA application, however, no such costs for the increase of defense chemicals in leaves and roots were detected. Instead, shoot biomass and root biomass increased. The results suggest that JA as a defense signal can be transferred from AG parts to BG parts of corn, and vice versa. Costs for induced defense elicited by continuous JA application were found in the early 2 wk, while distinct benefits were observed later, i.e., 4 wk after JA treatment.