Harnessing rhizospheric core microbiomes from arid regions for enhancing date palm resilience to climate change effects.

Date palm cultivation has thrived in the Gulf Cooperation Council region since ancient times, where it represents a vital sector in agricultural and socio-economic development. However, climate change conditions prevailing for decades in this area, next to rarefication of rain, hot temperatures, intense evapotranspiration, rise of sea level, salinization of groundwater, and intensification of cultivation, contributed to increase salinity in the soil as well as in irrigation water and to seriously threaten date palm cultivation sustainability. There are also growing concerns about soil erosion and its repercussions on date palm oases. While several reviews have reported on solutions to sustain date productivity, including genetic selection of suitable cultivars for the local harsh environmental conditions and the implementation of efficient management practices, no systematic review of the desertic plants' below-ground microbial communities and their potential contributions to date palm adaptation to climate change has been reported yet. Indeed, desert microorganisms are expected to address critical agricultural challenges and economic issues. Therefore, the primary objectives of the present critical review are to (1) analyze and synthesize current knowledge and scientific advances on desert plant-associated microorganisms, (2) review and summarize the impacts of their application on date palm, and (3) identify possible gaps and suggest relevant guidance for desert plant microbes' inoculation approach to sustain date palm cultivation within the Gulf Cooperation Council in general and in Qatar in particular.

Deciphering the regulatory networks involved in mild and severe salt stress responses in the roots of wild grapevine Vitis vinifera spp. sylvestris.

Transcriptional regulatory networks are pivotal components of plant's response to salt stress. However, plant adaptation strategies varied as a function of stress intensity, which is mainly modulated by climate change. Here, we determined the gene regulatory networks based on transcription factor (TF) TF_gene co-expression, using two transcriptomic data sets generated from the salt-tolerant "Tebaba" roots either treated with 50 mM NaCl (mild stress) or 150 mM NaCl (severe stress). The analysis of these regulatory networks identified specific TFs as key regulatory hubs as evidenced by their multiple interactions with different target genes related to stress response. Indeed, under mild stress, NAC and bHLH TFs were identified as central hubs regulating nitrogen storage process. Moreover, HSF TFs were revealed as a regulatory hub regulating various aspects of cellular metabolism including flavonoid biosynthesis, protein processing, phenylpropanoid metabolism, galactose metabolism, and heat shock proteins. These processes are essentially linked to short-term acclimatization under mild salt stress. This was further consolidated by the protein-protein interaction (PPI) network analysis showing structural and plant growth adjustment. Conversely, under severe salt stress, dramatic metabolic changes were observed leading to novel TF members including MYB family as regulatory hubs controlling isoflavonoid biosynthesis, oxidative stress response, abscisic acid signaling pathway, and proteolysis. The PPI network analysis also revealed deeper stress defense changes aiming to restore plant metabolic homeostasis when facing severe salt stress. Overall, both the gene co-expression and PPI network provided valuable insights on key transcription factor hubs that can be employed as candidates for future genetic crop engineering programs.

Evidence of an active role of resveratrol derivatives in the tolerance of wild grapevines (Vitis vinifera ssp. sylvestris) to salinity.

Resveratrol and its derivatives are the most important phytoalexins with a crucial role in plant defense mechanisms. These compounds can occur either naturally or in response to abiotic stresses. Among them, salinity is one of the major threats to the sustainability and productivity of agro-economically important species, particularly those involved in the vini-viticulture sector. Understating salinity tolerance mechanisms in plants is required for the development of novel engineering tools. This study aimed to investigate the potential role of resveratrol derivatives in salinity tolerance of wild grapevines. Our data revealed that the tolerant Tunisian wild grapevine genotype "Ouchtata" exhibited an increased accumulation of resveratrol derivatives (glycosylated and non-glycosylated resveratrol and t-ɛ-viniferin and hydroxylated t-piceatannol) in both stems and roots, along with an increased total antioxidant activity (TAA) compared to the sensitive genotype "Djebba" under stress conditions, suggesting an involvement of these stilbenes in redox homeostasis, thereby, protecting cells from salt-induced oxidative damage. Overall, our study revealed, for the first time, an active role for resveratrol derivatives in salt stress tolerance in wild grapevine, highlighting their potential use as metabolic markers in future grapevine breeding programs for a sustainable vini-viticulture in salt-affected regions.

A Tunisian wild grape leads to metabolic fingerprints of salt tolerance.

Soil salinity is progressively impacting agriculture, including viticulture. Identification of genetic factors rendering grapevine (Vitis vinifera L.) resilience that can be introgressed into commercial varieties is necessary for safeguarding viticulture against the consequences of global climate change. To gain insight into the physiological and metabolic responses enabling salt tolerance, we compared a salt-tolerant accession of Vitis sylvestris from Tunisia, "Tebaba", with "1103 Paulsen" rootstock widely used in the Mediterranean. Salt stress was slowly increased, simulating the situation of an irrigated vineyard. We determined that "Tebaba" does not sequester sodium in the root but can cope with salinity through robust redox homeostasis. This is linked with rechanneling of metabolic pathways toward antioxidants and compatible osmolytes, buffering photosynthesis, such that cell-wall breakdown can be avoided. We propose that salt tolerance of this wild grapevine cannot be attributed to a single genetic factor but emerges from favorable metabolic fluxes that are mutually supportive. We suggest that introgression of "Tebaba" into commercial varieties is preferred over the use of "Tebaba" as a rootstock for improving salt tolerance in grapevine.

The root transcriptome dynamics reveals new valuable insights in the salt-resilience mechanism of wild grapevine (Vitis vinifera subsp. sylvestris).

Introduction: Most of elite cultivated grapevine varieties (Vitis vinifera L.), conventionally grafted on rootstocks, are becoming more and more affected by climate changes, such as increase of salinity. Therefore, we revisited the valuable genetic resources of wild grapevines (V. sylvestris) to elaborate strategies for a sustainable viticulture. Methods: Here, we compared physiological and biochemical responses of two salt-tolerant species: a wild grapevine genotype "Tebaba" from our previous studies and the conventional rootstock "1103 Paulsen". Interestingly, our physio-biochemical results showed that under 150mM NaCl, "Tebaba" maintains higher leaf osmotic potential, lower Na+/K+ ratio and a significant peaked increase of polyphenol content at the first 8h of salinity stress. This behavior allowed to hypothesis a drastic repatterning of metabolism in "Tebaba's" roots following a biphasic response. In order to deepen our understanding on the "Tebaba" salt tolerance mechanism, we investigated a time-dependent transcriptomic analysis covering three sampling times, 8h, 24h and 48h. Results: The dynamic analysis indicated that "Tebaba" root cells detect and respond on a large scale within 8h to an accumulation of ROS by enhancing a translational reprogramming process and inducing the transcripts of glycolytic metabolism and flavonoids biosynthesis as a predominate non-enzymatic scavenging process. Afterwards, there is a transition to a largely gluconeogenic stage followed by a combined response mechanism based on cell wall remodeling and lignin biosynthesis with an efficient osmoregulation between 24 and 48 h. Discussion: This investigation explored for the first time in depth the established cross-talk between the physiological, biochemical and transcriptional regulators contributing to propose a hypothetical model of the dynamic salt mechanism tolerance of wild grapevines. In summary, these findings allowed further understanding of the genetic regulation mechanism of salt-tolerance in V. sylvestris and identified specific candidate genes valuable for appropriate breeding strategies.

Olive agroforestry shapes rhizosphere microbiome networks associated with annual crops and impacts the biomass production under low-rainfed conditions.

Agroforestry (AF) is a promising land-use system to mitigate water deficiency, particularly in semi-arid areas. However, the belowground microbes associated with crops below trees remain seldom addressed. This study aimed at elucidating the effects of olive AF system intercropped with durum wheat (Dw), barely (Ba), chickpea (Cp), or faba bean (Fb) on crops biomass and their soil-rhizosphere microbial networks as compared to conventional full sun cropping (SC) under rainfed conditions. To test the hypothesis, we compared the prokaryotic and the fungal communities inhabiting the rhizosphere of two cereals and legumes grown either in AF or SC. We determined the most suitable annual crop species in AF under low-rainfed conditions. Moreover, to deepen our understanding of the rhizosphere network dynamics of annual crops under AF and SC systems, we characterized the microbial hubs that are most likely responsible for modifying the microbial community structure and the variability of crop biomass of each species. Herein, we found that cereals produced significantly more above-ground biomass than legumes following in descending order: Ba > Dw > Cp > Fb, suggesting that crop species play a significant role in improving soil water use and that cereals are well-suited to rainfed conditions within both types of agrosystems. The type of agrosystem shapes crop microbiomes with the only marginal influence of host selection. However, more relevant was to unveil those crops recruits specific bacterial and fungal taxa from the olive-belowground communities. Of the selected soil physicochemical properties, organic matter was the principal driver in shaping the soil microbial structure in the AF system. The co-occurrence network analyses indicated that the AF system generates higher ecological stability than the SC system under stressful climate conditions. Furthermore, legumes' rhizosphere microbiome possessed a higher resilient capacity than cereals. We also identified different fungal keystones involved in litter decomposition and drought tolerance within AF systems facing the water-scarce condition and promoting crop production within the SC system. Overall, we showed that AF reduces cereal and legume rhizosphere microbial diversity, enhances network complexity, and leads to more stable beneficial microbial communities, especially in severe drought, thus providing more accurate predictions to preserve soil diversity under unfavorable environmental conditions.

Genome-wide analysis and expression profiling of H-type Trx family in Phaseolus vulgaris revealed distinctive isoforms associated with symbiotic N2-fixing performance and abiotic stress response.

Thioredoxins (Trxs) are implicated in plant development and stress tolerance through redox regulation of target proteins. Trxs of Type h (Trxhs) constitute the largest and the most complicated cluster in the Trx family because of their unknown individual functions. Here, we identified and characterized the Phaseolus vulgaris Trxh family during development, mutualistic interactions and in response to abiotic stress. P. vulgaris (common bean) Trxh gene family (PvTrxh) encompasses 12 isoforms (PvTrxh1-h12), subdivided into 3 groups according to their amino acid sequence features. In silico RNA-seq -based expression analysis showed a differential expression of PvTrxh genes during development. RT-qPCR analysis of PvTrxh genes during nodule organogenesis revealed their highest expression in the nodule primordium (NP). Interestingly, in response to symbiosis, specific PvTrxh isoforms (PvTrxh3 and h5) were found to be highly upregulated compared to mock-inoculated plants. In addition, their expression patterns in the NP positively correlated with the symbiotic N2-fixing efficiency of the Rhizobium strain, as revealed by a number of symbiotic efficiency parameters (ARA, leghemoglobin content, biomass, and total soluble proteins), concomitantly with increased amounts of hydrogen peroxide (H2O2). On the other hand, distinctive PvTrxh isoforms were found to be upregulated in plant leaves, where H2O2 amounts were elevated, in response to both salt and drought constraints. When exogenously applied, H2O2 upregulated specific PvTrxh isoforms in plant leaves and roots. These findings point to a specific, rather than redundant, function for Trxh proteins in common bean beside the association of distinctive Trxh isoforms with symbiosis and abiotic stress response.

Increasing aridity shapes beta diversity and the network dynamics of the belowground fungal microbiome associated with Opuntia ficus-indica.

AIMS: The effects of aridity on soil and water-use efficient (WUE) crop species are relatively well known. However, the understanding of its impacts on the dynamics of below-ground microorganisms associated with plant roots is less well understood. METHODS: To investigate the influence of increasing aridity on the dynamics of the fungal communities, samples from the root endosphere and rhizosphere associated with the prickly pear cactus trees (Opuntia ficus-indica) growing along the aridity gradient were collected and the internal transcribed spacer (ITS) were sequenced. The diversity and network analyses of fungal taxa were determined along with standard measurements of soil parameters. RESULTS: We found that (i) the fungal community exhibited similar alpha diversity and shared a set of core taxa within the rhizosphere and endosphere, but there was significant beta diversity differences; (ii) the relative abundance of major phyla was higher in the rhizosphere than in the endosphere; (iii) arbuscular endomycorrhizal colonization was highest in the humid climate and decreased under lower-arid, and was negatively correlated with increased concentration of Ca2+ in the soil; (iv) increased aridity correlated with increased connectivity of the soil microbial-root fungal networks in the arid soils, producing a highly cohesive network in the upper-arid area; and (v) distinct fungal hubs sculpt the fungal microbiome network structure in the rhizosphere and endosphere within each bioclimatic zone. CONCLUSIONS: Our findings highlight the importance of gradient analysis-based correlation network as a powerful approach to understand changes in the diversity, the dynamics, and the structure of fungal communities associated with the rhizosphere-endosphere interaction and led to the identification of microbes at each bioclimatic zone that are potentially involved in promoting the survival, protection, and growth of Opuntia trees. The variability of fungal hubs composition depending on plant compartment and bioclimatic zone will give key implications for the application of rhizospheric fungi and endophytes as microbial inoculants in agriculture, as well as in the conservation and restoration of cacti plants in arid and semi-arid lands against the backdrop of climate change. Overall, this study will enhance our understanding of the microbiomes'dynamic of CAM plants in nature.

Combinatorial reprogramming of lipid metabolism in plants: a way towards mass-production of bio-fortified arbuscular mycorrhizal fungi inoculants.

Arbuscular mycorrhizal fungi (AMF) are among the most ancient, widespread and functionally important symbioses on Earth that help feed the world. Yet, mass-production of clean (i.e. in vitro produced), safe and robust inoculum at affordable costs remains a critical challenge. Very recently, Luginbuehl et al. (2017) found that plants supply lipids to the symbiotic partner, thus 'providing the AMF with a robust source of carbon for their metabolic needs'. Hence, engineering plants for enhanced delivery of lipids to AMF could represent an innovative avenue to produce a novel generation of high-quality and cost-effective bio-fortified AMF inoculants for application in agro-ecosystems.

Climatic Aridity Gradient Modulates the Diversity of the Rhizosphere and Endosphere Bacterial Microbiomes of Opuntia ficus-indica.

Recent microbiome research has shown that soil fertility, plant-associated microbiome, and crop production can be affected by abiotic environmental parameters. The effect of aridity gradient on rhizosphere-soil (rhizosphere) and endosphere-root (endosphere) prokaryotic structure and diversity associated with cacti remain poorly investigated and understood. In the current study, next-generation sequencing approaches were used to characterize the diversity and composition of bacteria and archaea associated with the rhizosphere and endosphere of Opuntia ficus-indica spineless cacti in four bioclimatic zones (humid, semi-arid, upper-arid, and lower-arid) in Tunisia. Our findings showed that bacterial and archaeal cactus microbiomes changed in inside and outside roots and along the aridity gradient. Plant compartment and aridity gradient were the influencing factors on the differentiation of microbial communities in rhizosphere and endosphere samples. The co-occurrence correlations between increased and decreased OTUs in rhizosphere and endosphere samples and soil parameters were determined according to the aridity gradient. Blastococcus, Geodermatophilus, Pseudonocardia, Promicromonospora, and Sphingomonas were identified as prevailing hubs and were considered as specific biomarkers taxa, which could play a crucial role on the aridity stress. Overall, our findings highlighted the prominence of the climatic aridity gradient on the equilibrium and diversity of microbial community composition in the rhizosphere and endosphere of cactus.

Identification of the NaCl-responsive metabolites in Citrus roots: A lipidomic and volatomic signature.

It is known that the first osmotic phase affects the growth rates of roots immediately upon addition of salt; thus, dissecting metabolites profiling provides an opportunity to throw light into the basis of plant tolerance by searching for altered signatures that may be associated with tolerance at this organ. This study examined the influence of salt treatment on fatty acid composition and chemical composition of the essential oil of C. aurantium roots. Results proved that, under salt treatment, an increase of double bond index and linoleic desaturation ratio was pointed out. On the other hand, the reduction of saturated fatty acids was spotted. Such treatment also induced quantitative changes in the chemical composition of the essential oils from C. aurantium roots and increased markedly the rates of monoterpenes, while the sesquiterpenes decreased significantly. Both primary and secondary metabolites were found to be significantly salt responsive, including one fatty acid (palmitoleic acid) and six volatiles (E-2-dodecenal, tetradecanal, γ-Elemene, trans-caryophyllene, α-Terpinene and germacrene D). Plasticity at the metabolic level may allow Citrus plants to acclimatize their metabolic ranges in response to changing environmental conditions.

Recent advances in biotechnological studies on wild grapevines as valuable resistance sources for smart viticulture.

Cultivated grapevines, Vitis vinifera subsp. sativa, are thought to have been domesticated from wild populations of Vitis vinifera subsp. sylvestris in Central Asia. V. vinifera subsp. sativa is one of the most economically important fruit crops worldwide. Since cultivated grapevines are susceptible to multiple biotic and abiotic soil factors, they also need to be grafted on resistant rootstocks that are mostly developed though hybridization between American wild grapevine species (V. berlandieri, V. riparia, and V. rupestris). Therefore, wild grapevine species are essential genetic materials for viticulture to face biotic and abiotic stresses in both cultivar and rootstock parts. Actually, viticulture faces several environmental constraints that are further intensified by climate change. Recently, several reports on biotic and abiotic stresses-response in wild grapevines revealed accessions tolerant to different constraints. The emergence of advanced techniques such as omics technologies, marker-assisted selection (MAS), and functional analysis tools allowed a more detailed characterization of resistance mechanisms in these wild grapevines and suggest a number of species (V. rotundifolia, V. rupestris, V. riparia, V. berlandieri and V. amurensis) have untapped potential for new resistance traits including disease resistance loci and key tolerance genes. The present review reports on the importance of different biotechnological tools in exploring and examining wild grapevines tolerance mechanisms that can be employed to promote elite cultivated grapevines under climate change conditions.

Re-programming of gene expression in the CS8 rice line over-expressing ADPglucose pyrophosphorylase induces a suppressor of starch biosynthesis.

The CS8 transgenic rice (Oryza sativa L.) lines expressing an up-regulated glgC gene produced higher levels of ADPglucose (ADPglc), the substrate for starch synthases. However, the increase in grain weight was much less than the increase in ADPglc levels suggesting one or more downstream rate-limiting steps. Endosperm starch levels were not further enhanced in double transgenic plants expressing both glgC and the maize brittle-1 gene, the latter responsible for transport of ADPglc into the amyloplast. These studies demonstrate that critical processes within the amyloplast stroma restrict maximum carbon flow into starch. RNA-seq analysis showed extensive re-programming of gene expression in the CS8 with 2073 genes up-regulated and 140 down-regulated. One conspicuous gene, up-regulated ~15-fold, coded for a biochemically uncharacterized starch binding domain-containing protein (SBDCP1) possessing a plastid transit peptide. Confocal microscopy and transmission electron microscopy analysis confirmed that SBDCP1 was located in the amyloplasts. Reciprocal immunoprecipitation and pull-down assays indicated an interaction between SBDCP1 and starch synthase IIIa (SSIIIa), which was down-regulated at the protein level in the CS8 line. Furthermore, binding by SBDCP1 inhibited SSIIIa starch polymerization activity in a non-competitive manner. Surprisingly, artificial microRNA gene suppression of SBDCP1 restored protein expression levels of SSIIIa in the CS8 line resulting in starch with lower amylose content and increased amylopectin chains with a higher degree of polymerization. Collectively, our results support the involvement of additional non-enzymatic factors such as SBDCP in starch biosynthesis.

A Grapevine-Inducible Gene Vv-α-gal/SIP Confers Salt and Desiccation Tolerance in Escherichia coli and Tobacco at Germinative Stage.

Grapevine is an important fruit crop cultivated worldwide. Previously, we have reported the characterization of a salt stress-inducible gene Vv-α-gal/SIP isolated from the tolerant grapevine cultivar Razegui. In this study, we performed functional studies in both Escherichia coli and tobacco systems to gain more insights in the role of the Vv-α-gal/SIP gene. Our data revealed that the recombinant E. coli cells harboring the pET24b+ expression vector with the Vv-α-gal/SIP showed higher tolerance to desiccation and salinity compared to E. coli cells harboring the vector alone. In addition, the transgenic tobacco plants expressing the Vv-α-gal/SIP gene exhibited a higher percentage of seed germination and better growth under salt stress than the wild-type (WT) tobacco seedlings. This stress mitigation might be related to the putative function of this gene, which is thought to be involved in carbohydrate metabolism regulation. Collectively, these results suggest that Vv-α-gal/SIP is potentially a candidate gene for engineering drought and salt tolerance in cultivated plants.

Integrated analysis of zone-specific protein and metabolite profiles within nitrogen-fixing Medicago truncatula-Sinorhizobium medicae nodules.

Symbiotic nitrogen fixation (SNF) between rhizobia and legumes requires metabolic coordination within specialized root organs called nodules. Nodules formed in the symbiosis between S. medicae and barrel medic (M. truncatula) are indeterminate, cylindrical, and contain spatially distinct developmental zones. Bacteria in the infection zone II (ZII), interzone II-III (IZ), and nitrogen fixation zone III (ZIII) represent different stages in the metabolic progression from free-living bacteria into nitrogen fixing bacteroids. To better understand the coordination of plant and bacterial metabolism within the nodule, we used liquid and gas chromatography coupled to tandem mass spectrometry (MS) to observe protein and metabolite profiles representative of ZII, IZ, ZIII, whole-nodule, and primary root. Our MS-based approach confidently identified 361 S. medicae proteins and 888 M. truncatula proteins, as well as 160 metabolites from each tissue. The data are consistent with several organ- and zone-specific protein and metabolite localization patterns characterized previously. We used our comprehensive dataset to demonstrate how multiple branches of primary metabolism are coordinated between symbionts and zones, including central carbon, fatty acid, and amino acid metabolism. For example, M. truncatula glycolysis enzymes accumulate from zone I to zone III within the nodule, while equivalent S. medicae enzymes decrease in abundance. We also show the localization of S. medicae's transition to dicarboxylic acid-dependent carbon metabolism within the IZ. The spatial abundance patterns of S. medicae fatty acid (FA) biosynthesis enzymes indicate an increased demand for FA production in the IZ and ZIII as compared to ZI. These observations provide a resource for those seeking to understand coordinated physiological changes during the development of SNF.

Functional photosystem I maintains proper energy balance during nitrogen depletion in Chlamydomonas reinhardtii, promoting triacylglycerol accumulation.

BACKGROUND: Nutrient deprivation causes significant stress to the unicellular microalga, Chlamydomonas reinhardtii, which responds by significantly altering its metabolic program. Following N deprivation, the accumulation of starch and triacylglycerols (TAGs) is significantly altered following massive reprogramming of cellular metabolism. One protein that was found to change dramatically and early to this stress was TAB2, a photosystem I (PSI) translation initiation factor, whose transcript and protein levels increased significantly after only 30 min of N deprivation. A detailed physiological and omics-based analysis of an insertional mutant of Chlamydomonas with reduced TAB2 function was conducted to determine what role the functional PSI plays in regulating the cellular response to N deprivation. RESULTS: The tab2 mutant displayed increased acetate assimilation and elevated starch levels during the first 6 h of N deprivation, followed by a shift toward altered amino acid synthesis, reduced TAG content and altered fatty acid profiles. These results suggested a central role for PSI in controlling cellular metabolism and its implication in regulation of lipid/starch partitioning. Time course analyses of the tab2 mutant versus wild type under N-deprived versus N replete conditions revealed changes in the ATP/NADPH ratio and suggested that TAG biosynthesis may be associated with maintaining the redox state of the cell during N deprivation. The loss of ability to accumulate TAG in the tab2 mutant co-occurred with an up-regulation of photo-protective mechanisms, suggesting that the synthesis of TAG in the wild type occurs not only as a temporal energy sink, but also as a protective electron sink. CONCLUSIONS: By exploiting the tab2 mutation in the cells of C. reinhardtii cultured under autotrophic, mixotrophic, and heterotrophic conditions during nitrogen replete growth and for the first 8 days of nitrogen deprivation, we showed that TAG accumulation and lipid/starch partitioning are dynamically regulated by alterations in PSI function, which concomitantly alters the immediate ATP/NADPH demand. This occurs even without removal of nitrogen from the medium, but sufficient external carbon must nevertheless be available. Efforts to increase lipid accumulation in algae such as Chlamydomonas need to consider carefully how the energy balance of the cell is involved in or affected by such efforts and that numerous layers of metabolic and genetic regulatory control are likely to interfere with such efforts to control oil biosynthesis. Such knowledge will enable synthetic biology approaches to alter the response to the N depletion stress, leading to rewiring of the regulatory networks so that lipid accumulation could be turned on in the absence of N deprivation, allowing for the development of algal production strains with highly enhanced lipid accumulation profiles.

Iridoid and phenylethanoid/phenylpropanoid metabolite profiles of Scrophularia and Verbascum species used medicinally in North America.

INTRODUCTION: Botanicals containing iridoid and phenylethanoid/phenylpropanoid glycosides are used worldwide for the treatment of inflammatory musculoskeletal conditions that are primary causes of human years lived with disability (YLDs), such as arthritis and lower back pain. OBJECTIVES: We report the analysis of candidate anti-inflammatory metabolites of several endemic Scrophularia species and Verbascum thapsus used medicinally by peoples of North America. METHODS: Leaves, stems, and roots were analyzed by ultra-performance liquid chromatography-mass spectrometry (UPLC-MS) and partial least squares-discriminant analysis (PLS-DA) was performed in MetaboAnalyst 3.0 after processing the datasets in Progenesis QI. RESULTS: Comparison of the datasets revealed significant and differential accumulation of iridoid and phenylethanoid/phenylpropanoid glycosides in the tissues of the endemic Scrophularia species and Verbascum thapsus. CONCLUSIONS: Our investigation identified several species of pharmacological interest as good sources for harpagoside and other important anti-inflammatory metabolites.

Vitamins for enhancing plant resistance.

MAIN CONCLUSION: This paper provides an overview on vitamins with inducing activities in plants, the molecular and cellular mechanisms implicated, and the hormonal signalling-network regulating this process. Moreover, it reports how vitamins might be part of the molecular events linked to induced resistance by the conventional elicitors. Induced resistance (IR), exploiting the plant innate-defense system is a sustainable strategy for plant disease control. In the last decade, vitamins have been proven to act as inducers of disease resistance, and these findings have received an important attention owing to their safety and cost effectiveness. Vitamins, including thiamine (TH, vitamin B1), riboflavin (RF, vitamin B2), menadione sodium bisulfite (MSB, vitamin K3), Para-aminobenzoic acid (PABA, vitamin Bx), and folic acid (FA, vitamin B9) provided an efficient protection against a wide range of pathogens through the modulation of specific host-defense facets. However, other vitamins, such as ascorbic acid (AA, vitamin C) and tocopherols (vitamin E), have been shown to be a part of the molecular mechanisms associated to IR. The present review is the first to summarize what vitamins are acting as inducers of disease resistance in plants and how could they be modulated by the conventional elicitors. Thus, this report provides an overview on the protective abilities of vitamins and the molecular and cellular mechanisms underlying their activities. Moreover, it describes the hormonal-signalling network regulating vitamin-signal transduction during IR. Finally, a biochemical model describing how vitamins are involved in the establishment of IR process is discussed.

Metabolite profiles of essential oils and molecular markers analysis to explore the biodiversity of Ferula communis: Towards conservation of the endemic giant fennel.

Giant fennel (Ferula communis L.) is well known in folk medicine for the treatment of various organ disorders. The biological importance of members of genus Ferula prompted us to investigate the leaves of the endangered Tunisian medicinal plant F. communis L. not previously investigated. An estimate of genetic diversity and differentiation between genotypes of breeding germplasm is of key importance for its improvement. Thus, four F. communis populations were RAPD fingerprinted (63 RAPD markers generated by 7 primers) and the composition of their leaf essential oils (EO) (134 EO compounds) was characterized by GC-MS. Cluster analysis based on the leaf volatiles chemical composition of F. communis accessions defined three chemotypes according to main compounds have been distinguished: α-eudesmol/ß-eudesmol/γ-terpinene; α-eudesmol/α-pinene/caryophyllene oxide and chamazulene/α-humulene chemotypes. A high genetic diversity within population and high genetic differentiation among them, based on RAPDs, were revealed (H(pop)=0.320 and GST=0.288) caused both by the habitat fragmentation, the low size of most populations and the low level of gene flow among them. The RAPD dendrogram showed separation of three groups. Populations dominated by individuals from the ß-eudesmol/γ-terpinene; chemotype showed the lowest gene diversity (H=0.104), while populations with exclusively α-pinene/caryophyllene oxide chemotype showed the highest value (H=0.285). The UPGMA dendrogram and PCA analysis based on volatiles yielded higher separation among populations, indicated specific adaptation of populations to the local environments. Correlation analysis showed a non-significant association between the distance matrices based on the genetic markers (RAPD) and chemical compounds of essential oil (P>0.05) indicating no influence of genetic background on the observed chemical profiles. These results reinforce the use of both volatile compounds and RAPD markers as a starting point for in situ conservation. The analysis of chemical constitution of oil of the populations from a specific region revealed predominance of specific constituents indicating possibility of their collection/selection for specific end uses like phytomedicines. Sufficient molecular and biochemical diversity detected among natural populations of this species will form the basis for the future improvement. The correlation between matrices of RAPD and essential oils was not significant. The conservation strategies of populations should be made according to their level of genetic and chemical diversity in relation to geographic location of populations. Our results give some insights into the characterization of this as yet little investigated plant.

Neutral red-mediated microbial electrosynthesis by Escherichia coli, Klebsiella pneumoniae, and Zymomonas mobilis.

The aim of this work was to compare the effects of electrosynthesis on different bacterial species. The effects of neutral red-mediated electrosynthesis on the metabolite profiles of three microorganisms: Escherichia coli, Klebsiella pneumoniae, and Zymomonas mobilis, were measured and compared and contrasted. A statistically comprehensive analysis of neutral red-mediated electrosynthesis is presented using the analysis of end-product profiles, current delivered, and changes in cellular protein expression. K. pneumoniae displayed the most dramatic response to electrosynthesis of the three bacteria, producing 93% more ethanol and 76% more lactate vs. control fermentation with no neutral red and no electron delivery. Z. mobilis showed no response to electrosynthesis except elevated acetate titers. Stoichiometric comparison showed that NAD(+) reduction by neutral red could not account for changes in metabolites during electrosynthesis. Neutral red-mediated electrosynthesis was shown to have multifarious effects on the three species.