Nicotiana Glauca Research Articles

Let's connect nature with hypothesis-based experimentation and explore life in context.

In a recent paper in Nature, Edith Heard from the European Molecular Biology Laboratory (EMBL) suggested that molecular biologists should 'reconnect with nature' by diversifying sampling locations. Although this approach has its own benefits, we suggest that advanced methods should rather be used to take hypothesis-based experiments to nature, thereby supplying a much-needed context for experimentation under controlled conditions. Following the CRISPR (clustered regularly interspaced short palindromic repeats) revolution, this approach has become accessible to many research groups. For the past several years we have developed the groundwork and initiated such experimentation. This included the assembly of a mobile laboratory on a four-wheel drive truck and examining genome-edited metabolic mutants in wild tree tobacco (Nicotiana glauca), grown in nature. Our findings included both targeted answers to focused questions, but also surprising results that could only be reached while working in natural settings.

Tree tobacco (Nicotiana glauca) cuticular wax composition is essential for leaf retention during drought, facilitating a speedy recovery following rewatering.

Despite decades of extensive study, the role of cuticular lipids in sustaining plant fitness is far from being understood. We utilized genome-edited tree tobacco (Nicotiana glauca) to investigate the significance of different classes of epicuticular wax in abiotic stress such as cuticular water loss, drought, and light response. We generated mutants displaying a range of wax compositions. Four wax mutants and one cutin mutant were extensively investigated for alterations in their response to abiotic factors. Although the mutations led to elevated cuticular water loss, the wax mutants did not display elevated transpiration or reduced growth under nonstressed conditions. However, under drought, plants lacking alkanes were unable to reduce their transpiration, leading to leaf death, impaired recovery, and stem cracking. By contrast, plants deficient in fatty alcohols exhibited elevated drought tolerance, which was part of a larger trend of plant phenotypes not clustering by a glossy/glaucous appearance in the parameters examined in this study. We conclude that although alkanes have little effect on whole N.glauca transpiration and biomass gain under normal, nonstressed conditions, they are essential during drought responses, since they enable plants to seal their cuticle upon stomatal closure, thereby reducing leaf death and facilitating a speedy recovery.

Agrobacterium-mediated transformation of Nicotiana glauca and Nicotiana sylvestris.

Agrobacterium-mediated transformation is the most popular approach for obtaining transgenic plants nowadays. There are plenty of protocols developed for different plant species. These protocols usually include the medium composition, the technology for preparing plant explants and cultivation conditions, as well as the choice of agrobacteria strains. Nicotiana tabacum, or cultivated tobacco, was one of the f irst successfully transformed plant species. Nicotiana tabacum is a model object in plant genetics, particularly due to its ability for transformation and regeneration. N. tabacum is a naturally transgenic plant since its genome contains a cellular T-DNA acquired from Agrobacteria. The signif icance of cT-DNA for plants has not yet been established. Some assume that cT-DNA can increase the ability of plants to regenerate due to some of the genes they contain. For example, rolC has been shown to affect the hormonal balance of plants, but the molecular mechanisms underlying this have yet to be found. RolC is also somehow involved in the secondary metabolism of plants. Like N. tabacum, Nicotiana glauca produces a wide range of secondary metabolites and contains an intact rolC gene in its genome. At the same time, unlike N. tabacum, N. glauca is a diploid species, which makes it more suitable for genetic engineering approaches. Nicotiana sylvestris is one of the ancestral species of N. tabacum and does not contain cT-DNA. The aim of this work was to develop a protocol for transformation and regeneration of N. glauca and N. sylvestris. We managed to find an optimum ratio of auxins and cytokinins that promotes both active callus formation and organogenesis in N. glauca and N. sylvestris leaf explants. The developed technique will be useful both for fundamental research that includes the N. glauca and N. sylvestris species, and for practical application in the pharmaceutical industry and biosynthesis.

Effect of tree tobacco leaf extracts on mortality rate of carmine cochineal

Effect of tree tobacco leaf extracts on mortality rate of carmine cochineal

The Biosynthesis of Non-Endogenous Apocarotenoids in Transgenic Nicotiana glauca.

Crocins are high-value compounds with industrial and food applications. Saffron is currently the main source of these soluble pigments, but its high market price hinders its use by sectors, such as pharmaceutics. Enzymes involved in the production of these compounds have been identified in saffron, Buddleja, and gardenia. In this study, the enzyme from Buddleja, BdCCD4.1, was constitutively expressed in Nicotiana glauca, a tobacco species with carotenoid-pigmented petals. The transgenic lines produced significant levels of crocins in their leaves and petals. However, the accumulation of crocins was, in general, higher in the leaves than in the petals, reaching almost 302 µg/g DW. The production of crocins was associated with decreased levels of endogenous carotenoids, mainly β-carotene. The stability of crocins in leaf and petal tissues was evaluated after three years of storage, showing an average reduction of 58.06 ± 2.20% in the petals, and 78.37 ± 5.08% in the leaves. This study illustrates the use of BdCCD4.1 as an effective tool for crocin production in N. glauca and how the tissue has an important impact on the stability of produced high-value metabolites during storage.

Metabolic Engineering of Crocin Biosynthesis in Nicotiana Species.

Crocins are high-value soluble pigments that are used as colorants and supplements, their presence in nature is extremely limited and, consequently, the high cost of these metabolites hinders their use by other sectors, such as the pharmaceutical and cosmetic industries. The carotenoid cleavage dioxygenase 2L (CsCCD2L) is the key enzyme in the biosynthetic pathway of crocins in Crocus sativus. In this study, CsCCD2L was introduced into Nicotiana tabacum and Nicotiana glauca for the production of crocins. In addition, a chimeric construct containing the Brevundimonas sp. β-carotene hydroxylase (BrCrtZ), the Arabidopsis thaliana ORANGE mutant gene (AtOrMut), and CsCCD2L was also introduced into N. tabacum. Quantitative and qualitative studies on carotenoids and apocarotenoids in the transgenic plants expressing CsCCD2L alone showed higher crocin level accumulation in N. glauca transgenic plants, reaching almost 400 μg/g DW in leaves, while in N. tabacum 36 μg/g DW was obtained. In contrast, N. tabacum plants coexpressing CsCCD2L, BrCrtZ, and AtOrMut accumulated, 3.5-fold compared to N. tabacum plants only expressing CsCCD2L. Crocins with three and four sugar molecules were the main molecular species in both host systems. Our results demonstrate that the production of saffron apocarotenoids is feasible in engineered Nicotiana species and establishes a basis for the development of strategies that may ultimately lead to the commercial exploitation of these valuable pigments for multiple applications.

ENDOPHYTIC FUNGAL COMMUNITY OF ALIEN Nicotiana glauca IN TENERIFE, CANARY ISLANDS

Nicotiana glauca it is naturally distributed throughout South America. It was introduced in North America, Europe, Africa, Asia and Oceania and arrived to the Canary Islands as an ornamental plant, where has been invading altered soils. Endophytic fungi are known to produce active compounds that provide protection to their host against diseases and attack of herbivores, these microorganisms being an interesting source of novel molecules. So far, the endophytic fungal communities of Nicotiana have not been studied in the Canary Islands. The goal of this study is to evaluate the diversity of the fungal endophytes community associated with Nicotiana glauca. A total of 36 fungal species were isolated from roots, stems and leaves of plants collected in three locations from Tenerife Island - San Miguel de Abona, Fasnia and Puerto de la Cruz. The highest species richness values were found in leaves and stems (Margalef index = 3.33 and 3.36, respectively) versus roots (Margalef index = 2.52). Simpson's index complements the results of the Margalef index, indicating a fungal community with a high dominance value in roots (D = 0.65) due to the presence of multiple Fusarium species. Fungal community in Fasnia had the highest value of species richness (Margalef index = 3.69 versus 2.17 and 2.27 for San Miguel de Abona and Puerto de la Cruz, respectively). Results indicate fungal specificity to organ and location with 13 genera isolated from a single location and organ, among which rare species like Collariella and Gelasinospora. In this study was detected and isolated for the first time in Canary Islands the fungal species Collariella hilkhuijsenii which is of importance for the ecology of this genus scarcely known. Special attention should be offered to the presence of Fusarium, which possibly relates to the alkaloid production ability of both, the plant and the fungal strains.

ENDOPHYTIC FUNGAL COMMUNITY OF ALIEN Nicotiana glauca IN TENERIFE, CANARY ISLANDS

Nicotiana glauca it is naturally distributed throughout South America. It was introduced in North America, Europe, Africa, Asia and Oceania and arrived to the Canary Islands as an ornamental plant, where has been invading altered soils. Endophytic fungi are known to produce active compounds that provide protection to their host against diseases and attack of herbivores, these microorganisms being an interesting source of novel molecules. So far, the endophytic fungal communities of Nicotiana have not been studied in the Canary Islands. The goal of this study is to evaluate the diversity of the fungal endophytes community associated with Nicotiana glauca. A total of 36 fungal species were isolated from roots, stems and leaves of plants collected in three locations from Tenerife Island - San Miguel de Abona, Fasnia and Puerto de la Cruz. The highest species richness values were found in leaves and stems (Margalef index = 3.33 and 3.36, respectively) versus roots (Margalef index = 2.52). Simpson's index complements the results of the Margalef index, indicating a fungal community with a high dominance value in roots (D = 0.65) due to the presence of multiple Fusarium species. Fungal community in Fasnia had the highest value of species richness (Margalef index = 3.69 versus 2.17 and 2.27 for San Miguel de Abona and Puerto de la Cruz, respectively). Results indicate fungal specificity to organ and location with 13 genera isolated from a single location and organ, among which rare species like Collariella and Gelasinospora. In this study was detected and isolated for the first time in Canary Islands the fungal species Collariella hilkhuijsenii which is of importance for the ecology of this genus scarcely known. Special attention should be offered to the presence of Fusarium, which possibly relates to the alkaloid production ability of both, the plant and the fungal strains.

Impacts of Nicotiana glauca Graham Invasion on the Vegetation Composition and Soil: A Case Study of Taif, Western Saudi Arabia.

Invasive species are considered a serious problem in different ecosystems worldwide. They can compete and interfere with native plants, leading to a shift in community assembly and ecosystem function. The present study aimed to evaluate the effects of Nicotiana glauca Graham invasion on native vegetation composition and soil of the most invaded locations in the Taif region, Western Saudi Arabia, including Alwaht (WHT), Ar-Ruddaf (RDF), and Ash-shafa (SHFA). Plant species list, life span, life form, and chorotypes were assessed. Six locations highly infested with N. glauca shrubs were selected, and the morphological parameters of the shrubs were measured. Within each location, richness, evenness, relative density of species, and soil were measured either under the canopy of N. glauca shrubs or outside the canopy. Floristic analysis revealed the existence of 144 plant species, mainly perennial. The shrubs at the SHFA1 location showed the highest values of all measured morphological parameters. The WHT 1 location showed high richness and evenness, while the WHAT 2 location showed less richness and evenness. The invaded locations showed substantial variation in the community composition. Additionally, the effect of N. glauca on the understory species varied from competition to facilitation, where most of the understory species were inhibited. As an average of all locations, 65.86% of the plant species were recorded only outside the canopy of N. glauca. The vegetation analysis revealed that the SHFA location is more vulnerable to invasion that could be ascribed to its wide range of habitats and high disturbance. The soil–vegetation relationships showed significant variations among the studied locations regarding soil composition, and thereby showed a wide ecological range of the invasive shrubs N. glauca. Therefore, the invasion of N. glauca in the Taif region altered the species interactions, nutrients, and soil properties.

Elevated CO2 affects the rhizosphere microbial community and the growth of two invader plant species differently in semiarid Mediterranean soils

AbstractThe rise in atmospheric CO2 levels is foreseen to enhance the growth of exotic invasive plants and potentially alter the rhizosphere microbial community, which in turn could enhance the risk of colonization by such invaders. This response could be determined by the plant type and the features of invaded soil. The goal of this investigation was to compare the effects of elevated CO2 on the rhizosphere bacterial and fungal communities of two invaders with distinct degrees of invasiveness, Nicotiana glauca and Mirabilis jalapa, by growing the plants in five different semiarid soils at ambient (410 ppm) or elevated (760 ppm) CO2. The changes in soil physicochemical, biochemical, and biological features mediated by the invaders were also evaluated. The effect of CO2 supply on shoot dry biomass was only significant for N. glauca, the shoot and root biomass of plants grown under elevated CO2 being approximately 53% and 14% greater, respectively, than those of the plants grown under ambient CO2. Elevated CO2 only promoted shifts in the rhizosphere bacterial community composition and enhanced the bacterial functional potential related to nucleoside and nucleotide biosynthesis and N‐cycling in N. glauca. Among the bacterial indicator species, the genera Sphingomonas, Stenotrophobacter, and Gaiella were more abundant in the rhizosphere of N. glauca plants grown under elevated CO2. This study demonstrates that the responses of aboveground and belowground biomass of invasive plants to CO2 enrichment, as well as those of the composition and functioning of soil microbial communities, are dependent on their degree of invasiveness.

Two TOBAMOVIRUS MULTIPLICATION 2A homologs in tobacco control asymptomatic response to tobacco mosaic virus.

The most common response of a host to pathogens is arguably the asymptomatic response. However, the genetic and molecular mechanisms responsible for asymptomatic responses to pathogens are poorly understood. Here we report on the genetic cloning of two genes controlling the asymptomatic response to tobacco mosaic virus (TMV) in cultivated tobacco (Nicotiana tabacum). These two genes are homologous to tobamovirus multiplication 2A (TOM2A) from Arabidopsis, which was shown to be critical for the accumulation of TMV. Expression analysis indicates that the TOM2A genes might play fundamental roles in plant development or in responses to stresses. Consistent with this hypothesis, a null allele of the TOM2A ortholog in tomato (Solanum lycopersicum) led to the development of bent branches and a high tolerance to both TMV and tomato mosaic virus (ToMV). However, the TOM2A ortholog in Nicotiana glauca did not account for the asymptomatic response to TMV in N. glauca. We showed that TOM2A family is plant-specific and originated from Chlorophyte, and the biological functions of TOM2A orthologs to promote TMV accumulation are highly conserved in the plant kingdom-in both TMV host and nonhost species. In addition, we showed that the interaction between tobacco TOM1 and TOM2A orthologs in plant species is conserved, suggesting a conserved nature of TOM1-TOM2A module in promoting TMV multiplication in plants. The tradeoff between host development, the resistance of hosts to pathogens, and their influence on gene evolution are discussed. Our results shed light on mechanisms that contribute to asymptomatic responses to viruses in plants and provide approaches for developing TMV/ToMV-resistant crops.

UPLC-HRESI-MS and GC-MS analysis of the leaves of Nicotiana glauca.

The alkaloid-rich fraction obtained by fractionation of the crude methanolic extract of the leaves of wild tobacco tree Nicotiana glauca Graham (Solanaceae) was analyzed using UPLC-MS and GC-MS. Anabasine, a piperidine alkaloid, was identified as the major constituent with approximately 60 % (m/m) of the alkaloid-rich fraction. In addition to anabasine, six secondary metabolites were identified using high-resolution UPLC-MS. Anabasine was quantified in the leaves to be 1 mg g-1 dry plant material. The GC-MS analysis revealed five compounds with anabasine as the major component, while nicotine was not detected. Moreover, GC-MS was used for the analysis of the volatile oil that was obtained by hydro-distillation from the leaves of N. glauca. The volatile plant oil was found to be rich in oxygenated sesquiterpenes (e.g., β-bisabolol) and carboxylic acids and esters (e.g., ethyl linoleate and hexadecanoic acid), whereas anabasine was not detected.

Impact of wastewater discharge on the plant diversity, community structure and heavy metal pollution of range plants in eastern Saudi Arabia

The main objectives of this study were to determine the floristic composition of the vegetation cover and to find the effects of wastewater pollution on the plant community structure in eastern Saudi Arabia. 28 stands which were distributed among polluted and unpolluted sites, were chosen for this study. A total of 42 plant species were recorded (14 in the polluted and 28 in the unpolluted sites). The recorded plants comprised of 13 perennial plant species and 29 annual plant species. Seven vegetation communities were determined using TWINSPAN and DCA classification and ordination techniques. Three in the polluted sites, two in the unpolluted sites and the remaining two were mixed communities. The (Sarcopoterium spinosum – Pistacia len‐tiscus) community in the polluted sites, had the highest values of soil moisture, salinity, sulphate, calcium and potassium. On the other hand, Juniperus phoenicea – Olea europaea community in the unpolluted site, had the lowest value of organic matter, salinity and magnesium. In respect of genetic diversity, the community of Foeniculum vulgare - Nicotiana glauca in the unpolluted site, was the most diverse, while Ricinus communis - Chrysanthemum coronarium in the polluted sites was the least one. Both soil and wastewater heavy metal analysis indicated that Pb, Cd, Cr, Cu and Ni concentrations in the polluted sites were significantly higher than those in the unpolluted ones. The impact of wastewater discharge led to the appearance of new invasive plant species that may significantly affect plant diversity and community structure in eastern Saudi Arabia. Finally wastewater discharge in open rangelands could adversely affect the growth of plant species in the rangelands and thus adversely affect plant community structure and diversity.

Pseudomonas palmensis sp. nov., a Novel Bacterium Isolated From Nicotiana glauca Microbiome: Draft Genome Analysis and Biological Potential for Agriculture.

A novel Pseudomonas, designated strain BBB001T, an aerobic, rod-shaped bacterium, was isolated from the rhizosphere of Nicotiana glauca in Las Palmas Gran Canaria, Spain. Genomic analysis revealed that it could not be assigned to any known species of Pseudomonas, so the name Pseudomonas palmensis sp. nov. was proposed. A 16S rRNA gene phylogenetic analysis suggested affiliation to the Pseudomonas brassicae group, being P. brassicae MAFF212427 T the closest related type strain. Upon genomic comparisons of both strains, all values were below thresholds established for differentiation: average nucleotide identity (ANI, 88.29%), average amino acid identity (AAI, 84.53%), digital DNA-DNA hybridization (dDDH, 35.4%), and TETRA values (0.98). When comparing complete genomes, a total of 96 genes present exclusively in BBB001T were identified, 80 of which appear associated with specific subsystems. Phenotypic analysis has shown its ability to assimilate glucose, potassium gluconate, capric acid malate, trisodium citrate, and phenylacetic acid; it was oxidase positive. It is able to produce auxins and siderophores in vitro; its metabolic profile based on BIOLOG Eco has shown a high catabolic capacity. The major fatty acids accounting for 81.17% of the total fatty acids were as follows: C16:0 (33.29%), summed feature 3 (22.80%) comprising C16:1 ω7c and C16:1 ω6c, summed feature 8 (13.66%) comprising C18:1 ω7c, and C18:1ω6c and C17:0 cyclo (11.42%). The ability of this strain to improve plant fitness was tested on tomato and olive trees, demonstrating a great potential for agriculture as it is able to trigger herbaceous and woody species. First, it was able to improve iron nutrition and growth on iron-starved tomatoes, demonstrating its nutrient mobilization capacity; this effect is related to its unique genes related to iron metabolism. Second, it increased olive and oil yield up to 30% on intensive olive orchards under water-limiting conditions, demonstrating its capacity to improve adaptation to adverse conditions. Results from genomic analysis together with differences in phenotypic features and chemotaxonomic analysis support the proposal of strain BBB001T (=LMG 31775T = NCTC 14418T) as the type strain of a novel species for which the name P. palmensis sp. nov is proposed.

New records of alien plants – Ludwigia peploides (Kunth) P. H. Raven, Reynoutria sachalinensis (F. Schmidt) Nakai and Nicotiana glauca Graham in Croatia

Invasive alien species Ludwigia peploides, Reynoutria sachalinensis and Nicotiana glauca, currently registered in Croatia with small number of records, were found during fieldwork undertaken mostly through the national monitoring of waters from 2018 to 2020. Ludwigia peploides was previously recorded only once in the River Ilova, the existing data for R. sachalinensis indicate only three confirmed findings, in Čabar, Karlovac and Donja Stubica, while the previous data for N. glauca include several localities in Central and Southern Dalmatia. The new records are as follows: two findings of L. peploides refer to the River Česma (Obedišće and Sišćani); three records of R. sachalinensis refer to Gorski Kotar (Gerovo and Čabar), while N. glauca is newly recorded in the Neretva River Valley (Krvavac) and the island of Krk. Despite their potential invasiveness, all three are still locally naturalized and currently their spread is very slow and limited in Croatia.

Leaf Micromorphology and Pollen Grain Characteristics of Nicotiana glauca. R.C. Graham and Nicotiana tabacum. L.(Solanaceae, Nicotianoideae)

The micromorphological variation of the leaf and pollen grain characteristics in two species of Nicotiana was examined using a light microscope (LM) and scanning electron microscopy (SEM). These species are Nicotiana glauca R.C. Graham (wild species) and Nicotiana tabacum L. (cultivated species). The leaves are simple. The other leaf micromorphological features presented variation. The leaf architectural characteristics were also observed. Leaf venation is pinnate brochidodromous. The epidermal cell shape, on the abaxial leaf surface, is polygonal to irregular in Nicotiana glauca but it is so adaxially in all the two species the cells are irregular on both the epidermal layers. The anticlinal walls are either straight or sinuous. The leaves are amphistomatic. The stomata are commonly anomocytic to anisocytic. Foliar trichomes are glandular and non-glandular. Some of the foliar micromorphological characters as viewed under SEM were beneficial in species identification. The pollen shape is prolate with aperture tricolpate without opercula, the colpi shallow sunken with their ends acute. The exine sculpture is reticulate with granulate or granulate-microperforated to fine granulate and irregularly reticulate to perforate. Keywords: Leaf micromorphology- Pollen grains - Light microscope (LM); Scanning electron microscopy (SEM)- Nicotiana Solanaceae -Nicotianoideae.

Direct Evidence That Sunbirds' Gut Microbiota Degrades Floral Nectar's Toxic Alkaloids.

Orange-tufted sunbirds (Cinnyris osea) feed on the nectar of the tobacco tree (Nicotiana glauca) which contains toxic pyridine alkaloids characterized by high concentrations of anabasine and much lower concentrations of nicotine. We aimed at determining whether the gut microbiota of sunbirds harbors bacterial species that enable the birds to cope with these toxic alkaloids. An in vivo experiment that included 12 birds showed that inducing dysbiosis in sunbirds’ guts by the addition of sulfamethoxazole and trimethoprim, significantly reduced the birds’ ability to degrade anabasine (n = 3) compared to control birds (n = 3) with undisturbed microbiota. Sunbirds whose gut bacterial communities were altered by the antibacterial agents and who were fed with added nicotine, also showed a lower percentage of nicotine degradation (n = 3) in their excreta compared to the sunbirds with undisturbed microbiota (n = 3), though this difference was not significant. In an in vitro experiment, we studied the ability of Lactococcus lactis, Enterobacter hormaechei, Chryseobacterium gleum, Kocuria palustris, and Methylorubrum populi that were isolated from sunbirds’ excreta, to degrade anabasine and nicotine. By using gas chromatography-mass spectrometry (GC-MS) analysis, we successfully demonstrated, for the first time, the ability of these species to degrade the focal secondary metabolites. Our findings demonstrate the role of gut bacteria in detoxifying toxic secondary metabolites found in the N. glauca nectar. The degradation products may supply the birds with nitrogen which is scarce in nectar-rich diets. These findings support another role of bacteria in mediating the interactions between plants and their pollinators.

Andean Solanaceae species with resistance to biotic factors, such as tree tomato (Solanum betaceum Cav.) rootstocks

The infestation of the root system by nematodes ( Meloidogyne incognita ) and Fusarium solani to the rootneck hinders the production of tree tomato ( Solanum betaceum Cav.), an Andean native fruit consumed in Ecuador and other countries. This paper evaluates the potential of different Ecuadorian Andean Solanaceae species ( Solanum auriculatum , Solanum asperolanatum , Solanum arboreum and Nicotiana glauca ), such as tree tomato rootstocks towards Fusarium and nematode resistance through controlled inoculation trials. The experimental design used was complete randomized in factorial arrangement with three factors. The variables were: fungus incubation time, incidence and lesion size, increase in nematode population, plant height increase and plant fresh weight. The most promising results for an extended open field evaluation were N. glauca (no incidences of Fusarium and 0.36 times increase in nematode population), followed by S. auriculatum . Fruit of these plants were assessed for chaconine and solanine content. The results indicated that the two rootstocks did not induce toxic substances in the fruits, they are suitable for commercial production zones, enhance crop yield, increase productive plant life and use fewer chemicals to control soil pathogens.

Phytoconstituents screening and antimicrobial activity of the invasive species Nicotiana glauca collected from Al-Baha region of Saudi Arabia.

Nicotiana glauca belonging to the family Solanaceae is an exotic perinnial bushy species that recently has invaded the mountainous areas of Al-Baha region at the south-west of Saudi Arabia, causing degredation to soil and vegetation composition of those mountains. Accordingly, this plant must be either removed or exploited as a source of useful products such as medicines as it has been proven to contain many effective compounds with therapeutic properties. Thus, the current study aimd to screening N. glauca preliminary phytoconsitiuents and its anticmicrobial activity. Results showed that varying amounts of alkaloids, steroid, tannins, flavonoid, were present in the extracts of N. glauca leaves, stems and flowers. Saponins were present only in the flowers extract. However, all previuos bioactive compounds were absent in the roots except alkaloids, therefore, roots posses lesser amount of the phytoconstituents compared to the other parts of the plants. Leaves extracts inhibited the growth of E. coli (16.3 ± 0.71 mm) and also inhibited the growth of S. aureus (11.0 ± 0.23 mm), while, the flower extracts also inhibited the growth of E. coli (6.7 ± 0.65 mm), and also inhibited the growth of S. aureus (15.8 ± 0.52 mm). This result coincide with the previous results of the screening of N, glauca phytochemicals where the highest amounts found in leaves and flowers extracts. The inhibition zone of the antibiotic gentamycin (reference control) were 32 mm in S. aureus and 38 mm in E. coli. The inhibition zone of gentamycin (reference control) were 32 mm in S. aureus and 38 mm in E. coli. The minimum inhibitory concentration (MIC) of ethyl acetate was ranged (1.5–2 mg/ml). The lower MIC is an indication of high effectiveness of extract. Therefore, such bioactive property would support the idea that removing N. glauca from the mountainous areas of Al-Baha, Saudi Arabia, is not the only solution, but the plant can be exploited as a beneficial source of medicinal and economic purposes such as; antibacterial, antifungal and insecticidal, however, further comprehensive exploration is recommended to confirm such propreties.

Bioeffectors as Biotechnological Tools to Boost Plant Innate Immunity: Signal Transduction Pathways Involved.

The use of beneficial rhizobacteria (bioeffectors) and their derived metabolic elicitors are efficient biotechnological alternatives in plant immune system elicitation. This work aimed to check the ability of 25 bacterial strains isolated from the rhizosphere of Nicotiana glauca, and selected for their biochemical traits from a group of 175, to trigger the innate immune system of Arabidopsis thaliana seedlings against the pathogen Pseudomonas syringae pv. tomato DC3000. The five strains more effective in preventing pathogen infection were used to elucidate signal transduction pathways involved in the plant immune response by studying the differential expression of Salicylic acid and Jasmonic acid/Ethylene pathway marker genes. Some strains stimulated both pathways, while others stimulated either one or the other. The metabolic elicitors of two strains, chosen for the differential expression results of the genes studied, were extracted using n-hexane, ethyl acetate, and n-butanol, and their capacity to mimic bacterial effect to trigger the plant immune system was studied. N-hexane and ethyl acetate were the most effective fractions against the pathogen in both strains, achieving similar protection rates although gene expression responses were different from that obtained by the bacteria. These results open an amount of biotechnological possibilities to develop biological products for agriculture.