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.

Two TOBAMOVIRUS MULTIPLICATION 2A homologs in tobacco determine 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 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 non-host 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.

Fungal endophytes of some medicinal plant growing in northwestern coast of Egypt: Isolation, identification and two-way clustering analysis of its antimicrobial activity

One of hidden mine of antibiotics is endophytic fungi especially that inhibited medicinal plants. In this regard, leaves, stems, fruits and bulbs of some commonly medicinal plants growing in Northwestern coast of Egypt were subjected for isolation of endophytic fungi with screening study of its antimicrobial activity. Practically, more than one hundred (101) endophytic fungal species isolated from Scorpiurus muricatus, Mellilotus indicus, Lotus polyphyllos, Ononis vaginalis, Nicotiana glauca, Lycium europaeum, Asphodelus aestivus, Echium angustifolium,Fagonia cretica, Pancratium maritimum,and Carduus getulus were tested in vitro for their antimicrobial activities against E. coli, Pseudomonas argenosa, Staphylococcus aureus, Bacillus subtilus, Candida albicanus, Candida glabrata, Penicillium expansum, Aspergillus flavus. The values of applied diversity indices revealed significant differences in presence, absence and abundance among endophytic fungal isolates. To the best of our knowledge, the present study is the first to report of Alternaria pluriseptata as endophytic species with most dominant and most active in its anitimicrobial activity among the isolated species. Seven distinctive groups were revealed from the two-way cluster analysis showing the intensity of antimicrobial activity against tested pathogens: Twenty-five percent of the isolates (26 strains assembled together in group V) exhibited no antimicrobial activity against all tested pathogens while six percent (6 isolates) assembled in group VII revealed high antimicrobial activity against five pathogens.

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.

Fatty Alcohols, a Minor Component of the Tree Tobacco Surface Wax, Reduce Insect Herbivory

Despite decades of research resulting in a comprehensive understanding of epicuticular wax biosynthesis and metabolism, the function of these almost ubiquitous metabolites in plant-herbivore interactions remains unresolved. To develop a better understanding of this role, we investigated plant-herbivore interactions in four Nicotiana glauca (tree tobacco) genome edited mutants. This included [eceriferum1 (cer1), eceriferum3 (cer3), beta-ketoacyl-coA synthase6 (kcs6), and fatty acyl-coA reductase (far)] displaying a wide range of alkane and fatty alcohol abundances. Three interaction classes were examined: chewing herbivory with seven caterpillar and one snail species, phloem feeding with Myzus persicae (green peach aphid), and egg laying with Bemisia tabaci (sweet potato whitefly). We found that high wax load and alkane abundance did not reduce caterpillar or snail herbivory. However, fatty alcohol content was negatively correlated with caterpillar growth, suggesting a role in reducing insect herbivory despite its lower levels. Aphid reproduction and feeding activity were not correlated with wax load and composition but are potentially affected by altered cutin composition of cer1 mutants. When examining non-feeding activities, wax crystal morphology could explain the preference of B. tabaci to lay eggs on wildtype plants relative to cer1 and far mutants. Accordingly, the fatty alcohol wax component reduces caterpillar herbivory on the chemical level, but oviposition is increased when wax crystals are dense. The results suggest that this varied response between herbivore classes and species, at times displaying increased and at times reduced fitness in response to altered wax composition is in part a consequence of co-evolution that shaped the specific effects of different N. glauca metabolites such as anabasine and fatty alcohols in plant-herbivore interactions.

Cuticular Wax Composition is Essential for Plant Recovery Following Drought with Little Effect under Optimal Conditions

Despite decades of extensive study, the role of cuticular lipids in sustaining plant fitness is far from being understood. To answer this fundamental question, we employed genome editing in tree tobacco (Nicotiana glauca) plants and generated mutations in 16 different cuticular lipids-related genes. We chose tree tobacco due to the abundant, yet simply composed epicuticular waxes deposited on its surface. Five out of 9 different mutants that displayed a cuticular lipids-related phenotype were selected for in depth analysis. They had either reduced total wax load or complete deficiency in certain wax components. This led to substantial modification in surface wax crystal structure and to elevated cuticular water loss. Remarkably, under non-stressed conditions, mutant plants with altered wax composition did not display elevated transpiration or reduced growth. However, once exposed to drought, plants lacking alkanes were not able to strongly reduce their transpiration, leading to leaf death and impaired recovery upon resuscitation, and even to stem cracking, a phenomenon typically found in trees experiencing drought stress. In contrast, plants deficient in fatty alcohols exhibited an opposite response, having reduced cuticular water loss and rapid recovery following drought. This deferential response was part of a larger trend, of no common phenotype connecting plants with a glossy appearance. We conclude that alkanes are essential under drought response and much less under normal non-stressed conditions, enabling plants to seal their cuticle upon stomatal closure, reducing leaf death and facilitating a speedy recovery.

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.