Photoprotection by foliar anthocyanins mitigates effects of boron toxicity in sweet basil (Ocimum basilicum)

Boron (B) toxicity is an important agricultural problem in arid environments. Excess edaphic B compromises photosynthetic efficiency, limits growth and reduces crop yield. However, some purple-leafed cultivars of sweet basil (Ocimum basilicum) exhibit greater tolerance to high B concentrations than do green-leafed cultivars. We hypothesised that foliar anthocyanins protect basil leaf mesophyll from photo-oxidative stress when chloroplast function is compromised by B toxicity. Purple-leafed ‘Red Rubin’ and green-leafed ‘Tigullio’ cultivars, grown with high or negligible edaphic B, were given a photoinhibitory light treatment. Possible effects of photoabatement by anthocyanins were simulated by superimposing a purple polycarbonate filter on the green leaves. An ameliorative effect of light filtering on photosynthetic quantum yield and on photo-oxidative load was observed in B-stressed plants. In addition, when green protoplasts from both cultivars were treated with B and illuminated through a screen of anthocyanic protoplasts or a polycarbonate film which approximated cyanidin-3-O-glucoside optical properties, the degree of photoinhibition, hydrogen peroxide production, and malondialdehyde content were reduced. The data provide evidence that anthocyanins exert a photoprotective role in purple-leafed basil mesophyll cells, thereby contributing to improved tolerance to high B concentrations.     

In vitro rosmarinic acid accumulation in sweet basil (Ocimum basilicum L.)

Leaf-derived suspension cultures of sweet basil, Ocimum basilicum L. accumulated rosmarinic acid up to 10 mg g^–1 dry wt, a value up to 11 times higher than in callus cultures or in leaves of donor plants. Immobilized cells accumulated less than 15 g rosmarinic acid g^–1.     

UV-B is required for normal development of oil glands in Ocimum basilicum L. (sweet basil)

Plants of Ocimum basilicum L. grown under glass were exposed to short treatments with supplementary UV-B. The effect of UV-B on volatile essential oil content was analysed and compared with morphological effects on the peltate and capitate glandular trichomes. In the absence of UV-B, both peltate and capitate glands were incompletely developed in both mature and developing leaves, the oil sacs being wrinkled and only partially filled. UV-B was found to have two main effects on the glandular trichomes. During the first 4 d of treatment, both peltate and capitate glands filled and their morphology reflected their 'normal' mature development as reported in the literature. During the following days there was a large increase in the number of broken oil sacs among the peltate glands as the mature glands broke open, releasing volatiles. Neither the number of glands nor the qualitative or quantitative composition of the volatiles was affected by UV-B. There seems to be a requirement for UV-B for the filling of the glandular trichomes of basil.     

Aqueous and ethanolic leaf extracts of Ocimum basilicum (sweet basil) protect against sodium arsenite-induced hepatotoxicity in Wistar rats

We evaluated the effects of aqueous and ethanolic leaf extracts ofOcimum basilicum (sweet basil) on sodium arsenite-induced hepatotoxicity in Wistar rats. We observed that treatment of the animals with the extracts before or just after sodium arsenite administration significantly (p < 0.05) reduced mean liver and serum γ-Glutamyl transferase (γGT), and serum alkaline phosphatase (ALP) activities when compared with the group administered the toxin alone. In addition, treatments of the animals with aqueous or ethanolic extract of O. basilicum before the administration of sodium arsenite resulted in the attenuation of the sodium arsenite-induced aspartate and alanine aminotransferase activities: ALT (from 282.6% to 167.7% and 157.8%), AST (from 325.1% to 173.5% and 164.2%) for the group administered sodium arsenite alone, the aqueous extracts plus sodium arsenite, and ethanolic extracts plus sodium arsenite respectively, expressed as percentage of the negative control. These findings support the presence of hepatoprotective activity in the O.basilicum extracts.     

Scale-up micropropagation of sweet basil (Ocimum basilicum L.) in an airlift bioreactor and accumulation of rosmarinic acid

Nodal explants with lateral buds and leaf-derived suspension cultures of sweet basil, Ocimum basilicum L., were cultured in 5 l airlift bioreactors for three weeks, thereby increasing the fresh wt of suspension cultures 2.5-fold. Rosmarinic acid accumulated at 29 micromicrog g(-1) dry wt in the suspension culture but, for micropropagated plants, it reached 178 microg g(-1) dry wt.     

Anthocyanin inheritance and instability in purple basil (Ocimum basilicum L.)

The instability of the purple pigments (anthocyanins) in purple basil varieties (Ocimum basilicum L.) limits their use as ornamental plants and as a potential anthocyanin source. Several self-pollinated generations of all purple plants were unsuccessful in stabilizing anthocyanin expression. In this study we investigated the inheritance and stability patterns of leaf traits using the Purple Ruffles variety. The results from the complete diallele crosses indicated anthocyanin expression in vegetative tissue is controlled by two dominant genes and ruffled leaf texture is controlled by a single recessive gene. Genes controlling leaf margin and leaf base structures were tightly linked to leaf texture. Essential oil production and oil constituents in leaves did not change as a result of the reversion in color. Color stability in cuttings was affected by the environment and the location where cuttings were taken. An accumulation of secondary metabolites (apigenin, genistein, and kaempferol) in green-reverted sectors on purple leaves was detected using reverse-phase high-performance liquid chromatography (HPLC) analysis; this suggested a potential block in the anthocyanin pathway. We hypothesize the reversion mutation is occurring in an anthocyanin regulatory gene.     

Salinity-induced changes in essential oil,pigments and salts accumulation in sweet basil (Ocimum basilicum) in relation to alterations of morphological development

The objective of the project was to study salinity-induced effects on essential oil, pigments and salts accumulation in sweet basil (Ocimum basilicum, the cultivar Perrie) in relation to the alteration of plant morphological development and yield production. Hydroponically grown plants were exposed to one of six NaCl concentrations (1, 25, 50, 75, 100 and 130 mM NaCl). Inhibitory effects of salinity on biomass production of the shoot and the root, and area of individual leaves were apparent already under cultivation with 25 mM NaCl. Elevation of salinity from 1 to 100 mM NaCl induced 63% and 61% reductions in fresh and dry herb biomass production, respectively. The stress-induced reduction of foliage biomass sourced mainly from inhibition of leaf area development rather than reduction of internode and leaf number. Cl and Na concentrations in the leaves, stems and roots increased with elevation of NaCl concentration in the cultivation solution. While the extent of Cl accumulation was leaves>stems>roots, Na was largely excluded from the leaves and was preferentially accumulated in roots and the stems, potentially accounting for the moderate sensitivity of the leaf tissue to salinity. Salt stress increased the contents of essential oil and carotenoids in the leaves that may further account for the moderate sensitivity of sweet basil to salinity and suggest a potential for agro-industrial production. A twofold increase in both carotenoid concentration and the percent of essential oil in the fresh tissue was observed by elevation of the salinity from 1 to 130 mM NaCl. Overall, the stress induced increase of the percent of essential oil in the tissue in the salinity range 1–75 mM NaCl was about 50%, and thereby compensated for the similar reduction of biomass production in this salinity range, so that oil production on per plant basis was not reduced by salinity.     

RAPD and essential oil characterization of Turkish basil (Ocimum basilicum L.)

Sweet basil (Ocimum basilicum L., Lamiaceae), an important medicinal plant and culinary herb due to its delicate aroma and fragrance, shows great variation in both morphology and essential oil components. Genetic variation among basil accessions in Turkey has not been extensively examined with molecular markers. Genetic diversity was determined using random amplified polymorphic DNA (RAPD) markers of 14 genotypes of basil. A total of 375 bands were obtained from the RAPD analysis, and 273 of them (70.3 %) were polymorphic. The RAPD analysis allowed the grouping of samples into two main clusters. Genetic similarity values among the basil genotypes ranged between 0.46 and 0.87. Considerable genetic diversity was determined among basil genotypes. Essential oils were obtained by hydro-distillation and were characterized by gas chromatography. A total of 17 chemical components were identified. The evaluated genotypes of O. basilicum can be classified into seven chemotypes: (1) Linalool (7, 12, 16, 22, 25A and 33), (2) Methyl chavicol (6, 10A), (3) Citral/methyl chavicol (10L, 17), (4) Methyl eugenol (11), (5) Methyl cinnamate/linalool (23), (6) Linalool/methyl eugenol (25K), and (7) Methyl chavicol/linalool (Let). The chemical variability obtained from the essential oil composition of the genotypes in the study was remarkable. The chemical characterization of genotypes 10L and 17 was rich in citral (42.17 and 44.80 %) and methyl chavicol (30.56 and 32.03 %). Citral/methyl chavicol can be assessed as a new chemotype of basil cultivated in Turkey. The basil genotypes were grouped into two major clusters for both the RAPD analysis and chemical characterization with very few exceptions (genotype n. 6). A correlation analysis of the genetic distance matrix and the Euclidian distance matrix showed relatively low values (r = ?0.40). The results demonstrated a certain degree of correspondence between chemical and molecular data.     

In vitro clonal propagation of an aromatic medicinal herb Ocimum basilicum L. (sweet basil) by axillary shoot proliferation

Summary An efficient protocol for in vitro propagation of an aromatic and medicinal herb Ocimum basilicum L. (sweet basil) through axillary shoot proliferation from nodal explants, collected from field-grown plants, is described. High frequency bud break and maximum number of axillary shoot formation was induced in the nodal explants on Murashige and Skoog (1962) medium (MS) containing N⁶-benzyladenine (BA). The nodal explants required the presence of BA at a higher concentration (1.0 mg·l⁻¹, 4.4 μM) at the initial stage of bud break; however, further growth and proliferation required transfer to a medium containing BA at a relatively low concentration (0.25 mg·gl⁻¹, 1.1 μM). Gibberellic (GA₃) at 0.4 mg·l⁻¹ (1.2 μM) added to the medium along with BA (1.0 mg·l⁻¹, 4.4 μM) markedly enhanced the frequency of bud break. The shoot clumps that were maintained on the proliferating medium for longer durations, developed inflorescences and flowered in vitro. The shoots formed in vitro were rooted on half-strength MS supplemented with 1.0 mg·l⁻¹ (5.0 μM) indole-3-butyric acid (IBA). Rooted plantlets were successfully acclimated in vermi-compost inside a growth chamber and eventually established in soil. All regenerated plants were identical to the donor plants with respect to vegetative and floral morphology.     

Melatonin influence on in vitro callus induction and phenolic compound production in sweet basil (Ocimum basilicum L.)

The aim of the present study was to evaluate melatonin effects on the callus induction and phenolic compound production of Ocimum basilicum L. (sweet basil). Calluses, derived from leaf explants, were grown on Murashige and Skoog (MS) medium supplemented with 0, 100, or 200 μM melatonin, and subsequently extracted for determination of their phenolic contents. Melatonin decreased the callus induction in both concentrations. Based on the phytochemical analysis, the highest total phenolic acid contents (784.6 μg g⁻¹ and 335.2 μg g⁻¹, respectively) were recorded in calluses grown in 100 and 200 μM melatonin-supplemented medium, compared with the calluses induced with MS alone (192.0 μg g⁻¹). Among the five phenolic acids confirmed in the callus samples, rosmarinic acid was the major constituent. The amount of rosmarinic acid increased significantly in callus grown on 100 μM melatonin medium by nearly 5-fold (754.2 μg g⁻¹), compared with the control group callus. Major volatiles in basil calluses were represented by 3-methylbutanal, benzaldehyde, 1,8-cineole, 2-nonenal, eugenol, and methyl eugenol, and these were in the ranges of 4 to 14%, 24 to 50%, 2 to 3%, 0 to 0.55%, and 2 to 17% (in relative percentages), respectively. The qualitative and quantitative analyses of these substances found in calluses formed on melatonin-supplemented or melatonin-free medium were evaluated separately.

     

The impact of arbuscular mycorrhizal fungi in mitigating salt-induced adverse effects in sweet basil (Ocimum basilicum L.)

Salinity is one of the serious abiotic stresses adversely affecting the majority of arable lands worldwide, limiting the crop productivity of most of the economically important crops. Sweet basil (Osmium basilicum) plants were grown in a non-saline soil (EC = 0.64 dS m⁻¹), in low saline soil (EC = 5 dS m⁻¹), and in a high saline soil (EC = 10 dS m⁻¹). There were differences between arbuscular mycorrhizal (Glomus deserticola) colonized plants (+AMF) and non-colonized plants (−AMF). Mycorrhiza mitigated the reduction of K, P and Ca uptake due to salinity. The balance between K/Na and between Ca/Na was improved in +AMF plants. Growth enhancement by mycorrhiza was independent from plant phosphorus content under high salinity levels. Different growth parameters, salt stress tolerance and accumulation of proline content were investigated, these results showed that the use of mycorrhizal inoculum (AMF) was able to enhance the productivity of sweet basil plants under salinity conditions. Mycorrhizal inoculation significantly increased chlorophyll content and water use efficiency under salinity stress. The sweet basil plants appeared to have high dependency on AMF which improved plant growth, photosynthetic efficiency, gas exchange and water use efficiency under salinity stress. In this study, there was evidence that colonization with AMF can alleviate the detrimental salinity stress influence on the growth and productivity of sweet basil plants.     

The synergistic preservative effects of the essential oils of sweet basil (Ocimum basilicum L.) against acid-tolerant food microflora

Essential oils extracted by hydrodistillation from five different varieties of Ocimum basilicum L. plants (Anise, Bush, Cinnamon, Dark Opal and a commercial sample of dried basil) were examined for antimicrobial activity against a wide range of foodborne Gram-positive and -negative bacteria, yeasts and moulds by an agar well diffusion method. All five essential oils of basil showed antimicrobial activity against most of the organisms tested with the exception of Flavimonas oryzihabitans and Pseudomonas species. The inhibitory effect of Anise oil, in comparison with mixtures of the predominant components of pure linalool and methyl chavicol, against the acid-tolerant organisms, Lactobacillus curvatus and Saccharomyces cerevisiae , was examined in broth by an indirect impedance method. Synergistic effects between Anise oil, low pH (pH 4·2) and salt (5% NaCl) were determined. The antimicrobial effect of Anise oil was also assessed in a tomato juice medium by direct viable count, showing that the growth of Lact. curvatus and S. cerevisiae was completely inhibited by 0·1% and 1% Anise oil, respectively. The results of the current study indicate the need for further investigations to understand the antimicrobial effects of basil oils in the presence of other food ingredients and preservation parameters.     

Shoot regeneration of young leaf explants from basil (Ocimum basilicum L.)

Summary An efficient plant regeneration protocol was successfully developed for basil (Ocimum basilicum L.). Explants from 1 mo. old seedlings yielded the highest frequency of 85% regeneration with an average of 5.1 shoots per explant. The regeneration protocol was performed on three basil varieties (Sweet Dani; methylcinnamate; Green Purple Ruffles). Callus and shoot induction was initiated on Murashige and Skoog basal medium supplemented with thidiazuron (16.8 μM) for approximately 30 d. Shoot induction and development were achieved by refreshing the induction medium after 14 d. The most morphogenetically responsive explants were from the first fully expanded true leaves of greenhouse-grown basil seedlings. All developing bud tissue demonstrated temporary anthocyanin expression; however, anthocyanin expression in Green Purple Ruffles remained stable until maturity. Developing shoots were rooted in the dark on media with thidiazuron removed. Within 20 d, rooted plantlets were transferred and acclimatized under greenhouse conditions where they developed normal morphological characteristics. This is the first report of a successful in vitro regeneration system for basil through primary callus.     

Patterns and mechanisms of temporal resource partitioning among bee species visiting basil (Ocimum basilicum) flowers

The way in which flower visitors share floral resources or compete for them throughout the day is a decisive factor for the effectiveness of pollination. We described daily rhythms of flower visitation by bee species and tested whether such patterns depend on: (1) the body size of the species, (2) the daily patterns of variation in weather and nectar standing crop, and (3) the effects of weather on the daily rhythm of variation in nectar standing crop. After 1 year of biweekly samplings, we encountered 56 bee species visiting basil flowers. Larger bee species were more active in the cooler and more humid hours of the morning. Smaller species foraged later, during the warmer and drier hours. Throughout the day, nectar volume decreased. In the laboratory, we determined a positive effect of increase in temperature on nectar volume, unlike the negative correlation recorded in the field. Nectar volume decreased in plants under experimental drought, showing similarity with the driest hours of the day. The daily cycle of temperature is the fundamental factor that, directly and indirectly, via air humidity, soil moisture, and nectar supply, influences bee activity according to body size and physiological attributes. In the field, the positive effect of increasing temperatures on nectar volume is masked by a stronger, negative effect of decreasing air humidity and soil moisture throughout the day.     

Correlated accumulation of anthocyanins and rosmarinic acid in mechanically stressed red cell suspensions of basil (Ocimum basilicum)

A red basil cell line (T2b) rich in rosmarinic acid (RA) was selected for the stable production of anthocyanins (ACs) in the dark. Cell suspension cultures were subjected to mechanical stress through increased agitation (switch from 90 to 150 rpm) to determine the relationship between AC and RA accumulation. Cell extracts were analyzed by HPLC and LC-MS, and the resulting data were processed with multivariate statistical analysis. MS and MS/MS spectra facilitated the putative annotation of several complex cyanidin-based ACs, which were esterified with coumaric acid and, in some cases, also with malonic acid. It was also possible to identify various RA-related molecules, some caffeic and coumaric acid derivatives and some flavanones. Mechanical stress increased the total AC and RA contents, but reduced biomass accumulation. Many metabolites were induced by mechanical stress, including RA and some of its derivatives, most ACs, hydroxycinnamic acids and flavonoids, whereas the abundance of some RA dimers was reduced. Although AC and RA share a common early biosynthetic pathway (from phenylalanine to 4-coumaroyl-CoA) and could have similar or overlapping functions providing antioxidant activity against stress-generated reactive oxygen species, there appeared to be no competition between their individual pathways.     

Effects of oxidative stress caused by NaCl or Na2SO4 excess on lipoic acid and tocopherols in Genovese and Fine basil (Ocimum basilicum)

With this investigation, we aimed to study more deeply the antioxidative response to moderate doses of NaCl or Na₂SO₄ in two cultivars of basil differentially sensitive to salinity. Tolerance to salinity was previously evaluated by the extent of growth inhibition whereas the antioxidant response was assessed studying the changes in the activities of superoxide dismutase (SOD) and catalase as well as in the amounts of tocopherols and lipoic acid. To make possible the comparison of the responses of basil cv. Genovese and cv. Fine to different salts, the experiment was carried out with equimolar concentrations of Na⁺. The results showed that changes caused by salinity were dependent on cultivar and exposure time. In particular, cv. Genovese was more sensitive to Na₂SO₄ excess than cv. Fine whereas both of them had higher SOD activity under NaCl salinity. Generally, Fine basil withstood salinity better than Genovese, being endowed with higher constitutive levels of reduced lipoic acid [dihydrolipoic acid (DHLA)] as well as of α‐ and γ‐tocopherols. Moreover, cv. Fine showed the ability to utilise DHLA and to synthesise tocopherols during stressful conditions. Thus, more than one mechanism was involved in basil in the detoxification of reactive oxygen species during salt stress. In fact, when lipoic acid did not participate in the regeneration of reduced ascorbate and glutathione form, high amounts of tocopherols were present, likely protecting cell membranes from oxidative damage and making basil tolerant to moderate salinity.     

薄荷和罗勒提取物体外抗氧化及保肝活性研究

采用国际常用的ABTS和DPPH方法评价唇形科植物薄荷(Mentha haplocalyx) 和罗勒(Ocimum basilicum)水提物和乙醇提取物体外抗氧化活性,选用HepG2细胞,通过乙醇诱导损伤,构建体外酒精性肝损伤细胞模型,以细胞存活率评价薄荷和罗勒提取物的保肝效果。结果表明,DPPH自由基清除能力大小依次为薄荷醇提物、薄荷水提物、罗勒醇提物、罗勒水提物,半效应浓度(EC₅₀)分别为70.42 μg·mL^-1、75.77 μg·mL^-1、354.87 μg·mL^-1、451.53 μg·mL^-1。ABTS自由基清除能力大小依次为薄荷醇提物、罗勒醇提物、薄荷水提物、罗勒水提物,EC50值分别为9.04 μg·mL^-1、18.03 μg·mL^-1、22.18 μg·mL^-1、36.88 μg·mL^-1。薄荷提取物的抗氧化能力整体优于罗勒提取物,醇提物抗氧化能力优于水提物。酒精性肝损伤细胞活性检测表明,5、10、20、50 μg·mL^-1薄荷水提物、薄荷醇提物和罗勒水提物能剂量依赖性地提高乙醇诱导损伤的细胞存活率,具有一定的保肝活性。     

Light-mediated biosynthesis of phenylpropanoid metabolites and antioxidant potential in callus cultures of purple basil (Ocimum basilicum L. var purpurascens)

Plant Cell, Tissue and Organ Culture (PCTOC) - Ocimum basilicum L. var purpurascens (purple basil) contains medicinally valuable metabolites. Light greatly influences the physiological processes,...     

Repellent and acaricidal activities of basil (Ocimum basilicum) essential oils and rock dust against Ixodes scapularis and Dermacentor variabilis ticks

Repellent and acaricidal activity of essential oils extracted from three varieties of basil (Ocimum basilicum L.) were evaluated on blacklegged ticks (Ixodes scapularis Say) and American dog ticks (Dermacentor variabilis Say) in laboratory conditions. Essential oils were extracted and characterized through gas chromatography-mass spectrometry, and tested at different concentrations for long-term repellent activity using horizontal bioassays. In addition, basil essential oils were combined with an inert material (i.e., granite rock dust) with known insecticidal and miticidal properties to assess acaricidal activities against adult ticks. Among the tested basil varieties, var. Jolina essential oil at 15% vol/vol concentration repelled 96% of tested ticks up to 2 h post-treatment. The EC₅₀ for I. scapularis nymphs was 4.65% vol/vol (95% confidence interval: 4.73–4.57). In acaricidal tests, the combination of essential oil from var. Aroma 2 at 10% wt/wt with rock dust resulted in 100% tick mortality after only 24 h post-exposure, with a LD₅₀ of 3.48% wt/wt (95% CI 4.05–2.91) for freshly prepared treatment tested on I. scapularis adults. The most common compounds detected in basil essential oils by GC–MS were linalool (52.2% in var. Nu Far, 48.2% in Aroma 2, 43.9% in Jolina), sabinene (6.71% in Nu Far, 8.99% in Aroma 2, 8.11% in Jolina), eugenol (11.2% in Jolina, 8.71% in Aroma 2), and estragole (18.2% in Nu Far). The use of essential oils alone and in combination with rock dust provides an innovative and environmentally friendly approach for managing ticks and inhibiting vector-borne disease transmission.