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When conducting research on polyphenols and their effects on health, it is of primary importance to use standardised and validated dietary assessment tools. This paper aims at assessing the validity of a food frequency questionnaire (FFQ) for quantifying dietary polyphenol exposure among healthy adults using the method of triads. Fifty-three healthy adults, aged 20-60, were included in the study. Total dietary polyphenol intake (TDP) estimated by the FFQ was compared with TDP measured by a 3-day food record (FR) and with urinary excretion levels of total polyphenols (TUP). Pearson correlations were calculated between methods. Validity coefficients (VC) were estimated between the three measurements and the 'unknown' true intake. There was a strong correlation between both dietary methods (r = 0.70, p 0.0001). A moderate but significant association was observed between FFQ-derived TDP and TUP (r = 0.32, p = 0.020). The method of triads yielded a VC for the FFQ of 0.63 (95%CI: 0.41-0.84), indicating a strong relationship between FFQ-derived TDP and the true polyphenol intake. This study shows that the FFQ is an adequate tool not only for measuring dietary polyphenol exposure in nutrition epidemiological studies but also for guiding clinicians in dietary advice and counselling.

Introduction Medicinal applications of Genista species throughout the Mediterranean area are widespread. More specifically, Genista ferox Poirret., endemic to North Africa, holds important diuretic, anti-gout and –rheumatism actions. It is also employed for the treatment of scrofulous tumors. The aim of the present study was to evaluate the antioxidant and anti-proliferative effects of the ethanolic extract and isolated fractions of aerial parts of G. ferox. Identification by UPLC and NMR analyses of constituents of the most active fraction was equally carried out. Methods Genista ferox extract and fractions were examined for their total flavonoid content, scavenging activities against DPPH, ABTS and OH· radicals, H2O2 elimination, Fe++ chelating capacity. Anti-proliferative activity using breast carcinoma cells (MCF-7) and CDC25 phosphatase was also assessed. Results Significant levels of flavonoids were recorded in FIII fraction which exhibited the highest inhibition percentages against DPPH (95.79 ± 1.37), ABTS (83.17 ± 4.30) (p Conclusion Data from the present study suggest that Genista ferox is a rich source for value-added molecules as potential antioxidants and anti-proliferative agents for optimal human health.

The objective of this study is to investigate the effects of three home cooking methods traditionally used all around the world (boiling, steaming and microwaving) in two vegetables: broccoli and red cabbage. Their effects on phytochemical content (i.e., polyphenols, ascorbic acid, anthocyanins, glucosinolates, and sulforaphane) and on total antioxidant capacity were investigated. Steaming and microwaving were explored to understand the effect of cooking time and/or cooking power. Nutrient and health-promoting compounds in broccoli and red cabbage are significantly affected by domestic cooking. The boiling seems to result in a very significant loss of nutritional compounds by leaching in cooking water. However, steaming and microwaving allowed the preservation of the higher quantities of bioactive compounds such as antioxidant compounds and glucosinolates. Microwave cooking significantly influenced the concentrations of bioactive compounds such as ascorbic acid, anthocyanins and sulforaphane. Sulforaphane content increased four or six times during the first minute of microwaving in the two vegetables.

Objective Polyphenol-rich products such as fruit juices have been found to have strong antioxidant capacities and to induce potent endothelium-dependent relaxation. We evaluated whether the commercial blackcurrant juices induced endothelium-dependent relaxation of isolated coronary arteries can be related to their antioxidant capacity and/or phenolic content. Methods Six different commercial blackcurrant juices were selected. Their main phenolic compounds were measured by ultra-performance liquid chromatography and antioxidant capacity was evaluated by spectrometric methods. Vascular reactivity studies with these juices were done using isolated porcine coronary arteries. Results The six different commercial blackcurrant juices induced relaxation ranging from 21% to 100% at the concentration of 0.5% volume per volume (v/v). The relaxation induced at 0.5% v/v was not correlated to their antioxidant capacity measured by either oxygen radical antioxidant capacity or DPPH (2,2-diphenyl-1-picrylhydrazyl) assays and also not to the ascorbic acid, total polyphenols, total flavanols, and total phenolic acid contents. In contrast, the amplitude of the relaxation was correlated to the total anthocyanins content and the individual anthocyanin concentration. Conclusions Correlations between relaxation amplitude and total anthocyanin or individual anthocyanin contents are of interest for the development of functional blackcurrant beverages with the potential to promote vascular protection.

BACKGROUND: Several studies have shown that cherries, especially sour cultivars, contain substantial amounts of phenolic compounds. OBJECTIVE: This study aims to (i) analyze the total phenolic compound (TPC) content and the antioxidant capacity (AC) of a large range of cultivars using the same methodology in one laboratory, and (ii) determine the possible relationship between agronomic characteristics and AC. METHODS: A total of 245 samples including sweet, sour and hybrid cultivars from our collections were harvested at their optimum maturity and characterized according to their TPC, DPPH and ORAC values. RESULTS: The TPC content and DPPH and ORAC values varied greatly among the cherries, with the sour cultivars presenting higher levels than the sweet ones. The PCA plot showed a slight grouping by species and confirmed the high TPC content level in sour cultivars. The bi-colored cultivars had lower TPC and antioxidant capacity (AC) values than dark-colored ones, indicating that coloration could give an indication of the AC of fruits. No significant relationship between the agronomic and chemical properties was highlighted. CONCLUSIONS: Cherry fruits, especially from sour cultivars, represent an important source of bioactive compounds and could attract new interest as a ‘functional food’.

Chronic liver diseases with portal hypertension are characterized by a progressive vasodilatation, endothelial dysfunction, and NADPH oxidase-derived vascular oxidative stress, which have been suggested to involve the angiotensin system. This study evaluated the possibility that oral intake of polyphenol-rich blackcurrant juice (PRBJ), a rich natural source of antioxidants, prevents endothelial dysfunction in a rat model of cirrhosis induced by chronic bile duct ligation (CBDL), and, if so, determined the underlying mechanism. Male Wistar rats received either control drinking water or water containing 60 mg/kg gallic acid equivalents of PRBJ for 3 weeks before undergoing surgery with CBDL or sham surgery. After 4 weeks, vascular reactivity was assessed in mesenteric artery rings using organ chambers. Both the acetylcholine-induced nitric oxide (NO)- and endothelium-dependent hyperpolarization (EDH)-mediated relaxations in mesenteric artery rings were significantly reduced in CBDL rats compared to sham rats. An increased level of oxidative stress and expression of NADPH oxidase subunits, COX-2, NOS, and of the vascular angiotensin system are observed in arterial sections in the CBDL group. Chronic intake of PRBJ prevented the CBDL-induced impaired EDH-mediated relaxation, oxidative stress, and expression of the different target proteins in the arterial wall. In addition, PRBJ prevented the CBDL-induced increase in the plasma level of proinflammatory cytokines (interleukin [IL]-1α, monocyte chemotactic protein 1, and tumor necrosis factor α) and the decrease of the anti-inflammatory cytokine, IL-4. Altogether, these observations indicate that regular ingestion of PRBJ prevents the CBDL-induced endothelial dysfunction in the mesenteric artery most likely by normalizing the level of vascular oxidative stress and the angiotensin system.

The present study aimed to assess antioxidant activities of three organs (flower, fruit, and stem) extracts of Tunisian Ferula (F.) communis. Various experimental models were used to characterize the antioxidant activities in vitro as well as on ROS-induced fluorescence using dichlorofluorescein technique from phorbol myristate acetate (PMA)-stimulated human myeloid cell line HL-60. Results showed that the antioxidant activities varied considerably with organs. Thus, flower exhibited higher DPPH-scavenging ability, reducing and chelating power than stem and fruit. Also, antioxidant capacities using ORAC method and a cell-based assay showed that fruit and stem exhibited statistically similar antioxidant activities. Moreover, F. communis contains high amounts of flavonoids with various health benefits attributed to their antioxidant potential. Likewise, to obtain biologically relevant information, the antioxidant activities of the extracts were evaluated on cellular models implicating the antioxidant activities; this test generally showed that F. communis flower extracts have the highest antioxidant capacities correlated to the highest total phenolic content. The identification of phenolic compounds in F. communis extracts using RP-HPLC revealed that resorcinol, ferulic, and syringic acids together with coumarin were the major molecules.

Low multiplication ratio of yam and scarcity of planting materials are major constraints militating against sustainable yam production. In order to evaluate the behavior of the four various types of seeds of two species of yams Dioscorea cayenensis and Dioscorea rotundata, cultivated on the experimental ground of the Higher National Institute of Agronomy and Biotechnology (INSAB), a test was realized in a randomized complete block design with six replications. The samples were cut and three levels of each tuber were used: proximal, medial and distal parts of the tuber. The fragments of tuber and the whole tuber represent the various types of seed used in this work. The results showed significant (P

L’entretien de la culture d’hevea est une contrainte pour Olam Rubber pour une meilleure exploitation des arbres. La presente etude vise a evaluer l’efficacite de deux herbicides a base de glyphosate et fluroxypyr sur les adventices les plus frequents dans la culture d’hevea a Batouri au Gabon. L’essai etait compose de trois blocs d’interlignes, repartis sur trois sites et comportant 16 placettes chacun. Au total, 15 traitements chimiques (T1 a T15) ont ete compares a un traitement manuel (T0) avec trois repetitions. L’impact de ces traitements sur les adventices a ete mesure par la frequence de presence des especes, le temps d’execution des desherbages, les temps de fanaison, jaunissement, senescence et sur la remanence en fonction des traitements, des doses et des sites de culture. Les resultats montrent que l’inventaire floristique a permis de recenser 42 especes reparties en 33 genres et 20 familles dont 8 especes sont les plus frequentes sur les sites. La reaction des adventices aux traitements a varie d’une espece a l’autre. Le temps moyen pour executer le desherbage chimique (21,63 minutes) est inferieur a celui necessaire pour le desherbage manuel (36,57 minutes). Des differences hautement significatives au seuil de 5% (P

Objective: The objective is to evaluate the antioxidant potential of several polar fractions of Pluchea carolinensis and Pluchea rosea as well as pure chemicals, some of them quantified in both species by high-performance liquid chromatography (HPLC). Methods: The antioxidant potential of polar fractions and pure chemicals were assayed by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and oxygen radical potential methods. The phenolic content was performed by using Folin-Ciocalteu’s reagent. Specific phenolic acids and flavonoids were quantified by diode array detector-reversed phase-HPLC. Results: The highest DPPH antioxidant potential expressed in milligrams of trolox equivalents per gram of dry extract (mg TE/gDE) were frequently measured in fractions from n-butyl alcohol, i.e., 2 (192.1 ± 0.3); 6 (181.0 ± 0.1) of P. carolinensis and in fraction 7 (188.1 ± 5.5) of P. rosea while for oxygen radical scavenging capacity (mg TE/gDE) assay fraction 2 (543.0 ± 64.6) and 4 (501.4 ± 49.7) of P. carolinensis and 3 (401.3 ± 16.1) and 6 (401.3 ± 16.1) of P. rosea showed the best results. Some flavonoids and phenolic acids were also assayed; all of them showed highest oxygen radical absorbance capacity values. Conclusion: We report the antioxidant potential of polar fractions, as well as of some pure phenolics responsible of the antioxidant potential. Some phenolics were identified and quantified for the first time in both species. Apparently, caffeoylquinic acid derivatives contribute more significant to the total antioxidant potential of the extracts.

Wines produced from various grape varieties present different properties affecting taste and color. The hypothesis was that grape genotype could have a deep impact on wine antioxidant properties and phenolic composition. But in this study on 38 different wines of 4 main grape varieties, large variability in the levels of individual phenolic compounds as well as in antioxidant capacity was observed in each grape variety. Comparisons of the wine varieties based on their individual phenolic profile (flavonols, anthocyanidins, flavan-3-ols, phenolic acids, resveratrol, etc.) and antioxidant capacities (ORAC, DPPH, hemolysis, ESR, and total phenolics) showed limited differences. An exception was the group of wines made from the grape variety Pinot Noir, in which the range of phenolic compounds was different from the other wines: anthocyanidins (87 mg L−1, 119–206 mg L−1 in other grape varieties) and flavonols (17 mg L−1, 20–57 mg L−1in others except Primitivo) showed lower levels while flavanols (327 mg L−1, 152–244 mg L−1 in others) and phenolic acids (161 mg L−1, 103–152 mg L−1 in others) showed levels higher than in the other wines. This different profile was associated with a lower antioxidant capacity (i.e. mean ORAC value: 20988 for Pinot Noir, 27820–33651 for others; ORAC concentration μmol TE L−1; see Section 2.3.3 ).

BACKGROUND: Small dark fruits represent one of the most important sources of bioactive compounds with antioxidant capacity in the human diet. The content of health-promoting antioxidants in these fruits may be important information to take into account when a fruit producer has to choose which cultivar to grow. OBJECTIVE: It is important to know how antioxidant capacity and antioxidant compounds as total phenolics and ascorbic acid vary between 9 small dark fruit species and for each species among cultivars (2 to 10 per species). METHODS: The antioxidant capacity (ORAC assay), total phenolic (Folin-Ciocalteu) and ascorbic acid content were measured in 9 fruits (plums, blackcurrants, blackberries, blueberries, cherries, redcurrants, raspberries, white currants and gooseberries) / 42 cultivars harvested at maturity during their high production period. RESULTS: The comparison of the average of the various cultivars of each small fruits showed that blackcurrants had the best antioxidant capacity (with plums), the highest ascorbic acid content and the highest total phenolic content (with blackberries). The present study shows that total phenolic compounds, ascorbic acid and antioxidant capacity strongly differed between genotypes of each small dark fruits. Other parameters as harvest time, culture conditions and maturity degree at the harvest may also influence the antioxidant capacity of small fruits. CONCLUSIONS: Among small dark fruits, blackcurrants have high qualities. Choices of variety, harvest time and maturity degree are important for all fruits.

Hyperhydricity is a physiological disorder affecting tissue-culture-generated plants. It is associated with excessive hydration and poor lignification. The effects of exogenous polyamines (spermidine and putrescine) and polyamine precursors (arginine and ornithine) were studied on ‘Jonagold’ apple shoots subjected to hyperhydric conditions for one in vitro multiplication cycle (28 days) on a culture medium containing gelrite as gelling agent. Supplementation of the gelrite-containing medium with 10−5 M spermidine, ornithine, or arginine reduced the percentage of hyperhydricity by at least 50 %. Exogenous supplementation with spermidine or a polyamine precursor also caused total phenolics and the antioxidant capacity (measured by ORAC and DPPH assays) to decrease in shoots during the first 2 weeks. These results suggest an important role of spermidine and its precursor ornithine in countering hyperhydricity. Supplementation could help to maintain high endogenous levels of polyamines and phenolamides necessary for cell osmoregulation, antioxidant protection, cell wall cross-linking, and plant growth regulation.

The present study was designed to test the hypothesis that an increased consumption of fruits and vegetables up to 600 g per day in type 2 diabetes patients can reduce oxidative damages to lipids. After a clinical examination, 29 type 2 diabetes patients were divided into two groups: the first one did not receive any special instructions about the diet while the second one received fruits and vegetables consumption advices thanks to a picture catalogue describing types of fruits and vegetables as well as quantities to be eaten every day. After two months of intervention, plasma concentrations in vitamin C, b-carotene and polyphenols remained unchanged in both groups when compared to baseline values. No significant decrease in lipid peroxidation as evidenced by nine biomarkers (malonaldehyde as TBAR’s, lipid peroxides, oxidized LDL, antibodies against oxidized LDL, isoprostanes, 7-keto-cholesterol, 7b-hydroxycholesterol, 4-hydroxynonenal metabolite, LDL size) was also noted. In conclusion, our findings confirmed the fact that the effect of high intake of fruits and vegetables on reducing oxidative damage to lipids remains largely controversial even in patients having an oxidative stress profile. Moreover, the present leaves open the question of the most appropriate markers of lipid peroxidation since only small correlations were evidenced between the large battery of tests investigated.

The influence of sample dilution on the measurement of antioxidant capacity was analyzed. To ensure the reproducibility of results, it is necessary to realize such scarce investigations. This study focuses on different antioxidant capacity assays commonly used for the analysis of pure substances and food extracts. For all compounds and foods tested in most of the four assays (Trolox equivalent antioxidant capacity, 2,2-diphenyl-1-picrylhydrazyl, and oxygen radical absorbance capacity), effects of sample dilution on the measured (and recalculated) antioxidant capacity were observed, with differences up to 28 % between dilutions. An extrapolation method was proposed to obtain a “real value” thus to minimize the effects of the sample dilution. This extrapolation method is relatively simple, based on a linear regression of 4 or 5 appropriate dilutions of the sample and applicable to the various assays. The use of such a method will improve the consistency of interlaboratory antioxidant capacity data and thus permit better comparisons. In contrast, there was no dilution problem with ferric reducing antioxidant power assays.

It is widely accepted that ORAC is a useful method for assessing food extracts that contain various antioxidants. The principal aim of this study was to validate the ORAC assay. We first identified parameters that can interfere with the ORAC assay and we optimized it. Then, experiments were conducted to determine the limits of linearity and response function, to determine the accuracy profiles to circumvent some of the drawbacks of traditional validation procedures. Trueness, selectivity and limits of quantification of the method were also determined. Our objective of ORAC method validation is thus to give guarantees that most of the results generated during use of this method will be close enough to unknown true value of antioxidant capacity of food matrices. The validation results indicate that the described method will give accurate and reliable results for Trolox equivalent values ranging from 50 to 200 μmol/L.

A new application of surface-enhanced Raman scattering (SERS) in the field of plant material analysis is proposed in this study. The aim was to monitor the release of anatabine by methyl jasmonate (MeJa) elicited Bright Yellow-2 (BY-2) cells. Gold nanoparticles (AuNps) were used as SERS substrate. The first step was to study the SERS activity of anatabine in a complex matrix comprising the culture medium and BY-2 cells. The second step was the calibration. This one was successfully performed directly in the culture medium in order to take into account the matrix effect, by spiking the medium with different concentrations of anatabine, leading to solutions ranging from 250 to 5000 µg L−1. A univariate analysis was performed, the intensity of a band situated at 1028 cm−1, related to anatabine, was plotted against the anatabine concentration. A linear relationship was observed with a R2 of 0.9951. During the monitoring study, after the MeJa elicitation, samples were collected from the culture medium containing BY-2 cells at 0, 24 h, 48 h, 72 h and 96 h and were analysed using SERS. Finally, the amount of anatabine released in the culture medium was determined using the response function, reaching a plateau after 72 h of 82 µg of anatabine released/g of fresh weight (FW) MeJa elicited BY-2 cells.

Blackcurrant berries contain high amounts of flavonoids with various health benefits as anti-inflammatory properties attributed to their antioxidant potential. Leaves and buds actually used to produce food supplement could also exhibit such interesting properties. In the literature, various methods are often used and valid indicators of the antioxidant potential of dietary substances. However these assays do not provide evidence that antioxidants have in viv o or ex vivo activity when consumed. To obtain biologically relevant information, the antioxidant activities of the extracts were evaluated on cellular models implicating the measurement of blood haemolysis, the Cellular Antioxidant Activity on endothelial cells and the anti-inflammatory activities on isolated equine stimulated neutrophils and purified myeloperoxidase. These tests generally showed that the blackcurrant leaf extract have the highest antioxidant and anti-inflammatory (inhibition of MPO activity and ROS production on activated neutrophils) capacities correlated to the highest total phenolics content.

The estimated antioxidant capacity of different matrices can vary considerably between research reports. Besides intrinsic factors (not studied here), our work showed that may have various causes. Firstly, different methods are used to measure antioxidant capacity. Secondly, the results obtained for a single matrix by one method (such as ORAC) can vary with the extraction conditions. Parameters having a great impact on the amount and composition of antioxidants in extracts, and thus on the measured antioxidant capacity, notably include the extraction solvent composition, temperature, extraction time (duration), solvent-to-solid ratio, and storage conditions. Standardisation of the extraction procedure is thus necessary for accurate and reproducible determination of the antioxidant capacity and phenolics in different food matrices by different laboratories. In this study we optimised such a procedure for four fresh plant matrices (orange, apple, leek, and broccoli). The optimised procedure requires extraction in a mixture of acetone/water/acetic acid (70/28/2, v/v/v) for 1 h at 4 °C, with a solvent-to-solid ratio of 20 mL per 1 g. Fresh material should be used, but if this is not possible, one may lyophilise the plant matrices or store the extracts for a few days at −20 °C before analysis.

Small fruits such as berries have low energy contents, but high contents of vitamins, micronutrients, and dietary fibers and constitute a good source of natural antioxidant compounds that are important constituents of the human diet. This study identified a large number of compounds in an extract of black currant showing high antioxidant activity and compared their profile in various parts of the plants (leaves, buds, and berries). If it was known that berries contained very high levels of natural phenolic compounds, this study showed that leaves and buds could also be considered good sources of natural antioxidants. Indeed, they contained high amounts of phenolic acids, flavonoids, and carotenoids. An acetone mixture can extract several classes of phenolic compounds with a good yield of flavonols, flavan-3-ols, and anthocyanins.

Polyphenol compounds present in high quantity in wines are well-known to have potent cardio-protective properties through several biological mechanisms including antioxidant activity [1]. A large number of methods have been developed for evaluating the antioxidant capacity of food matrices. Most of them have, however, the disadvantage of being time consuming and require specific analytical protocols and devices. In the present study, we present the electrochemical PAOT (Pouvoir Antioxydant Total)-Liquid® Technology which can be easily used by winemakers for evaluating antioxidant activity of wine during all steps of making process. The methodology is based on the measurement of electric potential variation resulting from chemical reactions between wine polyphenols and a free radical mediator M• as source of oxidants. Total antioxidant activity as estimated by the PAOT-Liquid® activity was 6.8 fold higher in red wines (n = 14) when compared to rosé (n = 3) and white (n = 3) wines bought in a commercial market. Moreover, PAOT-Liquid® activity was highly correlated with total polyphenols content (TPC) of all wines (r = 0.9540, p &lt, 0.0001) and the classical DPPH (2,2-diphenyl-1-picryhydrazyl) assay which is often used for evaluating antioxidant capacity of food matrices (r = 0.9102, p &lt, 0.0001).

The aim of the present study was to investigate if the polyphenol content of various commercial plant, fruits and berries extracts was linked to vasorelaxation properties. A total of 24 commercial extracts (including black currant fruit, green tea, grape seed, leucocyanidins of grape seed, pine bark, apple, pomegranate, bilberry, red vine, citrus pericarp, bitter orange, cocoa, aronia, raspberry leaf, hibiscus, olive leaf, olive fruit and a mix of olive fruit and leaf) was assessed on porcine coronary artery rings. Among all extracts, the most important endothelium-dependent vasorelaxation were obtained with grape seed (EC50=0.87 µg/ml and 2.0 µg/ml), leucocyanidins of grape seed (EC50=1.6 µg/ml), pine bark (EC50=2.2 µg/ml and 3.1 µg/ml), apple (EC50=2.2 µg/ml), cocoa (EC50=3.6 µg/ml), black currant (EC50=6.6 µg/ ml), pomegranate (EC50=6.6 µg/ml) and aronia EC50=12.7 µg/ml). The efficiency of all extracts (EC50) were significantly correlated with their content in total polyphenols (r=0.70; p=0.0002; n=23), in flavanols (r=0.65; p=0.031; n=11) and in flavonols (r=0.57; p=0.016; n=17). Our results suggest that some polyphenol-rich extracts could be potentially interesting to maintain a good cardiovascular health.

The validity of different colorimetric methods used to quantify various families of antioxidant compounds was evaluated with standard compounds. The colorimetric tests for global evaluation of flavonoids, anthocyans, and flavanols were found generally unreliable, as reactions could be different for individual compounds within a family (anthocyanins or flavonols or flavan-3-ols) and not specific to one family. In the flavonoid test, for example, flavonols reacted very well, anthocyanins did not react, and flavanons reacted only slightly. The same methods were applied also to beverages known for their antioxidant content (apple, orange, grape, and vegetable juices, ice tea, and red wine) and the data were compared with the results of HPLC analysis of specific compounds. The values obtained in a colorimetric test were generally higher than the sum of the values obtained for the corresponding individual compounds by HPLC analysis, mainly because other compounds can interfere with the colorimetric tests. For example, in wine, anthocyanin concentrations obtained by colorimetric test were 9068 ± 1407 μmol/100 ml (mean ± SEM), higher than the sum of the six main anthocyanidins detected by HPLC, only 41 μmol/100 ml. The relative antioxidant capacity values determined for beverages on the basis of colorimetric tests could exceed by far the values previously measured in radical-scavenging tests (for instance, the antioxidant capacity attributable to anthocyans in wine on the basis of the colorimetric test was 50 times higher than the total antioxidant capacity measured by the ORAC assay). In conclusion, colorimetric tests for flavonoids, anthocyans, and flavanols appeared generally unreliable for estimating their content and thus the antioxidant capacity reliable to these compounds.

Leaves of three Cuban species of the genus Pluchea: Pluchea carolinensis, Pluchea odorata and Pluchea rosea were extracted with various solvents and analyzed. Highest values of phenolic compounds were detected after ethyl acetate (EtOAc) and n-butyl alcohol (n-BuOH) extractions. Flavonoids were detected after chloroform, EtOAc and n-BuOH extractions of the species Pluchea and three aglycone flavonol forms (quercetin, kaempferol and myricetin) were also quantified after EtOAc and n-BuOH extractions, using high performance liquid chromatography. The total antioxidant capacity (TAC), expressed as Trolox equivalents per gram of leaf dry weight (TE/g dw) was analyzed using 2,2-diphenyl-1-picrylhydrazyl (DPPH·), 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) and the oxygen radical absorbance capacity. The highest values of TAC were detected after EtOAc and n-BuOH extractions of the three species. P. carolinensis was the most promising species, being the n-BuOH extraction with the most bioactive compounds: 15.3 mg TE/g dw using DPPH·. PRACTICAL APPLICATIONS The study of the chemical and biological properties of natural crude extracts from plant sources constitutes an important way for discovering new chemical compounds beneficial for human health. Many disorders in humans are associated with the accumulation of free radicals in the body, as it is the case in atherosclerosis, arthritis, ischemia, central nervous system injury and some cancers among others. In the three Cuban species of the genus Pluchea, high amounts of natural compounds and especially phenolics have been detected. The antioxidant capacity of the plants has been tested by means of three different methods. These three species have high quantities of antioxidant substances that could be used in the treatment of different pathologies. In addition, these three species are well distributed in Cuba and they can be found in dense patches of individuals, so we have also access to high quantities of these natural sources.

Tubers can be initiated and developed in vitro from nodal cuttings of yam (Dioscorea cayenensis-D. rotundata complex). The effect of exogenous jasmonic acid, alone or in combination with putrescine, on these processes was investigated in relationship to endogenous jasmonic acid and polyamine levels. Application of exogenous jasmonic acid at various concentrations positively affected microtuber formation and growth from yam nodal cuttings. In control conditions, 3 weeks were needed to obtain 100% of tuberisation. Jasmonic acid at low level (0.1 μM) accelerated tuber formation (46% after 1 week) as did putrescine (10 μM). But endogenous levels of jasmonic acid were not significantly affected by its exogenous presence in the medium. Jasmonic acid also interacted with other growth regulators as polyamines, but the decrease in time necessary to observe tuber formation could not be correlated with endogenous modifications of PUT content. The presence of jasmonic acid (0.1–1 μM) as PUT (1 μM) induced also an increase of tuber length and weight. The combination of jasmonic acid (0.1 μM) and putrescine (1 μM) had no positive effect on tuber formation (precocity) but had an additive effect on further growth (length and weight). In the future, these results could help the optimising in vitro conditions for mass production of larger yam microtubers.

Adventitious roots (ARs) are induced by auxins. Jasmonic acid (JA) and methyl jasmonate (MeJA) are also plant growth regulators with many effects on development, but their role on ARs needs investigation. To this aim, we analyzed AR formation in tobacco thin cell layers (TCLs) cultured with 0.01-10 microM MeJA, either under root-inductive conditions, i.e., on medium containing 10 microM indole-3-butyric acid (IBA) and 0.1 microM kinetin, or without hormones. The explants were excised from the cultivars Samsun, Xanthii and Petite Havana, and from genotypes with altered AR-forming ability in response to auxin, namely the non-rooting rac mutant and the over-rooting Agrobacterium rhizogenes rolB transgenic line. Results show that NtRNR1 (G1/S) and Ntcyc29 (G2/M) gene activity, cell proliferation and meristemoid formation were stimulated in hormone-cultured TCLs by submicromolar MeJA concentrations. The meristemoids developed either into ARs and xylogenic nodules, or into xylogenic nodules only (rac TCLs). MeJA-induced meristemoid over-production characterized rolB TCLs. No rooting or xylogenesis occurred under hormone-free conditions, independently of MeJA and genotype. Endogenous JA progressively (days 1-4) increased in hormone-cultured TCLs in the absence of MeJA. JA levels were enhanced by 0.1 microM MeJA, on both days 1 and 4. Endogenous IBA was the only auxin detected, both in the free form and as IBA-glucose. Free IBA increased up to day 2, remaining constant thereafter (day 4). Its level was enhanced by 0.1 microM MeJA only on day 1, while IBA conjugation was not affected by MeJA. Taken together, these results show that an interplay between jasmonates and auxins regulates AR formation and xylogenesis in tobacco TCLs.

Tuberisation was obtained in vitro on yam (Dioscorea cayenensis–Dioscorea rotundata complex). The effect of exogenous polyamines on tuber formation and development (length and weight of microtubers) was investigated and discussed in relation with changes in endogenous polyamines. Application of exogenous polyamines, inhibitors of their metabolism, and polyamines precursors in various concentrations positively affected microtuber formation by yam nodal cuttings and their further development. In control conditions, 3 wk are needed to obtain 100% of tuberisation. With low concentrations of putrescine (10−5 or 10−6 M), tuber formation occurred earlier. Polyamine endogenous level and metabolism can be significantly affected by exogenous polyamines, but modifications of endogenous free polyamines could not be directly correlated to the tuber formation process. Increases in endogenous putrescine and auxins were observed in tubers showing a better development in the presence of putrescine. These results can be used for optimising in vitro conditions for mass production of larger microtubers of the D. cayenensis–D. rotundata complex.

The effects of reducing sucrose level on tuber formation (% of cultures with microtubers), development (length and fresh weight of microtubers) and sprouting in yam Dioscorea cayenensis–D. rotundata complex in vitro were investigated. Only 29% of the explants showed tuber formation after 3 weeks in the presence of 1% sucrose in contrast to 100% with 3%. After 120 days of culture, the length and the weight of the tubers obtained in the presence of 1% sucrose were less than with 3% sucrose. Addition of sorbitol to keep osmolarity at the same level did not restore normal rate of tuber formation. Similar results were obtained with the use of reduced fructose or glucose level. Microtuber sprouting was also affected by sucrose level incorporated into the tuberisation medium. Tubers obtained on reduced sucrose level sprouted later and the increase of osmolarity with sorbitol did not restore normal sprouting. The bigger tubers obtained on high sucrose media could contain more carbohydrate reserves that could partially explain a higher sprouting rate. These results can be used for optimising in vitro conditions for mass production of microtubers in yam and especially in Dioscorea cayenensis–D. rotundata complex, a very important species in West Africa. They specially showed the importance of tuberisation conditions on precocity of tuberisation, on tuber length and weight and on their further sprouting.

The purpose of this study was to compare the antioxidant capacities of standard compounds (phenolic compounds, ascorbic acid, and glutathione) as measured by various assays. Five methods were selected so as to span a diversity of technical approaches: TEAC (radical 2,2′-azino-bis(3-ethylbenzothiazoline)-6 sulphonic acid), DPPH (radical 2,2-diphenyl-1-picryhydrazyl used to measure reducing capacity), ORAC (oxygen radical scavenging capacity), red blood cell haemolysis (protection of biological sample), and ESR (electron spin resonance for direct free radical evaluation). Most compounds showed significant differences in free radical scavenging activity according to the method used. Of the 25 tested compounds, only a few, such as myricetin and gallocatechin, gave comparable activities in the various tests. To standardise reporting on antioxidant capacity, it is proposed to use a weighted mean of the values obtained using the DPPH, ORAC, resistance to haemolysis, and ESR assays. This strategy was used to test the antioxidant capacity of several beverages. The highest antioxidant capacity was observed for red wine, followed by green tea, orange juice, grape juice, vegetable juice, and apple juice.

Apple rootstock MM106 shoots, raised in vitro, rooted at 96.7% after culture on a medium supplemented with an auxin for 5 d in darkness followed by culture on a second medium without growth regulators for 25 d in light. In control conditions (in absence of auxin in the first medium), these shoots did not root. Putrescine (PUT), spermidine (SPD), cyclohexylamine (CHA), and aminoguanidine (AG) enhanced rooting when applied during the first d of culture in the absence of IBA; on the contrary, α-difluoromethylornithine (DFMO) added to the first medium with IBA inhibited rooting. The endogenous levels of indole 3-acetic acid (IAA) and indole 3-acetylaspartic acid (IAAsp) increased up to a maximum concentration at days 2 and 3, respectively, in initial rooting conditions. PUT, when added with IBA, did not affect the typical IAA and IAAsp increase; when applied alone, it provoked an increase of their levels. Similar results were recorded with CHA. SPD, AG, and DFMO did not induce an increase of IAA and IAAsp in nonrooting conditions. The levels of endogenous PUT increased to a maximum at day 2 in rooting conditions; it was slightly affected by exogenous PUT and CHA application but reduced by SPD, AG, and DFMO. In rooting conditions, if the first medium was supplemented with SPD or AG, a small increase in peroxidase activity was observed, similar to that obtained with PUT treatment. The present work indicates an involvement of polyamines in the control of rooting and an interaction with auxins during the physiological phase of rooting. The consequence of this relationship was a different rooting expression, according especially to the content of these regulators in the culture medium.

A study was conducted to investigate the influence of planting methods and tuber weight on growth and yield of local yam cultivars obtained by the minisett technique from white yam (D. rotundata) in Gabon. Trials were carried out in 2014 and 2015 at the experimental ground of the Higher National Institute of Agronomy and Biotechnology, under natural conditions of lightness, temperature and relative humidity. Twenty- four weeks old mini tubers obtained from local cultivar MVA of D. rotundata were harvested, weighed and categorized (40-80g; 100-150g; 200-300g), and three planting methods (horizontal, oblique and vertical),arranged in ridges constituted the main factors. The experiment was laid out in Randomized Completely Block Design with eighteen treatments and two replications. Data pertaining to sprouting were recorded for 30, 60, 90 and 180 DAP, for tuber length (cm), tuber weight (Kg) and number of tubers per plant 270 DAP. Significant differences among tuber weight in all variables tested were observed. The larger tubers had better sprouting ability than the rest of the tuber weight. The methods of planting had no effects on yield and its components but they affect the depth and spread of tubers. Vertical planting produced deeper but more compactly arranged tubers while horizontal planting produced tubers which were shallowerbut more widespread. Slanting was intermediate for both depth and spread. The number and weight of tubers obtained from mini tubers planted out according to slanting method were significantly different (P< 0.05) from other planting methods. The production of seedlings from mini tuber is an improvement of traditional production of seed yam. Mini tubers must have at least 100-300 g and they should be planted slanting or vertically.

Lignosulfonates (LIGNs), low-cost by-products from the paper industry, are already commercialized as fertilizers; they stimulate both vegetative and reproductive growths and fructification. LIGNs have been tested in in vitro cultures and here too, they improve shoot growth and vigor, and rooting of various plant materials. This study aimed at to extend the in vitro application of LIGNs at different developmental stages in order to increase the productivity of systems generating vitroplants. The present results showed the beneficial effects of various LIGN applications on growth of a tropical orchid, Phalaenopsis, multiplication of Saintpaulia ionantha and rooting of poplar and Sequoiadendron sempervirens shoot cuttings. One of the most interesting observations was the stimulating effect of Ca-chelated LIGN on growth of Phalaenopsis and on rooting of Sequoiadendron. The significant and reproducible effects of LIGNs at several steps of micropropagation of different plant materials represent a potential tool to improve quality without embarrassing side-effects.

Yams (Dioscorea spp) are tuber crops used as staple food in Africa because of their nutritional value. However agronomic constraints, phytosanitary problems and the lack of good healthy planting material restrict their production. In contrast to the inefficiency of traditional method of planting, tissue culture techniques allow to increase the multiplication and the rapid production of pathogen- free plant material. This work was undertaken to provide farmers in African countries with healthy microplants and microtubers as seeds. In vitro nodal segments of two varieties of local yams D. cayenensis–D. rotundata complex (cv. ‘Singo’, cv. ‘Singou’ and cv. ‘Gnidou’) were micropropagated on the modified medium of Murashige and Skoog. The morphogenesis, the growth of microplants and microtuber formation have been found to be controlled by external factors that act individually and synergistically. Addition of kinetin (2 mg l−1) to the culture media could reduce multiplication rate (node number) of some clones. An increase of the sucrose concentration from 3% to 5% induced no change in the multiplication and tuberisation parameters. An important reduction of the multiplication (shoot number, height and node number) and the tuberisation (tuber number and length) was observed with 8% sucrose. Multiplication (shoot and node number) was increased in the presence of jasmonic acid (10 μM). JA also induced an increase of tuber number in the absence of Kin. Multiplication of yam by in vitro growth of nodal segments is a way for rapid clonal multiplication and could allow solving the problem of lack of seed material faced by farmers. This method could also be used for multiplication of elite cultivars, independently of the growing season.

Health benefits of a diet rich in fruits and vegetables are attributed in part to their contents of phenolics and other antioxidant compounds. In this research, the extraction of phenolics and antioxidant compounds from black currant was optimised for different plant organs. The extraction solvent affected yield: aqueous acetone was better than methanol and acetate or glycine buffer. In aqueous buffer, maximum yields of total phenolics and antioxidant activities were obtained at pH 3. Extraction from lyophilised materials yielded extracts with higher phenolic contents and antioxidant activities. Stability of extracts made with acetate or glycine buffer was limited while the use of a mixture of acetone/acetic acid/water for extraction allowed a high phenolic content and antioxidant capacity in dry extract to be maintained for several months. This type of extract could be incorporated in functional food, beverage or dietary supplement.

The influence of lighting conditions, culture volume and four different auxins (indoleacetic acid (IAA), indolebutyric acid (IBA), 2,4-dichlorophenoxy- acetic acid (2,4-D) or 3-(benzo[b]selenyl)acetic acid (BSAA)) on Panax vietnamensis cell growth was evaluated in flasks. The highest biomass productivity was observed under continuous light and in the presence of IBA (0.36 g DW l−1 d−1) or BSAA (0.5 g DW|−1 d−1). Cultures in bioreactors were performed with these two auxins. The final biomass concentration was 107 g FW|−1 and 373 g FW|−1 in the presence of IBA or BSAA, respectively.

Defect in apoptosis has been implicated as a major cause of resistance to chemotherapy observed in B cell chronic lymphocytic leukaemia (B CLL). This study evaluated the pro-apoptotic effect of an anthocyanin-rich dietary bilberry extract (Antho 50) on B CLL cells from 30 patients and on peripheral blood mononuclear cells (PBMCs) from healthy subjects and determined the underlying mechanism. Antho 50 induced concentration- and time-dependent pro-apoptotic effects in B CLL cells but little or no effect in PBMCs. Among the main phenolic compounds of the bilberry extract, delphinidin-3-O-glucoside and delphinidin-3-O-rutinoside induced a pro-apoptotic effect. Antho 50-induced apoptosis is associated with activation of caspase 3, down-regulation of UHRF1, a rapid dephosphorylation of Akt and Bad and down-regulation of Bcl-2. Antho 50 significantly induced PEG-catalase-sensitive formation of reactive oxygen species in B CLL cells. PEG-catalase prevented the Antho 50-induced induction of apoptosis and related signaling. The present findings indicate that Antho 50 exhibits strong pro-apoptotic activity through redox-sensitive caspase 3 activation-related mechanism in B CLL cells involving dysregulation of the Bad/Bcl-2 pathway. This activity of Antho 50 involves the glucoside and rutinoside derivatives of delphinidin. They further suggest that Antho 50 has chemotherapeutic potential by targeting selectively B CLL cells.

Small berries such as black currant constitute one of the important sources of potential health-promoting phytochemicals because these fruits are rich sources of compounds with high antioxidant properties. In this work, antioxidant capacities of different parts (buds, leaves, fruits) of various black currant cultivars were compared throughout the growing season with the aim to prepare extracts with high antioxidant capacity. Buds (opened, at the end of March) and leaves (in June) had a higher content in phenolics and antioxidants than fully ripened berries (in July) and the best yield (per branch) was obtained with the leaves collected in June due to their higher biomass. The differences observed among the eight cultivars tested were small. Concerning flavonols, quercetin was dominant in all organs and cultivars, myricetin varied widely among the cultivars, and kampferol was very low.

Lignosulfonate (LS) is a lignin-based polymer obtained as a by-product from paper industry, which may have potential as an amendment with macronutrients. We studied effects of LS on the interaction between Scots pine (Pinus sylvestris L.) seedlings and hypocotyl cuttings and the ectomycorrhizal (ECM) fungusPisolithus tinctorius (Pers.) Coker and Couch. The experiments were performed in vitroon the MMN agar medium containing Fe–LS chelate at the concentrations of 0, 5, 10 and 25 mg/L. Inoculation with P. tinctoriusincreased root growth of the seedlings. Fe–LS enhanced P. tinctorius induced formation of lateral roots and had a dose-dependent positive effect on the establishment of mycorrhizas on the seedlings. The growth of the fungal mycelium was improved by Fe–LS, which might cause faster and more intensive contact with the roots and, thus, better root growth and mycorrhiza formation. P.␣tinctorius enhanced also adventitious root formation and subsequent root growth of the hypocotyl cuttings but without any synergistic effect with Fe–LS. Our study with P. tinctorius and Scots pine in vitro indicates that a low-cost by-product Fe–LS, obtained from paper industry, may be a potential tool to improve the efficiency of fungal inoculations, thus, facilitating the early interaction between an ECM fungus and host seedling.

Hyperhydricity of micropropagated shoots, formerly called vitrification, undoubtedly results from growth and culture conditions, subjectively reputated as stressing factors: wounding, infiltration of soft culture medium, generally of a high ionic strength, rich in nitrogen and in growth regulators in a special balance, in a humid and gaseous confined atmosphere. Stress is (objectively) defined as a disruption of homeostasis resulting from a constraint escaping the usual flexibility of metabolism. It induces another temporary (reversible) or definitive (irreversible) thermodynamic physiological state. The state-change concept developed by Strasser (1988) and Strasser and Tsimilli-Michael (2001) is applicable to the phenomenon of hyperhydricity. An appraisal of the redox capacities of hyperhydrated shoots together with a study of some enzymic activities that catalyse pentose phosphate and glycolytic pathways has indeed shown that such shoots have evolved towards a temporary state of lower differentiation or a juvenile state with a sufficient activity to survive and to defend themselves.

Lignification and xylem cell multiplication for wood formation were examined in in vitro propagated walnut shoot cuttings after transfer on an auxin- containing rooting medium for one week and subsequently during root development in vermiculite in the absence of growth regulators. Lignification in the shoot stems started immediately after the exogenous auxin treatment which implied changes in peroxidase activity and in free IAA levels. Sustained lignification required the completion of the following rooting phases. The lignin was exclusively located in xylem cells, the number of which increased with the number of developing roots. The mutual interactions between the aerial parts of the plants and their roots are discussed.

With the aim to differentiate the ionic and osmotic components of salt stress, short and long-term changes in free polyamines and proline induced by iso-osmotic concentrations of NaCl (0.1 mol/L and 0.2 mol/L) and mannitol (0.2 mol/L and 0.4 mol/L) were determined in Fraxinus angustifolia callus. The peculiarities of the short-term responses were: i) a very early (30 min) and temporary increase in Putrescine (Pu) and Spermine (Spm) as a consequence of salt treatment, and ii) a continuous accumulation of Spermidine (Spd) and Spm in response to mannitol. The changes of Proline (Pro) were quite limited both in the short and in the long term, and generally occurred later than Polyamine (PAs) changes took place, suggesting a regulatory mechanism of PAs metabolism on Pro biosynthesis. In the long-term, no drastic accumulations of Pro or PAs in response to NaCl and mannitol were observed, suggesting that their physiological role is unlikely to be that of osmo-compatible solutes in this plant system. The salt induced a higher callus growth inhibition effect than did mannitol and this inhibition was associated with the reduction of endogenous levels of PAs, especially Pu. However, while a diverging time course was observed under lethal salt concentration (0.2 mol/L NaCl), a high parallelism in the endogenous changes of Pro and Pu was observed under all non-lethal conditions (control--0.2 and 0.4 mol/L mannitol--0.1 mol/L NaCl). Therefore the synchronous changes of Pro and Pu can be considered as a physiological trait associated with cell survival. These results indicate a strong metabolic co-ordination between PAs and Pro pathways and suggest that the metabolic fluxes through these pathways start competing only when the stress level is high enough to be lethal for cells.

The lignin content of walnut shoots did not change during in vitro shoot multiplication. Lignin content started to increase as soon as shoots were passed to a rooting medium with auxin. Exogenous auxin (applied for rooting) caused a transient elevation of the endogenous free indoleacetic acid (IAA) content with a simultaneous decrease of peroxidase activity. These events typically marked the completion of the rooting inductive phase (before any visible histological event, that is before the cell divisions beginning the rooting initiation phase). This meant that either the given exogenous auxin or the endogenous IAA has served as signal for the stimulation of lignification. Continued increase of lignification in the shoots required completion of root formation; this increase indeed was slown down when root emergence did not occur. It was further shown that lignification varied conversely to the content of the soluble phenol content, itself apparently being related to the activity of phenylalanine ammonia-lyase activity.

The synthesis of 2,4-dichlorophenylselenoacetic acid (2,4-D-Se) may be completed in three steps starting from 2,4-dichloroaniline. The selenium is inserted in the molecule by reaction of a diazonium salt with potassium selenocyanate. 2,4-D-Se has been tested as an auxin in several bioassays including the regeneration of somatic embryos, adventitious root formation and the associated temporary increase of endogenous auxins at the induction phase, and callus formation, and compared with the natural auxin indoleacetic acid (IAA), the classical synthetic auxin(s) naphthaleneacetic acid (NAA) and/or 2,4-dichlorophenoxyacetic acid (2,4-D), and with the synthetic seleniated IAA, 3-(benzo[b]selenienyl) acetic acid, BSAA. These biological assays classified 2,4-D-Se together with BSAA among the most powerful synthetic auxins. The role of selenium is briefly discussed.

The present research work describes the effects of 2,4-dichlorophenoxyacetic acid (2,4-d)/Benzylaminopurine (BAP) ratio on callus induction, total phenolic and ascorbic acid production, and antioxidant activities in leaf-derived calli of Crataegus azarolus (hawthorn). The supplementation of 1.0 mg/L 2,4-d and 1.0 mg/L BAP to MS medium was found to be the most efficient for callus induction (as percentage and fresh weigh). The results of biochemical analysis showed that the highest total phenolic contents were obtained in callus cultured on MS medium supplemented with 2.0 mg/L 2,4-d and 1.0 mg/L BAP (52 ± 0.56 mg GAE/g DM) and were significantly lower than those of intact leaves (76 ± 1.72 mg GAE/g DM). However, the highest ascorbic acid contents were found in callus cultured on MS medium supplemented with 1.0 mg/L 2,4-d and 0.5 mg/L BAP (0.96 ± 0.13 mg AAE/g DM) and these amounts were statistically similar to those found in leaf tissues (0.74 ± 0.07 mg AAE/g DM). Antioxidant activities of callus extracts were determined using two TEAC assays and results showed that extract of callus cultured on MS medium supplemented with 2.0 mg/L 2,4-d and 1.0 mg/L BAP have the greatest antiradical activities against DPPH (124 ± 2.92 mg TE/g DM) and ABTS (0.19 ± 0.02 mg TE/g DM) compared to the leaves of field-grown plant. Thus, the use of high level of 2,4-d over BAP can be suitable to enhance the quality more than the quantity of bioactive compounds in leaf callus culture of hawthorn.

Adventitious stipular bud formation occurred in vitro in many strawberry cultivars during the proliferation phase onmedium containing Knop macronutrients, MS micronutrients, vitamins, aminoacids,2.22 μM BAP, 2.46 μM IBA and 0.29μM GA3. As described previously for cultivarGorella,cultivar Elsanta also showed adventitious stipular buds developing on theabaxial median zone between the stipule tips. To compare the shoots producedfrom both types of buds, clonal propagation was initiated from stipular budsandfrom axillary buds on the above mentioned medium. Stipular buds were separatedfrom the meristem-tip initiated plantlet and cultivated in the presence of alower BAP concentration (1.33 μM) to prevent further stipularbud formation.

La regeneration in vitro de plants de Fraisier (Fragaria x ananassa Duch. cv. Elsanta) a partir de bourgeons adventifs stipulaires etait a l'origine de l'obtention d'un clone dont le comportement vegetatif et reproducteur in vivo s'est nettement distingue de celui de son homologue d'origine axillaire. Hormis la couleur claire et la forme arrondie de ses feuilles, ce nouveau clone se caracterise par un rythme plastochronal plus lent qui correspond aussi a la production d'un plus grand nombre de bourgeons axillaires sous forme de stolons. Au niveau floral, le receptacle est moins allonge et se trouve a la hauteur des etamines dont les antheres sont plus volumineuses que celles du clone axillaire. Ce dernier, dont le receptacle emerge au dela des etamines, presente une moins bonne pollinisation qui se traduit par une importante deformation des fruits, surtout en hiver et en l'absence d'agents pollinisateurs.

Because the term stress is used, most often subjectively, with variousmeanings, this paper first attempts to clarify the physiological definition,andthe appropriate terms as responses in different situations. The flexibility ofnormal metabolism allows the development of responses to environmental changeswhich fluctuate regularly and predictably over daily and seasonal cycles. Thusevery deviation of a factor from its optimum does not necessarily result instress. Stress begins with a constraint or with highly unpredictablefluctuations imposed on regular metabolic patterns that cause bodily injury,disease, or aberrant physiology. Stress is the altered physiological conditioncaused by factors that tend to alter an equilibrium. Strain is any physicaland/or chemical change produced by a stress, i.e. every established condition,which forces a system away from its thermodynamic optimal state. The papersecondly summarises the Strasser's state-change concept which is preciselythat suboptimality is the driving force for acclimation (genotype level) oradaptation (population level) to stress. The paper continues with the actualknowledge on the mechanisms of stress recognition and cell signalling. Briefly:plasma membranes are the sensors of environmental changes; phytohormones andsecond messengers are the transducers of information from membranes tometabolism; carbon balance is the master integrator of plant response; betwixtand between, some genes are expressed more strongly, whereas others arerepressed. Reactive oxygen species play key roles in up- and down-regulation ofmetabolism and structure. The paper shows finally that the above concepts canbeapplied to plant tissue cultures where the accumulating physiological andgenetical deviations (from a normal plant behaviour) are related to thestressing conditions of the in vitro culture media and ofthe confined environment. The hyperhydrated state of shoots and the cancerousstate of cells, both induced under conditions of stress in invitro cultures, are identified and detailed, because they perfectlyillustrate the stress-induced state-change concept. It is concluded that stressresponses include either pathologies or adaptive advantages. Stress may thuscontain both destructive and constructive elements : it is a selection factoraswell as a driving force for improved resistance and adaptive evolution.