Establishment of optimized in vitro disinfection protocol of Pistacia vera L. explants mediated a computational approach: multilayer perceptron-multi-objective genetic algorithm.

BACKGROUND: Contamination-free culture is a prerequisite for the success of in vitro - based plant biotechnology. Aseptic initiation is an extremely strenuous stride, particularly in woody species. Meanwhile, over-sterilization is potentially detrimental to plant tissue. The recent rise of machine learning algorithms in plant tissue culture proposes an advanced interpretive tool for the combinational effect of influential factors for such in vitro - based steps. RESULTS: A multilayer perceptron (MLP) model of artificial neural network (ANN) was implemented with four inputs, three sterilizing chemicals at various concentrations and the immersion time, and two outputs, disinfection efficiency (DE) and negative disinfection effect (NDE), intending to assess twenty-seven disinfection procedures of Pistacia vera L. seeds. Mercury chloride (HgCl2; 0.05-0.2%; 5-15 min) appears the most effective with 100% DE, then hydrogen peroxide (H2O2; 5.25-12.25%; 10-30 min) with 66-100% DE, followed by 27-77% DE for sodium hypochlorite (NaOCl; 0.54-1.26% w/v; 10-30 min). Concurrently, NDE was detected, including chlorosis, hard embryo germination, embryo deformation, and browning tissue, namely, a low repercussion with NaOCl (0-14%), a moderate impact with H2O2 (6-46%), and pronounced damage with HgCl2 (22-100%). Developed ANN showed R values of 0.9658, 0.9653, 0.8937, and 0.9454 for training, validation, testing, and all sets, respectively, which revealed the uprightness of the model. Subsequently, the model was linked to multi-objective genetic algorithm (MOGA) which proposed an optimized combination of 0.56% NaOCl, 12.23% H2O2, and 0.068% HgCl2 for 5.022 min. The validation assay reflects the high utility and accuracy of the model with maximum DE (100%) and lower phytotoxicity (7.1%). CONCLUSION: In one more case, machine learning algorithms emphasized their ability to resolve commonly encountered problems. The current successful implementation of MLP-MOGA inspires its application for more complicated plant tissue culture processes.

Assessment of genetic diversity of thirty Tunisian fig (Ficus carica L.) accessions using pomological traits and SSR markers.

Sixteen pomological traits were employed to characterize the diversity of 30 fig accessions collected mainly from Southeastern Tunisia and maintained at CFPA 'El Gordhab', Tataouine, in Southeastern Tunisia. Additionally, 13 simple sequence repeat (SSR) loci were analyzed to detect the genetic diversity of the 30 fig accessions. In this study, qualitative data (fruit shape, fruit external color, fruit internal color, abscission of the stalk from the twig, skin peeling, fruit skin firmness) showed morphological variation within accessions. A highly significant difference (p < .01) among accessions was revealed for all the quantitative traits. The first three components (PC1, PC2, and PC3) of PCA accounted for 52.99% of the total variability. PC1, PC2, and PC3 accounted respectively for 28.02, 13.05, and 11.91% of the total variance. The most discriminating morphological parameters were fruit length and diameter, stalk length and diameter, neck length and diameter, stalk and flesh thickness, fruit shape, skin peeling, and skin firmness. Concerning the molecular results, 40 alleles were revealed. The number of alleles ranged between 2 to 6 with a mean of 3.08 alleles per locus. The observed heterozygosity (Ho) ranged from 0.03 (LMFC21, LMFC23, and LMFC32) to 0.83 (LMFC30) with an average of 0.43. The expected heterozygosity (He) varied from 0.03 (LMFC21, LMFC 23 and LMFC32) to 0.74 (LMFC30) with an average of 0.37. UPMGA cluster analysis and PCA grouped the accessions in 6 groups. Our results showed that the SSR markers used detected low genetic diversity within the accessions studied.

Variable Levels of Tolerance to Water Stress (Drought) and Associated Biochemical Markers in Tunisian Barley Landraces.

Due to its high tolerance to abiotic stress, barley (Hordeum vulgare) is cultivated in many arid areas of the world. In the present study, we evaluate the tolerance to water stress (drought) in nine accessions of "Ardhaoui" barley landraces from different regions of Tunisia. The genetic diversity of the accessions is evaluated with six SSR markers. Seedlings from the nine accessions are subjected to water stress by completely stopping irrigation for three weeks. A high genetic diversity is detected among the nine accessions, with no relationships between genetic distance and geographical or ecogeographical zone. The analysis of growth parameters and biochemical markers in the water stress-treated plants in comparison to their respective controls indicated great variability among the studied accessions. Accession 2, from El May Island, displayed high tolerance to drought. Increased amounts of proline in water-stressed plants could not be correlated with a better response to drought, as the most tolerant accessions contained lower levels of this osmolyte. A good correlation was established between the reduction of growth and degradation of chlorophylls and increased levels of malondialdehyde and total phenolics. These biochemical markers may be useful for identifying drought tolerant materials in barley.

Phenolic profiling and antioxidant capacity in flowers, leaves and peels of Tunisian cultivars of Punica granatum L.

The comprehensive phenolic fingerprints of flowers, peels and leaves of two Tunisian Punica granatum L. cultivars, namely Nabli and Gabsi, were investigated. The highest phenolic content was recorded in the Nabli flowers, followed by Gabsi peels extracts (152.6 and 125.8 mg gallic acid equivalent 100 g-1, respectively) while flavonoids and flavonols were highest in Gabsi peels (19.2 and 26.0 mg Rutin equivalent per 100 g-1). Besides, the antioxidant capacity was the highest in Gabsi peels (144.4 mg gallic acid equivalent 100 g-1) and in Nabli flowers (161.6 mg gallic acid equivalent per 100 g-1. Methanol extracts of all three plant portions of both cultivars were screened by ultra-high-performance liquid chromatography coupled to quadruple time of flight mass spectrometry, and the identified phenolics were further quantified. Nabli cultivar showed higher contents of flavonoids (in flowers and leaves), while phenolic acids were abundant in Gabsi leaves. Multivariate statistics highlighted differences in phenolic profile among organs and cultivars. These results showed that the pomegranate portions investigated are a valuable source of bioactive compounds with health-promoting properties, mainly belonging to the phenolic class of flavonoids.

Health-promoting compounds of broccoli (Brassica oleracea L. var. italica) plants as affected by nitrogen fertilisation in projected future climatic change environments.

BACKGROUND: The complex interactions between CO2 increase and salinity were investigated in relation to decreased N supply, in order to determine the nutritional quality of broccoli (Brassica oleracea L. var. italica) plants under these conditions. Three different decreased N fertilisation regimes (NO3(-)/NH4(+) ratios of 100:0, 50:50 and 0:100 respectively) were combined with ambient (380 ppm) and elevated (800 ppm) [CO2 ] under non-saline (0 mmol L(-1) NaCl) and saline (80 mmol L(-1) NaCl) conditions. Nutrients (minerals, soluble protein and total amino acids) and natural antioxidants (glucosinolates, phenolic acids, flavonoids and vitamin C) were determined. RESULTS: In NH4(+) -fed broccoli plants, a marked growth reduction was shown and a redistribution of amino acids to cope with NH4(+) toxicity resulted in higher levels of indolic glucosinolate and total phenolic compounds. However, the positive effect of the higher [CO2] - ameliorating adverse effects of salinity--was only observed when N was supplied as NO3(-). Under reduced N fertilisation, the total glucosinolates were increased by a decreased NO3(-)/NH4 (+) ratio and elevated [CO2] but were unaffected by salinity. CONCLUSION: Under future climatic challenges, such as increased salinity and elevated [CO2], a clear genotypic dependence of S metabolism was observed in broccoli plants. In addition, an influence of the form in which N was supplied on plant nutritional quality was observed; a combined NO3(-)/NH4(+) (50:50) supply allowed broccoli plants not only to deal with NH4(+) toxicity but also to modify their glucosinolate content and profile. Thus, for different modes of N fertilisation, the interaction with climatic factors must be considered in the search for an optimal balance between yield and nutritional quality.

Drought stress tolerance in grapevine involves activation of polyamine oxidation contributing to improved immune response and low susceptibility to Botrytis cinerea.

Environmental factors including drought stress may modulate plant immune responses and resistance to pathogens. However, the relationship between mechanisms of drought tolerance and resistance to pathogens remained unknown. In this study, the effects of drought stress on polyamine (PA) homeostasis and immune responses were investigated in two grapevine genotypes differing in their drought tolerance; Chardonnay (CHR), as sensitive and Meski (MSK), as tolerant. Under drought conditions, MSK plants showed the lowest leaf water loss and reduction of photosynthetic efficiency, and expressed a lower level of NCED2, a gene involved in abscisic acid biosynthesis, compared with CHR plants. The improved drought tolerance in MSK was also coincident with the highest change in free PAs and up-regulation of the genes encoding arginine decarboxylase (ADC), copper amine-oxidase (CuAO), and PA-oxidases (PAO) and their corresponding enzyme activities. MSK plants also accumulated the highest level of amino acids, including Arg, Glu, Gln, Pro, and GABA, emphasizing the participation of PA-related amino acid homeostasis in drought tolerance. Importantly, drought-tolerant plants also exhibited enhanced phytoalexin accumulation and up-regulation of PR genes, especially PR-2 and Chit4c, compared with the sensitive plants. This is consistent with a lower susceptibility of MSK than CHR to Botrytis cinerea. Data suggest a possible connection between water stress tolerance and immune response in grapevine. Pharmacological experiments revealed that under drought conditions CuAO and PAO pathways were involved in the regulation of photosynthetic efficiency, and also of immune response and resistance of grapevine to a subsequent pathogen attack. These results open new views to improve our understanding of crosstalk between drought tolerance mechanisms and immune response.

Analysis of genetic diversity of Tunisian caprifig (Ficus carica L.) accessions using simple sequence repeat (SSR) markers.

BACKGROUND: The common fig (Ficus carica L.) is a gynodioecious species with two sexual forms: male trees (caprifigs) with male and female flowers and female trees that produce only female flowers that will result in the edible fig syconium. In this study the genetic diversity of 20 Tunisian accessions of caprifig is analyzed using SSR markers previously developed for this crop. RESULTS: The results revealed that the 13 pairs of primers used amplified a total of 37 alleles in the accessions studied. The number of alleles per locus ranged from two to six, with a mean value of 2.85 alleles per locus. Observed and expected heterozygosities showed mean values of 0.33 and 0.29 respectively. UPGMA cluster analysis and Principal Component Analysis grouped the caprifig accessions analyzed in three groups. CONCLUSION: The results obtained show a low genetic diversity in the Tunisian accessions of caprifig studied and, in spite of analyzing samples from different geographic regions, no clear groupings based on geographical origin are observed suggesting widespread exchange of caprifig plant material through vegetative propagation among different areas in Tunisia.

Mineral accumulation, relative water content and gas exchange are the main physiological regulating mechanisms to cope with salt stress in barley.

Salinity has become a major environmental concern for agricultural lands, leading to decreased crop yields. Hence, plant biology experts aim to genetically improve barley's adaptation to salinity stress by deeply studying the effects of salt stress and the responses of barley to this stress. In this context, our study aims to explore the variation in physiological and biochemical responses of five Tunisian spring barley genotypes to salt stress during the heading phase. Two salinity treatments were induced by using 100 mM NaCl (T1) and 250 mM NaCl (T2) in the irrigation water. Significant phenotypic variations were detected among the genotypes in response to salt stress. Plants exposed to 250 mM of NaCl showed an important decline in all studied physiological parameters namely, gas exchange, ions concentration and relative water content RWC. The observed decreases in concentrations ranged from, approximately, 6.64% to 40.76% for K+, 5.91% to 43.67% for Na+, 14.12% to 52.38% for Ca2+, and 15.22% to 38.48% for Mg2+ across the different genotypes and salt stress levels. However, under salinity conditions, proline and soluble sugars increased for all genotypes with an average increase of 1.6 times in proline concentrations and 1.4 times in soluble sugars concentration. Furthermore, MDA levels rose also for all genotypes, with the biggest rise in Lemsi genotype (114.27% of increase compared to control). Ardhaoui and Rihane showed higher photosynthetic activity compared to the other genotypes across all treatments. The stepwise regression approach identified potassium content, K+/Na+ ratio, relative water content, stomatal conductance and SPAD measurement as predominant traits for thousand kernel weight (R2 = 84.06), suggesting their significant role in alleviating salt stress in barley. Overall, at heading stage, salt accumulation in irrigated soils with saline water significantly influences the growth of barley by influencing gas exchange parameters, mineral composition and water content, in a genotype-dependent manner. These results will serve on elucidating the genetic mechanisms underlying these variations to facilitate targeted improvements in barley's tolerance to salt stress.

Effect of water deficit on the cell wall of the date palm (Phoenix dactylifera 'Deglet nour', Arecales) fruit during development.

Date palm (Phoenix dactylifera) is an important crop providing a valuable nutrition source for people in many countries including the Middle East and North Africa. In recent years, the amount of rain in North Africa and especially in the Tunisian palm grove areas has dropped significantly. We investigated the growth and cell wall remodelling of fruits harvested at three key development stages from trees grown with or without water supply. During development, cell wall solubilization and remodelling was characterized by a decrease of the degree of methylesterification of pectin, an important loss of galactose content and a reduction of the branching of xylan by arabinose in irrigated condition. Water deficit had a profound effect on fruit size, pulp content, cell wall composition and remodelling. Loss of galactose content was not as important, arabinose content was significantly higher in the pectin-enriched extracts from non-irrigated condition, and the levels of methylesterification of pectin and O-acetylation of xyloglucan were lower than in irrigated condition. The lower levels of hydrophobic groups (methylester and O-acetyl) and the less intensive degradation of the hydrophilic galactan, arabinan and arabinogalactan in the cell wall may be implicated in maintaining the hydration status of the cells under water deficit.

Cytogenetic evidence of mixed disomic and polysomic inheritance in an allotetraploid (AABB) Musa genotype.

BACKGROUND AND AIMS: Edible bananas originated mainly from two wild species, Musa acuminata Colla (AA) and Musa balbisiana Colla (BB), and triploid cultivars with an AAA, AAB or ABB genome are the most widely used. In the present study, chromosome pairing affinities are investigated in a sterile AB Indian variety and in its fertile colchicine-induced allotetraploid (AABB) derivative to determine the inheritance pattern of the tetraploid genotype. The potential implications of interspecific recombination and chromosomal composition of diploid gametes for Musa improvement are presented. METHODS: The pairing of different chromosome sets at diploid and tetraploid levels was investigated through a combination of conventional cytogenetic and genomic in-situ hybridization (GISH) analyses of meiotic chromosomes, leading to a likelihood model of the pairing behaviour. GISH analysis of mitotic chromosomes was also conducted to reveal the chromosome constitution of hybrids derived from crosses involving the allotetraploid genotype. KEY RESULTS: Analysis of chromosome associations at both ploidy levels suggested that the newly formed allotetraploid behaves as a 'segmental allotetraploid' with three chromosome sets in a tetrasomic pattern, three sets in a likely disomic pattern and the five remaining sets in an intermediate pattern. Balanced and unbalanced diploid gametes were detected in progenies, with the chromosome constitution appearing to be more homogenous in pollen than in ovules. CONCLUSIONS: Colchicine-induced allotetraploids in Musa provide access to the genetic background of natural AB varieties. The segmental inheritance pattern exhibited by the AABB allotetraploid genotype implies chromosome exchanges between M. acuminata and M. balbisiana species and opens new horizons for reciprocal transfer of valuable alleles.

Differential responses of two broccoli (Brassica oleracea L. var Italica) cultivars to salinity and nutritional quality improvement.

The comparative responses of two broccoli cultivars (Brassica oleracea var. Italica, cv. Parthenon and cv. Naxos) to a 15 d exposure to different NaCl levels were investigated. Salinity led to increased concentrations of Na(+) and Cl(-) ions in both cultivars, a disruption of the endogenous minerals levels in the shoots and roots-that varied with the cultivar and salt concentration-and decreases in the osmotic potential (Ψ(π)), root hydraulic conductance (L(0)), and stomatal conductance (G(s)). The reduced biomass of Naxos at moderate NaCl indicates greater sensitivity to salinity, compared with Parthenon. Parthenon accumulated more soluble sugars, for osmotic adjustment, whereas Naxos accumulated proline, which gave the two cultivars differing nutritional characteristics. The total glucosinolates (GSLs) content was not affected by salinity in Parthenon while it decreased significantly in Naxos as a consequence of the decrease in the indole GSL. However, Naxos accumulated more aliphatic GSLs under salt stress than Parthenon, which confers on this cultivar a greater nutritional value when cultivated under salinity.These results suggest that, at distinct salinity levels, each broccoli cultivar adopts a specific strategy, indicating the crucial role of the genetic background on the organoleptic and nutritional properties that each cultivar acquires.

Drought effect on growth, gas exchange and yield, in two strains of local barley Ardhaoui, under water deficit conditions in southern Tunisia.

Two local barley strains cv. Ardhaoui originated from Tlalit and Switir, sourthern Tunisia were grown in pots in a glasshouse assay, under well-watered conditions for a month. Plants were then either subjected to water deficit (treatment) or continually well-watered (control). Control pots were irrigated several times each week to maintain soil moisture near field capacity (FC), while stress pots experienced soil drying by withholding irrigation until they reached 50% of FC. Variation in relative water content, leaf area, leaf appearance rate and leaf gas exchange (i.e. net CO(2) assimilation rate (A), transpiration (E), and stomatal conductance (gs)) in response to water deficit was investigated. High leaf relative water content (RWC) was maintained in Tlalit by stomatal closure and a reduction of leaf area. Reduction in leaf area was due to decline in leaf gas exchange during water deficit. Tlalit was found to be drought tolerant and able to maintain higher leaf RWC under drought conditions. Water deficit treatment reduced stomatal conductance by 43% at anthesis. High net CO(2) assimilation rate under water deficit was associated with high RWC (r = 0.998; P < 0.01). Decline in net CO(2) assimilation rate was due mainly to stomatal closure. Significant differences between studied strains in leaf gas exchange parameters were found, which can give some indications on the degree of drought tolerance. Thus, the ability of the low leaf area plants to maintain higher RWC could explain the differences in drought tolerance in studied barley strains. Results showed that Tlalit showed to be more efficient and more productive than Switir.

Anaerobic digestion of waste Tunisian date (Phoenix dactylifera L.): effect of biochemical composition of pulp and seeds from six varieties.

Large amounts of secondary date waste (pulp and seeds) are produced and discarded in Tunisia without proper valorisation methods. To study the possibility of valorising different varieties of Tunisian date waste (pulp and seeds) via anaerobic digestion, batch biochemical methane potential (BMP) tests were carried out under mesophilic temperature. The bio-methane production curves were fitted to the model of modified Gompertz in search of the kinetic parameters. The bio-chemical characterisation of the substrates from different varieties (total and volatile solids, COD and contents in carbohydrates, proteins, lipids, polyphenols) was realised. Principal component analysis (PCA) was used to investigate the correlations between the model parameters and biochemical variables. Results show that the biochemical compositions of date pulp and seeds strongly depend on the varieties. The BMP are in the range of 0.295-0.345 and 0.267-0.327 Nm3 CH4·kg COD-1 for pulp and seeds respectively, resulting from the significant biochemical variance among the varieties. The BMP of date seeds was significantly correlated with their VS/TS ratio, carbohydrate and protein contents (p < 0.05). For the pulp, significant correlation was found between BMP, carbohydrate and lipid contents. PCA shows that certain varieties (like pulp and seeds of Deglet Nour and seeds of Bejou) are most suitable for being valorised by anaerobic digestion. The most suitable date varieties for this innovative approach were revealed. This research provided useful knowledge for bioconversion of waste date pulp and seeds to biomass energy.

Homoeologous chromosome pairing between the A and B genomes of Musa spp. revealed by genomic in situ hybridization.

BACKGROUND AND AIMS: Most cooking banana and several desert bananas are interspecific triploid hybrids between Musa acuminata (A genome) and Musa balbisiana (B genome). In addition, M. balbisiana has agronomical characteristics such as resistance to biotic and abiotic stresses that could be useful to improve monospecific acuminata cultivars. To develop efficient breeding strategies for improving Musa cultivars, it is therefore important to understand the possibility of chromosome exchange between these two species. METHODS: A protocol was developed to prepare chromosome at meiosis metaphase I suitable for genomic in situ hybridization. A series of technical challenges were encountered, the main ones being the hardness of the cell wall and the density of the microsporocyte's cytoplasm, which hampers accessibility of the probes to the chromosomes. Key parameters in solving these problems were addition of macerozyme in the enzyme mix, the duration of digestion and temperature during the spreading phase. RESULTS AND CONCLUSIONS: This method was applied to analyse chromosome pairing in metaphase from triploid interspecific cultivars, and it was clearly demonstrated that interspecific recombinations between M. acuminata and M. balbisiana chromosomes do occur and may be frequent in triploid hybrids. These results provide new insight into Musa cultivar evolution and have important implications for breeding.

Fatty acids from Tunisian and Chinese pomegranate (Punica granatum L.) seeds.

Pomegranate seed oil is considered a powerful health-benefiting agent due to its anti-oxidative and anticarcinogenic properties. Lipids from 21 pomegranate cultivars (15 Tunisian and 6 Chinese) were extracted and fatty acids were identified. Total lipids (16% on a dry weight basis) are mainly unsaturated (ca. 88%). Qualitatively, the pomegranate fatty acid composition is identical. Quantitatively, the predominant fatty acid was linolenic acid (44.51-86.14%), followed by linoleic acid (3.57-13.92%), oleic acid (3.03-12.88%), palmitic acid (3.13-11.82%), stearic acid (1.68-15.64%), gadoleic acid (0.50-4.91%), lignoceric acid ( < 2.53%), arachidic acid ( < 1.70%) and myristic acid ( < 0.85%). Statistical methods revealed how Chinese and Tunisian pomegranate fatty acid contents may be affected by the sampling location.

Hydrotime analysis to explore the effect of H2O2-priming in the relationship between water potential (Ψ) and germination rate of Capsicum annuum L. seed under NaCl- and PEG-induced stress.

Hydrogen peroxide (H2O2) priming was proved to be effective to boost salt and drought stress tolerance in Capsicum annuum L. Hither, hydrotime (HT) approach, a population-based threshold model-germination dependence on water availability, was introduced to account for the effects of reduced water potential on H2O2-primed seeds in progress toward germination. Pre-optimized H2O2 concentrations (1 and 10 mM for 24 h at 25 °C) were applied. Subsequently, seeds were germinated over a range of water potential (Ψ) (0 to -1.2 MPa) induced by sodium chloride (NaCl) and polyethylene glycol (PEG-6000) at 25 °C. We suggest that H2O2-priming affects differently the three derived items of HT model; induced lower hydrotime constant (θH) thus, revealed more rapid germination particularly evident with PEG, shifted the threshold or base water potential for 50% germination (Ψb(50)) towards a more negative value in NaCl culture, reflected a better salinity tolerance, though, the opposite effect was recorded with PEG, and reduced the standard deviation (σΨb), proved a better uniformity of the germination process for both cultures. Thus, H2O2-priming increased GRg (1/tg) at all Ψ>Ψb(g) which is due to both a lower Ψb(50) and a smaller θH in the primed seeds for NaCl culture and primarily owing to reducing θH with no positive effect on Ψb(50) for PEG culture. A normalized time-scale, for comparing responses, was introduced and confirmed the aforementioned impact. Therefore, the crosstalk between H2O2 molecule and different cell pathways generates a constructive response in accordance with imposed stress.

Untargeted metabolomics reveals changes in phenolic profile following in vitro large intestine fermentation of non-edible parts of Punica granatum L.

In this study, the untargeted phytochemical profile of non-edible parts of pomegranate (i.e., flowers, leaves and peels) was depicted by using untargeted metabolomics. Each sample was in vitro digested and then fermented simulating a large intestinal process, then monitoring the changes of phenolic bioaccessibility. The most abundant compounds in pomegranate extracts were polyphenols, terpenoids, sterols, alkaloids and amino acids. The untargeted metabolomic approach revealed a transformation of flavonoids over 24 h of in vitro fermentation. In particular, an increase in the % bioaccessibility for phenolic acids and tyrosols in flowers (probably due to the insoluble dietary fibre content, i.e., 27.1 g 100 g-1) was observed. Accordingly, the highest % bioaccessibility was detected after 24 h of in vitro large intestine fermentation for flower (i.e., 53.8%). Results showed that non-edible parts of pomegranate could be used as ingredients for the development of potential value-added food and industrial products.

Physico-chemical properties and DPPH-ABTS scavenging activity of some local pomegranate (Punica granatum) ecotypes.

Peels and fresh pomegranate extracts were used in the present study for the determination of the physic-chemical properties and DPPH-ABTS scavenging activities. Total sugars of juice are fructose (ca. 7 g/100 ml) and glucose (ca. 8 g/100 ml). Contents of soluble proteins in juice extracts are about 7 g/l (Bradford assays) and 22% (Kjeldhal assays) from dry pulp. Minerals in peel and juice are respectively 9.43+/-0.93 and 9.46+/-1.05 mg/100 ml for posphorus and 210.86+/-10.70 and 271.94+/-60.59 mg/100 g for potassium. The sodium contents are nearly 7 mg/100 ml in both peel and juice. Highly antioxidant contents in peels were confirmed. Free radical scavenging is about 3.58+/-0.38 microg/ml in peel. The antioxidant capacity value determined by ABTS was 7.364+/-0.403 mM Trolox equivalent antioxidant capacity/100 g dry weight. These findings implied that bio-active compounds from the peel might be potential resources for the development of antioxidant function dietary food.

Simple phenolic composition, flavonoid contents and antioxidant capacities in water-methanol extracts of Tunisian common date cultivars (Phoenix dactylifera L.).

The purpose of this study was to determine and compare the phenolic acid composition, flavonoid content and antioxidant activity of fruits from common date cultivars. The simple phenolic content ranged from 15.73 (Mermella variety) to 54.66 mg/100 g fresh weight (Korkobbi variety). Korkobbi had also the highest content of total flavonoids (54.46 quercetin equivalents/100 g fresh weight). The percentage of inhibition can reach 83% in the lipoperoxyl radical of the Korkobbi variety, while it was about 95% with the Rotbi variety for OH.. The Trolox equivalent antioxidant capacity value provided a ranking in decreasing order at 6 min: Korkobbi > Bouhattam > Baht = Smiti > Bekreri = Garn ghzal > Mermilla = Kenta > Nefzaoui = Rotbi. It seems that the highest level of flavonoids in the Korkobbi variety was principally responsible for the highest antiradical efficiency of this cultivar.

Spike developmental stages and ABA role in spikelet primordia abortion contribute to the final yield in barley (Hordeum vulgare L.).

BACKGROUND: Salinity is a significant environmental stress factor limiting crops productivity. Barley (Hordeum vulgare L.) has a natural tolerance to salinity stress, making it an interesting study object in stress biology research. In the present study, for the first time the effect of salinity stress on barley inflorescence developmental stages was investigated. Five spring barley genotypes irrigated with saline water (12.5 ds/m NaCl) were compared to controls treated with normal tap water. We measured abscisic acid (ABA) concentrations in the apical, central and basal sections of the immature inflorescence at green anther (GA) stage. The role of ABA in spikelet primordia development, atrophy and abortion and final yield was evaluated. RESULTS: A time course experiment starting from double ridge until green anther (GA) stages revealed that salinity reduced the length of spike developmental stages in all genotypes causing shortened of the plant life cycle. The shortened plant life cycle negatively affected plant height and number of tillers/plant. Salinity also affected spikelet primordia development. In both control and salinity treated plants apical spikelet abortion started in late awn primordium (AP) stage. However, under salinity treatment, significantly more spikelets were aborted, thus directly affecting plant yield potential. ABA, which plays a role in the spikelet/floret abortion process, was markedly elevated in the base and apex of salt treated spikes correlating with an increased spikelet abortion in these regions. CONCLUSIONS: Overall, salinity treatment reduced all plant and yield-related parameters investigated and turned some of the correlations among them from positive to negative or vice versa. Investigations of ABA role in floral development and phase duration of barley spike showed that, ABA regulates the spikelet/floret abortion process affecting the yield potential under salinity and control conditions.