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Background and Objectives: This study reports for the first time the variation of prolamin profiles among 51 pearl millet landraces representing seven populations prospected from contrasted bioclimatic areas of Tunisia. Findings: A total of 27 prolamins bands were detected, ranging from 11 to 245 kDa. Among them, 14 were polymorphic, resulting in a polymorphism rate of 51.85%. The bands with lower molecular weights are the most frequent. The biochemical marker M25.4 showed the highest value of Nei genetic diversity (h = 0.500), Shannon information index (I = 0.693), and effective number of alleles per locus Ne (2). At the population level, the polymorphism rates ranged between 50% (Mahdia) and 92.86% (Hammem Jebli, Kairouan, Medenine). The population of Kairouan showed the highest genetic diversity indices (I = 0.511 ± 0.054, h = 0.345 ± 0.041), while the lowest levels were recorded for the population of Mahdia (I = 0.268 ± 0.076, h = 0.177 ± 0.052). Analysis of molecular variance analysis indicated that the highest amount of genetic diversity was encompassed within the studied populations (89%). This was supported by low genetic differentiation (PhiPT = 0.110, p =.029) and Nei genetic distance values. The classification pattern using ward dendrogram and factorial analyses revealed the distinction of two clusters with a low genetic structure based on the geographic origins of landraces. Significance and Novelty: The detected biochemical protein polymorphism could be a highly effective tool for the genetic resources characterization of pearl millet landraces, which will be further utilized in breeding investigations and taxonomic surveys of this cereal crop. [ABSTRACT FROM AUTHOR]

Bioactive compounds in wheat have received a great interest in the last few years due to their nutritional and health benefits. Various analytical procedures were used to identify these compounds in wheat kernels. An ultra‐performance liquid chromatography coupled to electrospray ionization quadrupole‐time‐of‐flight mass spectrometry (UPLC–ESI‐QTOF‐MS/MS) was used for the screening of bioactive compounds in seven Tunisian durum wheat extracts. The aim of this study was to realize a screening of several classes of bioactive compounds in the same analysis and to identify specific metabolite markers for discriminating the durum wheat varieties. The UPLC‐ESI‐QTOF‐MS/MS allows the detection of 81 metabolites, belonging to different chemical families such as sugars, organic acids, amino acids, fatty acids, and phenolic compounds represented by benzoic and cinnamic acid derivatives, phenolic alcohols, flavones, lignans, and condensed tannins. Chemical profiles identified varied greatly between different wheat genotypes. As far as the authors know, this is the first time that different chemical classes were detected at the same time in durum wheat kernels using UPLC‐ESI‐QTOF‐MS/MS. This study gives the most complete map of metabolites in Tunisian durum wheat and proves that UPLC‐QTOF‐MS/MS coupled with chemometric analysis is a great tool for discrimination between durum wheat cultivars. [ABSTRACT FROM AUTHOR]

Xylem vessels are essential pivotal organs in bulk hydraulic flow through the whole woody plant. However, environmental constraints generate disagreements in xylem structures, which are characterized by air emboli and occlusions formations, compromising water conductivity in grapevines. The aim of this work was to explore xylem morphology dynamics through the xylem sap flow of five Tunisian grapevine cultivars during the natural bleeding sap periods of 2019, 2021, and 2022. In fact, Sakasly, Khamri, Hencha, Razegui1, and Razegui2 rain-fed grapevine cultivars revealed differential responses towards xylem sap movement. The results demonstrated that the xylem sap flow was significantly more abundant in 2019 than 2021 and 2022 bleeding sap campaigns. A variation was revealed between the cultivars regarding the xylem sap flow. In fact, Sakasly gave the best xylem flow during the three campaigns. Razegui1 and Razegui2 registered approximately similar xylem sap flow, while Hencha and Khamri present the lowest sap fluxes during the three campaigns. Moreover, several vascular occlusions forms were identified from stem cross sections using environmental scanning electron microscopy (ESEM), including tyloses, gels, starch, and gum deposits. The highest occlusion number was observed in Sakasly, Razegui1, and Razegui2 cultivars. Among different biogenic calcium shapes, several were observed for the first time in grapevine, including multi-faceted druse, cubic, crystalline sand, styloids, spherical, or drop-like structures. Considering their lower flow and totally blocked vessels, both Hencha and Khamri confirmed their susceptibility to environmental constraints. However, Sakasly, Razegui1, and Razegui2 cultivars presented higher tolerance according to their sap flow and xylem morphology. [ABSTRACT FROM AUTHOR]

Salt stress negatively impacts crop production worldwide. Genetic diversity among barley (Hordeum vulgare) landraces adapted to adverse conditions should provide a valuable reservoir of tolerance genes for breeding programs. To identify molecular and biochemical differences between barley genotypes, transcriptomic and antioxidant enzyme profiles along with several morpho-physiological features were compared between salt-tolerant (Boulifa) and salt-sensitive (Testour) genotypes subjected to salt stress. Decreases in biomass, photosynthetic parameters, and relative water content were low in Boulifa compared to Testour. Boulifa had better antioxidant protection against salt stress than Testour, with greater antioxidant enzymes activities including catalase, superoxide dismutase, and guaiacol peroxidase. Transcriptome assembly for both genotypes revealed greater accumulation of differentially expressed transcripts in Testour compared to Boulifa, emphasizing the elevated transcriptional response in Testour following salt exposure. Various salt-responsive genes, including the antioxidant catalase 3, the osmoprotectant betaine aldehyde dehydrogenase 2, and the transcription factors MYB20 and MYB41, were induced only in Boulifa. By contrast, several genes associated with photosystems I and II, and light receptor chlorophylls A and B, were more repressed in Testour. Co-expression network analysis identified specific gene modules correlating with differences in genotypes and morpho-physiological traits. Overall, salinity-induced differential transcript accumulation underlies the differential morpho-physiological response in both genotypes and could be important for breeding salt tolerance in barley. [ABSTRACT FROM AUTHOR]

Knowledge about the extent of nutrient variability in local barley germplasm is an important prerequisite for efficient crop improvement. The present study is one of the first to assess the potential of Tunisian barley populations (named Testour, Gergis, and Enfidha) as sources of desirable traits for barley improvement and for the prevalence of Fusarium species and the mytoxin zearalenone (ZEN). Analysis of variance revealed highly significant differences between barley populations for nutrients density. The lowest phytate/zinc molar ratios were observed in Testour and Enfidha populations with 7.23 and 9.97, respectively. However, the bioavailability of iron of most barley populations (95.4%) was inhibited mainly by the high phytate content. Oleic acid (15.2–18.7%), linoleic acid (13.8–16.01%), and palmitoleic acid (4.7–14.2%) were identified as predominant fatty acid constituents in all three barley populations. Based on morphologic and molecular characterization, Fusarium graminearum and Fusarium culmorum were the predominant species that infected Testour, Gergis, and Enfidha populations. The concentration of zearalenone ranged between 0 and 140 µg kg−1. The highest levels of zearalenone, 92 μg kg−1 and 60 μg kg−1, were detected in Testour populations that were infected with F. graminearum and F. culmorum, respectively. These relatively low amounts of zearalenone in barley populations can be attributed to the Tunisian climate and the resistance of local genotypes. Testour and Enfidha barley populations could potentially be used to improve breeding programs for biofortification. [ABSTRACT FROM AUTHOR]

Salt stress is considered one of the most devastating environmental stresses, affecting barley growth and leading to significant yield loss. Hence, there is considerable interest in investigating the most effective traits that determine barley growth under salt stress. The objective of this study was to elucidate the contribution of osmotic and oxidative stress components in leaves and roots growth under salt stress. Two distinct barley (Hordeum vulgare) salt-stress tolerant genotypes, Barrage Malleg (BM, tolerant) and Saouef (Sf, sensitive), were subjected to 200 mM NaCl at early vegetative stages. Stressed and control leaves and roots tissue were assessed for several growth traits, including fresh and dry weight and plant length, as well as the content of osmoprotectants proline and soluble sugars. In addition, malondialdehyde content and activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX), as well as their corresponding gene expression patterns, were investigated. The results showed better performance of BM over Sf for leaf dry weight (LDW), root dry weight (RDW) and root length (RL). The salt-tolerant genotype (BM) had better osmoprotection against salt stress compared with the salt-sensitive genotype (Sf), with a higher accumulation of proline and soluble sugars in leaves and roots and a stronger antioxidant system as evidenced by higher activities of SOD, CAT and APX and more abundant Cu/Zn-SOD transcripts, especially in roots. Stepwise regression analysis indicated that under salt stress the most predominant trait of barley growth was Cu/Zn-SOD gene expression level, suggesting that alleviating oxidative stress and providing cell homeostasis is the first priority. [ABSTRACT FROM AUTHOR]

Background: Pearl millet (Pennisetum glaucum L.) has become increasingly attractive due to its health benefits. It is grown as food for human consumption and fodder for livestock in Africa and Asia. This study focused on five pearl millet populations from different agro‐ecological zones from Tunisia, and on characterization by morphological traits, total phenolic and flavonoid content, antioxidant activity, and occurrence of Fusarium. Results: Analysis of variance revealed highly significant differences between populations for the quantitative traits. The highest grain weights occurred in the pearl millet cultivated in Zaafrana and Gergis of Tunisia. Early flowering and early maturing populations cultivated in the center (Zaafrana, Rejiche) and south (Gergis) of Tunisia tended to have a higher grain yield. The Zaafrana population showed the highest value of green fodder potentiel (number and weight of leaves/cultivar and the weight of tillers and total plant/cultivar) followed by Gergis and Rejiche. The Kelibia population showed the highest total phenolic and flavonoid content. Rejiche exhibited the greatest antioxidant activity. Trans‐cinnamic, protocatechuic, and hydroxybenzoic acids were the major phenolic compounds in all the extracts. Three Fusarium species were identified in Tunisian pearl millet populations based on morphologic and molecular characterization. Fusarium graminearum and Fusarium culmorum occurred most frequently. The average incidence of the three Fusarium species was relatively low (<5%) in all populations. The lowest infection rate (0.1%) was recorded in the samples from Zaafrana. Conclusion: Chemometric analysis confirmed the usefulness of the above traits for discrimination of pearl millet populations, where a considerable variation according to geographical origin and bioclimatic conditions was observed. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

To better understand micromorphological and structural changes, histological sections provide additional insight into cellular process and developmental pathways occurring in oat somatic embryogenesis. Environmental scanning electron microscopy (ESEM) and transmission electron microscopy (TEM) were also used to follow the ultrastructural modifications during this system. Histological observations allowed following the events leading to the development of mature somatic embryos. The scheme includes the following steps: cell reactivation, the first organized cell division in diads, triads, tetrads as well as octant stages, the observation of an extracellular matrix (ECM) as a fibrillar material that bounded the surface of individualized proembryos. The transition from proembryo stage to an early globular somatic embryo was noted, where the embryogenic cortex is surrounded by the protoderm. The late globular stage was marked by bipolarity. The early and late transitional stages, the coleoptilar, mature and germinated stages were also described. The ESEM allowed us to follow some rearrangements, related to the morphology and surfaces involved in somatic embryos development. These events are proembryo formation, transition from proembryo to globular stage, marked by protoderm formation, scutellum and coleoptile development and finally somatic embryos germination. The TEM showed that embryogenic cells were very rich in organelles; mitochondria, rough endoplasmic reticulum, Golgi apparatus and ribosomes. Cells of proembryos, globular and late somatic embryos showed more vacuoles and differentiated organelles. The ECM was also detected by TEM as fibrillar material coating the cell walls. These results on structural and ultrastructural changes provided new insights and findings on oat somatic embryogenesis. [ABSTRACT FROM AUTHOR]

Hybridity and the genuineness of hybrids are prominent characteristics for quality control of seeds and thereby for varietal improvement. In the current study, the cross between two local barley genotypes (Ardhaoui: female; Testour: male) previously identified as susceptible/tolerant to salt stress in Tunisia was achieved. The hybrid genetic purity of the generated F putative hybrids and the fingerprinting of the parents along with their offspring were assessed using a set of 17 nuclear SSR markers. Among the analyzed loci, 11 nSSR were shown polymorphic among the parents and their offspring. Based on the applied 11 polymorphic SSR loci, a total of 28 alleles were detected with an average of 2.54 alleles per locus. The locus HVM33 presented the highest number of alleles. The highest polymorphism information content value was detected for the locus HVM33 (0.6713) whereas the lowest PIC value (0.368) was revealed by the loci BMAC0156, EBMAC0970 and BMAG0013 with a mean value of 0.4619. The probabilities of identical genotypes PI for the 11 microsatellite markers were 8.63 × 10. Banding patterns among parents and hybrids showed polymorphic fragments. The 11 SSR loci had produced unique fingerprints for each analyzed genotype and segregate between the two parental lines and their four hybrids. Parentage analysis confirms the hybrid purity of the four analyzed genotypes. Six Tunisian barley accessions were used as an outgroup in the multivariate analysis to confirm the efficiency of the employed 11 nSSR markers in genetic differentiation among various barley germplasms. Thus, neighbor joining and factorial analysis revealed clearly the discrimination among the parental lines, the four hybrids and the outgroup accessions. Out of the detected polymorphic 11 nuclear SSR markers, a set of five markers ( HVM33, WMC1E8, BMAC0154, BMAC0040 and BMAG0007) were shown to be sufficient and informative enough to discriminate among the six genotypes representing the two parental lines and the four hybrids from each others. These five nSSR markers presented the highest number of alleles per locus ( A), expected heterozygosity ( H), PIC values and the lowest probabilities of identity (PI). These nSSR loci may be used as referral SSR markers for unambiguous discrimination and genetic purity assessment in barley breeding programs. [ABSTRACT FROM AUTHOR]

Salinity problems for vineyards are in concerns, especially in coastal areas where several aquifers are reported to be affected by seawater intrusion and agricultural contamination. Saline irrigation affects growth, yield, and fruit quality of grapevines. Exploring germplasm base through wild ancestors of the target species is a novel adopted strategy to increase crop tolerance to irrigation with saline water. The effects of salt on growth, organic and inorganic solute accumulations, and chlorophyll florescence were studied on 3-month-old plants of six Tunisian wild grapevines with the objective to identify salt tolerance mechanisms and select tolerant genotypes. Potted plants were grown under controlled conditions and irrigated for 14 days with 0, 100, and 150 mM NaCl nutrient solution. Parameters analyzed were related to growth, water relations, mineral nutrition, and chlorophyll fluorescence. Several processes are operating either at the whole plant or at cell level. They appear to be involved in salt tolerance of wild grapevines and are more efficient in tolerant accessions. Salt adversely affects plant growth and plant nutrition. Reductions of shoot growth rate (relative growth rate, day) reached 49% of control since 100 mM NaCl. They were assigned to stomatal closure and alteration of potassium nutrition and photochemistry. There were significant differences ( P < 0.05) within accessions, Tebaba was the most tolerant and Houamdia the most sensitive, while the others were intermediate. [ABSTRACT FROM AUTHOR]

Tunisian barley (Hordeum vulgare L.) landraces, representing the oldest cultivated accessions, are growing in scattered populations across drought- and salt-stressed environments and constitute a precious reservoir of potentially useful traits for breeding programs. The objective of this study was to elucidate genetic diversity and population structure of barley landraces across the landscape of Tunisia. Populations from 11 geographic zones were genotyped using 21 nuclear microsatellites. A high level of genetic polymorphism with 170 detected alleles was recorded among the studied genotypes. The average allelic richness was 8.095 alleles per locus. The index of genetic diversity (He) showed an average of 0.741. Genetic diversity was very high within populations, whereas differences among populations were difficult to detect. Only 0.15% of the DNA variation was apportioned among landraces (P < 0.001), whereas 99.85% of the DNA variation was maintained within these landraces. A high gene flow (Nm) was revealed among the investigated populations, which has been facilitated by exchange of barley seeds between Tunisian cereal farmers of different regions. Genetic diversity within Tunisian barley landrace germplasms may help to maintain adaptation to a broad range of environmental conditions and provide genetically diverse resources for barley breeders. Both ex situ (seed banks) and in situ (on-farm) conservation strategies may be required to maintain barley landrace genetic resources. [ABSTRACT FROM AUTHOR]