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55. Evaluating the contribution of osmotic and oxidative stress components on barley growth under salt stress.

Author

Ouertani, Rim Nefissi, Abid, Ghassen, Karmous, Chahine, Chikha, Mariem Ben, Boudaya, Oumaima, Mahmoudi, Henda, Mejri, Samiha, Jansen, Robert K, and Ghorbel, Abdelwahed

Subjects
OXIDATIVE stress, BARLEY, LEAF growth, SALT, SUPEROXIDE dismutase, GENE expression, METALLOTHIONEIN
Abstract

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]

Published
2021
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58. Water activity and temperature effects on fungal growth and ochratoxin A production by ochratoxigenic Aspergillus carbonarius isolated from Tunisian grapes

Author

Lasram, Salma, Oueslati, Souheib, Valero, Ana, Marin, Sonia, Ghorbel, Abdelwahed, and Sanchis, Vicente

Subjects
Aspergillus -- Physiological aspects, Aspergillus -- Environmental aspects, Grapes -- Diseases and pests, Mycotoxins -- Chemical properties, Mycotoxins -- Thermal properties, Business, Food/cooking/nutrition
Published
2010

60. Elimination of Grapevine leafroll associated virus-3, Grapevine rupestris stem pitting associated virus and Grapevine virus A from a Tunisian Cultivar by Somatic Embryogenesis and Characterization of the

Author

Bouamama-Gzara, Badra, primary, Selmi, Ilhem, additional, Chebil, Samir, additional, Melki, Imene, additional, Mliki, Ahmed, additional, Ghorbel, Abdelwahed, additional, Carra, Angela, additional, Carimi, Francesco, additional, and Mahfoudhi, Naima, additional

Published
2017
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64. Status of herbicide-resistant Lolium populations in wheat fields in Tunisia

Author

Menchari, Yosra, Hajri Haifa H.,, Ben Salem Asma A.,, Delye, Christophe, Ghorbel, Abdelwahed, Centre de Biotechnologie de Borj Cedria (CBBC), Agroécologie [Dijon], Institut National de la Recherche Agronomique (INRA)-Université de Bourgogne (UB)-AgroSup Dijon - Institut National Supérieur des Sciences Agronomiques, de l'Alimentation et de l'Environnement, and ProdInra, Migration

Subjects
[SDV] Life Sciences [q-bio], [SDE] Environmental Sciences, ALS inhibitors, [SDV]Life Sciences [q-bio], Lolium rigidum, [SDE]Environmental Sciences, food and beverages, [SDV.BV]Life Sciences [q-bio]/Vegetal Biology, [SDV.BV] Life Sciences [q-bio]/Vegetal Biology, Target-site resistance, ACCase-inhibiting
Abstract

The evolution of herbicide resistance in weeds is a worldwide phenomenon in modern cropping systems. The presence of resistant populations can severely hamper herbicide-based weed control, thus leading to the need for a more accurate use of these products. In Tunisia, the first report of evolved herbicide resistance concerned Lolium rigidum populations collected in wheat fields in northern Tunisia in 1996 and found to be resistant to acetyl-coenzyme A carboxylase-inhibiting (ACCase) herbicides. The objective of this study is to detect and characterise herbicide resistance in ryegrass (Lolium spp). The sensitivity of nine ryegrass populations, collected in wheat fields in northern Tunisia, was performed with two ACCase-inhibiting herbicides and an acetolactate synthase (ALS)-inhibiting herbicide. Resistant plants were genotyped to detect mutant resistant ACCase and ALS alleles. The results showed that resistance to clodinafop is very developed, as it was observed in all populations tested. However, resistance to sulfonylurea is less developed but seems to be emerging. Although the mutant ALS resistant alleles account for most of the resistance to sulfonylurea, those of ACCase explain less than 20% of the resistance observed in ryegrass populations. The other part would be due to other mechanisms that are likely metabolism-based resistance. The cross-resistance pattern conferred by this type of resistance is very unpredictable as it may relate to different herbicide chemical families and this could explain the resistance observed in some populations for the new molecule pinoxaden. To reduce the spread of the phenomenon of resistance in wheat fields, chemical weed control could not by itself be a long term solution. The use of integrated crop management methods, including cultivation and the alternation of different herbicides and modes of action, would be proposed.

Published
2013

69. Micromorphology, structural and ultrastructural changes during somatic embryogenesis of a Tunisian oat variety ( Avena sativa L. var 'Meliane').

Author

Borji, Manel, Bouamama-Gzara, Badra, Chibani, Farhat, Teyssier, Caroline, Ammar, Awatef Ben, Mliki, Ahmed, Zekri, Sami, and Ghorbel, Abdelwahed

Abstract

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]

Published
2018
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70. Physiological comparative study of six wild grapevine ( Vitis sylvestris) accession responses to salinity.

Author

Askri, Hend, Gharbi, Fatma, Rejeb, Saloua, Mliki, Ahmed, and Ghorbel, Abdelwahed

Abstract

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]

Published
2017
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71. Low Genetic Diferentiation and Evidence of Gene Flow among Barley Landrace Populations in Tunisia.

Author

Romdhane, Mériam Ben, Riahi, Leila, Selmi, Ayet, Jardak, Rahma, Bouajila, Aida, Ghorbel, Abdelwahed, and Zoghlami, Nejia

Subjects
BARLEY genetics, BARLEY farming
Abstract

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]

Published
2017
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74. Conservation priorities for endangered coastal North African Pennisetum glaucumL. landrace populations as inferred from phylogenetic considerations and population structure analysis

Author

Ben Romdhane, Mériam, Riahi, Leila, Bouamama, Badra, Houissa, Hela, Ghorbel, Abdelwahed, and Zoghlami, Néjia

Abstract

The increasing anthropologic pressure and the modernization of agriculture have led to a forsaking of pearl millet traditional cultivars, inducing a progressive loss of the genetic variability encompassed in this locally adapted germplasm. Imperatively, national efforts based on robust data gleaned from genetic surveys have to be undertaken in order to set up suitable conservation priorities. In this study, in addition to the assessment of the genetic diversity and population structure among and within a set of seven pearl millet landrace populations from coastal North Africa, demographic and phylogenetic data, conservation priority scores were calculated according to Vane-Wright et al. (1991). To date, genetic diversity of pearl millet in North Africa is still poorly documented. The present survey reports for the first time the use of highly informative nSSR markers (PIC = 0.74) on Pennisetum glaucumlandraces representative of the Mediterranean coastline of North Africa. A high level of genetic diversity was obtained within the investigated landraces (He= 0.80) at the population level. FST, AFC-3D, and Bayesian clustering underlined significant differentiation and an apparent genetic structure, according to geographical origin. Phylogenetic considerations integrated with demographic and genetic information enabled conclusive inferences of highly prioritized populations for conservation. Populations Haouaria, Hammem Laghzez, Mahdia, and Medenine, representatives of the main pearl millet growing areas in Tunisia and cultivated in the North African littoral, should be strongly recommended for an ex situ conservation program. Dynamic on-farm conservation method is also required as it allows the local landraces to evolve in different environments, while maintaining their adaptation potentials.

Published
2019
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75. Differential physiological responses of Tunisian wild grapevines (Vitis viniferaL. subsp. sylvestris) to NaCl salt stress

Author

Askri, Hend, Gharbi, Fatma, Rejeb, Saloua, Mliki, Ahmed, and Ghorbel, Abdelwahed

Abstract

The effects of salt stress on growth, organic and inorganic solute accumulation and chlorophyll florescence were studied on 3-month-old plants of six Tunisian wild grapevine accessions in order 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 Long Ashton nutrient solution. Salt begins to adversely affect plant growth and plant nutrition at 100 mM NaCl. Compared to control, shoot growth rates were 21.5% less for Khedhayria, Tebabaand Ouchteta, 33% for Djebbaand Zouarâaand 49% for Houamdia. They were assigned to stomatal and non-stomatal factors. Stomatal conductance decreased after 1 day at 150 mM NaCl in all accessions in response to reduced leaf water potential. Leaves in tolerant accessions were well hydrated through efficient osmotic adjustment, sufficient potassium flux and selectivity of K+versus Na+. In addition, salt tolerance of wild grapes was related to limiting Na+transport to lamina and to compartmentalization of Cl−on root and leaf vacuoles, improved in Tebabaand Khedhayriaby the uptake of K+. At the same time, disturbances of the PSII have been noted as non-stomatal factors, and the most important photoprotective mechanism against photosynthetic damages was non-photochemical energy dissipation. However, chlorophyll fluorescence parameters were more stable in Tebabacompared to Khedhayria,thus showing better salt tolerance. Based on our results, wild grapevine accessions could be classified from most tolerant to most sensitive as follows: Tebaba > Khedhayria > Ouchteta > Zouarâa > Djebba > Houamdia.

Published
2018
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82. Fingerprinting and genetic purity assessment of F1barley hybrids and their salt-tolerant parental lines using nSSR molecular markers

Author

Ben Romdhane, Mériam, Riahi, Leila, Jardak, Rahma, Ghorbel, Abdelwahed, and Zoghlami, Nejia

Abstract

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 F1putative 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 HVM33presented 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, EBMAC0970and BMAG0013with a mean value of 0.4619. The probabilities of identical genotypes PI for the 11 microsatellite markers were 8.63 × 10−7. 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, BMAC0040and 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 (An), expected heterozygosity (He), 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.

Published
2018
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