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  • Author or Editor: A. Douira x
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The evolution of anthracnose symptoms on the aerial part (leaves, stems and strawberries) of three varieties Fortuna, Camarosa and Festival of strawberry plants inoculated with the conidial suspensions of Colletotrichum acutatum and Colletotrichum gloeosporioides isolates was followed. The severity index and infection coefficients increased in function of time. Seven days after inoculation they were low not exceeding 13.43% and 43.33, but they increased four weeks after inoculation, respectively, to 37.96% and 99 on strawberry plants of the Camarosa variety, 54.44% and 105 on those of Fortuna and 51.12% and 85 on those of Festival. At the sixth week, the severity index and infection coefficients became very high, reaching respectively 100% and 408 on Fortuna plants inoculated with C. gloeosporioides isolate (Coll3) followed by Coll2 (89.28% – 300), Coll1 (86.66% – 378) and Coll4 (80.45% – 198) of C. acutatum species. Similarly, the isolate Coll3 caused fruit rot; the percentage of rotten strawberries was 100% on Fortuna variety, 83.33% on Festival and 70.25% on Camarosa. A positive re-isolation of the tested Colletotrichum isolates has been noted from leaves of strawberry varieties and negative from crowns or the roots. A significant to moderate reduction in fresh and dry weights of the aerial part and roots was noted in inoculated strawberry plants compared to the control.

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Authors: S. Oulkheir, Khadija Ounine, N. Elhaloui, A. Douira, Latifa Ikko, Saadia Bricha and B. Attarassi

The effect of the acid and the osmotic stress on the heat resistance of Escherichia coli (EC 1 and EC 2 ) was studied at 63 °C in tryptic soy broth adjusted to various pHs (2.5, 4.5 and 6) and various NaCl concentrations (2, 4 and 8%). In the second study, the effect of pretreatment on thermotolerance of E. coli cells was determined.The heat resistance of both strains was low at pH 2.5, but strain EC1 was more resistant than strain EC 2 . On the contrary, the heat resistance increased with increasing the pH values. Addition of NaCl (2%) to TSB medium, was involved in the protection of cells against heat inactivation, this protective effect was, however, not observed by increasing the NaCl concentration up to 8%.The combined effect of the pH and NaCl on the thermal resistance of both strains was significantly lower at pH 2.5 and NaCl 8%, the number of viable cells decreased from approximately 10 8 CFU/ml to an undetectable number within 20 min for strain EC 1 and 15 min for strain EC 2 , respectively.This study indicates that heat resistance of strain EC1 was enhanced after acid or thermal adaptation. Heat resistance of strain EC2 was, however, enhanced only after thermal adaptation. For both strains no relationship was found between salt adaptation and the ability to resist thermal stress.

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Authors: S. Kribel, S. Qostal, A. Ouazzani Touhami, K. Selmaoui, A. Mouria, R. Benkirane, El. H. Achbani and A. Douira

Thirty Trichoderma isolates isolated from compost, various crops and soil with roots of adjacent sites to the phosphate mines of Morocco, were tested in vitro for their potential to solubilize phosphorus from phosphate rock. The qualitative assessment of phosphate solubilization by Trichoderma isolates was performed on Modified Pikovskaya Agar (MPA) solid medium. The visual observation of the 3- and 6-day-old cultures did not show any clear zone around the colony. However, all the isolates were able to grow on the culture medium 3 days after incubation, the maximum recorded diameter was 58.6 mm for isolate TR-B 98 (3) and the minimum value was 34.8 mm for isolate TS-EM-98 (2). After 6 days, they showed good radial growth that exceeded 79.8 mm with variable appearance of the mycelial density such as the isolates TS-B 98, TS-EM-98 (1) and TR-CB 2000 (1) that presented, respectively, high, regular and low mycelial density. Also, the Trichoderma isolates produced variable number of conidia on MPA medium. Quantitative estimation on the Modified Pikovskaya Broth (MPB) liquid medium showed a variable potential of the Trichoderma isolates to solubilize phosphate when the amount of soluble phosphorus remained low in the liquid medium without the fungus (0.26 mgL−1). The maximum concentration of soluble phosphorus was 11.92 mgL−1 with percentage of soluble phosphorus equal to 95.39% recorded by the isolate TR-TB 2000 after 9 days of incubation, followed by the isolates TR-B 98 (3), TS-B 98 and TR-EM 2 respectively, 11.20, 10.47 and 9.61 mgL−1 and 89.6, 83.76 and 76.38%. In addition, treatments with Trichoderma isolates provided a lower final broth pH which varied between 6.81 for TOL isolate and 3.40 for TS-B-2000 (2) compared to initial pH (7.2). The isolates that proved potent for phosphate solubilization displayed the highest fresh and dry weights such as TR-TB 2000 (FW = 4.11 g and DW = 2.56 g), while the lowest fresh and dry weight were noted in the weakest isolates for phosphate solubilization such as T27 (FW = 1.025 g and DW = 0.58 g).

The high solubilization potential of Trichoderma isolates can be exploited for the solubilization of fixed phosphorus present in the soil, thus improving soil fertility and plant growth.

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Authors: I. El Aymani, S. El Gabardi, M. Artib, M. Chliyeh, K. Selmaoui, A. Ouazzani Touhami, R. Benkirane and A. Douira

The diversity of endomycorrhizal fungi in the rhizosphere of Crocus sativus has been studied at five sites in the Taliouine region (Tinfat), located in Taroudant Province (Morocco), according to the number of years of soil exploitation by Saffron cultivation. In all sites, the roots of Crocus sativus carry structures of endomycorrhizal fungi. Root mycorrhizal frequencies are very high in site 1 (93.33%); site 2 (96.67%); site 4 (90%) and in site 6 (93.33%). In these sites, the spore density is, respectively, 39, 58, 138, 99 spores / 100 g of soil. The frequency of root mycorrhization is lower at the site (76.66%) which also exhibited a spore density of 27 spores / 100 g of soil.

The identification of isolated spores made it possible to note the presence of 36 species belonging to 6 genera: Glomus (15 species), Acaulospora (10 species), Scutellospora (6 species), Gigaspora (2 species), Pacispora (2 species), Entrophospora (1 species). Species such as Glomus clarum, G. etunicatum, G. aggregatum, G. intraradices, Acaulospora laevis, Scutellospora coralloidea, were present in all studied sites.

The greatest richness of MA fungi was registers in the site at four successive years of exploitation by Saffron (24 species), with a Shannon diversity index H ‘= 2.82 which is the highest among all studied sites, followed by the site at six years of occupation by Saffron (21 species), with H ‘= 2.61, while the lowest number of species was recorded in sites of two, three and ten years of exploitation of sol by Saffron, with H ‘= 1.77, respectively; 2.12 and 2.44.

This decrease in endomycorrhizal species richness confirms that Crocus sativus residues are probably the cause. In fact, the prolonged occupation of plots with safrana has an allelopathic effect on mycoflora and on the yield of Saffron.

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Authors: N. El Hazzat, M. Artib, J. Touati, M. Chliyeh, K. Selmaoui, A. Ouazzani Touhami, R. Benkirane and A. Douira

The endomycorrhizal fungi diversity in the rhizosphere of chickpea (Cicer arietinum L.) and the evaluation of root mycorrhizal level were studied in six regions of Morocco: Tahla, Sefrou, Souk Larbae, Souk Tlat, Ouazzane and Jarf Melha. All chickpea roots are carrying endomycorrhizal structures. Root mycorrhizal parameters varied from one site to another, and the highest frequency and intensity of mycorrhization was recorded in the roots of chickpea plants at the two sites Tahla and Jarf Melha respectively, 83%, 33% and 25.03%. In addition, the highest arbuscular content was also noted in the roots of plants growing in the site of Tahla (22.18%) while the lowest content was noted at the site of Sefrou (2.07%). However, the vesicles were not observed in all the sites.

The highest numbers of endomycorrhizal spores were recorded in the rhizosphere of plants collected in Jarf Melha and Tahla, respectively, 74 and 41 spores / 100 g soil. All spores found in the studied sites are represented by 22 morphotypes belonging to 7 genera: Glomus (13 species), Acaulospora (4 species), Gigaspora (one species), Radekera (one species), Entrophospora (one species), Pacispora (one species), Dentiscutata (one species).

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Authors: H. Aadel, R. Abdelwahd, S.M. Udupa, G. Diria, A. El Mouhtadi, K. Ahansal, F. Gaboun, A. Douira and D. Iraqi

Although significant progress has been made on Agrobacterium-mediated wheat transformation, current methodologies using immature embryos as recipient tissues are labor intensive, time consuming and expensive. The use of mature embryos as explants is increasingly being recognized as an optimal method for developing regenerable cell lines during wheat transformation. Therefore, we have developed an Agrobacterium-based transformation protocol using mature embryos while adjusting several factors that influence genetic transformation efficiency. In this study, we focussed on acetosyringone concentrations, genotypes and different types of mature embryos (intact or longitudinally halved-embryos or fragmented into four latitudinal pieces) used as a source of explants for the genetic transformation. A. tumefaciens strain EHA101 harboring the plasmid vector pTF101.1 carrying the barley HVA1 gene and bar-selectable marker gene were used. Mature intact-embryos and longitudinally halved-embryos yielded the highest number of putative transgenic plantlets on the selection medium. However, no plantlets were obtained from latitudinal fragmented mature embryos. ‘Amal’ and ‘Rajae’ genotypes regenerated the highest number of putative transgenic plants and 200 μM acetosyringone was found to be the optimal concentration for their transformation. A total of 47 transgenic plants were selected with 11 plantlets showing resistance to leaf painting. Molecular analysis revealed that 1% and 0.66% of T0 regenerated plantlets were successfully transformed and carried the HVA1 gene for the ‘Amal’ and ‘Rajae’ genotypes, respectively. Additional analysis shows the transgene is stably inherited in the T1 generation. Based on the results, we conclude that among the influencing factors tested, genotypes, mature embryo explant types and acetosyringone concentration contribute significantly to the success of bread wheat transformation.

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