Ahmed Qaddoury

Osmopriming improves seeds germination, growth, antioxidant responses and membrane stability during early stage of Moroccan alfalfa populations under water deficit

Osmopriming has a positive effect on the enhancement of seeds germination and seedlings growth, especially under stress conditions. This study investigated the effects of osmopriming with polyethylene glycol on alfalfa (Medicago sativa L.) seeds germination and seedlings antioxidant responses under drought stress. Seeds of five Moroccan alfalfa populations and an American Moapa variety were used to investigate the effect of osmopriming on seeds germination, seedlings growth, activities of antioxidant enzymes and membrane stability under two water deficit levels (-0.45 and -0.75 MPa). Seeds were primed with polyethylene glycol (PEG6000) (-0.6 MPa) for 24 h at 25 °C. The results showed that treated seeds presented higher germination rate and growth of 8 d-old seedlings than untreated ones. Particularly, osmoprimed seeds of ‘Adis-Tata’ (Ad) and ‘Riche’ (Rc) populations presented the highest final germination percentages of 90.8% and 64%, respectively, and seedlings shoot and root lengths under both levels of water deficit. The priming treatment enhanced the activity of peroxidase (PO) and catalase (CAT) and reduced the malonyldialdehyde (MDA) content and the electrolyte leakage under water deficit. Generally, the success of germination was positively correlated to PO and CAT activities and the degree of membrane stability in drought tolerant populations. However, the positive effect of the osmopriming technique on alfalfa drought tolerance remains limited in some tested populations, and severe water stress could inhibit germination and cause damages of alfalfa seedlings.

Improved rooting capacity and hardening efficiency of carob ( Ceratonia siliqua L.) cuttings using arbuscular mycorrhizal fungi

The present investigation was undertaken to improve the performance of carob cuttings in terms of adventitious roots formation and hardening using arbuscular mycorrhizal fungi (AMF). Softwood cuttings were treated with 5000 mg L -1 of indole-3-butyric acid (IBA) and kept non-inoculated (Non-AM) or inoculated with Funneliformis mosseae ( Fmo ) alone or combined with Rhizophagus fasciculatus ( Fmo+Rfa ) or R. intraradices ( Fmo+Rin ) or both ( Fmo+Rfa+Rin ) and then maintained under mist conditions. After two months, rooted cuttings were transplanted on sterilized substrate and transferred to a hardening greenhouse for five months. Obtained results showed that inoculation of the rooting substrate with AMF substantially improved the percentage of rooted cuttings and the number of roots per cutting. The highest rooting (63.33%) and number of roots per cutting (11.67) were recorded in the presence of the complex of the three AMF strains ( Fmo+Rfa+Rin ). Moreover, all mycorrhizal-rooted cuttings survived transplantation and hardening shocks and showed the highest growth and physiological performances. Indeed, in the Fmo-Rfa-Rin- plantlets the gains in plant height and shoot and root dry weights were 95.6%, 55.1% and 76.9% respectively. Furthermore, stomatal conductance, total chlorophyll content, photochemical efficiency of PSII (F v /F m ) and nutrient concentrations were higher in mycorrhizal plantlets than in non-AM ones. Thus, AMF substantially improved carob cuttings’ performance in terms of rooting capacity and hardening efficiency, thereby increasing the potential of carob propagation by cuttings. https://doi.org/10.2298/ABS160307100E Received: March 7, 2016; Revised: May 2, 2016; Accepted: May 31, 2016; Published online: October 17, 2016 How to cite this article: Essahibi A, Benhiba L, Oussouf FM, Babram MA, Ghoulam C, Qaddoury A. Improved rooting capacity and hardening efficiency of carob ( Ceratonia siliqua L.) cuttings using arbuscular mycorrhizal fungi. Arch Biol Sci. 2017;69(2):291-8.

Influence of arbuscular mycorrhizal fungi on the functional mechanisms associated with drought tolerance in carob (Ceratonia siliqua L.)

Key messageArbuscular mycorrhizal symbiosis strengthened the mechanisms developed by carob to withstand drought stress, including improved water relations, increased cell wall rigidity and osmolytes accumulation, and enhanced oxidative stress alleviation.AbstractThe present investigation was carried out to provide more insight into the influence of arbuscular mycorrhizal fungi (Funneliformis mosseae, Rhizophagus fasciculatus, and Rhizophagus intraradices) on drought tolerance of carob. Non-mycorrhizal (NM) and arbuscular mycorrhizal (AM) carob plants were subjected to two watering regimes, 75% of field capacity (well water) or 25% of field capacity (water stress). Obtained results showed that stressed AM plants exhibited increased performance in terms of growth and biomass production, water and nutrient acquisition, and oxidative stress alleviation compared to NM plants. In fact, under limited water regime, AM plants maintained high stomatal conductance and high relative water content (over 94%) due to their high water and nutrient uptake efficiency. Moreover, AM plants especially those associated with F. mosseae maintained high membrane integrity (over 80%), high cell wall rigidity, and high leaf water potential and osmotic potential at full turgor and at turgor loss, while these parameters steeply decreased in NM plants. Furthermore, drought-stressed AM plants showed decreased hydrogen peroxide and malondialdehyde contents associated with increased activities of superoxide dismutase, ascorbate peroxidase, guaiacol peroxidase, and catalase compared to their relative NM plants. Thus, AMF strengthened the mechanisms involved in drought tolerance of carob by improving water relations, increasing cell wall rigidity, and enhancing oxidative stress alleviation. Funneliformis mosseae was the most effective in improving carob tolerance to drought stress.

Medicago sativa-rhizobia symbiosis under water deficit: Physiological, antioxidant and nutritional responses in nodules and leaves

ABSTRACT Biological nitrogen fixation has positive effects in the enhancement of soil nutrition and plants growth, especially under difficult conditions. The study assesses the effect of drought (40% field capacity) on growth, physiological and biochemical parameters of six symbioses involving two Moroccan alfalfa populations Adis-Tata (Ad) and Riche (Rc) and Moapa (Mo) variety and ArfRh2 (Rh2) and AufRh8 (Rh8) rhizobia isolated from Arfoud and Aufous, respectively. Results showed that drought decreased plants growth and nodulation. Physiologically, as response to stress, the nodules membrane stability was negatively affected. Biochemically, activities of peroxidase (POX), catalase (CAT), superoxide dismutase (SOD) and acid phosphatase (APase) increased in leaves and nodules. Ad-Rh2, Rc-Rh2 and Ad-Rh8 have been qualified as more drought tolerant. They showed high antioxidant activities and as consequence less membrane damages especially in their nodules. The increase in nodules health and antioxidant defense could results in the enhancement of plant drought tolerance under stress.

International Congress on Mycorrhizae: mycorrhizal symbiosis a key factor for improving plant productivity and ecosystems restoration

The Mycorrhizae and Mediterranean Ecosystems Group (MYCOMED), the African Network on Mycorrhiza (AFRINOM) and the French Mycorrhizologist Network (RAMYF) co-organized an International Congress on BMycorrhizal Symbiosis a Key Factor for Improving Plant Productivity and Ecosystems Restoration^ in Marrakech, Morocco, October 15–17, 2014. Three hundred participants from 45 different countries attended the congress, which included 65 oral presentations and 100 posters. Abstracts of all talks and posters can be found at the website (http://icmycorrhizae2014.uca.ma) of Cadi Ayyad University. The congress was an international forum for exchange of knowledge and expertise between scientists developing fundamental and applied mycorrhizal research as well as companies commercializing mycorrhizal inoculum. The objectives were to update scientific and technical knowledge on mycorrhizal fungi as providers of key ecological services, to valorize the mycorrhizal symbiosis in practices in the socioeconomic environment of Mediterranean and tropical areas and to share the experiences of scientists with young researchers, policy makers and end-users. The contents addressed included three topics: (i) biology, ecology and diversity of mycorrhizal fungi in tropical and Mediterranean environments; (ii) mycorrhizal symbiosis and plant tolerance to biotic and abiotic stresses and (iii) valorization and transfer of mycorrhizal biotechnologies in agro-ecological engineering strategies and the socio-economic environment of tropical and Mediterranean areas. In the opening conference on the role of arbuscular mycorrhiza for plant health, Prof. Paola Bonfante (Italy) provided an overview on the cellular and molecular mechanisms which allow plants to take up essential minerals in model legume plants, and revealed how mycorrhiza may have a systemic impact on the fruit transcriptomics and nutrient content in agricultural important crops such as tomato. Dr. Marc Buee (France) introduced topic (i) by raising the fundamental question of how to connect metagenomics and mycorrhizal fungal ecology. Through various examples, spanning from local to large-scale studies using biogeographic approaches, he presented the advantages and risks of highthroughput sequencing to investigate ectomycorrhizal fungal ecology, with unprecedented scales of sampling, and illustrated how fungal genome resources feed metagenomics to increase knowledge on the ecology of mycorrhizal fungal communities and assemblages. In introducing topic (ii), Prof. Guillaume Becard (France) talked about plant mechanisms that discriminate beneficial and pathogenic microorganisms via microbial signals. These molecular signals are involved in the processes of nodulation, mycorrhization, root development and basal plant immunity. They could have a huge potential for sustainable agriculture because of their implication in enhancing plant nutrition, growth and defense against pathogens and pests. Dr. Silvio Gianinazzi (France) introduced topic (iii) by presenting the domestication of beneficial soil microorganisms as an innovative technology for agriculture. He suggested that Mohamed Hafidi, Ahmed Qaddoury, Robin Duponnois, Daniel Wipf, Mohamed Hijri and Amadou Bâ contributed equally to this work.

International Workshop of the African Network on Mycorrhiza (AFRINOM 1): advancing plant–microbe interactions in crop nutrition, integration of mycorrhiza into agroecosystems

The African Network on Mycorrhiza (AFRINOM, http:// senegal.ird.fr/afrinom) was created following an international workshop on “Mycorrhiza: a biological tool for sustainable development in Africa,” held in Dakar, Senegal, in 2011 (Bâ et al. Mycorrhiza 2011). The general objectives of AFRINOM are to strengthen research, encourage cooperation, and promote exchange of information on mycorrhiza in Africa. The network, which consists of 135 members from 31 countries, encourages the development of joint research activities between researchers in Africa and Europe, America, Oceania, and Asia. It also gathers data and published information on mycorrhiza in Africa and provides information about laboratories working on mycorrhiza in Africa and a database on cultures of ectomycorrhizal and arbuscular mycorrhizal fungi from Africa and abroad. The International Workshop of AFRINOM 1 on “Advancing plant–microbe interactions in crop nutrition, integration of mycorrhiza into agroecosystems” was organized in Nairobi, Kenya, October 22–26, 2012, as part of the ISFMAfrica 2012 conference on “Integrated Soil Fertility Management in Africa: from microbes to markets.” Thirty-one participants from 13 countries attended the workshop, which included oral presentations, poster sessions, and excursion. Abstract of all talks and posters can be found on the AFRINOM website. The workshop objectives were to analyze innovative mycorrhizal interventions (e.g., production of mycorrhizal inoculants) and their impact in land management strategies benefiting smallscale agriculture in Africa. The contents addressed included the following: integration of mycorrhiza into agrosystems, optimization of mycorrhizal interventions and adaptation, mycorrhiza in ecosystems management, alternative interventions and bioprospecting tools, and strain selection and delivery. In the plenary session, Prof. Joanna Dames (South Africa) introduced challenges and future prospects of mycorrhizal agrotechnology for Africa and raised a fundamental question: why have we not embraced mycorrhizal technology and adopted it as standard agricultural practice in Africa? In her talk, she covered the many constraints linked to production of mycorrhizal inoculants, i.e., mass production, formulation, quality control, maintenance of culture collections, mycorrhizal fungal species/plant host matching, persistence among native strains, cost of the product for small-scale farmers, and farmer perception. In a session on integration ofmycorrhiza into agroecosystems, H. Dupre de Boulois (Belgium) presented the potentials and advantages of monoxenic AM fungal cultures, and concluded that present knowledge is inadequate to proposemass production of mycorrhizal inoculants by this method. Amadou Bâ (Senegal) presented results on the domestication of different provenances J. M. Jefwa CIAT, Nairobi, Kenya