Changes in Antioxidant Enzymes Activity and Oxidative Damage in Four Argania spinosa Ecotypes Under Water Stress Conditions

_Argania spinosa_ L. Skell, a tree endemic of Morocco, grows in semiarid and arid areas. Biochemical response to drought in four ecotypes of the _A. spinosa_ was compared. Choice of ecotypes was based on evident differences in geographical features in south-west Morocco: two coastal ecotypes (Essaouira and Agadir) and two paralittorale ecotypes (Aoulouz and Lakhssas). Lipid peroxidation (malonyldialdehyde (MDA)), content of endogenous hydrogen peroxide (H2O2) and antioxidant enzyme system (Catalase (CAT), Ascorbate peroxidase (APX), Total peroxidase (POD) and Polyphenoloxidase (PPO) were measured in control (100% relative humidity (RH) at field capacity (FC)) and water-stressed plants (50 and 25% RH at FC). For all ecotypes, drought stress significantly increased the contents of MDA and H2O2 and an ecotype effect was noted. According Two-way ANOVA analysis, the ecotype x watering regime interaction was highly significant. We found an increase in the activities of the four ROS-scavenging enzymes and an ecotype effect was noted. Ecotype x watering regime interaction shows that only the CAT and APX activities were significant. Highest values of POD and PPO activities were found in both paralittorale ecotypes. Increase in antioxidant enzyme activities appears to be an adaptive response to restore the reactive oxygen species in their homeostasis. The four study ecotypes were separated by two discriminant functions obtained by canonical discriminant analysis. Coastal ecotypes are separated from the paralittorale ecotypes mainly by POD and PPO activities and MDA content

Inoculation of Ceratonia siliqua L. with native arbuscular mycorrhizal fungi mixture improves seedling establishment under greenhouse conditions

The potential benefits of inoculation with arbuscular mycorrhizal (AM) fungi were investigated on carob tree Ceratonia siliqua, a Mediterranean legume in Morocco. The parameters under study were the effect of an inoculation on growth, mineral nutrition and roots mycorrhizal colonization of the plant under nursery conditions. C. siliqua growth was measured after six months of culture in plastic bags arranged in a randomised complete block under greenhouse conditions. Fungal inoculation consisted of a mixture of native AM fungi propagated on Zea mays roots. Results show that the fungal symbionts were effective to improve the growth of C. siliqua, confirming the requirement of mycorrhizal symbiosis for the successful establishment of C. siliqua in a degraded soil. The approach used with indigenous AM fungi complex isolated under C. siliqua appeared to be effective in promoting growth and nutrition of C. siliqua. After 6 months of culturing in nursery conditions, height, shoot and root biomass, total biomass, phosphorus and nitrogen foliar contents of the plants inoculated with native AM fungi were significantly higher than in the control. Glomus spores were extracted from the soil under C. siliqua and were observed on permanent slides under a microscope connected to a computer with digital image analysis software. Seven spore morphotypes were detected under C. silqua in the Ourika Valley, Morocco. Five Glomus species were classified as Glomus aggregatum, Glomus intraradices and Glomus constrictum, whereas, two other Glomus species were not identified. The analysis of this spore community revealed the presence of two other species belonging to Gigaspora genera. The use of a mixture of native AM fungi as fungal inoculum improves clearly growth, nutrition and roots colonization of C. siliqua seedling.Key words: Arbuscular mycorrhizal fungi, diversity, growth, soil microbial activity, Ceratonia siliqua

Electrolyte ions and glutathione enzymes as stress markers in Argania spinosa subjected to drought stress and recovery

Understanding the mechanisms underlying Argania spinosa responses to drought stress is essential for its regeneration and domestication. Toward that end, an integrative study of tolerance responses to drought stress in four A. spinosa ecotypes (2 contrasting coastal ecotypes (Adm and Rab) and 2 contrasting inland ecotypes (Alz and Lks)) have been conducted. Responses to soil drying and re -watering were measured at physiological and biochemical levels. Soil drying resulted in significant increase in leaf concentrations of potassium (K+), calcium (Ca2+) and magnesium (Mg2+) with differential responses between ecotypes. The glutathione-related enzymes: glutathione peroxidase (GP), glutathione reductase (GR) and glutathione S-transferase (GST) showed a significant increase in their enzymatic activity in A. spinosa plants subjected to drought stress. Additionally, a significant increase in thiol protein content in the four ecotypes was recorded, during drought stress. These antioxidant traits responded differently depending on ecotype. However, rapid and significant changes in the studied physiological and biochemical traits were observed during recovery from drought, only after four days. According to the traits having the most discriminating power, the both inland ecotypes, especially Lks ecotype, seem to be potential candidates for regeneration of argan forest and their domestication in arid and semi-arid environments.Key words: Argania spinosa, drought stress, glutathione enzymes, thiol compounds, recovery