Physiological and Biochemical Mechanisms of Drought Stress Tolerance in the Argan Tree

Role of exogenous application of abscisic acid ABA in drought tolerance and evaluation of antioxidant activity in durum wheat genotypes

“…The degree of cell membrane injury induced by water stress may be easily estimated through measurements of electrolyte leakage from the cells [28]. It has been also demonstrated recently that electrolyte leakage measurements may be correlated with several physiological and biochemical parameters conditioning the plant responses to environmental conditions such as antioxidative enzyme synthesis [29,30,31], stomatal resistance [32,33,34]. Water stress generally causes a decrease in the concentration of ABA in the roots of stressed varieties (Figure 3).…”

Agro-Fruit-Forest Systems Based on Argan Tree in Morocco: A Review of Recent Results

“…A. spinosa ecotypes collected from coastal, inland, and mountainous Moroccan regions showed differential physiological, morphological, and phenological responses to seasonal variations in temperature, relative humidity, and water availability (Bani-Aameur and Zahidi, 2003;Bouzoubaâ et al, 2005;Díaz-Barradas et al, 2010;Zahidi et al, 2013a,b,c). A close coordination of stomatal conductance (gs) with leaf-air vapor pressure deficit and the leaf water potential has been recorded in A. spinosa under natural and experimental conditions (Díaz-Barradas et al, 2010Chakhchar et al, 2015bChakhchar et al, ,c, 2016Chakhchar et al, , 2018b. Closure of argan stomata under low moisture could be the result of a decrease in bulk foliar water potential as leaf-air VPD increases (Díaz-Barradas et al, 2010.…”

“…-Increase in the activity of ascorbate-glutathione cycle enzymes: ascorbate peroxidase, monodehydro-ascorbate reductase, dehydroascorbate reductase, and glutathione reductase -Increase in the activity of catalase, superoxide dismutase, peroxidase, polyphenoloxidase, and glutathione S-transferase -Increase in the content of ascorbic acid, α-tocopherol, and reduced glutathione -Increase in the thiol protein content Chakhchar et al, 2015a,c, 2017b, Lamaoui, 2015 Secondary metabolism -Induction of shikimate and phenylpropanoid pathways (stimulation of the activity of phenylalanine ammonium lyase, shikimate dehydrogenase, and cinnamate-4-hydroxylase enzymes) and increase of total polyphenols content Chakhchar et al, 2015b Carbohydrate metabolism -Stimulation of carbohydrate enzymes: aldose 6-phosphate reductase, glucose-6-phosphate dehydrogenase, acid invertase, and sorbitol dehydrogenase -Accumulation of hexoses (glucose and fructose) Chakhchar et al, 2018bChakhchar et al, , 2019 Pigments, photosynthetic carbon metabolism and gas exchange -Decrease of leaf chlorophyll content and increase of leaf anthocyanin concentration -Maintain of the photosynthetic activity at low levels of foliar water content and co-ordination of photosynthesis, stomatal behavior, and metabolism -Positive relationship between the rate of respiration in the dark and Photosynthesis, indicative of coordination of metabolic and photosynthetic activity Díaz-Barradas et al, 2010, Chakhchar et al, 2017a, 2018c distribution of soil moisture is mostly affected by precipitation, evapotranspiration, and soil hydraulic properties. Nonetheless, higher soil moisture remains available, mainly underneath the argan roots, and the microbial activities are more important especially with regard to nitrogen mineralization and phosphorus availability .…”

A Review on the Root System of Argania spinosa

“…It limits water loss through stomatal closure, increased leaf water potential and solute accumulation. [43][44][45][46][47] But to reduce consumption and enhance water absorption, trees respond to drought stress by contributing to increase root-to-shoot ratio and rooting depth 15,48,49 further. The change in dry root / shoot biomass ratio is one of mechanisms involved in drought avoidance.…”