Ecophysiological Response and Morphological Adjustment of Argania spinosa L. Skeels under Contrasting Climates: Case Study of Marginal Populations

Abstract

In this paper, we investigated the seasonal physiological performance and morphological adjustment of Argania spinosa growing under contrasting climatic and biogeographic conditions.Two marginal populations were selected in the main distribution area of the species, one at the Northwest and the other one at the South-west. Trees from the North showed a Mediterranean pattern in Photosynthetic performances, exhibiting maximal carbon assimilation during spring and minimum in summer. In contrast, trees from the South showed a different pattern with maximum values recorded in winter and minimum in spring. Photochemical efficiency of PSII results evidenced the absence of damage to PSII in both sites, probably due to an efficient energy dissipation processed by carotenoid pigments. We recorded increased LMA values in the South, which improves drought resistance. Increasing stomatal length and decreasing stomatal density were registered during the drought season in both populations. A. Spinosa is sensitive to changes in the length of drought stress at its Southern limit. The scarcity of rainfall leading to persistent drought has limited the distribution of the species to the banks of dry Wadis and depressions, where it finds some water compensations during summer. In the North, the summer drought severely impacted the species carbon assimilation.

SlIAA9 Mutation Maintains Photosynthetic Capabilities under Heat-Stress Conditions

“…On the other hand, increased leaf carotenoid contents of iaa9-3 and iaa9-5 under normal conditions might be an antioxidant response to oxidative stress present in both IAA9 mutants even under normal conditions [ 46 ] since increased auxin concentration within plant tissue has been linked with increased ROS within plant tissue [ 53 ]. Higher leaf carotenoids of both iaa9 mutants were beneficial for their photosynthetic capabilities since carotenoids were known to mediate photo-oxidative stress and also help in heat dissipation [ 54 ]. Carotenoids are also known for their importance as a light-harvesting apparatus during environmental stress [ 55 ].…”

“…The aforementioned antioxidants are important ROS scavenger enzymes [ 18 ]. Higher leaf carotenoid content of iaa9-3 and iaa9-5 may also help prevent photosystem damage ( Figure 4 b) since carotenoids were known to mediate photo-oxidative stress and also helps in heat dissipation [ 54 ]. This result suggests that heightened auxin response and biosynthesis due to IAA9 mutation were beneficial for preventing leaf tissue damage ( Figure 5 ).…”

Comparative and Correlation Analysis of Young and Mature Kaffir Lime (Citrus hystrix DC) Leaf Characteristics

“…Carotenoid is also a plant pigment essential for fruit coloring [71] and light harvesting during environmental stress [72]. The presence of a high carotenoid content could help the process of heat dissipation of excess excitation energy in the photosystem [73]. Aside from the photo-protection effect, this pigment serves as an antioxidant, phytohormone precursor, and color attractant agent [74].…”

Photosynthetic Behavior of Argania spinosa (L.) Skeels Induced under Grazed and Ungrazed Conditions

“…The Argan forests are the second forestry stands in the country, as they extend into arid and semi-arid areas in the west central area of Morocco [1]. A. spinosa is well adapted to arid environments, exhibiting elevated productivity even in the summer season [2,3]. This species plays a crucial role, especially for the local population, in terms of its ecological, botanical, economical, and social interests [4][5][6][7].…”