Oxidative Stress Responses of Some Endemic Plants to High Altitudes by Intensifying Antioxidants and Secondary Metabolites Content

Abstract

<jats:p>Most endemic plant species have limited altitudinal ranges. At higher altitudes, they are subjected to various environmental stresses. However, these plants use unique defense mechanisms at high altitudes as a convenient survival strategy. The changes in antioxidant defense system and accumulation of different secondary metabolites (SMs) were investigated as depending on altitude in five endemic endangered species (Nepeta septemcrenata, Origanum syriacum subsp. Sinaicum, Phlomis aurea, Rosa arabica, and Silene schimperiana) naturally growing in Saint Katherine protectorate (SKP). Leaves were collected from different sites between 1600 and 2200 m above sea level to assess the biochemical and physiological variations in response to high altitudes. At higher altitudes, the soil pH and micronutrient soil content decreased, which can be attributed to lower mineralization processes at lower pH. Total phenols, ascorbic acid, proline, flavonoids, and tannins increased in response to different altitudes. SMs progressively increased in the studied species, associated with a significant decrease in the levels of antioxidant enzyme activity. R. arabica, as the most threatened plant, showed the maximum response compared with other species. There was an increase in photosynthetic pigments, which was attained via the increase in chlorophyll a, chlorophyll b, and carotenoid contents. There was a significant increase in total soluble sugars and total soluble protein content in response to different altitudes. SDS-PAGE of leaf proteins showed alteration in the protein profile between different species and the same species grown at a different altitude. These five species can adapt to high-altitude habitats by various physiological mechanisms, which can provide a theoretical basis for the future conservation of these endangered endemic species in SKP.</jats:p>

Isolation and Characterization of Fungal Endophytes Isolated from Medicinal Plant Ephedra pachyclada as Plant Growth-Promoting

“…Herein, all isolated fungal strains had the ability to produce ammonia with a varying degree after adding Nessler’s reagent to broth media ( Table 4 ). These results are inconsistent with Ripa et al [ 9 ], who reported that, out of 16 endophytic fungal strains associated with the Triticum aestivum plant, only six strains had the ability for ammonia production.…”

“…Fungal endophytes are those colonized intra- or intercellular spaces of plant tissues that do not show any illness symptoms [ 6 ]. Fungal endophytes have various mechanisms to promote plant growth, including phytostimulation, biocontrol, and biofertilizations [ 7 , 8 ]; for example, plant growth-promoting fungi (PGPF) directly promote plant growth by the production of phytohormones such as indole-3-acetic acid (IAA) and gibberellic acid [ 9 ]. Fungal IAA synergistically reacts with endogenous plant IAA, which then stimulate plant growth.…”

Regulation of Agronomic Traits, Nutrient Uptake, Osmolytes and Antioxidants of Maize as Influenced by Exogenous Potassium Silicate under Deficit Irrigation and Semiarid Conditions

“…This response could help in scavenging ROS and inducing the ascorbate-glutathione cycle [8,76]. Phenolic compounds could also be involved in plant tolerance to drought stress and play a significant role as a sink for carbon under stress conditions [77,78]. These effects could explain the improvement in total soluble phenols by reducing the irrigation level in this study ( Figure 4C).…”

Untargeted Metabolomics Analysis Using FTIR and UHPLC-Q-Orbitrap HRMS of Two Curculigo Species and Evaluation of Their Antioxidant and α-Glucosidase Inhibitory Activities

“…The accumulation of secondary metabolites is reported to have a vital role in tolerance to environmental biotic and abiotic stresses. These secondary metabolite help in the adaptation of stressed plants to different environmental conditions, for example, the accumulation of phenols and flavonoids as antioxidants [ 19 ].…”