Salt tolerance of selected halophytes at the two initial growth stages for future management options

Scarcity of water and the small area of the agricultural land are considered as the crucial environmental issues challenged the Arabian Gulf countries. In this study, experiments were conducted to identify the salt tolerance during the germination and the seedling stages of some native halophytes in the State of Qatar. Seeds of eight native species (Salsola setifera, Halopeplis perfoliata, Caroxylon imbricatum, Suaeda aegyptiaca, Acacia tortilis, Limonium axillare, Tetraena qatarensis and Aeluropus lagopoides) were investigated. Except for Tetraena qatarensis, Acacia tortilis and Suaeda aegyptiaca, all achieved ≥ 30% of seed germination at a concentration of 200 mM NaCl. Around 30% of Salsola setifera seeds were able to germinate in a salt concentration of 400 mM. Germination recovery of seeds that have been treated with 800 mM NaCl for 3 weeks was the greatest for Halopeplis perfoliata (94%) and the lowest for Aeluropus lagopoides (22%). Five halophytes were investigated for seedling growth under saline irrigation ranged from 0 to 600 mM NaCl. No significant differences obtained in growth biomass of seedlings of each of Caroxylon imbricatum, Suaeda aegyptiaca and Tetraena qatarensis between saline and non-saline treatments.

Effects of light, temperature, salinity, and maternal habitat on seed germination of Aeluropus lagopoides (Poaceae): an economically important halophyte of arid Arabian deserts

In this study, salt tolerance during germination of Aeluropus lagopoides (L.) Trin. was tested using fresh seeds collected from three different maternal habitats under three thermoperiods and two light regimes. Additionally, we tested the ability of non-germinated seeds that had been exposed to different concentrations of NaCl to recover their germination in distilled water. The results showed a significant effect of seed source, temperature, and salinity, and some of their two- and three-way interactions on final germination and recovery percentage. The seeds from non-saline provenances had the highest percentages for germination (ca. 79%) under the 35/25 °C temperature regime, whereas the lowest percentages for germination (ca. 21%) was recorded for seeds from saline conditions under the 25/15 °C treatment. Additionally, percent germination was significantly lower for the seeds incubated in the saline solutions (100, 200, 400, and 600 mmol/L NaCl) and germinated under colder conditions (15/25 °C), compared with the seeds incubated in non-saline solutions (control group, 0 mmol/L NaCl) and germinated under warmer conditions (35/25 °C). The highest recovery percentage was recorded for seeds of the hyper-saline habitat incubated at 35/25 °C. Thus, seeds maintained their viability despite experiencing a range of saline conditions and were able to germinate upon the arrival of suitable conditions, which can be an adaptation to its saline arid desert habitat.

Cell Cycle Arrest in Different Cancer Cell Lines (Liver, Breast, and Colon) Induces Apoptosis under the Influence of the Chemical Content of Aeluropus lagopoides Leaf Extracts

Natural products, especially secondary metabolites produced by plants under stressed conditions, are shown to have different pharmacological impacts from one to another. Aeluropus lagopoides is one of the common halophyte plants that survive under stressed conditions, and has been used for healing wounds and as a painkiller. The bioactivity and the chemical composition of this plant have been poorly investigated. Consequently, the chemical components of A. lagopoides leaves were extracted using hexane (nonpolar), ethyl acetate (semi-polar), and n-butanol (polar) to extract the most extensive variety of metabolites. The cytotoxicity and anticancer impact of extracted secondary metabolites were evaluated against breast (MCF-7), colon (HCT-116), and liver (HepG2) cancer cell lines using a SulphoRhodamine-B (SRB) test. Their mechanisms of action were verified by observing the appearance of apoptotic bodies using the fluorescent microscope, while their antiproliferative impacts were evaluated using a flow cytometer. Results revealed that secondary metabolites extracted using hexane and ethyl acetate had the highest cytotoxicity and thus the greatest anticancer activity effect on HepG2 with IC50 (24.29 ± 0.85 and 11.22 ± 0.679 µg/mL, respectively). On the other hand, flow cytometer results showed that secondary metabolites could inhibit the cell cycle in the G0/G1 phase. To ascertain the chemical composition–function relationship, the extracts were analyzed using LC-MS/MS. Accordingly, A. lagopoides hexane and ethyl acetate extracts may contain agents with anticancer potential.

Effect of edaphic factors on the vegetation zonation in some littoral and inland salt marshes of Egypt

Shawky R., 2018: Effect of edaphic factors on vegetation zonation in some littoral and inland salt marshes of Egypt. - Botanica, 24(2): 202-210. The segregation of a few dominant plant species into distinctive zones is characteristic of salt marshes. Vegetation zonation was investigated in the littoral salt marshes (South Marsa Alam region) and the inland salt marshes (Wadi El-Natrun region) of Egypt. Twenty taxa belonging to 18 genera and 11 families were recorded and classified into two sets at the two studied sites and subdivided into four groups by TWINSPAN, according to a relevance value: group A) co-dominated by Juncus acutus and Juncus rigidus; B) - dominated by Aeluropus lagopoides; C, D) - Limonium axillare. The analysis of species diversity in the inland salt marshes as well as the Shannon and the Simpson indices showed the highest species richness compared to that in the littoral salt marshes. The soil of the inland salt marshes was characterized by high percentages of silt, clay, also the soluble anion SO4-2was the highest. While the most effective factor in the littoral salt marshes was EC, sand fractions, moisture content, soluble cations as Na+, Ca+2, soluble anions as Cl-, organic matter and CaCO3. The proximity matrix between the two types of salt marshes indicated that they were different, except for the stands of Juncus rigidus, the elucidation distance was the smallest and they were similar together.