Morphological, Biochemical, and Metabolomic Strategies of the Date Palm (Phoenix dactylifera L., cv. Deglet Nour) Roots Response to Salt Stress

Abstract

Numerous Tunisian arid and semi-arid regions are subjected to soil salinity. Thus, they are known for halophytes plants cultivation, including date palms. Phoenix dactylifera L., cv. ‘Deglet Nour’, is a valuable Tunisian cultivar subjected to high salinity levels. In this way, our purpose is to evaluate the response of its roots to long period exposition to increasing salt concentrations. We started by studying the effects of 4 g/L, 8 g/L, 12 g/L, and 16 g/L NaCl on the parameters of germination (Growth rate—GR, Seed Mortality Rate—SLM, Germination Mean Time—GMT, and Germination Speed—GS) of date palm seeds for a 2-month period. We found that 4 g/L NaCl did not affect the seeds germination, and, hereinafter, the parameters of germination and the radicle length decreased with the increase of NaCl concentrations and experiment time. Then, we demonstrated a high antioxidative enzymes CAT and SOD production in case of salt stress augmentation. Lastly, a metabolomic approach was carried out by LC-HRMS, followed by an untargeted and targeted analysis using the XCMS online and MZmine tools, respectively. The roots chemical composition was compared using PCA. We identified 25 secondary metabolites, divided into 3 categories. Metabolites known for their role in salt stress alleviation include δ-tocotrienol, metabolites identified in salt stress for the first time, and other unknown metabolites.

The Regulation of Ion Homeostasis, Growth, and Biomass Allocation in Date Palm Ex Vitro Plants Depends on the Level of Water Salinity

“…The halophytic nature of the date palm has been discussed and suggested by several studies, because of the palm's ability to tolerate high salinity levels [6,18,21,45,46]. The result obtained here shows a significant improvement in the biomass of young date palms, which can constitute a solid argument for this and confirm the salt-loving nature of this species, and even encourages a discussion on the type of halophyte it is, whether facultative or obligatory.…”

Integrated transcriptome and metabolome analysis reveals antioxidant machinery in grapevine exposed to salt and alkali stress

“…Studies conducted on Dendrobium officinale (Zhang, Yu, et al, 2021), Catharanthus roseus (Wang & Liu, 2010), and Date Palm (Bouhouch et al, 2021) have demonstrated that SS can lead to an increase in alkaloid compounds. Consistent with these findings, our study revealed that out of the 30 DAMs in the Salt versus CT comparison, 16 were upregulated in the alkaloid category.…”

Alleviation of Salt Stress via Habitat-Adapted Symbiosis

“…Salt stress is one of the most important threats to agricultural production and food security. For more than 3000 years, it has been a threat to agriculture in many regions of the world [1][2][3][4][5][6]. Globally, 22% of the total arable land and 33% of the total irrigated agricultural area are under salt stress.…”

“…Osmotic pressure leads to nutritional imbalance, morphological damage and reduced photosynthesis. This leads to a decline in growth and productivity, which can lead to cell death [3,9]. Like many other abiotic stresses, salt stress restricts plant growth by increasing soil osmotic potential and reducing water uptake through the roots.…”

“…High salt concentration disturbs the steady state of water potential and the distribution of ions at the cellular level and throughout the plant. To cope with these limitations, plants have established several physiological and biochemical mechanisms to adapt [3,10]. In order to achieve salt tolerance, the damage must be mitigated; then, homeostatic conditions should be restored under the new stress conditions and, finally, growth must start again, but at a slower rate [3,11].…”