To better understand the mechanisms involved in salinity stress, the adaptability of quinoa cv. Titicaca—a halophytic plant—was investigated at the transcriptome level under saline and non-saline conditions. RNA-sequencing analysis of leaf tissue at the four-leaf stage by Illumina paired—end method was used to compare salt stress treatment (four days after stress at 13.8 dsm⁻¹) and control. Among the obtained 30,846,354 transcripts sequenced, 30,303 differentially expressed genes from the control and stress treatment samples were identified, with 3363 genes expressed ≥ 2 and false discovery rate (FDR) of < 0.001. Six differential expression genes were then selected and qRT-PCR was used to confirm the RNA-seq results. Some of the genes (Include; CML39, CBSX5, TRX1, GRXC9, SnRKγ1 and BAG6) and signaling pathways discussed in this paper not been previously studied in quinoa. Genes with ≥ 2 were used to design the gene interaction network using Cytoscape software, and AgriGO software and STRING database were used for gene ontology. The results led to the identification of 14 key genes involved in salt stress. The most effective hub genes involved in salt tolerance were the heat shock protein gene family. The transcription factors that showed a significant increase in expression under stress conditions mainly belonged to the WRKY, bZIP and MYB families. Ontology analysis of salt stress-responsive genes and hub genes revealed that metabolic pathways, binding, cellular processes and cellular anatomical entity are among the most effective processes involved in salt stress.

Salinity is a major factor limiting agricultural lands that causes adverse effects on plant growth and production. The use of exogenous compounds or growth regulators has often been effective in reducing the effects of environmental stresses and/or identifying stress-coping mechanisms in plants. Among 1560 halophytes, Salicornia europaea is known as a salt-tolerant species. This study aimed to understand the effects of the endogenous application of abscisic acid (ABA) and melatonin hormones and their combined effects on mechanisms involved in plant resistance to salinity stress to identify these mechanisms, genes associated with ion channels, and antioxidant enzymes involved in response to stress using real-time technology. S. europaea metabolism compounds, namely hydrogen peroxide (H₂O₂), malondialdehyde, proline, phenol, sodium, potassium, and calcium were studied in control plants and under 400 mM salinity stress at 0, 6, 48, and 720 h (1 month) intervals. The best effects in terms of morphological, biochemical, and molecular traits were observed in spraying with both hormones at 400 mM salinity. This treatment reduced polyphenol oxidase activity, malondialdehyde content (by 35%), and H₂O₂ content, while it increased shoot (2.04 times) and root (76%) wet weights, shoot dry weight (2.45 times), K (by 19%) and Ca (by 79%) contents, and the Na/K ratio (by 30%). ABA spraying elevated catalase activity at 400 mM salinity. Spraying treatments led to the overexpression of SOD (by 21 times), SOS1 (by 1218 times), NHX1 (by 16 times), APX (by 214 times), HKT1 (by 470 times), and VHA-A (by 27 times) genes in some treatments compared to NT plants. The rapid response to stress is the main difference between stress-sensitive and tolerant plants. Spraying treatments resulted in elevated overexpression of genes involved in stress-responding mechanisms at early hours of salinity stress compared to control treatments, thereby increasing the tolerance of S. europaea to salinity stress.