Integrated transcriptomic and proteomic analysis of Tritipyrum provides insights into the molecular basis of salt tolerance

Background Soil salinity is a major environmental stress that restricts crop growth and yield. Methods Here, crucial proteins and biological pathways were investigated under salt-stress and recovery conditions in Tritipyrum ‘Y1805’ using the data-independent acquisition proteomics techniques to explore its salt-tolerance mechanism. Results In total, 44 and 102 differentially expressed proteins (DEPs) were identified in ‘Y1805’ under salt-stress and recovery conditions, respectively. A proteome-transcriptome-associated analysis revealed that the expression patterns of 13 and 25 DEPs were the same under salt-stress and recovery conditions, respectively. ‘Response to stimulus’, ‘antioxidant activity’, ‘carbohydrate metabolism’, ‘amino acid metabolism’, ‘signal transduction’, ‘transport and catabolism’ and ‘biosynthesis of other secondary metabolites’ were present under both conditions in ‘Y1805’. In addition, ‘energy metabolism’ and ‘lipid metabolism’ were recovery-specific pathways, while ‘antioxidant activity’, and ‘molecular function regulator’ under salt-stress conditions, and ‘virion’ and ‘virion part’ during recovery, were ‘Y1805’-specific compared with the salt-sensitive wheat ‘Chinese Spring’. ‘Y1805’ contained eight specific DEPs related to salt-stress responses. The strong salt tolerance of ‘Y1805’ could be attributed to the strengthened cell walls, reactive oxygen species scavenging, osmoregulation, phytohormone regulation, transient growth arrest, enhanced respiration, transcriptional regulation and error information processing. These data will facilitate an understanding of the molecular mechanisms of salt tolerance and aid in the breeding of salt-tolerant wheat.

Quinoa (Chenopodium quinoa Willd.): Genetic Diversity According to ISSR and SCoT Markers, Relative Gene Expression, and Morpho-Physiological Variation under Salinity Stress

Quinoa (Chenopodium quinoa Willd.) is a halophytic crop that can withstand a variety of abiotic stresses, including salt. The present research examined the mechanisms of salt tolerance in five different quinoa genotypes at four different salinity levels (control (60), 80, 120, and 160 mM NaCl). ISSR and SCoT analysis revealed high polymorphism percentages of 90.91% and 85.26%, respectively. Furthermore, ISSR 1 and SCoT 7 attained the greatest number of polymorphic amplicons (27 and 26), respectively. Notably, LINE-6 and M-28 genotypes demonstrated the greatest number of unique positive and negative amplicons (50 and 42) generated from ISSR and SCoT, respectively. Protein pattern analysis detected 11 bands with a polymorphism percentage 27.27% among the quinoa genotypes, with three unique bands distinguishable for the M-28 genotype. Similarity correlation indicated that the highest similarity was between S-10 and Regeolone-3 (0.657), while the lowest similarity was between M-28 and LINE-6 (0.44). Significant variations existed among the studied salinity treatments, genotypes, and the interactions between them. The highest and lowest values for all the studied morpho-physiological and biochemical traits were recorded at 60 and 160 mM NaCl concentrations, respectively, except for the Na and proline contents, which exhibited the opposite relationship. The M-28 genotype demonstrated the highest values for all studied characteristics, while the LINE-6 genotype represented the lowest in both seasons. On the other hand, mRNA transcript levels for CqSOS1 did not exhibit differential expression in roots and leaf tissues, while the expression of CqNHX1 was upregulated more in both tissues for the M-28 genotype than for the LINE-6 genotype, and its maximum induction was seen in the leaves. Overall, the genotypes M-28 and LINE-6 were identified as the most and least salinity-tolerant, respectively.

Genome-Wide Characterization of Salt-Responsive miRNAs, circRNAs and Associated ceRNA Networks in Tomatoes

Soil salinization is a major environmental stress that causes crop yield reductions worldwide. Therefore, the cultivation of salt-tolerant crops is an effective way to sustain crop yield. Tomatoes are one of the vegetable crops that are moderately sensitive to salt stress. Global market demand for tomatoes is huge and growing. In recent years, the mechanisms of salt tolerance in tomatoes have been extensively investigated; however, the molecular mechanism through which non-coding RNAs (ncRNAs) respond to salt stress is not well understood. In this study, we utilized small RNA sequencing and whole transcriptome sequencing technology to identify salt-responsive microRNAs (miRNAs), messenger RNAs (mRNAs), and circular RNAs (circRNAs) in roots of M82 cultivated tomato and Solanum pennellii (S. pennellii) wild tomato under salt stress. Based on the theory of competitive endogenous RNA (ceRNA), we also established several salt-responsive ceRNA networks. The results showed that circRNAs could act as miRNA sponges in the regulation of target mRNAs of miRNAs, thus participating in the response to salt stress. This study provides insights into the mechanisms of salt tolerance in tomatoes and serves as an effective reference for improving the salt tolerance of salt-sensitive cultivars.

Antioxidant enzymes and non-enzymatic antioxidants as defense mechanism of salinity stress in cowpea (Vigna unguiculata L. Walp)—Ife brown and Ife bpc

Background Several mechanisms had been exhibited by plants to mitigate deleterious effects of salinity stress. A screen house experiment was conducted to investigate the effects of salinity stress on the activities of osmolytes (antioxidative and non-antioxidative enzymes) in the leaves of two cowpea (Vigna unguiculata L. Walp)—Ife brown and Ife bpc, with the aim of better understanding the biochemical mechanisms of salt tolerance. Salts of sodium chloride (NaCl) and sodium sulfate (Na2SO4) at 5, 10 and 15 dS/m concentrations were used for this study. The saline solution was prepared following standard methods. Proline, lipid peroxidase (LP), superoxide dismutase (SOD) and glutathione (GSH) were determined following standard protocols. Results Results showed that minimum proline content (12.07 mg/g) and maximum proline determination (16.05 mg/g) were observed in Ife bpc at 5 and at 15 dS/m under NaCl and Na2SO4 treatments. The LP content significantly increased in Ife brown at 15 dS/m under NaCl treatment and at 10 dS/m (9.49 mg/g) under Na2SO4 salinity. Minimum GSH content (120 µm/g) and maximum glutathione accumulation (138.97 µm/g) were observed in Ife bpc in the stressed cowpea seedlings (5 and 10 dS/m) under NaCl treatment with respect to the control. Also, SOD activities in the leaves of Ife brown increase with increase in salinity stress in both NaCl and Na2SO4 treatments. Conclusions This study concludes that the accumulation of enzymatic and non-enzymatic antioxidants is capable of detoxifying and scavenging reactive oxygen species, thereby mitigating salinity-induced oxidative damage.

Osmolyte Accumulation and Sodium Compartmentation Has a Key Role in Salinity Tolerance of Pistachios Rootstocks

Physio-biochemical responses of pistachio varieties including Pistacia vera L. ‘Ghazvini’ (GH), P. vera ‘Ghermez-Pesteh’ (GP) and P. atlantica subsp. mutica (M) were assessed under salt stress to understand the common mechanisms of salt tolerance in two popular Pistacia species. In the experiment, half-sib seedlings of the varieties were subjected to high (100 mM) and severe (200 mM) levels of NaCl-induced salinity for 90 days. Growth, physiological, biochemical and ionic parameters in the roots and shoots of plants were measured in the experiment. Salinity markedly declined plant growth, and increased the number of necrotic leaves (NL) and leaf abscission. In terms of physiological responses, salinity reduced the relative water content (RWC), membrane stability index (MSI) and the concentrations of photosynthetic pigments, but increased carbohydrates and proline content in the leaves. MSI of the leaves was positively correlated with the concentrations of anthocyanins and carotenoids. Salinity increased sodium content in root and shoot tissues of the plants, and decreased potassium concentration and K/Na ratio. Among the rootstocks, GH had better performance on all parameters. Despite the high concentration of Na+ and low K/Na ratio in the shoots, the lowest number of NL was found in GH under both salinity levels. The results indicated that salt tolerance in GH was most likely related to compartmentation of Na+ ions. Finally, accumulation of osmolytes and sodium compartmentation were considered to be the most important mechanisms in the salt tolerance of pistachio rootstocks.

Responses to Salinity in Four Plantago Species from Tunisia

The genus Plantago is particularly interesting for studying the mechanisms of salt tolerance in plants, as it includes both halophytes and glycophytes, as well as species adapted to xeric environments. In this study, the salt stress responses of two halophytes, P. crassifolia and P. coronopus, were compared with those of two glycophytes, P. ovata and P. afra. Plants obtained by seed germination of the four species, collected in different regions of Tunisia, were subjected to increasing salinity treatments for one month under greenhouse conditions. Morphological traits and biochemical parameters, such as ion accumulation and the leaf contents of photosynthetic pigments, osmolytes, oxidative stress markers and antioxidant metabolites, were measured after the treatments. Salt-induced growth inhibition was more pronounced in P. afra, and only plants subjected to the lowest applied NaCl concentration (200 mM) survived until the end of the treatments. The biochemical responses were different in the two groups of plants; the halophytes accumulated higher Na+ and proline concentrations, whereas MDA levels in their leaves decreased, indicating a lower level of oxidative stress. Overall, the results showed that P. coronopus and P. crassifolia are the most tolerant to salt stress, and P. afra is the most susceptible of the four species. Plantago ovata is also quite resistant, apparently by using specific mechanisms of tolerance that are more efficient than in the halophytes, such as a less pronounced inhibition of photosynthesis, the accumulation of higher levels of Cl− ions in the leaves, or the activation of K+ uptake and transport to the aerial part under high salinity conditions.

Advances in Sensing, Response and Regulation Mechanism of Salt Tolerance in Rice

Soil salinity is a serious menace in rice production threatening global food security. Rice responses to salt stress involve a series of biological processes, including antioxidation, osmoregulation or osmoprotection, and ion homeostasis, which are regulated by different genes. Understanding these adaptive mechanisms and the key genes involved are crucial in developing highly salt-tolerant cultivars. In this review, we discuss the molecular mechanisms of salt tolerance in rice—from sensing to transcriptional regulation of key genes—based on the current knowledge. Furthermore, we highlight the functionally validated salt-responsive genes in rice.

Morphophysiological responses and mechanisms of salt tolerance in four ornamental perennial species under tropical climate

ABSTRACT Salinity affects growth and quality of ornamental plants, but studies on mechanisms of salt tolerance in these plants are scarce, particularly under tropical climate conditions. Thus, the morphophysiological leaf responses of four tropical ornamental species were studied, in order to identify the mechanisms involved in the tolerance to salinity and their potentials to be irrigated with brackish water. The research was conducted in a greenhouse using a completely randomized block design, in a 10 x 4 factorial scheme, with four repetitions. The treatments consisted of ten levels of electrical conductivity of irrigation water (0.5; 1.0; 2.0; 3.0; 4.0; 5.0; 6.0; 8.0; 10.0 and 12.0 dS m-1) and four ornamental tropical species (Catharanthus roseus, Allamanda cathartica, Ixora coccinea, and Duranta erecta). At 30 and 60 days after the beginning of saline treatments (DAST), measurements of leaf gas exchange and chlorophyll index were performed. At 60 DAST, leaf area, specific leaf area, leaf area ratio, leaf succulence, Na+ and proline concentrations were measured. The physiological and morphophysiological responses of the leaves indicate that I. coccinea species has high capacity to grow under irrigation with saline water. Its higher tolerance to salinity is related to the lower concentration of Na+ in the leaves. Conversely, the sensitivity of D. erecta was associated with high Na+ and proline concentrations in leaves. The leaf concentration of proline showed to be an indicator more related to the sensitivity of ornamental plants to salt stress; however this relationship should not be generalized for all ornamental species studied.