Soil salinization has become more and more serious. Exogenous nitric oxide (NO) could act in alleviating toxicity in plants. In this study, we aimed to explore the growth, photosynthetic pigments, water-solubles content, proteins, antioxidant enzyme parameters, and element contents of two types of wild barley (Hordeum brevisubulatum (Trin.) Link.), wild-type barley and Saertu wild barley cultivars, in response to salt stress. Both cultivars were first treated with 300 µmol·L−1 NaCl (increased in 25 µmol·L−1 increments to 300 µmol·L−1 for 7 days). Next, plants were sprayed with different NO concentrations on days 1, 5, 10, 15 and 20 after the NaCl concentration reached 300 µmol·L−1. The results showed that salt stress alone decreased all growth parameters [plant height (HT), fresh weight (FW), total dry weight (DW)], the photosynthetic pigment and protein contents, and the activity of the antioxidant enzymes [ascorbic acid peroxidase (APX), peroxidase (POD), catalase (CAT), superoxide dismutase (SOD)], and significantly increased the K+ and Na+ elements contents, water solubles and malondialdehyde (MDA) compared with the controls. However, the inhibitory effects of salt stress in both wild barley cultivars were alleviated by exogenous NO treatment, and 200 µmol·L−1 NO was the most effective concentration to improve plant growth, ion element levels and the physiology of wild barley under high salt stress. Altogether, this study demonstrated the beneficial role of exogenous NO donor, sodium nitroprusside, on wild barley under salinity stress and the underlying physiological and biochemical mechanisms.
Abiotic stress affects metabolic processes in plants and restricts plant growth and development. In this experiment, Caucasian clover (Trifolium ambiguum M. Bieb.) was used as a material, and the CDS of TaMYC2, which is involved in regulating the response to abiotic stress, was cloned. The CDS of TaMYC2 was 726 bp in length and encoded 241 amino acids. The protein encoded by TaMYC2 was determined to be unstable, be highly hydrophilic, and contain 23 phosphorylation sites. Subcellular localization results showed that TaMYC2 was localized in the nucleus. TaMYC2 responded to salt, alkali, cold, and drought stress and could be induced by IAA, GA3, and MeJA. By analyzing the gene expression and antioxidant enzyme activity in plants before and after stress, we found that drought and cold stress could induce the expression of TaMYC2 and increase the antioxidant enzyme activity. TaMYC2 could also induce the expression of ROS scavenging-related and stress-responsive genes and increase the activity of antioxidant enzymes, thus improving the ability of plants to resist stress. The results of this experiment provide references for subsequent in-depth exploration of both the function of TaMYC2 in and the molecular mechanism underlying the resistance of Caucasian clover.
Additional file 2: Table S2. Statistics of AS. The QueryName and SubjectName are the IDs of the identified AS events. QhspStart1, QhspEnd1, QhspStart2, QhspEnd2, ShspStart, ShspEnd1, ShspStart2 and ShspEnd2 indicate the start and end positions of the 2 HSPs for these two AS events.
Phytoremediation is a promising remediation strategy for degraded soil restoration. Root exudates are the main carrier substances for information communication and energy transfer between plant roots and soil, which play non-negligible roles in the restoration process. This work investigated the adaptation of Leymus chinensis root exudates to different degraded levels of soil and the mechanism of rhizosphere restoration in a 3-year degraded soil field study. We found that the soil quality at each degradation level significantly increased, with the soil organic matter (SOM) content slightly increasing by 1.82%, moderately increasing by 3.27%, and severely increasing by 3.59%, and there were significant increases in the contents of available nutrients such as available phosphorus (AP), ammonia nitrogen (AN), and nitrate nitrogen (NN). The physiological activities indicated that root tissue cells also mobilize oxidative stress to respond to the soil environment pressure. A total of 473 main components were obtained from root exudates by gas chromatography-time-of-flight mass spectrometry (GC-TOFMS), including acids, alcohols, carbohydrates, and other major primary metabolites. OPLS-DA revealed that soil degradation exerted an important influence on the metabolic characteristics of root exudates, and the numbers of both up- and downregulated metabolic characteristic peaks increased with the increase in the degree of degradation. Forty-three metabolites underwent clear changes, including some defense-related metabolites and osmotic adjustment substances that were significantly changed. These changes mainly mobilized a series of lipid metabolism pathways to maintain the fluidity of membrane function and help plants adapt to unfavorable soil environmental conditions. The PPP energy metabolism pathway was mobilized in response to slight degradation, and TCA energy pathways responded to the environmental pressure of severe soil degradation.
Amphicarpaea edgeworthii , an annual twining herb, is a widely distributed species and an attractive model for studying complex flowering types and evolutionary mechanisms of species. Herein, we have generated a high-quality assembly of A. edgeworthii by using a combination of PacBio, 10× Genomics libraries, and Hi-C mapping technologies. The final 11 chromosome-level scaffolds covered 90.61% of the estimated genome (343.78Mb), which is a chromosome-scale assembled genome of an amphicarpic plant. Subsequently, we characterized the genetic diversity and population structure of A. edgeworthii species by resequencing individuals collected from their natural area of distribution. Using transcriptome profiling, we observed that specific phenotypes are regulated by a complex network of light, hormones, and MADS-box gene families. These data are beneficial for the discovery of genes that control major agronomic traits and spur genetic improvement of and functional genetic studies in legumes, as well as supply comparative genetic resources for other amphicarpic plants.
Alkaline salts (e.g., NaHCO3 and Na2CO3) causes more severe morphological and physiological damage to plants than neutral salts (e.g., NaCl and Na2SO4) due to differences in pH. The mechanism by which plants respond to alkali stress is not fully understood, especially in plants having symbotic relationships such as alfalfa (Medicago sativa L.). Therefore, a study was designed to evaluate the metabolic response of the root-nodule symbiosis in alfalfa under alkali stress using comparative metabolomics. Rhizobium-nodulized (RI group) and non-nodulized (NI group) alfalfa roots were treated with 200 mmol/L NaHCO3 and, roots samples were analyzed for malondialdehydyde (MDA), proline, glutathione (GSH), superoxide dismutase (SOD), and peroxidase (POD) content. Additionally, metabolite profiling was conducted using gas chromatography combined with time-of-flight mass spectrometry (GC/TOF-MS). Phenotypically, the RI alfalfa exhibited a greater resistance to alkali stress than the NI plants examined. Physiological analysis and metabolic profiling revealed that RI plants accumulated more antioxidants (SOD, POD, GSH), osmolytes (sugar, glycols, proline), organic acids (succinic acid, fumaric acid, and alpha-ketoglutaric acid), and metabolites that are involved in nitrogen fixation. Our pairwise metabolomics comparisons revealed that RI alfalfa plants exhibited a distinct metabolic profile associated with alkali putative tolerance relative to NI alfalfa plants. Data provide new information about the relationship between non-nodulized, rhizobium-nodulized alfalfa and alkali resistance.
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