Saline-alkali Stress Research Articles

Complete chloroplast genome of a high-quality forage in north China, Medicago ruthenica (Fabaceae：Trifolieae)

Medicago ruthenica is a well-known high-quality forage due to its good palatability and strong tolerance to drought, cold and saline-alkali stress. Here, the complete chloroplast genome sequence of M. ruthenica was reported. The chloroplast genome is 126,939 bp in length. This chloroplast genome has no inverted repeat (IR) regions, which is very common in the family Fabaceae. The M. ruthenica chloroplast genome encodes 107 genes, including 73 protein-coding genes, 30 tRNA genes, and 4 rRNA genes. Phylogenetic analysis result strongly suggested that M. ruthenica is a distinct lineage in Medicago, being sister to highly supported clade composed of three species (M. hybrida, M. papillosa and M. sativa).

Characteristics of complete chloroplast genome of a high-quality forage on Qinghai-Tibet Plateau, Medicago archiducis-nicolai Sirj. (Fabaceae：Trifolieae)

Medicago archiducis-nicolai Sirj. is a well-known high-quality forage as its good palatability and strong tolerance to drought, cold and saline-alkali stress. Here, the complete chloroplast genome sequence of M. archiducis-nicolai was reported. The size of the complete chloroplast genome is 127,072 bp in length. The chloroplast genome has no inverted repeat (IR) regions, which is very common in the family Fabaceae. The M. archiducis-nicolai chloroplast genome encodes 106 genes: 72 protein-coding genes, 30 tRNAs, and 4 rRNAs. The phylogenetic analysis result strongly suggested that M. archiducis-nicolai is a distinct lineage in Medicago, being sister to highly supported clade composed of three species (M. hybrida, M. papillosa and M. sativa).

Integrative Analysis of the Metabolome and Transcriptome of Sorghum bicolor Reveals Dynamic Changes in Flavonoids Accumulation under Saline-Alkali Stress.

With the perpetuation of soil salinization, it is imperative to improve the salt and alkaline tolerance of crops. Sorghum bicolor, a C4 crop, is often grown in semiarid areas due to its high tolerance of various abiotic stresses. Whether to improve the resistance of the sorghum itself or that of other crops, it is necessary to understand the response of sorghum under saline-alkali stress. An integrative analysis of the metabolome and transcriptome of sorghum under normal conditions and treatments of moderate and severe saline-alkali stress was performed. Among the different accumulated metabolites (DAMs) and differentially expressed genes (DEGs), flavonoid-related DAMs and DEGs were clearly changed. The level of flavonoids was increased under saline-alkali stress, and the change in flavonoids was dynamic as to whether total flavonoids or most flavonoid components accumulated more under moderate saline-alkali stress compared to severe stress. Some flavonoid metabolites were significantly correlated with the expression of flavonoid biosynthesis genes. MYB transcription factors may also contribute to the regulation of flavonoids levels. These findings present the dynamic changes and possible molecular mechanisms of flavonoids under different saline-alkali stresses and provide a foundation for future research and crop improvement.

Cu and Na contents regulate N uptake of Leymus chinensis growing in soda saline-alkali soil.

Leymus chinensis (L. chinensis) is the dominant plant in the eastern margins of the Eurasian temperate grasslands. It is a very robust species, exhibiting good saline-alkali resistance and stabilizing soil. In this study, 67 soil samples and L. chinensis were collected in western Jilin province, China. The contents of N, P, K, S, Mn, Fe, Zn, Cu and Na were measured, revealing that the growth of L. chinensis was mainly restricted by N based on the stoichiometric N: P ratios of plant. Furthermore, path analysis indicated that N was significantly correlated with K, S, Cu, and Zn. Imbalances in the homeostasis of these four elements may thus constrain N. The homeostasis index of Cu (HCu) in sites with 100%-70% of vegetation cover was only 0.79, it was classified as a sensitive element. However, K, S and Zn, whose concentrations in L. chinensis were significantly related to those of N, exhibited no homeostatic characteristics. These results suggest that when seeking to treat saline-alkali stress, it is important to add fertilizers containing K, S, and Zn to avoid growth limitation. Na+, an ion associated with high soil alkalinity, exhibited weak homeostasis in L. chinensis even in sites with only 40%-10% of vegetation cover. When soil Na exceeded 16000 mg/kg, the homeostasis mechanism of L. chinensis appeared to be overwhelmed, resulting in rapid and probably harmful accumulation of Na. Proper control of N content can alleviate the toxicity of Na stress in L. chinensis and enhance its Na tolerance. Together, these results suggest that combined fertilization with N, K, S, Zn and Cu should be applied to improve grasslands growth. The results of this study can provide a reference basis for sustainable grassland management.

Hyper Spectral Image Characteristics of Aronia Melanocarpa Leaves under Saline Alkali Stress

<p>Objective: To obtain the characteristics analysis results of aronia melanocarpa leaves under saline alkali stress state and improve yield and quality of aronia melanocarpa. Methods: Using hyper spectral imaging system to obtain hyper spectral images of aronia melanocarpa leaves under saline alkali stress. The clear hyper spectral image is obtained by the conversion of reflectance, spectral envelope removal, and spectral denoising, and final hyper spectral image is obtained by the normalization of a clearer hyper spectral image. Results: Spectral information of aronia melanocarpa leaves under slight saline alkali stress: in the visible band, leaf reflectance is lower than leaf nutrient rich stress condition; in the near infrared band, the nutrient rich leaves was significantly higher than that of stress leaves. Spectral information of leaves under moderate saline alkali stress: spectral reflectance of different lesion spots for a same leaf in 550-680nm band is: severe > moderate > slight > normal, in the near infrared band is on the contrary; spectral reflectance for different lesion grades in 550-680 nm, severe lesion leaves have highest reflectance, and normal leaves have the lowest reflectance. Under severe saline alkali stress, the leaf spectral information is: there is no significant difference in leaf spectral reflectance between the attachment aphid and the damaged leaf, but the difference is obvious for normal leaves in the band of 450-500 nm, 560-680 nm and 750-900 nm. Comparative results analysis for the three of saline alkali stress degree is: the near infrared band of 560-680 nm and the visible band of 780-900 nm is the sensitive band for the diagnosis of three kinds of stress; slight saline alkali stress has the most significant differences at 550 nm, and 780-900 nm; severe saline alkali stress has at 680 nm and 780-900 nm. Conclusion: The proposed method can analyze hyper spectral image characteristics of aronia melanocarpa leaves under different saline alkali stress the condition of is a kind of plant leaves, which is an efficient method for the analysis of characteristics of plant leaves under saline alkali stress.</p>

Identification and screening of saline-alkali tolerant peanut cultivars during whole growth stage

<p indent=0mm>In order to improve the planting structure of coastal saline-alkali land and enlarge the growing area of peanut in the Yellow River Delta. A total of 22 peanut elite cultivars were tested in saline-alkali area of Dongying in 2016 and 2017. Nine trait indices were separately investigated for five randomly selected individuals during whole growth stage. Variance analysis, correlation analysis and clustering analysis were used to evaluate the saline-alkali tolerance of the materials and to screen saline-alkali tolerant indices. Variance analysis showed that the seedling rates of all cultivars had an obvious decrease compared with those of the control. The growth, development and yield formation were essentially inhibited by saline-alkali stress. There were great differences among tested materials based on nine identification indices. Correlation analysis indicated that RYP and RPY had a significantly positive correlation with RSDW, RMSH and RBL. Additionally, RPY was also obviously related to RSR, RRDW, and RYP. Based on the results of clustering analysis, tested materials were divided into four saline-alkali tolerance grades, in which seven belonged to high tolerant grade I, 11 to tolerant grade II, 3 to susceptible grade III and 1 to highly susceptible grade IV. Huayu 9307, Huayu 9312, Huayu 9313, 6P03, Huayu 9305 and Huayu 6303 could be widely grown in the coastal saline-alkali area as high yield cultivars. In conclusion, the results suggested that RSDW, RMSH, RSR, RYP, RBL, and RRDW could be taken as simple and intuitive indices in the identification of saline-alkali tolerant peanut genotypes.

Biological function of Klebsiella variicola and its effect on the rhizosphere soil of maize seedlings.

BackgroundDeterioration of the ecological environment in recent years has led to increasing soil salinization, which severely affects the cultivation of agricultural crops. While research has focused on improving soil environment through the application of pollution-free microbial fertilizers, there are relatively few plant growth-promoting bacteria suitable for saline-alkali environments. Although Klebsiella variicola can adapt to saline-alkali environments to successfully colonize rhizosphere microenvironments, only a few studies have investigated its role in promoting crop growth. Its effect on the crop rhizosphere soil microenvironment is especially unclear.MethodsIn this study, the biological function of K. variicola and its colonization in maize seedling rhizosphere soil were studied in detail through selective media and ultraviolet spectrophotometry. The effects of K. variicola on the rhizosphere soil microenvironment and the growth of maize seedlings in saline-alkali and neutral soils were systematically analysed using the colorimetric method, the potassium dichromate volumetric method, and the diffusion absorption method.ResultsOur results showed that K. variicola played a role in indole acetic acid, acetoin, ammonia, phosphorus, and potassium production, as well as in nitrogen fixation. A high level of colonization was observed in the rhizosphere soil of maize seedlings. Following the application of K. variicola in neutral and saline-alkali soils, the nutrient composition of rhizosphere soil of maize seedlings increased in varying degrees, more notably in saline-alkali soil. The content of organic matter, alkali-hydrolysable nitrogen, available phosphorus, available potassium, alkaline phosphatase, sucrase, urease, and catalase increased by 64.22%, 117.39%, 175.64%, 28.63%, 146.08%, 76.77%, 86.60%, and 45.29%, respectively, insaline-alkalisoil.ConclusionK.variicola, therefore, performed a variety of biological functions to promote the growth of maize seedlings and effectively improve the level of soil nutrients and enzymes in the rhizosphere of maize seedlings, undersaline-alkali stress conditions. It played an important role in enhancing the rhizosphere microenvironment of maize seedlings under saline-alkali stress.

Ecological significance of arbuscular mycorrhiza on plant rhizosphere stress

In recent years, Chinese scientists have made remarkable achievements in on mycorrhizal molecular biology, nutrition, taxonomy, and ecology, with arbuscular mycorrhizal fungus (AMF) having been mostly studied. AMF can form symbiotic relationship with roots of most terrestrial plants, promote plant growth and development, improve plant stress resistance, maintain ecological balance, and protect ecological environment. This review mainly introduced the ecological function and mechanism of AMF in plant rhizosphere stress from the aspects of abiotic (drought stress, heavy metal pollution, saline-alkali stress) and biotic stresses (pathogenic bacteria and nematode infection). We proposed the remaining deficiencies and research prospects in this field to provide refe-rence for future research of AMF.

Overexpression of transcription factor SlWRKY28 improved the tolerance of Populus davidiana \xd7 P. bolleana to alkaline salt stress

BackgroundWRKY transcription factors (TFs) have been suggested to play crucial roles in the response to biotic and abiotic stresses. This study is the first to report the alkaline salt regulation of the WRKY gene.ResultsIn this study, we cloned a WRKY gene (SlWRKY28) from the Salix linearistipularis and then transferred to the Populus davidiana × P. bolleana for expression. Sequence analysis on the transcriptome of Salix linearistipular showed the significant up-regulation of WRKY gene expression in response to salt-alkali stress in seedlings. Our data showed that SlWRKY28 localized to the nucleus. Furthermore, the expression of the SlWRKY28 from female plants increased with saline-alkali stress according to the northern blot analysis results. The results of 3,3′-Diaminobenzidine (DAB) staining showed that hydrogen peroxide (H2O2) concentration was lower under stress, but ascorbate peroxidase (APX) enzyme activity was significantly higher in the overexpressed plants than that in non-transgenic (NT) plants.ConclusionsWe found out the SlWRKY28 induced regulation of the enzyme gene in the reactive oxygen species (ROS) scavenging pathway is a potential mechanism for transgenic lines to improve their resistance to alkaline salt. This study shows theoretical and practical significance in determining SlWRKY28 transcription factors involved in the regulation of alkaline salt tolerance.

Application of Plant Print Identification Technology in Salt-resistant Soybean Breeding

This study aimed to employ plant print identification to screen a wild-type soybean (Glycine soja Seib. and Zucc.) and then hybridize it with a cultivated soybean (Glycine max (L.) Merr.) (Lu, Chin Sci Bull 43:2074–2078, 1998) with a view to produce a salt-resistant variety. Scanning electron microscopy, optical microscopy, and paraffin sectioning were employed to compare two varieties of wild soybeans (#028 and #029) captured from different eco-environments, and the one with a salt gland present –– wild soybean #029 – was chosen as the male parent for hybridization. Considering a soybean variety with low stem as female parent, hybridization was performed and a new variety of salt-resistant soybean resulted, Ji-Yu59, which opened up a new, cost-efficient way of soybean breeding. Under saline-alkali stress, our salt-tolerant wild soybean is anticipated to exhibit antagonism by evolving a series of salt-resistant structures, including a salt-containing vacuolar package and a salt gland. The salt gland would help eliminate salts from the soybean plant; upon maturity, a salt gland is known to be able to break up salts to release their respective ions, effectively reducing salt and alkali stress. Therefore, a wild soybean with salt gland is an excellent choice for the hybridization of salt-resistant soybean varieties.

DNA methylation of the prkaca gene involved in osmoregulation in tilapia hybrids (Oreochromis mossambicus×Oreochromis hornorum).

Prkaca consists of the catalytic subunit alpha protein kinase A (PKA), which is involved in many cellular processes. In this study, the cDNA and genomic sequences of prkaca in tilapia hybrids (Oreochromis mossambicus×Oreochromis hornorum) were cloned and analysed. The results showed the prkaca gene consists of 11 exons and 10 introns, and its protein contains 351 amino acid residues and is clustered with Oreochromis niloticus, Maylandia zebra and Haplochromis burtoni first in a phylogenetic tree. Amino acid alignment indicates that prkaca shares the highest identity (100%) to Oreochromis niloticus, Maylandia zebra and Haplochromis burtoni. Two CpG islands of prkaca were found by MethPrimer software, and 32 CG sites were found in the proximal promoter. The methylation level of prkaca in the hybrids (0.31%) was significantly lower than that of their parents (0.94% and 3.43%) in kidney tissue (P<0.05). The gene expression levels and DNA methylation levels of prkaca in muscle and kidney tissues of the tilapia hybrids were detected by quantitative real-time PCR and bisulfite sequencing PCR and showed a negative correlation under saline-alkali stress. The results of this research demonstrated that DNA methylation levels and prkaca mRNA expression levels were inversely correlated under saline-alkali stress, implying that heterosis is likely accompanied by DNA methylation alterations. This research provides new clues for further investigations of DNA methylation and heterosis in hybrid fish.

Moderate clipping stimulates over-compensatory growth of Leymus chinensis under saline-alkali stress through high allocation of biomass and nitrogen to shoots

Leymus chinensis, a dominant species in the Songnen Plain of northeast China, has a strong ability to resist grazing and tolerate saline-alkali stress. Compensatory growth is a positive response of plants, when subjected to grazing or clipping stress; however, little information is available on how plant nitrogen allocation strategies affect compensatory growth under saline-alkali stress. A field experiment using two saline-alkali levels and three clipping levels was conducted in conjunction with the belowground 15N-urea labelling method. Irrespective of clipping and salt-alkali stress, moderate clipping significantly promoted allocation of newly-absorbed nitrogen (N) to shoots, resulting in high biomass and over-compensatory growth of L. chinensis. However, severe clipping dramatically decreased uptake of total 15N by 20% under saline-alkali conditions, resulting in under-compensatory growth, and plants allocated more N to stem bases than to other plant organs, showing a conservative N allocation strategy. Our results suggest that plants have different nitrogen allocation strategies under different combinations of environmental stresses.

A Na2CO3-Responsive Chitinase Gene From Leymus chinensis Improve Pathogen Resistance and Saline-Alkali Stress Tolerance in Transgenic Tobacco and Maize.

Salinity and microbial pathogens are the major limiting factors for crop production. Although the manipulation of many genes could improve plant performance under either of these stresses, few genes have reported that could improve both pathogen resistance and saline-alkali stress tolerance. In this study, we identified a new chitinase gene CHITINASE 2 (LcCHI2) that encodes a class II chitinase from Leymus chinensis, which grows naturally on alkaline-sodic soil. Overexpression of LcCHI2 increased chitinase activity in transgenic plants. The transgenic tobacco and maize exhibited improved pathogen resistance and enhanced both neutral salt and alkaline salt stress tolerance. Overexpression of LcCHI2 reduced sodium (Na+) accumulation, malondialdehyde content and relative electrical conductivity in transgenic tobacco under salt stress. In addition, the transgenic tobacco showed diminished lesion against bacterial and fungal pathogen challenge, suggesting an improved disease resistance. Similar improved performance was also observed in LcCHI2-overexpressed maize under both pathogen and salt stresses. It is worth noting that this genetic manipulation does not impair the growth and yield of transgenic tobacco and maize under normal cultivation condition. Apparently, application of LcCHI2 provides a new train of thought for genetically engineering saline-alkali and pathogen resistant crops of both dicots and monocots.

Alfalfa MsCBL4 enhances calcium metabolism but not sodium transport in transgenic tobacco under salt and saline-alkali stress.

MsCBL4 expression in tobacco enhanced its salt and saline-alkali stress tolerance by regulating calcium accumulation in roots, indicating the important role of calcium metabolism in plant saline-alkali stress tolerance The calcineurin B-like (CBL) family of proteins play important roles in plant abiotic stress tolerance and signal transduction. CBL4 is known to participate in the Salt Overly Sensitive pathway; however, little is currently known regarding the mechanisms underlying the response of CBL4 to saline-alkali stress. In this study, we cloned and characterized the alfalfa MsCBL4 gene. We found that MsCBL4 showed the highest expression in root tissues and was induced by salt and saline-alkali stress, with the latter causing higher induction. Overexpression of MsCBL4 in tobacco enhanced salt and saline-alkali stress tolerance and reduced the Na+/K+ ratio in roots of transgenic lines. Salt (30 and 300mM NaCl) and saline-alkali (30mM NaHCO3) stress assays performed for MsCBL4 transgenic tobacco lines revealed a substantial influx of sodium ions in roots under saline-alkali stress and indicated that the expression of MsCBL4 had little influence on sodium ion content reduction. In contrast, in roots subjected to saline-alkali stress, calcium accumulation occurred and was significantly enhanced by the overexpression of MsCBL4. Physiological and biochemical analyses indicated that MsCBL4 plays an important role in saline-alkali stress tolerance via its influence on the regulation of calcium transport and accumulation. These results provide novel insights into the saline-alkali stress tolerance mechanisms of plants.

Effects of exogenous nitric oxide on seed germination and seedling growth of Chenopodium quinoa under complex saline-alkali stress

Effects of exogenous nitric oxide on seed germination and seedling growth of Chenopodium quinoa under complex saline-alkali stress

Carbon Mineralization under Different Saline—Alkali Stress Conditions in Paddy Fields of Northeast China

Soil organic carbon (SOC) mineralization (conversion of carbonaceous material to carbon dioxide) plays a central role in global carbon cycle. However, the effects of SOC mineralization under different saline–alkali stress conditions are poorly understood. In order to understand the carbon mineralization processes, four paddy fields with different saline and alkali degrees were chosen as the experimental samples and the soil CO2 emission fluxes at nine different time steps of the whole simulation experiment were observed. The physical and chemical properties of soils of four field conditions were compared for the dynamic changes of CO2 flux in the progress of paddy field cultivation simulations. The results showed that the first three fields (P1, P2, and P3) were weakly alkaline soils and the last one (P4) was strongly alkaline soil. The SOC content of each plot was significantly different and there was a near-surface enrichment, which was significantly negatively correlated with the degree of alkalization. The accumulation process of the SOC mineralization during the incubation time was consistent with the first-order kinetic model. In the initial stage of mineralization, the amount of CO2 released massively, and then the release intensity decreased rapidly. The mineralization rate decreased slowly with time and finally reached a minimum at the end of the incubation period. This study indicates that the SOC mineralization process is affected by a variety of factors. The main factors influencing SOC mineralization in the saline–alkaline soils are the exchangeable sodium percentage (ESP), followed by enzyme activities. Salinization of the soils inhibits the rate of soil carbon cycle, which has a greater impact on the carbon sequestration than on the carbon source process. The intensity and completeness of the SOC mineralization reactions increase with increasing SOC contents and decrease with increasing ESP levels.

Saline–alkaline resistance analysis of rice overexpressing the CsCYP1A gene of alkaline Chlorella

AbstractPlant cyclophilin (CYP) is related to chloroplast photoprotection, redox and other growth and developmental regulatory processes and responds to stress and improves tolerance to saline–alkali stress. Besides, it exerts peptidyl-prolyl cis/trans isomerase activity to participate in protein synthesis and folding. In this study, Northern blot was used to analyse the CsCYP1A gene (a CYP gene isolated from a Chlorella species) (accession number: KY207381) of tolerant Chlorella vulgaris in soda saline–alkali soil. The result showed that the expression of the CsCYP1A gene was induced by NaHCO3, NaCl and sorbitol. Additionally, Agrobacterium tumefaciens was used to infect the callus of rice (Oryza sativa var. Longjing11) for genetic transformation. Molecular detection confirmed that transgenic seedlings overexpressing CsCYP1A were obtained by hygromycin selection. Treatment with NaCl and NaHCO3 at the five-leaf stage was performed in the seedlings, and the results showed that there were significant differences between the CsCYP1A overexpressed rice lines and non-transgenic (NT) Longjing11 in terms of plant height, fresh weight, chlorophyll content, malondialdehyde content and ascorbate peroxidase activity. The CsCYP1A overexpression rice lines had higher tolerance to NaCl and NaHCO3 than NT. The current findings indicate that CsCYP1A can enhance the tolerance of rice to saline–alkali stress possibly through its involvement in reactive oxygen scavenging pathways.

Cytosolic Ca2+ Involved in Seed Germination of Naked Oat Enhanced by Exogenous H2S under Saline-Alkali Stress

Cytosolic Ca2+ Involved in Seed Germination of Naked Oat Enhanced by Exogenous H2S under Saline-Alkali Stress

Effects of saline-alkali stress on the growth and ion micro-distribution of ryegrass plants

Effects of saline-alkali stress on the growth and ion micro-distribution of ryegrass plants

Apply biochar to ameliorate soda saline-alkali land, improve soil function and increase corn nutrient availability in the Songnen Plain

Soda saline-alkali soils are characterized by high concentration of sodium cations on the exchange complex or in soil-water resulting in soils which are physically as well as nutritionally challenging for crop production. Biochar application has received growing interest as a sustainable technology to improve physicochemical properties in non-saline and non-alkali soils. However, information is inadequate regarding potential of using corn straw derived biochar as an organic material to reduce soda saline-alkali stress. Based on the established model of corn straw biochar-soda saline alkali soil-corn system, soil and plant samples were collected from long-term field experiment in soda saline-alkali land with different addition rates of corn straw biochar (CK: control, T5: 5 ton ha−1, T10: 10 ton ha−1, T15: 15 ton ha−1, T20: 20 ton ha−1, T25: 25 ton ha−1, T30: 30 ton ha−1). In the seedling and harvest period, addition of corn straw biochar enhanced the contents of cation exchange capacity (CEC), organic matter, and nutrients of 0–20 cm and 20–40 cm saline-alkali soil layers and the above ground and underground parts of corn. However, the results were contrary as far as pH, salt, and Na+ were concerned, and the effect of T20 was the most significant. Principal component analysis showed that CEC, pH, salinity, and organic matter could be used as indicators to evaluate the improvement effect of biochar on soda saline-alkali soil. Irrespective of the application of biochar, pH, salt content, Na+, and nutrients concentrations at seedling stage were higher than those at harvest stage, indicating that planting corn could improve soda saline-alkali soil. It may be concluded that corn straw biochar can be used as an organic amendment for reducing adverse effects of salinity and alkalinity on soil functions governed by their rates of addition.