Soil salinity plays a key role in influencing the soil dielectric constant and soil backscatter coefficient. However, soil moisture (SM) retrieval models constructed based on active microwave data ...hardly consider soil salinity. Thus, obtaining the SM datasets with various salinity on regional and local scales is difficult. This study aimed to employ theoretical model simulation to investigate the errors of SM retrieval due to not considering the impact of soil salinity. Then, three typical saline soil dielectric constant models were validated and compared based on the experimental measurement datasets. Results show that the WYR saline soil dielectric constant model has excellent performance. The soil salinity mainly affects the imaginary part of the dielectric constant and the effect of salinity on the soil dielectric constant is more significant when the SM has larger values. In addition, in retrieving SM with soil salinity more than 10 g/kg, the retrieval result of SM has an absolute error of 0.04 <inline-formula> <tex-math notation="LaTeX">\text{m}^{3}/\text{m}^{3} </tex-math></inline-formula> and a relative error of 5% when not considering the soil salinity impact. In retrieving SM with soil salinity less than 10 g/kg, the retrieved SM error increased by 2%, and the absolute error increased by 0.01 <inline-formula> <tex-math notation="LaTeX">\text{m}^{3}/\text{m}^{3} </tex-math></inline-formula> as soil salinity increased by 3 g/kg. We believe that The study will give a theoretical reference for establishing the SM retrieval model in saline soil areas using microwave data.
The European Space Agency (ESA) has recently published the Soil Moisture and Ocean Salinity Mission (SMOS) third mission reprocessing data, which include the changes in calibration and image ...reconstruction that have been made to the Level 1 Operational Processor (L1OP) version v724 during the past few years. The new L1 processor incorporates several improvements to the calibration and image reconstruction algorithms. The present article proposes a new methodology used by the SMOS team to evaluate the quality and stability of the L1 data. This is done by comparison with an ocean forward model over a well-known, sea-surface salinity stable, region. The L1 reprocessed radiometry accuracy and stability are studied in detail. The results presented here confirm the improvement on data quality expected for the new baseline algorithm. Furthermore, the remaining biases and open points are described and analyzed, establishing the basis for their improvement in following reprocessing campaigns.
Soil salinity is a primary factor limiting soybean (Glycine max) productivity. Breeding soybean for tolerance to high salt conditions is therefore critical for increasing yield. To explore the ...molecular mechanism of soybean responses to salt stress, we performed a comparative transcriptome time-series analysis of root samples collected from two soybean cultivars with contrasting salt sensitivity.
The salt-tolerant cultivar 'Qi Huang No.34' (QH34) showed more differential expression of genes than the salt-sensitive cultivar 'Dong Nong No.50' (DN50). We identified 17,477 genes responsive to salt stress, of which 6644 exhibited distinct expression differences between the two soybean cultivars. We constructed the corresponding co-expression network and performed Gene Ontology term and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. The results suggested that phytohormone signaling, oxidoreduction, phenylpropanoid biosynthesis, the mitogen-activated protein kinase pathway and ribosome metabolism may play crucial roles in response to salt stress.
Our comparative analysis offers a comprehensive understanding of the genes involved in responding to salt stress and maintaining cell homeostasis in soybean. The regulatory gene networks constructed here also provide valuable molecular resources for future functional studies and breeding of soybean with improved tolerance to salinity.
The study of effect of elevated temperature on the mechanisms of salt tolerance in plants are of great interest and perspective under global climate change. This study investigated the individual and ...combined effects of prolonged heat and four days moderate salinity on morphophysiological and biochemical parameters (biomass, photosystems I and II (
F
v
/
F
m
) efficiencies, apparent photosynthesis intensity, transpiration, dark respiration, water-use efficiency, contents of water, free proline, Na
+
and K
+
in aboveground parts of plants) in the С
4
xero-halophyte
Кochia prostrata.
The physiological processes and biochemical parameters actively involved during acclimation to stress under different treatments (control, heat, salinity, heat + salinity) were identified. A decrease in biomass and change in the K
+
/Na
+
ratio was observed under all treatments. Acclimation to heat resulted in increased dark respiration intensity (Rd) and K
+
content. Under salinity conditions, an increase in Na
+
content, a decrease in PSI efficiency and transpiration intensity were observed. Combined stress (heat + salinity) resulted in increased proline and Na
+
contents in addition to high values of Rd and K
+
. Principal component analysis showed that under combined stress, dark respiration, K
+
and proline are actively involved in acclimation. It was found that acclimation to elevated temperature affects the salt tolerance mechanisms in
K. prostrata,
since under combined stress, sodium ions accumulated 3-fold less than in plants under normal temperature and salinity. It is assumed that in
K. prostrata
plants grown at elevated temperature, K
+
and proline are more involved in the acclimation to salinity than Na
+
. Dark respiration is likely the source of additional energy costs. We conclude that acclimation of С
4
halophytes to elevated temperature changes the importance of sodium and potassium ions, as well as proline, in the mechanisms of salt tolerance.
Stomata regulate photosynthesis and transpiration, and these processes are critical for plant responses to abiotic stresses such as salinity. A barley double haploid population with 108 lines derived ...from a cross between CM72 (salt-tolerant) and Gairdner (salt-sensitive) was used to detect quantitative trait loci (QTLs) associated with stomatal and photosynthetic traits related to salinity tolerance.
A total of 11 significant QTLs (LOD > 3.0) and 11 tentative QTLs (2.5 < LOD < 3.0) were identified. These QTLs are distributed on all the seven chromosomes, except 5H and explain 9.5-17.3% of the phenotypic variation. QTLs for biomass, intercellular CO
concentration, transpiration rate and stomatal conductance under control conditions co-localised together. A QTL for biomass also co-located with one for transpiration rate under salinity stress. A linkage was found between stomatal pore area and gas exchange. A QTL for salinity tolerance also co-localised with QTLs for grain yield and biomass on chromosome 3H. Based on the draft barley genome, the candidate genes for salinity tolerance at this locus are proposed.
The lack of major QTLs for gas exchange and stomatal traits under control and saline conditions indicates a complex relationship between salinity and leaf gas exchange due to the fact that these complex quantitative traits are under the control of multiple genes.
Rice (Oryza sativa L. ssp. indica) seeds as plant microbiome present both an opportunity and a challenge to colonizing bacterial community living in close association with plants. Nevertheless, the ...roles and activities of bacterial endophytes remain largely unexplored and insights into plant-microbe interaction are compounded by its complexity. In this study, putative functions or physiological properties associated with bacterial endophytic nature were assessed. Also, endophytic roles in plant growth and germination that may allow them to be selectively chosen by plants were also studied.
The cultivable seed endophytes were dominated by Proteobacteria particularly class Gammaproteobacteria. Highly identical type strains were isolated from the seed endosphere regardless of the rice host's physiological tolerance to salinity. Among the type strains, Flavobacterium sp., Microbacterium sp. and Xanthomonas sp. were isolated from the salt-sensitive and salt-tolerant cultivars. PCA-Biplot ordination also showed that specific type strains isolated from different rice cultivars have distinguishing similar characteristics. Flavobacterium sp. strains are phosphate solubilizers and indole-3-acetic acid producers with high tolerance to salinity and osmotic stress. Pseudomonas strains are characterized as high siderophore producers while Microbacterium sp. and Xanthomonas sp. strains have very high pectinase and cellulase activity. Among the physiological traits of the seed endophytes, bacterial pectinase and cellulase activity are positively correlated as well as salt and osmotic tolerance. Overall characterization shows that majority of the isolates could survive in 4-8% salt concentration as well as in 0.6 M and 1.2 M sucrose solution. The activities of catalase, pectinase and cellulase were also observed in almost all of the isolates indicating the importance of these characteristics for survival and colonization into the seed endosphere. Seed bacterial endophytes also showed promising plant growth promoting activities including hormone modulation, nitrogen fixation, siderophore production and phosphate solubilization.
Though many of the isolates possess similar PGP and endophytic physiological traits, this study shows some prominent and distinguishing traits among bacterial groups indicating key determinants for their success as endophytes in the rice seed endosphere. Rice seeds are also inhabited by bacterial endophytes that promote growth during early seedling development.
Salinity stress is a chief abiotic hindrance affecting crop productivity and yield particularly in arid and semi-arid regions across the globe. Plants have evolved a network of physiological and ...molecular mechanisms to cope with salinity stress. The complex and multi-faceted nature of salinity tolerance involve several mechanisms and a comprehensive approach on how plants employ tolerance to salinity at distinct levels and combining physiological measurements with new molecular technologies is an emerging area of crop research. Recent evidences from salinity tolerance mechanisms highlight osmolytes that play a key role in quenching free radicals, induce antioxidant machinery, and osmotic regulation. Polyamines (PAs) also exhibit a promising role in salt tolerance mechanism and adaptation strategies mainly by stabilization of membranes, neutralization of acids, and suppressing ROS synthesis. Interconnection of PAs and nitric oxide biosynthesis also raise hopes for better tolerance to plants under stressful environment. Based on recent findings, the present review highlights the protective role of ion pumps, osmolytes, and polyamines during salt stress. All these strategies have emerged as potential targets for researchers to confer salt stress tolerance in plants.
Background and aims
In sustainable agricultural systems, different beneficial soil microorganisms are explored to improve crop production and tolerance of plants to different environmental stresses. ...The present research aimed to examine the potential of plant beneficial rhizospheric microorganisms (PBRMs) for ameliorate the negative effects of salinity stress on sage (
Salvia officinalis
).
Methods
In this study, the effect of symbiosis with
Piriformospora indica
and
Pseudomonas fluorescens
in counteracting salinity stress on sage plants was quantified. The biomass production, physiological and biochemical markers and essential oil content and composition were evaluated under four salinity levels (0, 25, 50 and100 mM NaCl) in inoculated and non-inoculated sage plants.
Results
Fresh and dry herb yield, relative water content (RWC), chlorophyll and essential oil content exhibited a reduction in response to salinity. In contrast, salinity increased electrolyte leakage (EL), amount of malondialdehyde (MDA), accumulation of proline and total soluble sugars (TSS), activity of catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX) enzymes, total antioxidant activity, total phenol and flavonoids. Inoculation with microorganisms increased fresh and dry herb yield, RWC, chlorophyll content, accumulation of proline and TSS, antioxidant enzymes activity, total antioxidant activity, total phenol and flavonoids and essential oil content and decreased EL and amount of MDA. The dominant constituents of essential oils (α-thujone, β-thujone, camphor, 1,8-cineole, α-pinene, camphene and viridiflorol) showed changes in response to salinity stress.
Conclusion
The findings of this study showed that symbiotic association with PBRMs can help sage plants overcome the adverse effects of salinity stress.
For the use of saline waters in agriculture to be a viable option, solutions must be adopted to mitigate the impacts caused by these waters. In this context, the present study aimed to evaluate the ...foliar application of algae (Ascophyllum nodosum) extract as a strategy to mitigate the deleterious effects of salinity on the production and post-harvest variables of the 'BRS 324' sunflower. The experiment was conducted in a randomized block design with a split-split-plot arrangement, composed of four salinity levels of water (1.2, 3.0, 4.5, and 6.0 dS m.sup.-1) and four doses of algae extract (0, 100, 150, and 200% of recommended dose) in two crop cycles, with four blocks. The 100% of the recommended dose (32 mg L.sup.-1) of the algae extract positively influenced the 1000-achenes weight (increases of 6.05 and 3.63% for the levels of 1.2 and 3.0 dS m.sup.-1, respectively) and the achene yield (increments of 7.07 and 4.59% for the levels of 1.2 and 3.0 dS m.sup.-1). The algae extract did not influence the oil and protein content and yield. The increase in salinity levels reduced all variables studied. Algae extract mitigated the deleterious effects of salinity on 1,000-achene weight and yield of achenes at the lowest water salinity level (1.2 dS m.sup.-1). The most effective dose of the algae extract to mitigate the negative effects of salinity on the 1,000-achene weight and achene yield was 100% (32 mg L.sup.-1) of the recommendation of the extract. Key words: salinity, Ascophyllum nodosum, Helianthus annuus Para que o uso de aguas salinas na agricultura seja uma opcao viavel a necessario que soluc es sejam adotadas para atenuar os impactos provocados por essas aguas. Nesse sentido, objetivou-se avaliar a aplicacao foliar de extrato de algas (Ascophyllum nodosum) como estratagia para atenuar os efeitos deletarios da salinidade sobre as variaveis de producao e pos-colheita do girassol 'BRS 324. O experimento foi conduzido em delineamento de blocos casualizados, com esquema de parcelas sub-sub-divididas, composto por quatro niveis de salinidade da agua (1,2; 3,0; 4,5 e 6,0 dS m.sup.-1) e quatro doses do extrato de algas (0, 100, 150 e 200% da dose recomendada), em dois ciclos de cultivos, com quatroblocos. A dose de 100% da recomendacao (32 mg L.sup.-1) do extrato influenciou positivamente o peso de 1.000 aquenios (acrascimos de 6,05 e 3,63% para os niveis de 1,2 e 3,0 dS m.sup.-1, respectivamente) e o rendimento de aquenios (incrementos de 7,07 e 4,59% para os niveis de 1,2 e 3,0 dS m.sup.-1). O teor de oleo e proteina, rendimento de oleo e proteina nao foram significativamente influenciados pelo extrato. Os niveis crescentes de salinidade reduziram todas as variaveis estudadas. O extrato de algas mitigou os efeitos deletarios da salinidade no peso de 1.000 aquenios e na producao de aquenios no nivel mais baixo da salinidade da agua (1,2 dS m.sup.-1). A dose mais eficaz do extrato para mitigar os efeitos negativos da salinidade no peso de 1.000 aquenios e no rendimento de aquenios foi 100% da recomendacao do extrato (32 mg L.sup.-1). Palavras-chave: salinidade, Ascophyllum nodosum, Helianthus annuus
Main conclusion
A total of 27 rose thaumatin-like protein (TLP) genes were identified from the rose genome through bioinformatics analyses. RcTLP6 was found to confer salinity stress tolerance in ...rose.
Thaumatin-like proteins (TLPs) play critical roles in regulating many biological processes, including abiotic and biotic stress responses in plants. Here, we conducted a genome-wide screen of TLPs in rose (
Rosa chinensis
) and identified 27 RcTLPs. The identified RcTLPs, as well as other TLPs from six different plant species, were placed into nine groups based on a phylogenetic analysis. An analysis of the intron–exon structures of the TLPs revealed a high degree of similarity. RcTLP genes were found on all chromosomes except for chromosome four.
Cis
-regulatory elements (CEs) were identified in the promoters of all RcTLPs, including CEs associated with growth, development and hormone-responsiveness, as well as abiotic and biotic responses, indicating they play diverse roles in rose. Transcriptomics analysis revealed that RcTLPs had tissue-specific expression patterns, and several root-preferential RcTLPs were responsive to drought and salinity stress. Quantitative PCR analysis of six RcTLPs under ABA, PEG and NaCl treatment confirmed the differentially expressed genes identified in the transcriptomics experiment. In addition, silencing
RcTLP
6 in rose leaves led to decreased tolerance to salinity stress. We also screened proteins which may interact with RcTLP6 to understand its biological roles. This study represents the first report of the TLP gene family in rose and expands the current understanding of the role that
RcTLP
6 plays in salt tolerance. These findings lay a foundation for future utilization of RcTLPs to improve rose abiotic stress tolerance.
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