Isolated Thellungiella shoots do not require roots to survive NaCl and Na2SO4 salt stresses

Current knowledge about Na2SO4 effects on plants: what is different in comparison to NaCl?

In some areas of the world, high levels of sodium sulfate (Na₂SO₄) are found in the soil together with sodium chloride (NaCl). However, most studies on salinity are performed utilizing only NaCl as a salinizing agent. Generally, plant species have different tolerance/susceptibility responses when grown in the presence of these salts. Some studies showed that Na₂SO₄ seems to be more inhibitory than NaCl for the growth of species such as barley, wheat, sugar cane, beet, tomato, wild potato, and others. However, studies focusing on how Na₂SO₄ can affect the biochemical and physiological processes of plants are very scarce. This review provides an overview on the effects of Na₂SO₄ on different crops and plants species with a special emphasis on the tolerance/non-tolerance mechanisms of the halophyte Prosopis strombulifera under elevated NaCl and Na₂SO₄. A better understanding of the tolerance mechanisms in this particular species will help to identify cultivars of crop species that are more tolerant to Na₂SO₄. This knowledge could be used to extent cultivation of certain crop plants on Na₂SO₄ containing soils.

Cytokinetic and anatomical analysis of Thellungiella botschantzevii meristem cells in high concentrations of NaCl and Na2SO4

The study of cytokinetic and anatomical properties of the extramophile plant Thellungiella botschantzevii (German) at high concentrations of NaCl and Na2SO4 and without them (control) allowed to identify structural and functional transformations at the cellular level and evaluate the effect of salinity. Cytophotometric method showed the accumulation of cells in the root meristem in G1 and S stages, which indicated the adaptation of Thellungiella botschantzevii to high concentrations of NaCl and Na2SO4. A high level of ploidy (up to 16C) and the maximum number of polyploid cells at the level of 4C and 8C gave the plant stability. Anatomical characteristics of Thellungiella botschantzevii root and leaf were obtained on semi-thin and ultra-thin sections, and accumulation of lipid and protein inclusions in the root cell was determined. The data obtained indicate that Thellungiella botschantzevii is a unique model for various kinds of research, including genetic research, and can help to develop proposals for increasing resistance in crops.

Cold stress increases salt tolerance of the extremophytes Eutrema salsugineum (Thellungiella salsuginea) and Eutrema (Thellungiella) botschantzevii

A comparative study was performed to analyze the effect of cold acclimation on improving the resistance of Arabidopsis thaliana, Eutrema salsugineum and Eutrema botschantzevii plants to salt stress. Shoot FW, sodium and potassium accumulation, metabolite content, expression of proton pump genes VAB1, VAB2,VAB3, VP2, HA3 and genes encoding ion transporters SOS1, HKT1, NHX1, NHX2, NHX5 located in the plasma membrane or tonoplast were determined just after the cold treatment and the onset of the salt stress. In the same cold-acclimated E. botschantzevii plants, the Na⁺ concentration after salt treatment was around 80% lower than in non-acclimated plants, whereas the K⁺ concentration was higher. As a result of cold acclimation, the expression of, VAB3, NHX2, NHX5 genes and of SOS1, VP2, HA3 genes was strongly enhanced in E. botschantzevii and in E. salsugineum plants correspondently. None of the 10 genes analyzed showed any expression change in A. thaliana plants after cold acclimation. Altogether, the results indicate that cold-induced adaptation to subsequent salt stress exists in the extremophytes E. botschantzevii and to a lesser extend in E. salsugineum and is absent in Arabidopsis. This phenomenon may be attributed to the increased expression of ion transporter genes during cold acclimation in the Eutrema species.

De novo assembly and characterization of the transcriptome of seagrass Zostera marina using Illumina paired-end sequencing

Background

The seagrass Zostera marina is a monocotyledonous angiosperm belonging to a polyphyletic group of plants that can live submerged in marine habitats. Zostera marina L. is one of the most common seagrasses and is considered a cornerstone of marine plant molecular ecology research and comparative studies. However, the mechanisms underlying its adaptation to the marine environment still remain poorly understood due to limited transcriptomic and genomic data.

Principal Findings

Here we explored the transcriptome of Z. marina leaves under different environmental conditions using Illumina paired-end sequencing. Approximately 55 million sequencing reads were obtained, representing 58,457 transcripts that correspond to 24,216 unigenes. A total of 14,389 (59.41%) unigenes were annotated by blast searches against the NCBI non-redundant protein database. 45.18% and 46.91% of the unigenes had significant similarity with proteins in the Swiss-Prot database and Pfam database, respectively. Among these, 13,897 unigenes were assigned to 57 Gene Ontology (GO) terms and 4,745 unigenes were identified and mapped to 233 pathways via functional annotation against the Kyoto Encyclopedia of Genes and Genomes pathway database (KEGG). We compared the orthologous gene family of the Z. marina transcriptome to Oryza sativa and Pyropia yezoensis and 11,667 orthologous gene families are specific to Z. marina. Furthermore, we identified the photoreceptors sensing red/far-red light and blue light. Also, we identified a large number of genes that are involved in ion transporters and channels including Na⁺ efflux, K⁺ uptake, Cl⁻ channels, and H⁺ pumping.

Conclusions

Our study contains an extensive sequencing and gene-annotation analysis of Z. marina. This information represents a genetic resource for the discovery of genes related to light sensing and salt tolerance in this species. Our transcriptome can be further utilized in future studies on molecular adaptation to abiotic stress in Z. marina.