Salt Tolerance Mechanisms and Approaches:Future Scope of Halotolerant Genes and Rice Landraces

All rice plant developmental stages are severely affected by soil salinity. Salinity-induced ionic and osmotic stresses affect stomata closure and gaseous exchange, and reduce transpiration and the rate of carbon assimilation, and hence decrease plant yield. Understanding the response of rice plants toward salinity stress at the genetic level and developing salt-tolerant varieties are the vital mandates for its effective management. This review described the present status of salt-tolerance achieved in rice by various mechanisms including the ion homeostasis(Na^+/H^+, OsNHX antiporters), compatible organic solutes(glycine betaine and proline), antioxidative genes(OsECS, OsVTE1, OsAPX and OsMSRA4.1), salt responsive regulatory elements(transcription factors, cis-acting elements and miRNAs) and genes ecoding protein kinases(MAPKs, SAPKs and STRKs). Further, the future perspective of developing salt-tolerant varieties lies in exploring halotolerant gene homologs from rice varieties, especially the landraces. Genetic diversity among rice landraces can serve as a valuable resource for future studies toward variety improvement through breeding and genome editing. Further, identification, multiplication, preservation and utilization of biodiversity among landraces are the urgent buffers to be saved as a heritage for future generations to come.

Halomonas Erhaiensis sp. nov.,a Moderately Halotolerant Bacterium Isolated from Erhai Lake,Qinghai Province,China

The strain CUG00003T was isolated from the sediment of Erhai Lake of Qing Hai Province,China.Results of 16S r RNA gene sequence analyses indicated a close relationship(97%similarity)of the isolate to

Halomonas Xiaochaidanensis sp. nov.,a Halotolerant Bacterium Isolated from Xiaochaidan Lake of Qadam Basin,China

A short-rod-shaped halotolerant bacterium,designated CUG00002T,was isolated from the sediment of Xiaochaidan Lake of Qadam Basin,China,using R2A medium.The cells are Gram-negative,aerobic and forming creamy and circular colonies with diameter of 1-

A summary of Copepoda:synthesis,trends,and ecological impacts

Copepoda are one of the most significant animal groups present in aquatic ecosystems.Ecologists,evolutionary biologists,and biotechnologists continue to test new methods to study the application of Copepoda as model organisms in various fields of pure and applied science,from evolution and ecology to aquaculture as live feed,as biological control of mosquito larvae,as biological indicators of water and sediment quality,in environmental monitoring and as a source of protein in the food industry.This paper reviews the current progress and trends within copepod research from a number of different perspectives.We emphasize the importance of Copepoda and the necessity of strengthening research on various topics related to copepod biology,some of which are of great significance to local sustainable development.

Cultivable Nitrogen Fixing Bacteria from Extremely Alkaline-Saline Soils

Three soils with different Electrolytic Conductivity (EC) from the former Lake Texcoco (soil with low EC 1.2 dS·m-1, medium with EC 83.1 - 107.8 dS·m-1, and high with EC 137.3 - 152.5 dS•m-1) were used to isolate nitrogen-fixing bacterial strains through enrichment cultures in nitrogen-free media. The medium and high EC in the soil affected negatively the nitrogen-fixing activity, which was generally ten times lower compared to the activity in the soil with low EC. Twenty-one bacterial strains were isolated, identified and characterized for their nitrogen fixation capacity. The diazotrophic genetic potential of all isolates was confirmed by amplification and sequencing of partial nifH and nifD genes and diazotrophic activity quantified by the acetylene reduction assay. Azospirillum brasilense, and several species of Paenibacillus (P. fujiensis, P. durus, P. borealis, P. graminis, P. massiliensis and P. wynnii) were identified. Isolates belonging to the Paenibacillus genus were found in the three soils. Paenibacillus fujiensis and P. durus showed a high nitrogenase activity. The phylograms based on nifH and nifD gene sequences were consistent with 16S rRNA gene phylogeny.

Study on halotolerance of phyllosoma larva of Chinese spiny lobster (Panulirus stimpsoni Holthuis)

The halotolerance of phyllosoma larva of Chinese spiny lobster (Panulirus stimpsoni Holthuis) was experimentally studied in a man-made seawater of 13, 15, 19, 23, 27, 31, 35, 39, 43, 47 and 49 salinity. The experimental results showed that phyllosoma larve survived for 4~6 d with a rate of 25.0% to 47.5% if seawater salinity was increased or decreased gradually from 31 to 49 or to 13 respectively. In a range of 23 to 39 salinity, the phyllosoma larva grew, developed and metamorphosed normally, the metamorphosis rate of which in Stages II and III being 85% and 48% , respectively, when cultured in seawater of 31 salinity. It seems that some regular dispersion of larvae appeared in various salinities of seawater; In lower salinity, they mainly dispersed in the lower layer and in higher salinity,almost stayed in the upper and middle layers. Also, the results indicated that the phyllosoma larva of Chinese spiny lobster had a strong halotolerance to various salinities of seawater ranging from 15 to 47,in which 27 to 35 salinities were appropriate for larva growth and development.

Heterogeneity of Heterotrophic Bacteria Dominating in Brackish Lake Shira (Republic of Khakasia, Russia) Subjected to Anthropogenic Impact

In this work data on heterogeneity in halotolerance and the resistance to antibiotics of heterotrophic bacteria dominating in Lake Shira (Republic of Khakasia, Russia) were presented. It was established that halotoler-ance of the bacteria is determined by genetic and epigenetic mechanisms. Influence of anthropogenic factor (entering the ecosystem allochthonous bacteria) on the appearance of multiple antibiotic resistance appear-ance by dominating bacterial species is discussed.

Role of beneficial microbial gene pool in mitigating salt/nutrient stress of plants in saline soils through underground phytostimulating signalling molecules

Soil salinity diminishes soil health and reduces crop yield,which is becoming a major global concern.Salinity stress is one of the primary stresses,leading to several other secondary stresses that restrict plant growth and soil fertility.The major secondary stresses induced in plants under saline-alkaline conditions include osmotic stress,nutrient limitation,and ionic stress,all of which negatively impact overall plant growth.Under stressed conditions,certain beneficial soil microflora are known to have evolved phytostimulating mechanisms,such as the synthesis of osmoprotectants,siderophores,1-aminocyclopropane-1-carboxylic acid(ACC)deaminase activity,phosphate solubilization,and hormone production,which enhance plant growth and development while mitigating nutrient stress.Beneficial soil-borne bacterial species such as Bacillus,Pseudomonas,and Klebsiella and fungal strains such as Trichoderma,Aspergillus,Penicillium,Alternaria,and Fusarium also aid in reducing salinity stress.Phosphate-solubilizing microorganisms also assist in nutrient acquisition via both enzymatic and non-enzymatic processes.In the case of enzymatic processes,they produce different enzymes such as alkaline phosphatases and phytases,whereas non-enzymatic processes produce organic acids such as gluconic,citric,malic,and oxalic acids.The native halotolerant/halophilic soil microbial gene pool with multifunctional traits and stress-induced gene expression can be developed as suitable bio-inoculants to enhance stress tolerance and optimize plant growth in saline soils.