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PubMed2002

[Research progress in salt tolerance genes of SOS in Arabidopsis thaliana].

The soil salination is a significant abiotic stress for agricultural production and ecological environment. The research on salt tolerance represents an important part for basic plant biology. Genetic analysis of salt tolerance genes in Arabidopsis has become a central issue in this research areas. In recent years, efforts from some laboratories in the world have led to some significant progresses in this field. In this paper, we will review the progress in salt tolerance genes SOS (salt overly sensitive): SOS1,SOS2 and SOS3.

English Abstract↗
PubMed1994

The plant vacuolar Na+/H+ antiport.

Salt stress imposes severe limitations on plant growth, however, the extent of growth reduction depends upon the soil salinity level and the plant species. One of the mechanisms employed by salt tolerant plants is the effective vacuolar compartmentalization of sodium. The sequestration of sodium into the vacuole occurs by the operation of a Na+/H+ antiport located at the tonoplast. Evidence for a plant vacuolar Na+/H+ antiport has been demonstrated in tissues, intact vacuoles and isolated tonoplast vesicles. In sugar beet cell suspensions, the activity of the vacuolar Na+/H+ antiport increased with increasing NaCl concentrations in the growth medium. This increased activity was correlated with the increased synthesis of a 170 kDa tonoplast polypeptide. In vivo labelling of tonoplast proteins showed the enhanced synthesis of the 170 kDa polypeptide not only upon exposure of the cells to salt, but also when the cells were grown in the presence of amiloride. Exposure of the cells to amiloride also resulted in increased vacuolar Na+/H+ antiport activity. Polyclonal antibodies raised against the 170 kDa polypeptide almost completely inhibited the antiport activity, suggesting the association of this protein with the plant vacuolar Na+/H+ antiport. Antibodies against the Na+/H+ antiport-associated polypeptide were used to screen a Beta lambda ZAP expression library. A partial clone of 1.65 kb was sequenced and found to encode a polypeptide with a putative transmembrane domain and a large hydrophilic C terminus. This clone showed no homology to any previously cloned gene at either the nucleic acid or the amino acid level.

Amiloride↗
PubMedDate not supplied

Comparative helminth infections of man in two rural communities of the Niger Delta, Nigeria.

The intestinal parasitic helminth infections of man in Bonny and Isiokpo communities were studied between May 1992 and March 1994. Of the 2008 stool samples examined from Bonny community, 503 (25.0%) were infected. 305 (26.7%) of these infections were males while 198 (22.9%) were females. Ascaris lumbricoides (24.1%) occurred most frequently, followed by Hookworms (18.0%), Trichuris trichiura (17.3%,) Strongyloides stercoralis (10.1%) and Enterobius vermicularis (0.1%). Peak infection (41.7%) was recorded for the males in (10-14) years age bracket. The use of bush as a toilet facility had the highest parasitic infection (38.3%), followed by that of shoreline (35.3%), pit (33.3%), Bucket (27.8%) and of water closet (7.5%). Degree of infection relative to source of drinking water showed that well water was associated with highest infection (43.3%) while the pipe borne water was the lowest (18.0%). From Isiokpo community 2,462 stool samples were examined for intestinal parasites 1,633 (66.3%) people were infected consisting of 862 (64.8%) males and 771 (68.2%) females. Higher parasitic infection of females in this community was attributed to the cultural and occupational factors. Frequency of occurrence of individual helminth was as follows: A-lumbricoides (64.5%), T. trichiura (59.4%), Hookworms (58.8%), S. stercoralis (25.1%), Hymenolepsis nana (2.9%) and E. vermicularis (0.3%). Prevalence of infection was significantly higher in Isiokpo than in Bonny because the climatic and edaphic factors were conducive to larval development and infectivity. On the contrary, the saline soil and surface water of Bonny community constituted harsh environmental conditions inimical to larval development and infectivity. Observations on parasitic infections in relation to toilet facilities and source of drinking water were similar to those made in Bonny. The study therefore demonstrated that the provision of pipe borne water and water closet facilities in rural Niger Delta communities could reduce helminth infections of man.

Adolescent↗
PubMed2006

Kocuria aegyptia sp. nov., a novel actinobacterium isolated from a saline, alkaline desert soil in Egypt.

A coccoid, non-motile actinobacterium, designated strain YIM 70003T, was isolated from a saline, alkaline, desert-soil sample from Egypt. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the organism formed a distinct phyletic line within the genus Kocuria and was most closely related to Kocuria polaris DSM 14382T (98.6 % sequence similarity) and Kocuria rosea DSM 20447T (98.2 %). Chemotaxonomic data, including the Lys-Ala3 peptidoglycan type, the presence of phosphatidylglycerol and diphosphatidylglycerol as the predominant phospholipids, the presence of MK-8(H2) and MK-9(H2) as the major menaquinones, the predominance of fatty acids ai-C(15 : 0) and i-C(15 : 0) and the DNA G+C content, also supported the affiliation of the isolate to the genus Kocuria. The low DNA-DNA relatedness with K. polaris DSM 14382T (56.6 %) and K. rosea DSM 20447T (15.5 %) in combination with phenotypic data show that strain YIM 70003T should be classified as a novel species of the genus Kocuria. The name Kocuria aegyptia sp. nov. is proposed, with strain YIM 70003T (=CCTCC AA203006T = CIP 107966T = KCTC 19010T = DSM 17006T) as the type strain.

Actinobacteria↗
PubMed2026

Transmission dynamics and driving mechanisms of antibiotic resistance genes through a chronosequence of saline-sodic rice cultivation.

Rice cultivation reclaims saline-sodic soils and improves fertility, but may also promote antibiotic resistance genes (ARGs) accumulation and horizontal transfer, posing ecological risks. This study investigated long-term co-evolution of soil properties, microbial communities, ARGs, and mobile genetic elements (MGEs) across a 1-78 year cultivation chronosequence in saline-sodic fields. Results indicated that prolonged cultivation effectively alleviated soil salinization and increased fertility. Microbial communities shifted directionally, with functional taxa enriched, while opportunistic pathogen-containing genera peaked during 5-20 years. ARGs abundance and diversity increased markedly after five years and peaked at 10-20 years. Multidrug efflux pump genes persisted throughout the chronosequence, whereas aminoglycoside resistance genes declined after 30 years. MGEs activity increased over time and was significantly correlated with key ARGs. Path analysis identified improved soil properties as the primary direct driver of ARGs accumulation, while cultivation-induced declines in microbial diversity indirectly promoted ARGs dissemination by weakening the community's suppression of MGEs-mediated horizontal transfer. Collectively, long-term rice cultivation not only ameliorated saline-sodic soils but also created a dynamic, stage-specific resistome, with the 5-20 year period representing a critical risk window for ARGs propagation. These findings highlight the need to integrate ARGs monitoring into soil health assessments for sustainable management of reclaimed saline-sodic lands.

Oryza↗
PubMed1984

Salinity-loving fungi in Egyptian soils. I. Numbers, identities, and halophilism.

The total numbers and the frequencies of fungi in one normal and three saline soils were determined, using a nutrient medium containing sodium chloride concentrations up to 10% (w/v). The most salinity-tolerant fungi were found to belong to the two genera Aspergillus and Penicillium. Four selected Penicillium isolates showed a typical halophilic behaviour. Their growth was directly proportional to the concentration of sodium chloride in the nutrient medium up to 10% (w/v). Some of the isolates could tolerate up to 30% sodium chloride in the medium (w/v).

Aspergillus↗
PubMed1985

Salinity-loving fungi in Egyptian soils. II. Preliminary notes on antibiotics from halophilic Penicillium spp.

Two halophilic Penicillium spp., isolated from saline soils, were selected for the present study. Their growth was best with 10% NaCl (w/v) in the nutrient media, but no antibiotics were produced unless relatively high proportions of potassium salts were also available. Conditions for the economic antibiotic production without achieving sterilization are specified. An economic biphasic process of fermentation in replacement culture for the production of antibiotics by halophilic Penicillium species is described.

Anti-Bacterial Agents↗
PubMed2026

Metagenomics indicates new taxa in Candidatus Saccharimonadia and proposal of Parviradicicola hetaonensis gen. nov. sp. nov. and Parviputeicola dengkouensis gen. nov. sp. nov. following the rules of the SeqCode.

Candidatus Saccharimonadia is a core lineage within the phylum Patescibacteriota (formerly the bacterial candidate phyla radiation, CPR), yet the class has long lacked a standardized, complete taxonomic framework. This nomenclatural gap severely hinders consistent academic exchange and global research into its diversity, evolutionary history, and ecological roles. Here, we recovered 29 medium- to high-quality Ca. Saccharimonadia metagenome-assembled genomes (MAGs) from groundwater, rhizosphere soil, and saline-alkali soil in the Hetao Irrigation District, Inner Mongolia, China, and performed integrated phylogenomic, genome size evolution, and metabolic analyses alongside reference genomes from the GTDB r220 database. Based on robust polyphasic taxonomic evidence (multi-dimensional phylogenetic analyses, widely accepted genome-wide ANI/AAI thresholds) and SeqCode rules, we formally propose two novel taxa: Parviradicicola hetaonensis gen. nov., sp. nov. (type material: txb011_bin.8.strictTS) and Parviputeicola dengkouensis gen. nov., sp. nov. (type material: sgl022_bin.19.origTS), plus two novel families and one novel order. We further identified potential drivers and important associations related to Ca. Saccharimonadia genome size evolution and adaptive metabolic traits. This work refines the Ca. Saccharimonadia taxonomic framework, providing critical genomic references for follow-up research.

Phylogeny↗
PubMed2000

Influence of salinity on methanogenesis and associated microflora in tropical rice soils.

In a laboratory incubation study, methane (CH4) production in two saline soils and a nonsaline soil sample was investigated under flooded conditions. Mean CH4 production was remarkable (630.86 ng CH4/g) in nonsaline alluvial soil, but low (12.97 ng CH4/g) in acid sulfate saline (Pokkali) soil which was attributed to the high sulfate content of the later. CH4 production was also low in the coastal saline (Canning) soil (142.36 ng CH4/g) but increased upon leaching the soil of its salt content. Addition of salts to the nonsaline alluvial soil at 4, 8, 16 and 20 dS/m progressively decreased CH4 production. The inhibition of CH4 production was related to low microbial activities as reflected by decreased microbial biomass C and low soil microbial population including that of methanogens.

Agriculture↗
PubMed2002

Diversity of azospirillum strains isolated from rice plants grown in saline and nonsaline sites of coastal agricultural ecosystem.

The diversity of indigenous Azospirillum spp. associated with rice cultivated along the coastline of Tamil Nadu was analyzed. Twelve sites with varying soil characteristics such as salinity, texture, and the host variety were chosen. Of the 402 strains isolated using NFB media, 302 were confirmed to be Azospirillum spp. and subjected to DNA polymorphism analysis using PCR-RFLP of 16S rDNA. They were also screened for their salt tolerance and microaerobic N2-fixing-dependent growth. On species identification, all the strains were found to be A. brasilense, A. lipoferum, or unidentified. On comparing the influence of the previously noted variability on the indigenous population, soil salinity was found to play a dominant role. This was revealed by PCR-RFLP studies and salt tolerance studies. A high association between soil salinity and the distribution of Azospirillum genotypes reveals that soil salinity should be taken into consideration while developing biofertilizers specifically for the coastal agricultural ecosystem.

Agriculture↗
PubMed2005

Pencycuron application to soils: degradation and effect on microbiological parameters.

Clay loam soil from agricultural fields of alluvial (AL) soil (typic udifluvent) and coastal saline (CS) soil (typic endoaquept) were investigated for the degradation and effect of pencycuron application at field rate (FR), 2-times FR (2FR) and 10-times FR (10FR) with and without decomposed cow manure (DCM) on soil microbial variables under laboratory conditions. Pencycuron degraded faster in CS soil and in soil amended with DCM. Pencycuron spiking at FR and 2FR resulted in a short-lived (in case of 10FR slightly longer) and transitory toxic effect on soil microbial biomass-C (MBC), ergosterol content and fluorescein diacetate hydrolyzing activity (FDHA). Amendment of DCM did not seem to have any counteractive effect of the toxicity of pencycuron on the microbial variables. The ecophysiological status of the soil microbial communities as expressed by microbial metabolic quotient (qCO2) and microbial respiration quotient (Q(R)) changed, but for a short period, indicating pencycuron induced disturbance. The duration of this disturbance was slightly longer at 10FR. Pencycuron was more toxic to the metabolically activated soil microbial populations, specifically the fungi. It is concluded that side effects of pencycuron at 10FR on the microbial variables studied were only short-lived and probably of little ecological significance.

Agriculture↗
PubMed1976

Evaluation of some biological tests as parameters for microbial activities in soils. I. Laboratory experiments.

The experiments were confined to the effects of the addition of different sources of carbon (glucose, wheat straw, and sawdust) on the microbial activities in soils: loamy sand, loam and saline clay were used. The parameters used for this purpose were total bacterial counts, dehydrogenase test, CO2 evolution, and oxidation of organic carbon. Salinity of soils had deleterious effects on all the parameters used. Addition of organic matter resulted in marked increases in bacterial counts, formazan production, and CO2 evolution. Glucose showed the most rapid effect and highest levels. Wheat straw yielded the highest results and sawdust always showed the least effect.

Bacteria↗
PubMed2006

Butachlor degradation in tropical soils: effect of application rate, biotic-abiotic interactions and soil conditions.

The degradative characteristics of butachlor (N-Butoxymethyl-2-chloro-2',6'-diethyla- cetanilide) were studied under controlled laboratory conditions in clay loam alluvial (AL) soil (Typic udifluvent) and coastal saline (CS) soil (Typic endoaquept) from rice cultivated fields. The application rates included field rate (FR), 2-times FR (2FR) and 10-times FR (10FR). The incubation study was carried out at 30 degrees C with and without decomposed cow manure (DCM) at 60% of maximum water holding capacity (WHC) and waterlogged soil condition. The half-life values depended on the soil types and initial concentrations of butachlor. Butachlor degraded faster in AL soil and in soil amended with DCM under waterlogged condition. Microbial degradation is the major avenue of butachlor degradation from soils.

Acetanilides↗
PubMed2006

Effect of pencycuron on microbial parameters of waterlogged soil.

A laboratory study was conducted to monitor the effect of pencycuron [1-(4-chlorobenzyl)-1-cyclopentyl-3-phenylurea] on microbial parameters of alluvial (AL) soil (Typic udifluvent) and coastal saline (CS) soil (Typic endoaquept) under waterlogged condition. Pencycuron at field rate (FR), 2FR and 10FR affected the microbial biomass C (MBC), soil ergosterol content and fluorescein diacetate hydrolyzing activity (FDHA) differentially. The DCM amendment did not seem to have any counteractive effect on the toxicity of pencycuron on the microbial variables. The change in microbial metabolic quotient (qCO2) and microbial respiration quotient (QR), indicated pencycuron induced disturbance at 10FR. Present study revealed that the metabolically activated microbial population was more suppressed compared to the dormant population.

Agriculture↗
PubMed2006

A kinetic approach to evaluate salinity effects on carbon mineralization in a plant residue-amended soil.

The interaction of salinity stress and plant residue quality on C mineralization kinetics in soil is not well understood. A laboratory experiment was conducted to study the effects of salinity stress on C mineralization kinetics in a soil amended with alfalfa, wheat and corn residues. A factorial combination of two salinity levels (0.97 and 18.2 dS/m) and four levels of plant residues (control, alfalfa, wheat and corn) with three replications was performed. A first order kinetic model was used to describe the C mineralization and to calculate the potentially mineralizable C. The CO(2)-C evolved under non-saline condition, ranged from 814.6 to 4842.4 mg CO(2)-C/kg in control and alfalfa residue-amended soils, respectively. Salinization reduced the rates of CO(2) evolution by 18.7%, 6.2% and 5.2% in alfalfa, wheat and corn residue-amended soils, respectively. Potentially mineralizable C (C(0)) was reduced significantly in salinized alfalfa residue-treated soils whereas, no significant difference was observed for control treatments as well as wheat and corn residue-treated soils. We concluded that the response pattern of C mineralization to salinity stress depended on the plant residue quality and duration of incubation.

Carbon↗
PubMed2001

Engineering salt-tolerant Brassica plants: characterization of yield and seed oil quality in transgenic plants with increased vacuolar sodium accumulation.

Transgenic Brassica napus plants overexpressing AtNHX1, a vacuolar Na(+)/H(+) antiport from Arabidopsis thaliana, were able to grow, flower, and produce seeds in the presence of 200 mM sodium chloride. Although the transgenic plants grown in high salinity accumulated sodium up to 6% of their dry weight, growth of the these plants was only marginally affected by the high salt concentration. Moreover, seed yields and the seed oil quality were not affected by the high salinity of the soil. Our results demonstrate the potential use of these transgenic plants for agricultural use in saline soils. Our findings, showing that the modification of a single trait significantly improved the salinity tolerance of this crop plant, suggest that with a combination of breeding and transgenic plants it could be possible to produce salt-tolerant crops with far fewer target traits than had been anticipated.

Journal Article↗