Identification and verification of key salt-tolerant amino acid sites of banana MaNHX5 / 生物工程学报

In order to improve the salt tolerance of banana NHX genes, we cloned a MaNHX5 gene from Musa acuminata L. AAA group and predicted the key salt-tolerant amino acid sites and mutant protein structure changes of MaNHX5 by using bioinformatics tools. The 276-position serine (S) of MaNHX5 protein was successfully mutated to aspartic acid (D) by site-directed mutagenesis, and the AXT3 salt-sensitive mutant yeast was used for a functional complementation test. The results showed that after the mutated MaNHX5 gene was transferred to AXT3 salt-sensitive mutant yeast, the salt tolerance of the mutant yeast was significantly improved under 200 mmol/L NaCl treatment. It is hypothesized that Ser276 of MaNHX5 protein plays an important role in the transport of Na+ across the tonoplast.

Intrinsically disordered proteins (IDPs) and the impact on cell stress resistance / 生物工程学报

Intrinsically disordered proteins (IDPs) are proteins or protein regions that fail to get folded into definite three-dimensional structures but participate in various biological processes and perform specific functions. Defying the traditional protein "sequence-structure-function" paradigm, they enrich the protein "structure-function" diversity. Ubiquitous in organisms, they show extreme hydrophilicity, charged amino acids, and highly repetitive amino acid sequences, with simple arrangement. As a result, they feature highly variable binding affinities and high coordination, which facilitate their functions. IDPs play an important role in cell stress response, which can improve the tolerance to a variety of stresses, such as freezing, high salt, heat shock, and desiccation. In this study, we briefed the characteristics, classifications, and identification of IDPs, summarized the molecular mechanism in improving cell stress resistance, and described the potential applications.

Effect of Salinity Stress on Antioxidative Enzyme Activity in the Leaves of Tolerant and Susceptible Genotypes of Groundnut

Aims: To better understand the physiological and biochemical mechanisms in the light of antioxidative enzymes activity under salinity stress between tolerant and susceptible genotypes of groundnut. Study Design: Completely Randomized Design. Place and Duration of Study: The laboratory experiment was carried out in the departmental laboratory of Plant Physiology, Bidhan Chandra Krishi Viswavidyalaya (BCKV), Mohanpur, Nadia, and West Bengal during the year 2017-18. Methodology: A controlled study was conducted to screen 26 genotypes of groundnut under 200 mM NaCl salinity stress. Fourteen-day old seedlings were subjected to salinity treatment. For this, the modified Hoagland nutrient solution containing 200 mM NaCl (osmotic potential: -0.8 MPa) was applied in each case and the pH was adjusted to 6.3. The treatments were repeated on every third day. Control set without salinity stress was also maintained similarly in each case for comparison of results. Results: The salt tolerance index or STI of the genotypes ranged from 47.57% to 96.40%. Out of all the genotypes KDG-197 (STI= 96.40%) was found to be the most tolerant under a salinity stress of 200 mM NaCl and it was closely followed by R 2001-2 (STI=87.92%), VG 315 (STI=84.05%), TCGS 1157 (STI=77.59%) and TG 51 (STI=73.67%). While the genotypes Girnar 3 (STI= 47.57%), OG 52-1 (STI=49.09%), TVG 0856 (STI= 49.28%) and J 86 (STI= 50.66%) were the most susceptible genotypes based on their relative performance under stress in respect of total dry weight. It has been noted further that, out of the nine genotypes, enhancement of antioxidative enzyme like super oxide dismutase (SOD), guaiacol peroxidase (GPOX) and catalase (CAT) activity was recorded maximally in tolerant genotype KDG 197 (64.18%, 71.74% and 52.82% increase over control respectively) and R 2001-2 (53.68 %, 93.48% and 53.96 % increase over control respectively) but the activity of these enzyme in the four susceptible genotypes declined considerably under salinity treatment. Conclusion: Tolerant genotypes of groundnut in general registered much higher activities of antioxidative enzymes in their leaves as compared to the susceptible genotype under high salinity stress.

Silicon Mediated Alleviation of Salinity Stress Regulated by Silicon Transporter Genes (Lsi1 and Lsi2) in Indica Rice

Abstract Silicon accumulation is known to improve tolerance of plants under both biotic and abiotic stress. Salinity stress is an inevitable crisis causing wide spread damage to rice leading to food insecurity. The influence of Si (1mM) on two rice cultivars cv. Ghanteswari (high accumulator) and cv.Badami (low accumulator) which differs in Si uptake potential under saline (10ds/m EC) and non- saline conditions were studied in nutrient culture. The Si transporter genes were isolated and characterized to determine their function in salinity tolerance. Under stress, there was an increase in Si accumulation, Na+/K+ ratio, electrolyte leakage, lipid peroxidation and antioxidant activities. On addition of silicon, the K+ uptake increased, membrane damage reduced and osmolytes balance improve under salinity. But, the level of resurgence was varied in both cultivars, due to their differential Si-accumulation. Molecular characterizations of Lsi1 protein revealed its involvement in the movement of ion and water and therefore prevent osmotic stress. The Lsi2 is responsible for removal of Na+, reducing salt toxicity. Silicon accumulation is responsible for maintenance of cell water status, osmotic balance and Na+ ion exclusion during high salinity. The variable relative expression of Lsi2 provides a possible explanation for differential genotypic uptake of silicon.

Advances in studies on ion transporters involved in salt tolerance and breeding crop cultivars with high salt tolerance / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Soil salinity is a global major abiotic stress threatening crop productivity. In salty conditions, plants may suffer from osmotic, ionic, and oxidative stresses, resulting in inhibition of growth and development. To deal with these stresses, plants have developed a series of tolerance mechanisms, including osmotic adjustment through accumulating compatible solutes in the cytoplasm, reactive oxygen species (ROS) scavenging through enhancing the activity of anti-oxidative enzymes, and Na+/K+ homeostasis regulation through controlling Na+ uptake and transportation. In this review, recent advances in studies of the mechanisms of salt tolerance in plants are described in relation to the ionome, transcriptome, proteome, and metabolome, and the main factor accounting for differences in salt tolerance among plant species or genotypes within a species is presented. We also discuss the application and roles of different breeding methodologies in developing salt-tolerant crop cultivars. In particular, we describe the advantages and perspectives of genome or gene editing in improving the salt tolerance of crops.

Advances in studies on ion transporters involved in salt tolerance and breeding crop cultivars with high salt tolerance / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Soil salinity is a global major abiotic stress threatening crop productivity. In salty conditions, plants may suffer from osmotic, ionic, and oxidative stresses, resulting in inhibition of growth and development. To deal with these stresses, plants have developed a series of tolerance mechanisms, including osmotic adjustment through accumulating compatible solutes in the cytoplasm, reactive oxygen species (ROS) scavenging through enhancing the activity of anti-oxidative enzymes, and Na/K homeostasis regulation through controlling Na uptake and transportation. In this review, recent advances in studies of the mechanisms of salt tolerance in plants are described in relation to the ionome, transcriptome, proteome, and metabolome, and the main factor accounting for differences in salt tolerance among plant species or genotypes within a species is presented. We also discuss the application and roles of different breeding methodologies in developing salt-tolerant crop cultivars. In particular, we describe the advantages and perspectives of genome or gene editing in improving the salt tolerance of crops.

Evaluation of Morphological and Biochemical Characteristics of Sorghum [Sorghum bicolor [L.] Moench] Varieties in Response Salinity Stress

Salinity is among the most severe and widespread environmental constrains to global crop production, especially in arid and semi-arid climates and negatively affecting productivity of salt sensitive crop species. Breeding and selection of salt tolerant crop varieties is therefore necessary for sustainable plant productivity. Given that germination and seeding phases are the most critical phase in the plant life cycle, this study aimed to evaluate seed germination potential and associated traits under salt stress conditions as a simple approach to identify salt tolerant sorghum varieties [Gadam, Sc Sila and Serena] which are adaptated to various agroecological regions. Salinity stress was applied by addition of NaCl at three different levels of stress [100, 200 and 300 mM NaCl], while plants irrigated with water were used as control. Evaluation of tolerance was performed on the basis of germination percentage, shoot and seed water absorbance, shoot and root length, leave water content, seedling total chlorophyll content and morphologic abnormality. Our results showed that salinity stress significantly impacts all features associated with germination and early development of seedlings. Our results indicated that salinity stress substantially affects all traits associated with germination and early seedling growth, with the effect of salinity being dependent on the variety used and level of salinity stress applied. Among the tested sorghum varieties, Gadam was established to the most salt tolerant variety, suggesting its potential use for cultivation under salinity stress conditions as well as its suitability for use as germplasm material in future sorghum breeding programmes. For a greater insight into comprehensive mechanisms of salinity tolerance in sorghum, we suggest further research on genomic and molecular analysis.

Salt Preference is Linked to Hypertension and not to Aging / A Preferência ao Sal está Relacionada à Hipertensão e não ao Envelhecimento

Abstract Background: Seasoning is one of the recommended strategies to reduce salt in foods. However, only a few studies have studied salt preference changes using seasoning. Objectives: The aim of this study was to compare preference for salty bread, and if seasoning can change preference in hypertensive and normotensive, young and older outpatients. Methods: Outpatients (n = 118) were classified in four groups: older hypertensive subjects (OH) (n = 32), young hypertensive (YH) (n = 25); older normotensive individuals (ON) (n = 28), and young normotensive (YN) (n = 33). First, volunteers random tasted bread samples with three different salt concentrations. After two weeks, they tasted the same types of breads, with seasoning added in all. Blood pressure (BP), 24-hour urinary sodium and potassium excretion (UNaV, UKV) were measured twice. Analysis: Fisher exact test, McNamer's test and ANCOVA. Statistical significance: p < 0.05. Results: Systolic BP, UNaV, and UKV were greater in HO and HY and they had a higher preference for saltier samples than normotensive groups (HO: 71.9%, HY: 56% vs. NO: 25%, NY; 6%, p<0.01). With oregano, hypertensive individuals preferred smaller concentrations of salt, with reduced choice for saltier samples (HO: 71.9% to 21.9%, and HY: 56% to 16%, p = 0.02), NO preferred the lowest salt concentration sample (53.6% vs. 14.3%, p < 0.01), and NY further increased the preference for the lowest one (63.6% vs. 39.4%, p = 0.03). Conclusions: Older and younger hypertensive individuals prefer and consume more salt than normotensive ones, and the seasoned bread induced all groups to choose food with less salt. Salt preference is linked to hypertension and not to aging in outpatients.

Resumo Fundamento: Adicionar temperos aos alimentos é umas das estratégias recomendadas para diminuir a quantidade de sal nos alimentos. No entanto, poucos estudos investigaram alterações na preferência ao sal através do uso de temperos. Objetivos: O objetivo deste estudo foi comparar a preferência pelo pão salgado, e até que ponto o uso de temperos pode alterar as preferências dos indivíduos hipertensos e normotensos, pacientes ambulatoriais jovens e idosos. Métodos: Os pacientes ambulatoriais (n = 118) foram classificados em quatro grupos: idosos com hipertensão (IH) (n = 32), jovens hipertensos (JH) (n = 25); indivíduos idosos normotensos (IN) (n = 28), e jovens normotensos (JN) (n = 33). Primeiro, os voluntários provaram amostras aleatórias de pão com três diferentes concentrações de sal. Após duas semanas, eles provaram os mesmos tipos de pão, porém acrescidos de temperos. A pressão arterial (PA), e a excreção urinária de sódio e potássio de 24 horas (UNaV, UKV) foram medidas duas vezes. Análise: Teste exato de Fisher, teste de McNemar e teste ANCOVA. Significância estatística: p < 0,05. Resultados: A PA sistólica e a excreção urinária de sódio e potássio foram maiores nos grupos IH e JH, e eles tiveram maior preferência por amostras mais salgadas quando comparados com os grupos de normotensos (IH: 71,9%, JH: 56% vs. IN: 25%, JN; 6%, p < 0,01). Quando o orégano foi adicionado, a preferência dos indivíduos hipertensos foi pelas amostras com menores concentrações de sal, com uma diminuição da escolha por amostras mais salgadas (IH: 71,9% a 21,9%, e JH: 56% a 16%, p = 0,02); o grupo IN preferiu a amostra com a concentração de sal mais baixa (53,6% vs. 14,3%, p < 0,01) e no grupo JN aumentou ainda mais o número de indivíduos com preferência pela amostra com concentrações mais baixas de sal (63,6% vs. 39,4%, p = 0,03). Conclusões: Os idosos e jovens hipertensos preferem e consomem mais sal do que os normotensos, e o pão adicionado de tempero ajudou todos os grupos a escolher alimentos menos salgados. A preferência ao sal está ligada à hipertensão e não à idade nos pacientes ambulatoriais.

Impact of Salinity Stress on Germination of Water Spinach (Ipomoea aquatica)

Aims: Salinity is one of the major abiotic stress that negatively affects plant growth in germination and early seedling stages. Salinity has becoming a serious problem as most of the parts of worldwide lands were affected by high salt concentration. Therefore, the effects of salinity ranging from 0 mM, 25 mM, 50 mM and 75 mM Sodium chloride (NaCl) concentrations on germination and early seedling growth of water spinach and their salt tolerance mechanism. Study Design: Completely Randomized Design (CRD). Place and Duration of Study: This study was conducted at Tissue Culture Laboratory, Department of Biology, Faculty of Science in University Putra Malaysia (UPM) from June to August, 2018. Methodology: In order to study the effects of salinity on water spinach, several parameters have been taken into account for measurement which include water uptake percentage, germination percentage, germination index, mean germination time, relative injury rate, seed vigor, seedling height reduction, hypocotyl and radicle length, seedling biomass, salt tolerance, total phenolic content and total flavonoids contents. Results: The results obtained showed that salinity adversely reduced water uptake efficiency, seed vigor, hypocotyl and radicle length, total phenolic content and total flavonoids content of water spinach. The seedling height reduction of water spinach increased significantly in relative to increasing salinity. However, seeds treated in mild salt concentration at 25 mM of NaCl showed an increment of germination percentage and germination index. Conclusion: Salt tolerance of water spinach increased as the response towards increasing salinity.

Seed priming improves the germination and growth rate of melon seedlings under saline stress / Condicionamento de sementes melhora a germinação e a taxa de crescimento das plântulas de melão sob estresse salino

ABSTRACT: The germination and growth of melon (Cucumis melo L.) plants can be severely affected by excess salts in the soil or irrigation water; however, negative effects of salt stress can be attenuated using appropriate methods of seed priming. Thus, effects of osmopriming as inducer of salt stress tolerance in melon seeds exposed to salinity levels were investigated in this study. Seeds were soaked for 22 h at 25 °C in the dark in distilled water (hydropriming) or 0.5% KNO3 solution (osmopriming), and after drying, were distributed in plastic boxes with blotter paper containing different NaCl solutions prepared with osmotic pressure of 0.0 MPa (control), -0.3 MPa (mild stress), and -0.6 MPa (severe stress). Unprimed dry seeds were taken as control. The plastic boxes were kept into a seed germinator, at 25 °C for 14 days. A completely randomized design in a 3 × 3 factorial schemes with four replicates of 25 seeds was used. Results showed that the seed priming with water and KNO3 may be successfully applied on melon seeds to alleviate the adverse effects of saline stress in initial stages of plant growth. However, under severe salt stress conditions, hydropriming should be used because it results in higher germination and initial growth rate of the seedlings when compared to the osmopriming. Use of unprimed seeds should not be adopted in cultivation areas affected by salinity because they result in low germination rate and reduced initial plant growth.

RESUMO: A germinação e o crescimento de plantas de melão (Cucumis melo L.) podem ser severamente afetadas pelo excesso de sais no solo ou na água de irrigação. No entanto, os efeitos negativos do estresse salino podem ser amenizados com o uso de métodos adequados de condicionamento das sementes. Assim, este estudo objetivou investigar os efeitos do osmocondicionamento como indutor da tolerância ao estresse salino em sementes de melão expostas à níveis de salinidade. As sementes foram imersas por 22 h à 25 °C em água destilada (hidrocondicionamento) ou em solução de 0,5% de KNO3 (osmocondicionamento). Após secagem, as sementes foram distribuídas em caixas plásticas com papel mata-borrão contendo as diferentes soluções de NaCl preparadas com potencial osmótico de 0,0 MPa (controle), -0,3 MPa (estresse suave) e -0,6 MPa (estresse severo). Um tratamento com sementes secas não condicionadas foi utilizado como controle. As caixas plásticas foram mantidas em germinador de sementes, a 25 °C por 14 dias. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 3 × 3, com quatro repetições de 25 sementes. Os resultados mostraram que o condicionamento de sementes com água e KNO3 pode ser aplicado com sucesso em sementes de melão para amenizar os efeitos adversos do estresse salino durante o estágio inicial de crescimento das plantas. No entanto, sob estresse salino severo, o hidrocondicionamento deve ser utilizado por resultar em maior percentagem de germinação e maior taxa de crescimento inicial das plântulas quando comparado ao osmocondicionamento. O uso de sementes de melão sem condicionamento prévio não deve ser adotado em áreas de cultivo afetadas pela salinidade, pois resultam em baixa taxa de germinação e reduzido crescimento inicial das plantas.

Isolation, Identification and Enzymatic Activity of Halotolerant and Halophilic Fungi from the Great Sebkha of Oran in Northwestern of Algeria

The Great Sebkha of Oran is a closed depression located in northwestern of Algeria. Despite the ranking of this sebkha among the wetlands of global importance by Ramsar Convention in 2002, no studies on the fungal community in this area have been carried out. In our study, samples were collected from two different regions. The first region is characterized by halophilic vegetation and cereal crops and the second by a total absence of vegetation. The isolated strains were identified morphologically then by molecular analysis. The biotechnological interest of the strains was evaluated by testing their ability to grow at different concentration of NaCl and to produce extracellular enzymes (i.e., lipase, amylase, protease, and cellulase) on solid medium. The results showed that the soil of sebkha is alkaline, with the exception of the soil of cereal crops that is neutral, and extremely saline. In this work, the species Gymnoascus halophilus, Trichoderma gamsii, the two phytopathogenic fungi, Fusarium brachygibbosum and Penicillium allii, and the teleomorphic form of P. longicatenatum observed for the first time in this species, were isolated for the first time in Algeria. The halotolerance test revealed that the majority of the isolated are halotolerant. Wallemia sp. and two strains of G. halophilus are the only obligate halophilic strains. All strains are capable to secrete at least one of the four tested enzymes. The most interesting species presenting the highest enzymatic index were Aspergillus sp. strain A4, Chaetomium sp. strain H1, P. vinaceum, G. halophilus, Wallemia sp. and Ustilago cynodontis.

Subordinate function and principal component analysis of salt tolerance of seedlings germinated from microtubers of Jiangxi local yam / 中草药

Objective: The physiological regulation mechanism of seedlings germinated from Jiangxi local yam (Ruichang yam, Nancheng yam, Yongfeng yam, and Guangfeng yam) microtubers under salt stress was studied and the salt tolerance of seedlings germinated from microtubers of four kinds of local yams in Jiangxi was compared, which provided some references for salt tolerance mechanism research and salt tolerance breeding of four local yams in Jiangxi. Methods: Some physiological and biochemical index detection of seedlings germinated from Jiangxi local yam microtubers under salt stress were studied by spectrophotometer method. The subordinate function, principal component analysis (PCA), and clustering analysis of their salt tolerance were accomplished by fuzzy mathematics subordinate function formula and SPSS 19.0 software, respectively. Results: The total chlorophyll content and root activity of seedlings germinated from Jiangxi local yam microtubers under 0-300 mmol/L salt stress decreased significantly. The soluble protein content of seedlings germinated from Ruichang yam, Nancheng yam, and Guangfeng yam microtubers under 0-300 mmol/L salt stress increased firstly and then decreased, while the soluble protein content of seedlings germinated from Yongfeng yam microtubers under 0-300 mmol/L salt stress decreased significantly. The total soluble sugar content, proline content, MDA content and membrane permeability of seedlings germinated from Jiangxi local yam microtubers under 0-300 mmol/L salt stress significantly increased. The POD, SOD, and CAT activities of seedlings germinated from Jiangxi local yam microtubers under 0-300 mmol/L salt stress firstly increased and then decreased. Based on the subordinate function and PCA of SPSS 19.0 software, three principal components of 10 physiological and biochemical indexes of seedlings germinated from Jiangxi local yam microtubers under salt stress were induced. The salt tolerance order of seedlings germinated from Jiangxi local yam microtubers was Guangfeng yam > Yongfeng yam > Ruichang yam > Nancheng yam. Through the cluster analysis by SPSS 19.0 software, the salt resistance of four kinds of Jiangxi local yam is divided into two types, the salt tolerance of Guangfeng yam and Yongfeng yam was strong, and of Ruichang yam and Nancheng yam were sensitive to salt stress. Conclusion: The regulation mechanism of salt tolerance of seedlings germinated from four kinds of Jiangxi local yam microtubers is revealed and the objective evaluation of salt tolerance of four kinds of Jiangxi local yam is made in the paper, which will provide a theoretical basis for sowing in the field of four kinds of Jiangxi local yam microtubers.

Induced defence responses of contrasting bread wheat genotypes under differential salt stress imposition.

Plants, being sessile in nature, have developed mechanisms to cope with high salt concentrations in the soil. In this study, the effects of NaCl (50-200 mM) on expression of high-affinity potassium transporters (HKTs), antioxidant enzymes and their isozyme profiles were investigated in two contrasting bread wheat (Triticum aestivum L.) genotypes viz., HD2329 (salt-sensitive) and Kharchia65 (salt-tolerant). Kharchia65 can successfully grow in salt affected soils, while HD2329 cannot tolerate salt stress. Differential expression studies of two HKT genes (TaHKT2;1.1 and TaHKT2;3.1) revealed their up-regulated expression (~1.5-fold) in the salt-sensitive HD2329 and down-regulated (~5-fold) inducible expression in the salt-tolerant genotype (Kharchia65). Specific activity of antioxidant enzymes, viz. superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APX), catalase (CAT) and glutathione reductase (GR) was found to be higher in the salt-tolerant genotype. Isozyme profile of two (POX and GR) antioxidant enzymes showed polymorphism between salt-tolerant and salt-sensitive genotypes. A new gene TaHKT2;3.1 was also identified and its expression profile and role in salt stress tolerance in wheat was also studied. Partial sequences of the TaHKT2;1.1 and TaHKT2;3.1 genes from bread wheat were submitted to the EMBL GenBank database. Our findings indicated that defence responses to salt stress were induced differentially in contrasting bread wheat genotypes which provide evidences for functional correlation between salt stress tolerance and differential biochemical and molecular expression patterns in bread wheat.

Microorganisms associated to tomato seedlings growing in saline culture act as osmoprotectant

Less than 0.5% of total water in the world is available for human consumption and agriculture. The major part of the world's water is saline and salinity in soils interferes in germination of seeds and the posterior development of the plant. In order to increase the osmotolerance of tomato, seedlings were associated with Azospirillum brasilense Cd, Azospirillum brasilense Cd transformed bacteria with a plasmid harboring a trehalose biosynthesis gene-fusion or Chlorella vulgaris. Two plant culture media: Hydroponic and Murashige and Skoog were tested. In the first set of studies seedlings were associated to single free cells meanwhile in a second set single and combined free cells were studied. A positive interaction between transformed Azospirillum and Chlorella vulagris and tomato plants was observed. Seedlings showed a salt concentration tolerance, as sodium chloride, up to 200 mM. According to our results, the association of plants with A. brasilense Cd-BIF and C. vulgaris is a viable approach to increase their salt tolerance and biomass, as consequence the possible use of sea water to irrigate horticultural plants.

Incorporation of Na+/H+ antiporter gene from Aeluropus littoralis confers salt tolerance in soybean (Glycine max L.).

To develop a salt-tolerant soybean (Glycine max L.) cultivar, a minimal linear Na+/H+ antiporter gene cassette (35S CaMV promoter, open-reading-frame of AlNHX1 from Aeluropus littoralis and NOS terminator) was successfully expressed in soybean cultivar TF-29. Southern and Northern blot analysis showed that AlNHX1 was successfully incorporated into the genome and expressed in the transgenic plants. The AlNHX1 transgenic plant lines exhibited improved growth in severe saline condition (150 mM NaCl). The transgenic lines accumulated a lower level of Na+ and a higher level of K+ in the leaves than wild-type plants under saline condition (150 mM NaCl). Observations on the chlorophyll content, photosynthetic rates, malondialdehyde and relative electrical conductivity indicated that transgenic plants exhibited tolerance to salt stress, growing normally at salt concentrations up to 150 mM. These results demonstrated that AlNHX1 was successfully transferred into soybean and the salt-tolerance was improved by the overexpression of AlNHX1.

Effectiveness of halo-tolerant, auxin producing Pseudomonas and Rhizobium strains to improve osmotic stress tolerance in mung bean (Vigna radiata L.)

Halo-tolerant, auxin producing bacteria could be used to induce salt tolerance in plants. A number of Rhizobium and auxin producing rhizobacterial strains were assessed for their ability to tolerate salt stress by conducting osmoadaptation assay. The selected strains were further screened for their ability to induce osmotic stress tolerance in mung bean seedlings under salt-stressed axenic conditions in growth pouch/jar trials. Three most effective strains of Rhizobium and Pseudomonas containing ACC-deaminase were evaluated in combination, for their ability to induce osmotic stress tolerance in mung bean at original, 4, and 6 dS m-1 under axenic conditions. Results showed that sole inoculation of Rhizobium and Pseudomonas strains improved the total dry matter up to 1.4, and 1.9 fold, respectively, while the increase in salt tolerance index was improved up to 1.3 and 2.0 fold by the Rhizobium and Pseudomonas strains, respectively. However, up to 2.2 fold increase in total dry matter and salt tolerance index was observed due to combined inoculation of Rhizobium and Pseudomonas strains. So, combined application of Rhizobium and Pseudomonas strains could be explored as an effective strategy to induce osmotic stress tolerance in mung bean.

Yield and ion content in maize irrigated with saline water in a continuous or alternating system / Produtividade e teores de íons no milho irrigado com águas salinas de forma contínua ou alternada

Irrigation with water containing salt in excess can affect crop development. However, management strategies can be used in order to reduce the impacts of salinity, providing increased efficiency in the use of good quality water. The objective of this research was to study the effects of use of high salinity water for irrigation, in continuous or cyclic manner, on vegetative growth, yield, and accumulation of ions in maize plants. Two experiments were conducted during the months from October to January of the years 2008/2009 and 2009/2010, in the same area, adopting a completely randomized block design with four replications. Irrigation was performed with three types of water with electrical conductivities (ECw) of 0.8 (A1), 2.25 (A2) and 4.5 (A3) dS m-1, combined in seven treatments including the control with low salinity water (A1) throughout the crop cycle (T1). Saline waters (A2 and A3) were applied continuously (T2 and T5) or in a cyclic way, the latter being formed by six irrigations with A1 water followed by six irrigations by eitherA2 or A3 water, starting with A1 at sowing (T3 and T6) or 6 irrigations with A2 or A3 water followed by 6 irrigations with A1 water (T4 and T7) . The use of low and high salinity water resulted in lower accumulation of potentially toxic ions (Na and Cl) and improvement in the Na/K balance in the shoots of maize plants. Application of saline water in a cyclic way also allows the substitution of about 50% of water of low salinity in irrigation, without negative impacts on maize yield.

A irrigação com águas que contenham sais em excesso pode afetar de forma negativa o desenvolvimento das culturas. No entanto, estratégias de manejo devem ser utilizadas de modo a reduzir os impactos da salinidade, proporcionando aumento na eficiência do uso de água de boa qualidade. O objetivo deste trabalho consistiu em estudar os efeitos de uso de água de alta salinidade na irrigação, de forma contínua ou cíclica, sobre o crescimento vegetativo, a produtividade e o acúmulo de íons em plantas de milho. Foram realizados dois experimentos durante os meses de outubro a janeiro, em 2008/2009 e 2009/2010, na mesma área, adotando-se um delineamento experimental em blocos casualizados, com quatro repetições. A irrigação foi realizada com três tipos de água com condutividade elétrica (CEa) de 0,8 (A1), 2,25 (A2) e 4,5 (A3) dS m-1, combinadas em sete tratamentos, incluindo o controle com água de baixa salinidade (A1) durante todo o ciclo (T1). As águas salinas A2 e A3 foram aplicadas de forma contínua (T2 e T5) ou cíclica, sendo esse último manejo formado por seis irrigações com A1, seguidas de seis irrigações com A2 ou A3 (T3 e T6), iniciando com A1 na semeadura ou seis irrigações com A2 ou A3, seguidas por seis irrigações com A1 (T4 e T7). O uso cíclico de águas de baixa e alta salinidade resultou em menor absorção de íons potencialmente tóxicos (Na e Cl) e melhoria no balanço Na/K na parte aérea das plantas de milho. A aplicação de água salina de forma cíclica permitiu também a substituição de cerca de 50% de água de baixa salinidade na irrigação, sem impactos negativos sobre a produtividade do milho.

Salt stress tolerance and stress proteins in pearl millet (Pennisetum glaucum (L.) R. Br.).

Salt stress as a major adverse factor can lower leaf water potential, leading to reduced torgor and some other responses, and ultimately lower crop productivity in arid and semi arid zone. Plant responses to salt stress have much in common. Salt stress reduces the ability of plants to take up water and this quickly causes reductions in growth rate. The initial reduction in shoot growth is probably due to salt effects. If excessive amounts of salt enter into the plant, salt will eventually rise to toxic levels and reduce the photosynthetic leaf area of the plant that cannot sustain growth. In order to understand the processes that give rise to tolerance of salt and to identify the salt stress proteins in the salt stress effect of on plant growth was studied using different salt solutions like Copper sulphate, Cadmium chloride and zinc sulphate with different concentrations like 200μM, 150μM, 100μM.

Isolation of choline monooxygenase (CMO) gene from Salicornia europaea and enhanced salt tolerance of transgenic tobacco with CMO genes.

Glycinebetaine (GB) is an osmoprotectant accumulated by certain plants in response to high salinity, drought, and cold stress. Plants synthesize GB via the pathway choline → betaine aldehyde → glycinebetaine, and the first step is catalyzed by choline monooxygenase (CMO). In the present study, by using RT-PCR and RLM-RACE, a full-length CMO cDNA (1844 bp) was cloned from a halophyte Salicornia europaea, which showed high homology to other known sequences. In order to identify its function, the ORF of CMO cDNA was inserted into binary vector PBI121 to construct the chimeric plant expression vector PBI121-CMO. Using Agrobacterium (LBA4404) mediation, the recombinant plasmid was transferred into tobacco (Nicotiana tabacum). The PCR, Southern blot and RT-PCR analysis indicated the CMO gene was integrated into the tobacco genome, as well as expressed on the level of transcription. The transgenic tobacco plants were able to survive on MS medium containing 300 mmol/L NaCl and more vigorous than those of wild type with the same concentration salt treatment. In salt-stress conditions, transgenic plants had distinctly higher chlorophyll content and betaine accumulation than that of the control, while relative electrical conductivity of transgenic plants was generally lower. The results suggested the CMO gene transformation could effectively contribute to improving tobacco salt-resistance.