Salinity Tolerance Of Crops Research Articles

Overexpression of sheepgrass R1-MYB transcription factor LcMYB1 confers salt tolerance in transgenic Arabidopsis

Sheepgrass [Leymus chinensis (Trin.) Tzvel.] is a dominant, rhizomatous grass that has extensive plasticity in adapting to various harsh environments. Based on data from 454 high-throughput sequencing (GS FLX) exposure to salt stress, an unknown functional MYB-related gene LcMYB1 was identified from sheepgrass. Tissue specific expression profiles showed that the LcMYB1 gene was expressed ubiquitously in different tissues, with higher expression levels observed in the rhizome and panicle. The expression of LcMYB1 was induced obviously by high salt, drought and abscisic acid and was induced slightly by cold. A fusion protein of LcMYB1 with green fluorescent protein (GFP) was localized to the nucleus, and yeast one-hybrid analysis indicated that LcMYB1 was an activator of transcriptional activity. LcMYB1-overexpressing plants were more tolerant to salt stress than WT plants. The amounts of proline and soluble sugars were higher in transgenic Arabidopsis than in WT plants under salt stress conditions. The overexpression of LcMYB1 enhanced the expression levels of P5CS1 and inhibited other salt stress response gene markers. These findings demonstrate that LcMYB1 influences the intricate salt stress response signaling networks by promoting different pathways than the classical DREB1A- and MYB2-mediated signaling pathway. Additionally, LcMYB1 is a promising gene resource for improving salinity tolerance in crops.

Elucidation of salt stress defense and tolerance mechanisms of crop plants using proteomics-Current achievements and perspectives

Salinity is a major threat limiting the productivity of crop plants. A clear demand for improving the salinity tolerance of the major crop plants is imposed by the rapidly growing world population. This review summarizes the achievements of proteomic studies to elucidate the response mechanisms of selected model and crop plants to cope with salinity stress. We also aim at identifying research areas, which deserve increased attention in future proteome studies, as a prerequisite to identify novel targets for breeding strategies. Such areas include the impact of plant-microbial communities on the salinity tolerance of crops under field conditions, the importance of hormone signaling in abiotic stress tolerance, and the significance of control mechanisms underlying the observed changes in the proteome patterns. We briefly highlight the impact of novel tools for future proteome studies and argue for the use of integrated approaches. The evaluation of genetic resources by means of novel automated phenotyping facilities will have a large impact on the application of proteomics especially in combination with metabolomics or transcriptomics.

Bacterial Mannitol-1-Phophate Dehydrogenase (mtlD) Transgene, Confers Salt Tolerance in the Fourth Generation Transgenic Maize (Zea Mays. L) Plants

About 15% of global agricultural lands are exposed to high salinity, resulting in low crop yields and reduced food supplies. Attempts to develop salinity tolerant crops via selection and breeding have not been sufficient. Bacterial mannitol-1-phophate Dehydrogenase (mtlD) has been known for its tolerance to salinity. Maize is the third cereal crop (after wheat and rice) that is severely affected by soil salinity. We have genetically engineered maize plants with the bacterial mtlD gene, confirmed the integration and expression of this transgene in upto forth progenies, and have confirmed that transgenic plants transcribing the mtlD gene have higher rate of photosynthesis and are more tolerant to different concentrations of NaCl (especially at 200 mM level) as compared with their wild-type nontransgenic control plants.

Bacterial Mannitol-1-Phophate Dehydrogenase (mtlD) Transgene, Confers Salt Tolerance in the Fourth Generation Transgenic Maize (Zea Mays. L) Plants

About 15% of global agricultural lands are exposed to high salinity, resulting in low crop yields and reduced food supplies. Attempts to develop salinity tolerant crops via selection and breeding have not been sufficient. Bacterial mannitol-1-phophate Dehydrogenase (mtlD) has been known for its tolerance to salinity. Maize is the third cereal crop (after wheat and rice) that is severely affected by soil salinity. We have genetically engineered maize plants with the bacterial mtlD gene, confirmed the integration and expression of this transgene in upto forth progenies, and have confirmed that transgenic plants transcribing the mtlD gene have higher rate of photosynthesis and are more tolerant to different concentrations of NaCl (especially at 200 mM level) as compared with their wild-type nontransgenic control plants.

Effect of Combined Use of Brackish Water and Nitrogen Fertilizer on Biomass and Sugar Yield of Sweet Sorghum

Soil salinization and non-point source pollution are among the most important and widespread environmental problems in European Mediterranean regions. Sweet sorghum (Sorghum bicolor (L.) Moench var. saccharatum) is a moderate to high salinity tolerant crop with low water and nutrient needs, seen as an alternative to grow in the water scarce regions. A three-year multifactorial study was conducted in southern Portugal to evaluate the combined effects of saline water and nitrogen application on the dry biomass (total, stems, and leaves), sugar content (total reducing sugars and sucrose contents), and sugar yield (here defined as the product of total reducing sugars and stems dry biomass) functions of sweet sorghum. Sorghum dry biomass and sugar yield showed diminishing returns for each incremental change of nitrogen. The use of saline irrigation waters also led to yield reduction. Exception was sucrose content which increased with increasing levels of sodium in the soil. Nitrogen need decreased as the amount of sodium applied increased. Stem dry biomass, sucrose content, and sugar yield progressively increased with progress in the experiment. The effect could be attributed to the increase of the amount of irrigation applied throughout the years, thus increasing the leaching fraction which promoted salt leaching from the root zone, reduced the salinity stress, increased plant transpiration, nitrogen uptake and biomass yield.

SOS1 gene overexpression increased salt tolerance in transgenic tobacco by maintaining a higher K +/Na + ratio

Crop productivity is greatly affected by soil salinity, so improvement in salinity tolerance of crops is a major objective of many studies. We overexpressed the Arabidopsis thaliana SOS1 gene, which encodes a plasma membrane Na +/H + antiporter, in tobacco ( Nicotiana tabacum cv. Xanthi-nc). Compared with nontransgenic plants, seeds from transgenic tobacco had better germination under 120 mM (mmol L −1) NaCl stress; chlorophyll loss in the transgenic seedlings treated with 360 mM NaCl was less; transgenic tobacco showed superior growth after irrigation with NaCl solutions; and transgenic seedlings with 150 mM NaCl stress accumulated less Na + and more K +. In addition, roots of SOS1-overexpressing seedlings lost less K + instantaneously in response to 50 mM NaCl than control plants. These results showed that the A. thaliana SOS1 gene potentially can improve the salt tolerance of other plant species.

English

Screening and increasing of salinity tolerance of crops is an important aim of many plant breeders. Screening a large number of plants for salinity tolerance is not easy, therefore this investigation was performed to evaluate and screen 186 F 8 recombinant inbred lines (RILs) derived from a cross between Superhead#2 (Super Seri) and Roshan wheat varieties for salinity tolerance. All the individuals were evaluated under two treatments including control (10 mM NaCl) and salt stress (150 mM NaCl). Different traits relating to salt tolerance, including dry matter of shoot and root, sodium and potassium concentration, chlorophyll content and relative water content (RWC) were measured. Significant differences were observed among wheat RILs for all the measured traits. Seedling growth was reduced by salinity in all RILs and we observed a significant negative correlation between shoot dry matter and sodium concentration (r = -0.52**), whereas significant positive correlations between shoot dry matter and K + /Na + ratio (r = 0.36**), chlorophyll content (r = 0.20**) and RWC (r = 0.39**) were detected. Based on our results, sodium concentration of leaf, K + /Na + ratio, chlorophyll content and RWC are good indexes for screening bread wheat genotypes for salinity tolerance. Key words: Screening, salinity tolerance, recombinant inbred lines, wheat.

Transgenic potato overproducing l-ascorbic acid resisted an increase in methylglyoxal under salinity stress via maintaining higher reduced glutathione level and glyoxalase enzyme activity

Salt-tolerance was studied in transgenic potato. It was conferred by overexpression of ascorbate pathway enzyme (D-galacturonic acid reductase, GalUR). As genetic engineering of the GalUR gene in potato enhances its ascorbic acid content (L-AsA), and subsequently plants suffered minimal oxidative stress-induced damage, we now report on the comprehensive aptness of this engineering approach for enhanced salt tolerance in transgenic potato (Solanum tuberosum L. cv. Taedong Valley). Potatoes overexpressing GalUR grew and tuberized in continuous presence of 200 mM of NaCl. The transgenic plants maintained a higher reduced to oxidized glutathione (GSH:GSSG) ratio together with enhanced activity of glutathione dependent antioxidative and glyoxalase enzymes under salinity stress. The transgenics resisted an increase in methylglyoxal that increased radically in untransformed control plants under salinity stress. This is the first report of genetic engineering of ascorbate pathway gene in maintaining higher level of GSH homeostasis along with higher glyoxalase activity inhibiting the accumulation in methylglyoxal (a potent cytotoxic compound) under salt stress. These results suggested the engineering of ascorbate pathway enzymes as a major step towards developing salinity tolerant crop plants.

Genetically Modified Crops: A Pre-Introductory Assessment of Farmer Readiness, Its Determinants and Extent of Support in India

India has become the focal point of biggest debates on GM Crops and their Risk benefit analysis. The present study reveals extent of farmer readiness and support for Genetically Modified crops and biotechnology applications in Indian agriculture. A set of new indices developed could reveal farmers' readiness towards GM Crops, willingness to pay for GM seeds, to trial in time, to invest additionally and to substitute available area. 5 factors namely Biotechnology awareness, innovativeness, extension participation and cosmopoliteness were found to determine farmer readiness towards GM crops. A model was developed for predicting GM readiness which explained up to 78.4 per cent variation. A set of 14 biotechnology applications were rated for their farmer acceptability . Farmer support for ongoing GM research was found highest for crops requiring lesser chemical fertilizers followed by crops requiring less water for growth, crops having longer shelf life periods, drought tolerant crops and saline tolerant crops. The findings will serve researchers, industry and Government in developing biotech communication strategies, pricing, production and timing of market entry as well as development of GM crops based on farmer needs in future.

Scaling up: the essence of effective agricultural research

Successful scaling up from laboratory research to application in the field depends on practitioners being aware of the constraints and other interactions that arise as scaling up proceeds. Although exploration of promising ideas are often of intrinsic scientific interest, such ideas fail the test of utility if they do not get adopted by agronomists or plant breeders, and if practices and cultivars based on such ideas do not get adopted by farmers. This notion of scaling up is explored here using salinity tolerance of crops as a case study, with examples drawn from gene expression, tissue culture, controlled environment studies of plants grown in hydroponics and in pots, and the behaviour of plants at the field scale. The most effective research in this arena has resulted from a culture of collegiate dialogue between scientists working at different scales.

Wheat cultivars can be screened for NaCl salinity tolerance by measuring leaf chlorophyll content and shoot sap potassium

An efficient screening procedure is essential for breeding for salinity-tolerant crops, but there is no consensus regarding the best approach. While some authors argue that the selection of tolerant genotypes should be undertaken under field conditions, others believe that field-based trials for salinity tolerance is problematic due to confounding environmental factors. Also, the choice of specific physiological trait(s) used is often subjective, frequently depending on the ‘personal philosophy’ of the researcher. In this work, we undertook an unbiased assessment of a multitude of physiological and agronomical parameters in an attempt to find a combination that would satisfy two main criteria: (1) be relatively easy and quick to measure; and (2) possess a high predictive power. Fourteen physiological and agronomical traits were measured and analysed using various statistical methods (multiple regression, cluster analysis, principal component analysis). Our results indicate that measuring just two parameters; changes in the chlorophyll content in the 5th leaf after 6 weeks of NaCl treatment, and shoot sap K+ content in control plants, measured at the same time, satisfied these requirements and could be used as efficient screening tools in wheat breeding programs. Interestingly, salt tolerance was associated with lower but not higher K+ content in control plants. The physiological mechanisms involved are discussed.

Histidine kinase and response regulator genes as they relate to salinity tolerance in rice

We have previously shown that Oryza sativa L. Pokkali maintains higher levels of transcripts under non-saline conditions, which are otherwise induced under salinity in the sensitive genotype-IR64. We wanted to test this hypothesis of differential gene regulation further, within the members of a given stress responsive gene family, which share significant structural and functional similarities. For this purpose, we chose to work on the two-component system (TCS family) which plays an important role in stress perception and signal transduction under hormonal, abiotic stress, light and developmental regulation. We present data to show that all members of TCS family, including sensory histidine kinases, phosphotransfer proteins and response regulators, are having differential transcript abundance (under both non-stress and salinity stress conditions) in contrasting rice genotypes. Further, under non-stress conditions, transcript abundance for all TCS members (except RR21) was found to be higher in the salt-tolerant genotype-Pokkali. TCS transcripts are otherwise induced by salinity stress to a relatively higher level in the sensitive cultivar IR64. A few of these members were also found to be localised within important salinity-related quantitative trait loci identified earlier. Based on the above findings, we propose that the TCS members may have a significant role in salinity tolerance in rice and can serve as useful 'candidate genes' for raising salinity-tolerant crop plants.

Irrigation planning using geographic information system

PurposeThe purpose of this paper is to present a procedure to estimate the total irrigation water requirement for a command area of 2,500 hectares in an arid environment under various crops and soil types using GIS for data storage, analysis and visualization of results.Design/methodology/approachBani Al‐Harith agricultural area in Sana'a basin, Yemen was chosen for the study. ArcView GIS was used to plan for suitable crops and estimate the irrigation water requirements based on the farmer's preference and soil types. Using the available soil maps, the soil characteristics such as salinity, texture and suitable crop types were overlaid to produce the crop blocks map. The water balance equation was used to produce the crop water requirement map considering the crop coefficient for different crop stages. The total water demand for each irrigation block was calculated by summing the three components, namely percolation loss through the soil, maximum evapotranspiration of the crop and leaching requirement (LR) to maintain an acceptable salinity level.FindingsThe case study is an example of using GIS as an effective tool in irrigation planning. GIS facilities to acquire, store, analyze and display spatial data were used to produce the soil class map, soil profile map, crop map and water requirement map. The profile ECe values for the chosen crops is within the crop salinity tolerance for 100 percent yield except for blocks 4 and 5 where grape and coffee respectively are suggested to be grown. The profile ECe values are 18.37 dS/m in block 4 and 3.27 to 7.88 dS/m in block 5. The tolerance threshold of 100 percent yield for grape is 1.5 dS/m and for coffee is 3 to 6 dS/m. The salinity of the irrigation water was 2.08 dS/m. From the crop blocks map, the salinity tolerance level for 100 percent yield of onion for block 1 is 1.2 dS/m, tomato for block 2 is 2.5 dS/m, alfalfa for block 3 is 2 dS/m, grape for block 4 is 1.5/ dS/m, and the salinity tolerance level for 100 percent yield of coffee for block 5 is 5 dS/m. Leaching requirements were obtained by taking ECw value of 2.08 and ECe of 1.2, 2.5, 2, 1.5 and 5 for onion, tomato, alfalfa, grape and coffee respectively. The peak total water requirement occurred in May and was found to be 5,595 m3/ha, or 560 mm. The design irrigation water requirement for every block is shown in a map for easy visualization and manipulation to produce the best combination of soils, crops and water use.Research limitations/implicationsThis method of determining the total irrigation water requirement is dependent on the selected irrigation system and crops whether shallow‐rooted, deep‐rooted or tree crops. The use of water in agriculture should be judicious, precise and sustainable. Application of GIS can be a useful tool in irrigation management since it provides rapid access to underlying information of crop suitability. The designer can try out various combinations of crops, to suit the soils and available water.Practical implicationsThis methodology is useful for training irrigation engineers and water resource planners on the use of GIS technique to plan irrigation projects in arid areas.Originality/valueThis technique has never been applied to the study area.

Improving resistance to drought and salinity in plants

As has been reported previously (Parry et al., 2004), a European Commission sponsored conference on the “Optimisation of Water Use by Plants in the Mediterranean, OPTIMISE” (INCOMED ICA3-CT-2002-50005) was held in Palma de Mallorca, Balearic Islands, Spain in March 2003. Water is a scarce commodity in Mediterranean countries. Agriculture accounts for 75% of the total water consumption, but drought is the major limitation for growing many crops. The predicted change in climate, greater use through tourism, industrialisation and salinisation of water supplies, will further exacerbate the situation (Araus, 2004; Clary et al., 2004). There is therefore an important requirement to improve the drought and salinity tolerance of agricultural crops. Considerable advances have been made in the selection of crop varieties that are able to tolerate drought and salinity. These have been through traditional breeding (Araus et al., 2003; Munns et al., 2003; Slafer, 2003), mutant selection (Mahar et al., 2003; Ahloowalia et al., 2004) and more recently QTL analysis (Baum et al., 2003; Thomas 2003; Foolad, 2004; Forster et al., 2004; Talame et al., 2004). The identification of wild relatives (e.g. Porteresia coarctata for rice), that are able to grow in saline soils, may also provide a useful supply of new germplasm for future breeding (Latha et al., 2004). Molecular approaches have identified a large number of genes that are induced following the application of drought or saline conditions. These genes and the proteins that they encode can be divided into three categories: (1) signalling and transcriptional control; (2) the protection of membranes and proteins and (3) water and ion transport (Shinozaki et al., 2003; Wang et al., 2003). As a result of these studies there have been a number of attempts to genetically manipulate plants to become more tolerant to drought and salinity stresses. Potential candidate genes have included those encoding: (1) transcription factors; (2) compatible solutes (e.g. proline); (3) antioxidants and detoxifying enzymes; (4) ion transport and (5) heat shock and late embryogeneis abundant proteins. A number of articles have discussed at length the results obtained from the laboratory testing of transgenic plants containing such potentially useful genes (Yoshida 2002; Chaves et al. 2003; Figueras et al., 2004; Wang et al., 2004). As yet we are awaiting evidence from major field trials to establish if such genetic manipulation will eventually lead to useful drought and salinity tolerant crop plants that are safe and acceptable to the public.

Spatial variability of salt-affected soils in the middle Ebro Valley (Spain) and implications in plant breeding for increased productivity

The assessment of the level and spatial variability of soil salinity and the knowledge of the salinity-yield response functions of crops are required to ascertain the best management strategies aimed at optimizing crop's productivity in saline environments. This work analyzed the spatial distribution of ECe in six irrigated, salt-affected fields of the middle Ebro River Valley (Spain) using electromagnetic survey and geostatistical techniques, and the implications of this salinity variability in plant breeding strategies for increased productivity. The average field ECe varied between 4.9 and15.4 dS m-1, with within-field coefficients of variation between 37 and 79%. The yield simulation analysis of 20 barley and durum wheat cultivars showed that almost 60% of the total yield came from the less saline areas (ECe < 6 dS m-1). The model-estimate Ym (maximum yield under non-saline conditions)and the simulated yields were significantly correlated (p <0.01) in ten out of the twelve analysis performed. Thus, the best strategy for increasing the productivity in moderately salt-affected soils (average field ECe between 5 and 7 dS m-1) of the middle Ebro Valley is to breed and grow high potential yielding barley and durum wheat cultivars. On the other hand, breeding for increased productivity in highly salinized soils (average field Ece around 15 dS m-1) should be based, at least at the parental line's selection stage, on the combination index B(ECe50 Ym 10-3) which takes into account both the potential yield and the salinity tolerance of crops.

Diurnal Changes in Mineral Composition of Xylem Sap and Bleeding Rate at Harvest Stage in Pepper and Melon Cultivated by Drip Irrigation under Desert Condition in Baja California, Mexico.

メキシコ合衆国バハ・カリフォルニア州のゲレロ・ネグロで, 日本政府とメキシコ政府の共同事業として, メキシコ沙漠地域農業開発プロジェクト(以下, プロジェクト)が実施された.プロジェクトの目的は, 沙漠地域で野菜と果樹を点滴灌漑栽培するための技術を開発し, 移転することであった.プロジェクトの圃場の土壌と, そこで用いられる灌漑水は, いずれもpHと塩類濃度が高いという問題を持っているため, 作物の耐塩性に関する問題は重要な課題である.そこで本研究では, 耐塩性の問題を研究していくための基礎的なデータを得るために, 根から吸収されて茎葉部へ転流される様々なイオンについて検討した.すなわち, プロジェクトで重要な作物であるトウガラシとメロンについて, 成熟期の出液中に含まれているイオンの分析を行なうとともに, 出液速度を測定した.露地栽培したトウガラシでは出液中のイオン濃度に昼夜で差があったが, 出液速度も昼頃にピークを持つ山型の日変化パターンを示した.一方, 畝立マルチ栽培のメロンでは, イオン濃度も出液速度も昼夜に関係なくほぼ同じレベルであった.そこで, 出液速度を考慮して検討したところ, 耐塩性に関係しているナトリウムイオンの濃度は出液速度が大きいと低く, 出液速度が小さいと高いことが明らかとなった.なお, 土壌のイオン濃度も場所によって異なっていたため, バックグラウンドとして土壌成分を基準にした比較も行なった.以上のように, 出液成分に着目したアプローチによって, 作物の耐塩性を研究するために基礎的データが得られるが, 出液速度や土壌条件を考慮して解析する必要があることが明らかとなった.

Soil Pore Structural Stability and Irrigation Water Quality: III. Evaluation of Soil Stability and Crop Yield in Relation to Salinity and Sodicity

AbstractA method is proposed for quantitative evaluation of the relationship between irrigation water quality and soil structural stability under a specified set of climatic conditions. Quantitative criteria for pore structural stability are provided by a family of threshold concentration curves determined empirically for each soil. After estimating the variation in composition and concentration of soil water as a function of rainfall, evapotranspiration, and soil drainage, intersection of the sodium stability curve with the irrigation water‐soil solution rectangle provides the necessary quantitative index. A similar approach for evaluating crop response to salinity is presented. The method provides quantitative evaluation of irrigation water quality in relation to soil structural stability and crop salinity tolerance.

Effect of Salinity on the South Indian Field Crops Yield in Ragi (Eleusine coracana Gaertn)

Salinity is one of the problems posed by nature. Tamil Nadu with vast coastline and extensive areas of black cotton soil suffers from salinity havoc in considerable area. Reclamation of saline soils with various methods is being done. However, selection of saline tolerant crops is important to bring the saline lands under plough and to grow some crops in the recla- mation phase. Different plant species respond to salinity, differentially. Even saline tolerant varieties in field crops are also met with. Eleusine coracana usually considered to be a saline tolerant crop is being cultivated in areas under saline conditions. Hence a study on the influence of salinity on the varieties of this crop will provide useful information on their response to saline conditions. An investigation has been taken up to study the influence of salinity on three varieties of ragi and the yield performance of these varieties are discussed in this paper.