Salt-tolerant Genotypes Research Articles

Biochemical Markers of Salt Stress in European Larch (Larix decidua)

Larix decidua, the European larch, does not grow in natural saline areas, but it can be affected by salinity either by the common practice of winter de-icing of mountain roads with NaCl, or when grown as an ornamental tree in urban areas by the use of low quality, salinised irrigation water. In the present study, the responses to salt stress of young seedlings obtained from seeds of seven Carpathian larch populations were analysed. After 30 days of treatments with 150 mM NaCl, growth and biochemical parameters were determinated. Salt stress inhibited growth of all seedlings, as shown by the relative reduction of stem length and fresh weight, and induced significant changes in the needle levels of several biochemical stress markers. Seedlings from all populations showed a marked reduction of photosynthetic pigments contents and an increase of proline and malondialdehyde (MDA) concentrations. Under salt stress, plants accumulated Na+ and Cl- in the needles, whereas K+ was maintained at a steady level. Responses of seedlings from the different populations were similar, with only small quantitative differences that did not allow the identification of more salt tolerant genotypes. However, the study revealed that several of the biochemical markers mentioned above can be suitable for the rapid and non-destructive assessment of the effects of salinity in European larch.

Silicon-mediated growth and yield improvement of sunflower (Helianthus annus L.) subjected to brackish water stress

Silicon is known to compensate crop yield losses under diverse biotic and abiotic stress conditions; however, reports about its protective role for plants exposed to brackish water stress are very limited. A pot culture experiment was conducted to assess the beneficial effect of silicon supplementation (0 and 100 mg/kg) in alleviating growth adversities of brackish water (saline, sodic, alkaline, and saline–sodic water) stress in two contrasting sunflower cultivars, SF-187 (salt tolerant), and Hysun-33 (salt sensitive) grown in greenhouse. Results demonstrated that hostile growth environments, mainly the combined stress of saline–sodic water, severely affected the physiological attributes, growth, yield, and yield contributing components in sunflower. However, the response to brackish water stress differed genotypically, with greater magnitude of damage to the Hysun-33 as compared to SF-187 genotype. It hampered plant growth due to membrane damage and reduced water uptake, but silicon supplementation minimized the negative effects of stress by limiting toxic Na+ ions uptake, improving membrane stability, and increasing relative water contents caused by higher silicon and K+ uptake that eventually led to improved biomass yield. The response was further evaluated at yield level and data regarding head diameter, achene yield, and 100 achene weight were taken. Results indicated that silicon supplementation to growth medium of saline and/or sodic water treated plants significantly enhanced the head diameter (22–30%), thus ultimately producing 15–25% higher achene yield, and weight of the biological harvest of both sunflower genotypes. Overall, the beneficial effect of silicon supplementation was more evident in Hysun-33 (salt sensitive) as compared to SF-187 (salt tolerant) genotype. Taken together, the results of this study suggest silicon fertilization as a potential strategy to increase crop productivity under brackish water stress; however, experimental trials at farmer field level should be conducted before setting any recommendations.

Nitrogen assimilation pathways and ionic homeostasis are crucial for photosynthetic apparatus efficiency in salt-tolerant sunflower genotypes

Sunflower (Helianthus annuus L.) is an important oilseed crop that is sensitive to salt stress. We performed an investigation to elucidate the mechanisms of salinity tolerance in two commercial sunflower genotypes of contrasting salt tolerance. The BRS 321 genotype exhibited greater plant growth than the Catissol genotype upon exposure to 100 mM NaCl-stress, indicating that BRS 321 is more tolerant to salt stress than Catissol. The superior performance of BRS 321 plants was attributed to the decreased accumulation of toxic ions (Na+) in roots and improved photosynthetic machinery efficacy. In NaCl-stress conditions, BRS 321 plants displayed greater CO2 assimilation which was associated with an increase in the effective quantum yield of PSII, electron transport rate, and photochemical quenching (qP), as well as improved chlorophyll and carotenoid contents. Significantly, nitrogen metabolism in the salt-tolerant genotype was altered to act as an alternative electron sink, dissipating excess energy and increasing the plant’s capacity to withstand the deleterious salt effects. In conclusion, salt tolerance in BRS 321 compared to the Catissol genotype could be attributed to improved photosynthetic performance and decreased Na+ uptake.

Screening of Rice (<i>Oryza sativa</i> L.) Genotypes at Reproductive Stage for their Tolerance to Salinity

Soil salinity is one of the most devastating environmental stresses for rice production in the coastal areas of Bangladesh. Improvement in salt tolerance of rice is an important way for the economic utilization of coastal zones. An experiment was conducted at the vinyl house of the Department of Agronomy, Bangabandhu Sheikh Mujibur Rahman Agricultural University (BSMRAU), Bangladesh during December 2016 to April 2017 to determine the effects of different salinity levels on the yield and yield components of some rice (Oryza sativa L.) genotype sand finally, screening of rice genotypes for salt tolerance. The experiment containing four treatments was laid out in a complete randomized design with five replications. The treatments were four levels of saline water with electrical conductivities at control (0.3 dSm-1), 5, 10 and 15dSm-1. Based on screening at germination stage, relatively salt-tolerant eleven genotypes with two check varieties were used in this experiment. The study showed that increase in salinity level significantly decreased yield and yield contributing characters of rice. However, among the eleven, three genotypes (Chapali, Patnai 23 and Soloi) were considered as moderately salt tolerant at 15 dSm-1 on the basis of their yields and yield contributing characteristics such as plant height reduction, total tiller reduction, effective tiller reduction, reduction of fertile grains per panicle, grain yield and relative grain yield. Therefore, Chapali, Patnai 23 and Soloi might be recommended as moderately salt tolerant rice genotypes. The Agriculturists 2018; 16(1) 65-77

Evaluation of Guar (Cyamopsis tetragonoloba L.) genotypes performance under different irrigation water salinity levels: Growth parameters and seed yield

Water scarcity and salinity are the major challenges faced by arid regions such as Thar Desert in Pakistan. Developing information on salt tolerance of genotypes and appropriate salinity management practices are necessary to ensure long-term viability of agriculture in these stressed environments. This study evaluated growth and seed yield of 25 different guar genotypes irrigated with waters having varying salinity (control – 0.6, 3, 6 and 9 dS m−1) under field conditions to characterize their salt tolerance. Results indicated salinity levels had significant influence on growth and yield of guar crop. At the highest salinity level of 9 dS m−1, out of 26 genotypes three genotypes (S-6005, S-8885 and 2/1) showed less than 20% reduction in plant height, one genotype (BR 90) had 15% reduction in number of branches and two genotypes (S-6049 and S-5611) produced 70% of the branches compared to control. Seed yields of genotypes ranged from 0.94 to 1.82 Mg ha−1 under control salinity but at 9 dS m−1 it ranged from 0.28 to 0.89 Mg ha−1. BR 99 produced highest seed yield under both control and highest salinity levels. Straw yield ranged from 0.89 to 3.34 Mg ha−1 under control and the range was reduced to 0.57 to 1.4 Mg ha−1 at 9 dS m−1. Sodium concentration increased whereas K concentration and K/Na ratio decreased with increasing salinity levels in both straw and seed samples of all the guar genotypes evaluated in this study. Based on salinity tolerance index (STI) and geometric mean productivity (GMP), out of 25 guar genotypes only four (BR-99, S-5608, 2/1, S-5615 and S-8885) were considered as tolerant. Results of our study indicated that select genotypes of guar can be appropriate for water scarce and salt affected arid regions of the world.

Identification of jumonjiC domain containing gene family among the Oryza species and their expression analysis in FL478, a salt tolerant rice genotype

The jumonji (JMJ)-C domain containing proteins belong to histone demethylases family with the ability to demethylate the tri-methylated histone residues. They act as chromatin regulators to regulate many physiological functions in plants. The present study deals with the characterization of JMJ-C gene family members in wild as well as cultivated rice species and their expression analysis in salt tolerant rice genotype, FL478. The genome wide study identified 151 members belonging to JMJ-C gene family in 11 different Oryza species. We also studied their structure, genomic location, gene duplication events, phylogenetic relationship, in silico expression analysis and identified cis elements in their promoters. We also found a few JMJ-C gene family members in rice which underwent duplication before the whole genome duplication event of the rice. The qRT-PCR based expression profiling revealed that out of the total 15 rice JMJ-C members, two were highly expressed in the flag leaf stage of FL478 under salt treatment. These two candidate JMJ-C members were also found to render salinity tolerance when over-expressed in yeast cells. Thus, the present study helps in further structural as well as functional characterization of JMJ-C genes under salinity stress in Oryza species.

Genotypic differences in agro-physiological, biochemical and isotopic responses to salinity stress in quinoa (Chenopodium quinoa Willd.) plants: Prospects for salinity tolerance and yield stability

Quinoa is an important nutritive crop that can play a strategic role in the development of marginal and degraded lands. Genotypic variations in carbon isotope composition (δ13C), carbon isotope discrimination (Δ13C), ratio of intercellular to atmospheric CO2 concentration (Ci/Ca), intrinsic water use efficiency (iWUE), seed yield and grain protein contents were analyzed in 6 quinoa cultivars grown in the field under saline conditions (0, 10, 20 dS m−1). Significant variations occurred in dry biomass, seed yield, plant height, number of branches, number of panicles, panicle weight, harvest index, N and C content. Some genotypes produced yields with values significantly higher than 2.04 t ha−1 (Q12), with an average increased to 2.58 t ha−1 (AMES22157). The present study indicates a large variation in Δ13C for salinity treatments (3.43‰) and small magnitude of variations among genotypes (0.95‰). Results showed that Δ might be used as an important index for screening, and selection of the salt tolerant quinoa genotypes with high iWUE. Quinoa genotypes differs in foliar 13C and 15N isotope composition, which reflected complex interactions of salinity and plant carbon and nitrogen metabolisms. Grain protein contents were found higher in Q19 and Q31 and lowest in Q26. The study demonstrates that AMES22157 and Q12, were salt tolerant and high yielder while the AMES22157 was more productive. This study provides a reliable measure of morpho-physiological, biochemical and isotopic responses of quinoa cultivars to salinity in hyper arid UAE climate and it may be valuable in the future breeding programs. The development of genotypes having both higher water use efficiency and yield potential would be a very useful contribution for producers in the dry region of Arabian Peninsula.

DETECTION OF TAST SALT TOLERANCE GENE IN THREE SELECTED WHEAT GENOTYPES FOR SALINITY STRESS UNDER SALINITY CONDITIONS

The aim of this study is detection of salt tolerant gene (TaST) selected wheat genotypes for salt tolerance (1H, 2H , 3H) through plant breeding program as compared with local cultivars (sensitive) under salinity condition. Quantitative reverse transcription-PCR (q-RT-PCR) was used to detect TaST salt tolerant gene in these selected genotypes. Also chlorophyll and organic compounds contents were estimated in the upper leaves of the selected genotypes and local cultivars. Results of the PCR showed that the gene band of TaST appeared only in the selected genotypes with length 175bp at both salinity conditions, while this band absent in the local cultivars, (sensitive) (Iraq and latefyi), also at both salinity conditions. All the selected genotypes had the same band size (175bp). Chlorophyll content in the upper leaves of selected genotypes increased at salinity treatment, while it decreased in the leaves of local cultivars at this treatment as compared with non-saline conditions. The results also, showed that the selected genotypes had the highest organic compounds in their leaves, especially under salinity condition. It can be concluding that the selected genotypes (1H, 2H, and 3H) were more salt tolerance than local cultivars (Iraq, latefyi).

Using Growth and Ionic Contents of Wheat Seedlings as Rapid Screening Tool for Salt Tolerance

High germination percentage with vigorous early growth is preferred for harvesting good wheat stand under saline soils. Therefore, an attempt for rapid screening of wheat genotypes for salt tolerance was made in this study. Eleven wheat genotypes including salt tolerant check Kiran-95were subjected to salinity (120 and 160 mMNaCl) along with non-saline control. Results showed a gradual decrease in seed germination and restricted seedling growth in tested wheat genotypes in response to increasing NaCl concentration in nutrient solution. Among the genotypes, NIA-AS-14-6 and NIA-AS-14-7 exhibited more sensitivity towards the salt stress at the germination stage but NIA-AS-14-6 performed quite satisfactorily later on at the seedling stage. Wheat genotypes NIA-AS-14-2, NIA-AS-14-4, NIA-AS-14-5, NIA-AS-14-10, and Kiran-95 showed better performance in term of root-shoot length, plant biomasses (fresh and dry), K+:Na+ ratio with least Na+ content, and high accumulation of K+ at higher levels of NaCl stress. On the basis of overall results, the categorization of genotypes was carried out as sensitive, moderately tolerant, and tolerant. Wheat genotypes NIA-AS-14-2, NIA-AS-14-4, NIA-AS-14-5, NIA-AS-14-10, and Kiran-95 grouped as tolerant, moderately salt tolerant group comprised of NIA-AS-14-1, NIA-AS-14-3, NIA-AS-14-6, and NIA-AS-14-8, whereas, NIA-AS-14-7 and NIA-AS-14-9 were found sensitive to salt stress. Principal component analysis revealed that components I and II contributed 70 and 16.5%, respectively. All growth parameters are associated with each other except RDW. In addition to growth traits, low Na+ and improved K+ content with better K+:Na+ ratio may be used for screening of salt tolerance in wheat as potential physiological criteria.

Global transcriptome analysis of grapevine (Vitis vinifera L.) leaves under salt stress reveals differential response at early and late stages of stress in table grape cv. Thompson Seedless

Among the different abiotic stresses, salt stress has a significant effect on the growth and yield of grapevine (Vitis vinifera L.). In this study, we employed RNA sequence based transcriptome analysis to study salinity stress response in grape variety Thompson Seedless. Salt stress adversely affected the growth related and physiological parameters and the effect on physiological parameters was significant within 10 days of stress imposition. A total of 343 genes were differentially expressed in response to salt stress. Among the differentially expressed genes (DEGs) only 42 genes were common at early and late stages of stress. The gene enrichment analysis revealed that GO terms related to transcription factors were over-represented. Among the DEGs, 52 were transcription factors belonging to WRKY, EREB, MYB, NAC and bHLH families. Salt stress significantly affected several pathways like metabolic pathways, biosynthesis of secondary metabolites, membrane transport development related pathways etc. 343 DEGs were distributed on all the 19 chromosomes, however clustered regions of DEGs were present on chromosomes 2, 5, 6 and 12 suggesting probable QTLs for imparting tolerance to salt and other abiotic stresses. Real-time PCR of selected genes in control and treated samples of grafted and own root vines demonstrated that rootstock influenced expression of salt stress responsive genes. Microsatellite regions were identified in ten selected salt responsive genes and highly polymorphic markers were identified using fifteen grape genotypes. This information will be useful for the identification of key genes involved in salt stress tolerance in grape. The identified DEGs could also be useful for genome wide analysis for the identification of polymorphic markers for their subsequent use in molecular breeding for developing salt tolerant grape genotypes.

In vitro evaluation of phenolic and osmolite compounds, ionic content, and antioxidant activity in safflower (Carthamus tinctorius L.) under salinity stress

Carthamus tinctorius L., rich in antioxidant compounds, is a herbal medicine. Biochemical mechanisms of adaptation to salinity stress in safflower are still poorly understood at the cellular level. For this purpose, callus cultures of four different genotypes of safflower were used in this study to evaluate changes in their biochemical (ionic content, proline, and glycine betaine), total phenolics content (TPC), total flavonoids content (TFD), antioxidant responses (2,2-diphenyl-1-picrylhydrazyl: DPPH assay and carotenoid content), and lipid peroxidation (malon dialdehyde content: MDA) under salinity stress. The calluses derived from hypocotyls were exposed to in vitro salt stress at different concentrations of sodium chloride (0, 100, 200, and 300 mM). A reducing trend was observed in K+ and carotenoid reserves of the calluses with increasing NaCl concentration while an increasing trend was observed in Na+ content, proline, MDA, TPC, TFD, and DPPH activity under the same conditions. Callus glycine betaine content was found to decrease in the medium containing 100 mM NaCl but increased beyond this concentration up to 300 mM NaCl. Positive and significant correlations were recognized between DPPH and total phenolics as well as DPPH and total flavonoid contents, demonstrating that phenolics are the main contributors to the potential antioxidant activity of safflower at the cellular level. Overall, the salt-tolerant genotypes of Mex.2-137 and Mex.2-138 were found capable of being processed for the production of secondary metabolites via NaCl elicitation.

Evaluation of salt tolerance and contributing ionic mechanism in nine Hami melon landraces in Xinjiang, China

Melon (Cucumis melo L.) is an important horticultural crop in the world. The objective of this work was to evaluate salinity stress tolerance and understand the ionic mechanism conferring this trait in nine Hami melon landracesfrom Xinjiang, China. Plants were grown in a potting mix (peat: vermiculite: perlite = 1:1:1, v/v) under glasshouse conditions and irrigated with Hoagland’s nutrient solution containing either 0 (control) or 100 mM NaCl. Plant dry weight, single fruit weight, Na+ and K+ content of all leaves, stem and roots of the whole plant were measured at day 70 after commencing the treatment. Also, Na+ and K+ content of the second fully expanded leaf from the top were measured at day 20, 40 and 60 after stress onset. Net fluxes of K+ and Na+ were measured from plant roots in laboratory experiments using a noninvasive MIFE (microelectrode ion flux estimation) technique, and expression levels of the leaf tonoplast Na+/H+ antiporters (NHX) were investigated. Salt injury index and leaf chlorophyll content were also measured. The results showed that, according to the relative (NaCl/Control) plant dry weight and a single fruit weight, the salt tolerance of the nine landraces can be classified into three types: ‘Huangdanzi’, ‘Zajiaojiashigua’, ‘Kalakesai’ and ‘Paotaihong’ are salt tolerant; ‘Laotiepi’, ‘Kaeryunxi’ and ‘Sairekekekouqi’ are intermediate in salt tolerance; and ‘Akekekouqi’ and ‘Paodangua’ are salt sensitive. This conclusion was also supported by the results of measuring of the salt injury index and leaf chlorophyll content. The salt tolerance of landraces was positively correlated with the relative K+ content of all leaves, but correlated negatively with the relative Na+ content of the second fully expanded leaf, and relative K+ content of the root. Compared with salt sensitive landraces, salt tolerant genotypes had significantly lower relative Na+ content of the second fully expanded leaf, lower relative root K+ content (except Paotaihong), and higher relative K+ content of all leaves. They also displayed lower root net K+ efflux and higher Na+ efflux (except Zajiaojiashigua) capacity. The intermediate landrace ‘Laotiepi’ had very high Na+ content and high level of NHX2/3/6 expression in leaves but still possessed high chlorophyll content, suggesting that this landrace had an efficient vacuolar Na+ sequestration mechanism in the leaf mesophyll. Taken together, our results showed that Hami melon landraces in Xinjiang showing significant difference in salt tolerance, and that K+ retention in the shoot and Na+ exclusion from young leaves are the main mechanisms conferring salinity stress tolerance of Hami melon landraces in Xinjiang.

Evaluation of the genetic variability and genetic advance for salt tolerance in rice genotypes

Soil salinity is considered as one of the greatest threats for rice production. Genetic variability analysis of morphological traits related to salt injury is mandatory, which could be helpful in the development of an appropriate breeding program for the selection of salt tolerant rice genotypes from the existing germplasm towards developing new salt tolerant rice varieties. Therefore, the present study has been aimed to evaluate the genetic variability parameters for fourteen morphological traits in thirty local and high yielding rice genotypes using hydroponic culture. Among the rice genotypes under study, Boilam, Nonabokri, Gunshi, Motabamonkhir showed the best performance regarding the morphological traits under different saline conditions (6 dSm -1 and 10 dS m-1). The PCV values were greater than the GCV values for all studied traits indicating the greater environmental influence on the traits. The highest percentage of GCV and PCV were observed in root dry weight, while the lowest were exhibited in main axis diameter. To assist the breeding program, along with variability, estimation of heritability and genetic advance has also been done. High heritability ranging from 80.24% to 94.66% was found among the traits. The genetic advance was highest for survival rate and the lowest was in root dry weight. Eventually, the results indicated the presence of high genetic variability, along with high heritability and genetic advance among genotypes and studied traits, which could provide further insight towards selection of parents for the development of salt tolerant rice varieties.Progressive Agriculture 28 (4): 262-270, 2017

Effect of Growth Regulators on Germination and Early Seedling Growth of Salt Stressed Sensitive and Tolerant Genotypes of Rice

Effect of Growth Regulators on Germination and Early Seedling Growth of Salt Stressed Sensitive and Tolerant Genotypes of Rice

RNA sequencing analysis of salt tolerance in soybean (Glycine max)

Salt stress causes foliar chlorosis and scorch, plant stunting, and eventually yield reduction in soybean. There are differential responses, namely tolerance (excluder) and intolerance (includer), among soybean germplasm. However, the genetic and physiological mechanisms for salt tolerance is complex and not clear yet. Based on the results from the screening of the RA-452 x Osage mapping population, two F4:6 lines with extreme responses, most tolerant and most sensitive, were selected for a time-course gene expression study in which the 250 mM NaCl treatment was initially imposed at the V1 stage and continued for 24 h (hrs). Total RNA was isolated from the leaves harvested at 0, 6, 12, 24 h after the initiation of salt treatment, respectively. The RNA-Seq analysis was conducted to compare the salt tolerant genotype with salt sensitive genotype at each time point using RNA-Seq pipeline method. A total of 2374, 998, 1746, and 630 differentially expressed genes (DEGs) between salt-tolerant line and salt-sensitive line, were found at 0, 6, 12, and 24 h, respectively. The expression patterns of 154 common DEGs among all the time points were investigated, of which, six common DEGs were upregulated and seven common DEGs were downregulated in salt-tolerant line. Moreover, 13 common DEGs were dramatically expressed at all the time points. Based on Log2 (fold change) of expression level of salt-tolerant line to salt-sensitive line and gene annotation, Glyma.02G228100, Glyma.03G226000, Glyma.03G031000, Glyma.03G031400, Glyma.04G180300, Glyma.04G180400, Glyma.05 g204600, Glyma.08G189600, Glyma.13G042200, and Glyma.17G173200, were considered to be the key potential genes involving in the salt-tolerance mechanism in the soybean salt-tolerant line.

English

Salinity being a serious limitation to crop production is an established fact since ages. It has adversely affected the adaptive behavior of our field crops particularly at seed germination and seedling stages. Identification of particular plant traits conferring salinity tolerance is important for inducing genetic variation among the target traits and adjusting the selection pressure for them in field. This experimental study was conducted to explore percent (%) weight loss of roots and shoots at increasing salt stresses (control, 10 dS m-1 and 15 dS m-1) along with certain dry weight and cationic ratio tolerance indices. The experiment was conducted in the glasshouse to screen seedlings of 25 tomato genotypes. Principal component analysis and correlation analysis were used to screen the genotypes for variability and salt tolerance. Based on associative interactions for salt tolerance traits and highly negative response towards weight percent (%) reductions, three genotypes were identified as salt tolerant; BEAVER LODGE SLICER, ZARNITZA, and FORME DE COEUR. Two genotypes GLACIER and Rio-GRANDE were highly positive for K+/Na+ and Ca2+/Na+ ratios tolerance indices. Based on these findings, the genotypes BEAVER LODGE SLICER, ZARNITZA and FORME DE COEUR are suggested to be planted in salt affected area. The six genotypes (ANAHU, LO-2707, 17860, UOVO ROSEO, NAGINA and LA-2821) showed significant negative behavior towards weight % reduction, and a little positive towards salt tolerance indices were considered as moderately salt tolerant. Key words: Weight percent reduction, NaCl, tomato seedling, physio-agronomic, salt tolerance.

Germination profiling of lentil genotypes subjected to salinity stress.

Salinity is one of the most severe environmental stresses, negatively affecting productivity of salt-sensitive crop species. Given that germination is the most critical phase in the plant life cycle, the present study aimed to determine seed germination potential and associated traits under salt stress conditions as a simple approach to identify salt-tolerant lentil genotypes. The genetic material consisted of six lentil genotypes whose adaptation to various agroclimatic conditions is not well elucidated. Salinity stress was applied by addition of NaCl at three different levels of stress, while non-stressed plants were included as controls. Evaluation of tolerance was performed on the basis of germination percentage, seed water absorbance, root and shoot length, seedling water content, seedling vigour index and number of seedlings with an abnormal phenotype. Overall, our findings revealed that salinity stress substantially affects all traits associated with germination and early seedling growth, with the effect of salinity being dependent on the level of stress applied. It is noteworthy, however, that genotypes responded differently to the varying salinity levels. In this context, Samos proved the most salt-tolerant genotype, indicating its possible use for cultivation under stress conditions. In conclusion, the determination of seed germination and early growth potential may be exploited as an efficient strategy to reveal genetic variation in lentil germplasm of unknown tolerance to salinity stress. This approach allows selection of desirable genotypes at early growth stages, thus enabling more efficient application of various breeding methods to achieve stress-tolerant lentil genotypes.

Ion homeostasis, osmoregulation, and physiological changes in the roots and leaves of pistachio rootstocks in response to salinity.

Pistachio, one of the important tree nuts, is cultivated in arid and semi-arid regions where salinity is the most common abiotic stress encountered by this tree. However, the mechanisms underlying salinity tolerance in this plant are not well understood. In the present study, five 1-year-old pistachio rootstocks (namely Akbari, Badami, Ghazvini, Kale-Ghouchi, and UCB-1) were treated with four saline water regimes (control, 8, 12, and 16dSm-1) for 100days. At high salinity level, all rootstocks showed decreased relative water content (RWC), total chlorophyll content (TCHC), and carotenoids in the leaf, while ascorbic acid (AsA) and total soluble proteins (TSP) were reduced in both leaf and root organs. In addition, the total phenolic compounds (TPC), proline, glycine betaine, total soluble carbohydrate (TSC), and H2O2 content increased under salinity stress in all studied rootstocks. Three different ion exclusion strategies were observed in the studied rootstocks: (i) Na+ exclusion in UCB-1, because most of its Na+ is retained in the roots; (ii) Cl- exclusion in Badami, in which most of its Cl- remained in the roots; and (iii) similar concentrations of Na+ and Cl- were observed in the leaves and roots of Ghazvini, Akbari, and Kale-Ghouchi. Transport capacity (ST value) of K+ over Na+ from the roots to the leaves was more observable in UCB-1 and Ghazvini. Overall, the root system cooperated more effectively in UCB-1 and Badami for retaining and detoxifying an excessive amount of Na+ and Cl-. The results presented here provide important inputs to better understand the salt tolerance mechanism in a tree species for developing more salt-tolerant genotypes. Based on the results obtained here, the studied rootstocks from tolerant to susceptible are arranged as follows: UCB-1 > Badami > Ghazvini > Kale-Ghouchi > Akbari.

Effect of brackish water irrigation on soil degradation and performance of salt tolerant wheat and maize genotypes

A field experiment was conducted to study the effect of brackish water on soil physical and chemical conditions and yield of wheat and maize genotypes at the farmers’ field. Two salt tolerant genotypes for each crop were selected from previous hydroponic and lysimeters studies. Wheat-maize cropping system was followed using tubewell brackish water alone and with chemical (gypsum) and organic (FYM) amendments. The results revealed that treatments have significant effect on all growth and yield parameters and followed the trend of T1>T3 >T4 > T2. Highest grain yield of wheat genotypes (SARC-1 & V-8670) was observed in control (4050 & 3800 kg/ha) and lowest was in T2 (2862 & 2200 kg/ha). Similar trend was observed in maize fodder yield that was 9625 & 8875 kg/ha in control and 4350 & 2253 kg/ha in T2 for Sahiwal-02 and Akbar, respectively. Maximum reduction in wheat grain and maize fodder yield observed in T2 (tubewell water alone) where high EC, SAR and RSC water was applied that was 39 & 57% for 1st year (wheat crop) and 89 & 74% for 2nd year (maize crop) respectively. Data revealed that use of gypsum and FYM along with brackish water improved the wheat grain yield and maize fodder as compared to T2. More adverse effect of brackish water was observed in high EC, SAR and RSC treatment (tubewell water alone) as compared to other treatments. Application of amendments (gypsum and FYM) along with brackish tubewell water reduced adverse effect of brackish water. Among genotypes SARC-1 and Sahiwal-2002 performed better in all treatments and textures especially under brackish water treatments.Bangladesh J. Agril. Res. 42(4): 693-705, December 2017

Comparative transcriptome analysis reveals molecular response to salinity stress of salt-tolerant and sensitive genotypes of indica rice at seedling stage

Abiotic stresses, such as salinity, greatly threaten the growth and productivity of plants. Rice (Oryza sativa L.) is one of the most important food crops, as well as a monocot model for genomic research. To obtain a global view of the molecular response to salinity stress, we conducted a leaf transcriptome analysis on rice seedlings. Two cultivars of rice subspecies indica, including the salt-tolerant genotype Xian156 and the salt-sensitive genotype IR28, were used in the present study. Eighteen RNA libraries were obtained from these two genotypes at three timepoints (0 h, 48 h and 72 h) after applying salinity stress. We obtained the reference-guided assembly of the rice transcriptome, which resulted in 1,375 novel genes, including 1,371 annotated genes. A comparative analysis between genotypes and time points showed 5,273 differentially expressed genes (DEGs), of which 286 DEGs were only found in the tolerant genotype. The Disease resistance response protein 206 and TIFY 10 A were differentially expressed, which were validated by quantitative real-time PCR. The differentially expressed genes identified through the mRNA transcriptome, along with the structure, provide a revealing insight into rice molecular response to salinity stress and underlie the salinity tolerance mechanism between genotypes.