Screening For Salt Tolerance Research Articles

Salt Tolerance in Soybeans: Focus on Screening Methods and Genetics.

Salinity greatly affects the production of soybeans in arid and semi-arid lands around the world. The responses of soybeans to salt stress at germination, emergence, and other seedling stages have been evaluated in multitudes of studies over the past decades. Considerable salt-tolerant accessions have been identified. The association between salt tolerance responses during early and later growth stages may not be as significant as expected. Genetic analysis has confirmed that salt tolerance is distinctly tied to specific soybean developmental stages. Our understanding of salt tolerance mechanisms in soybeans is increasing due to the identification of key salt tolerance genes. In this review, we focus on the methods of soybean salt tolerance screening, progress in forward genetics, potential mechanisms involved in salt tolerance, and the importance of translating laboratory findings into field experiments via marker-assisted pyramiding or genetic engineering approaches, and ultimately developing salt-tolerant soybean varieties that produce high and stable yields. Progress has been made in the past decades, and new technologies will help mine novel salt tolerance genes and translate the mechanism of salt tolerance into new varieties via effective routes.

Screening for Salt Tolerance in Chenopodium quinoa Genotype Seedlings through Germination in a Hydroponic System

Quinoa (Chenopodium quinoa Willd.) is poised to be a global life changer with its ability to adapt to a wide range of abiotic stresses and as a highly nutritious and sustainable food source. A trial on screening of salt tolerance was conducted at the germination and seedling stages of 69 quinoa genotypes in different concentrations of NaCl 0 (CK), 100, 200, 300, 400, and 500 mM for 21 days in the MS/2 mixture. This results in 16 genotypes with >50% germination at 400 mM NaCl. These were reassessed in germination indices and relative growth. Results indicated that Chadmo had the highest germinability of 97% and 32.76% relative height among the 16 genotypes. Considering the germination indices, Chadmo had significantly different values (3.05±0.19 day-1) in mean germination time, coefficient of variation of the germination time (38.76±1.97%), the velocity of germination (0.23±0.01 day-1), the uncertainty of germination (0.54±0.08 bit), synchrony of germination (0.42±0.05 and Timson’s index (48.89) with significant differences (P<0.05) among the genotypes. Moreover, Chadmo had the highest membrane stability index (MSI) (60.03±11.84) at 400 mM NaCl and the least relative change between the CK and 400 mM NaCl with 30.87±2.01%. Assessing the stress inhibitory effect of the 16 genotypes, Chadmo had the least relative difference between the CK and 400 mM NaCl with shoot length of 34.34%, root length of 25.57%, fresh weight of 22.05%, dry weight of 3.62% and moisture content of 1.99% with Tukey analyses identifying significant differences (p<0.05). To select the salt-sensitive genotype, an assessment was done on five genotypes that exhibited the least germination at 200 mM NaCl. Kankolla had the least germinability with 12 and 4% at 100 and 200 mM NaCl, respectively. Considering all these parameters, Chadmo and Kankolla were selected as salt-tolerant and salt-sensitive for further analyses.

Screening For Salt Tolerance of 12 Turkish Triticale Cultivars during Germination and Early Seedling Stage

This investigation was carried out to determine the response of 12 Turkish cultivars to different salt stress levels during the germination and early seedling stages at Hatay Mustafa Kemal University in 2022. In present research, four different sodium chloride treatments (60, 120, 180 and 240 mM) and a control (0 mM) treatment were used. Germination ratio, germination index, mean germination time, root and shoot length, root and shoot fresh weight, root and shoot dry weight and biomass weight parameters were investigated to determine the salt tolerance of triticale cultivars. Cultivars, salt doses and their interactions had significant effects on all examined characteristics. In general, germination parameters and early seedling stage characteristics of the cultivars were adversely affected by increasing salt doses. Yet, it was determined that the responses to increasing salt doses were different among the cultivars. Although Mehmetbey cultivar was undesirably affected by increased salt doses, it was found to be more resistant than the other cultivars. On the other hand, Umranhanim was determined as the most sensitive cultivar to salt stress. After investigating the resistance of Mehmetbey cultivar to salt stress under field conditions, this cultivar can be included into breeding programs or cultivated in fields with salinity problems.

Polymorphic analysis of the OsHKT1;5 exon 1 gene region on seasonal rice varieties with salt tolerant capacity

Abstract. Nguyen TP, La HTG, Do TK, Tran DG. 2023. Polymorphic analysis of theOsHKT1;5exon 1 gene region on seasonal rice varieties with salt tolerant capacity. Biodiversitas 24: 4159-4165. In recent years, saline intrusion has caused serious damage to agricultural production in the Mekong Delta; therefore, research on salinity-tolerant rice varieties is necessary. This study was carried out to screen the salt tolerance capacity of 38 seasonal rice varieties in four concentrations of NaCl supplements, including 4‰, 6‰, 8‰, and 10‰ in comparison with IR28 and Pokkali checks according to IRRI (2021) methods. Eight rice cultivars in four levels of salinity tolerance (two varieties of each level) were selected to evaluate the nucleotide sequence polymorphism in the coding region of OsHKT1;5exon 1, comparedwith that of IR28 and Pokkali checkcultivars and Nipponbare referential variety. The results of salt tolerance screening showed that the salt concentration and the rate of reduction of plant height and root length were positively correlated. Nucleotide sequence polymorphism analysis of OsHKT1;5exon 1 indicated six nucleotide substitutions (SNP) at positions 382, 418, 551, 994, 1119, and 1152. Further analysis revealed thatfive SNPs were detected withthree missense mutations (P60A, R63H, and H255D) in salt tolerant check variety (Pokkali), three to four SNPs with one to two missense mutations H255D or P60A and H255D were observed in salt moderate tolerant varieties, while salt-sensitive varieties and sensitive check variety IR28 were observed with two SNPs and one missense mutation (H255D).

The Effect of Salinity on the Chlorophyll Content of Wheat

Abiotic stress caused by salinity soil affects the development and plant growth, seed production and quality in a negative way. Salinity is an important factor influencing the quality of water. Saline stress causes negative reactions in plants both morphologically, biochemically and physiologically. The chlorophyll content is an important indicator of photosynthetic capacity of plants. Amount of chlorophyll is very influenced by nutrients reserve and by environment stress. Salinity in soil occurs as a result of the factors such as improper irrigation, lack of drainage, excessive accumulation of soluble salts. The research aims to study the behavior of an assortement of wheat varieties in terms of variability in salinity tolerance. To this end, an indirect test method for salinity tolerance, based on the determination of the influence of saline stress on chlorophyll accumulation, was pursued. Determination of chlorophyll content was performed at 7, 14, 21 days after saline stress induction. The duration of stress had the highest contribution (41.72%) to the variability of the chlorophyll content, followed by the saline (10.88%) and the varieties 7.63% respectively. At the level of the whole experiment it is observed that the chlorophyll content decreased progressively as saline stress prolongation. The change in the concentration from 200 to 240 Mm showed the highest influence on this property, materialized by a significant decrease in photosynthetic capacity. A good way to understand the plant photosynthetic regime is to determine the chlorophyll content as an indirect method. A selection criterion in screening for salt tolerance can be considered the physiological features that are positively associated with production under conditions of saline stress.

Salt tolerance screening of a newly developed wheat variety (AZRC-DK-84) in saline environment using halophytic grass (Cenchrus penisettiformis) as a test model

Salt tolerance screening of a newly developed wheat variety (AZRC-DK-84) in saline environment using halophytic grass (Cenchrus penisettiformis) as a test model

Physiological, metabolic, and stomatal adjustments in response to salt stress in Jatropha curcas

Salinity is a major issue affecting photosynthesis and crop production worldwide. High salinity induces both osmotic and ionic stress in plant tissues as a result of complex interactions among morphological, physiological, and biochemical processes. Salinity, in turn, can provoke inactivation of some enzymes in the Calvin-Benson cycle and therefore affect the fine adjustment of electron transport in photosystem I and carbon related reactions. Here, we used three contrasting Jatropha curcas genotypes namely CNPAE183 (considered tolerant to salinity), CNPAE218 (sensible), and JCAL171 (intermediate) to understand salinity responses. By performing a long-term (12 months) experiment in land conditions, we investigated distinct mechanisms used by J. curcas to cope with threatening salinity effects by analyzing gas exchange, mineral nutrition and metabolic responses. First, our results highlighted the plasticity of stomatal development and density in J. curcas under salt stress. It also demonstrated that the CNPAE183 presented higher salt-tolerance whereas CNPAE218 displayed a more sensitive salt-tolerance response. Our results also revealed that both tolerance and sensitivity to salinity were connected with an extensive metabolite reprogramming in the Calvin-Benson cycle and Tricarboxylic Acid cycle intermediates with significant changes in amino acids and organic acids. Collectively, these results indicate that the CNPAE183 and CNPAE218 genotypes demonstrated certain characteristics of salt-tolerant-like and salt-sensitive-like genotypes, respectively. Overall, our results highlight the significance of metabolites associated with salt responses and further provide a useful selection criterion in during screening for salt tolerance in J. curcas in breeding programmes.

Salt-tolerance screening in Limonium sinuatum varieties with different flower colors

Limonium sinuatum, a member of Plumbaginaceae commonly known as sea lavender, is widely used as dried flower. Five L. sinuatum varieties with different flower colors (White, Blue, Pink, Yellow, and Purple) are found in saline regions and are widely cultivated in gardens. In the current study, we evaluated the salt tolerance of these varieties under 250 mmol/L NaCl (salt-tolerance threshold) treatment to identify the optimal variety suitable for planting in saline lands. After the measurement of the fresh weight (FW), dry weight (DW), contents of Na+, K+, Ca2+, Cl−, malondialdehyde (MDA), proline, soluble sugars, hydrogen peroxide (H2O2), relative water content, chlorophyll contents, net photosynthetic rate, and osmotic potential of whole plants, the salt-tolerance ability from strongest to weakest is identified as Pink, Yellow, Purple, White, and Blue. Photosynthetic rate was the most reliable and positive indicator of salt tolerance. The density of salt glands showed the greatest increase in Pink under NaCl treatment, indicating that Pink adapts to high-salt levels by enhancing salt gland formation. These results provide a theoretical basis for the large-scale planting of L. sinuatum in saline soils in the future.

Response of Lettuce Germplasm to Salt Stress at Different Developmental Stages

Salinity is one of the most detrimental abiotic stresses leading to considerable yield and economic losses worldwide. Lettuce is a relatively salt sensitive species, thus placing the interest in the release of salt-tolerant cultivars to enhance production in saline soils. This study aimed at investigating the response of lettuce germplasm to salt stress at the germination and at the whole plant level and to examine possibilities of early selection for salt tolerant genotypes. Fifteen lettuce commercial varieties were initially screened for salt tolerance on the basis of seed germination and seedling growth potential under salt stress conditions (0, 50, 100, 150 mM NaCl). The in vitro evaluation revealed the existence of considerable genetic variation related to salt tolerance at germination and allowed for the classification of genotypes into tolerant, moderately tolerant and sensitive to salt stress. Based on this classification, six cultivars were assessed at the whole plant level using plant height, chlorophyll content and fresh and dry biomass weight as evaluation criteria. Overall findings point to the existence of a satisfactory association of genotype performance between germination and later growth stages, thus suggesting the feasibility of screening for salt tolerance at early growth stages. This approach may considerably upgrade the efficiency of selecting suitable germplasm material for cultivation in saline soils or introgression into relevant breeding programs.

Thuricin17 Production and Proteome Differences in Bacillus thuringiensis NEB17 Cell-Free Supernatant Under NaCl Stress

Bacillus thuringiensis strain NEB17, produces a bacteriocin, thuricin17 (Th17) and is known to promote the growth more effectively under salt stress conditions. In this study, bacterial salt stress tolerance screening and the possible changes in its secretome under two levels of NaCl stress was evaluated. The salt tolerance screening suggested that the bacterium is able to grow and survive in up to 900 mM NaCl. Thuricin17 production at salt levels from 100 to 500 mM NaCl was quantified using High Performance Liquid Chromatography (HPLC). Salt stress adversely affected the production of Th17 at levels as low as 100 mM NaCl; and the production stopped at 500 mM NaCl, despite the bacterium thriving at these salt levels. Hence, a comparative proteomic study was conducted on the supernatant of the bacterium after 42 h of growth, when Th17 production peaked in the control culture, as determined by Liquid Chromatography - Tandem Mass Spectrometry (LC-MS/MS). Optimal (salt free) bacterial culture served as a control and 200 and 500 mM NaCl as stress conditions. As salt levels increased, the major enzyme classes, transferases, hydrolases, lyases, and ligases showed increased abundance as compared to the control, mostly related to molecular function mechanisms. Some of the notable up-regulated proteins in 500 mM NaCl stress conditions included an S-layer protein, chitin binding domain 3 protein, enterotoxins, phosphopentomutase, glucose 6-phosphate isomerase and bacterial translation initiation factor; while notable down-regulated proteins included hemolytic enterotoxin, phospholipase, sphingomyelinase C, cold shock DNA-binding protein family and alcohol dehydrogenase. These results indicate that, as the salt stress levels increase, the bacterium probably shuts down the production of Th17 and regulates its molecular functional mechanisms to overcome stress. This study indicates that end users have the option of using Th17 as a biostimulant or the live bacterial inoculum depending on the soil salt characteristics, for crop production. The mass spectrometry proteomics data have been deposited to Mass Spectrometry Interactive Virtual Environment (MassIVE) with the dataset identifier PXD024069, and doi: 10.25345/C5RB8T.

Salt stress of two rice varieties: root border cell response and multi-logistic quantification.

How to capture the rice varieties salt stress sensitivity? Here, we measure responses of root border cells (1 day, ± 60 mM NaCl) and apply multi-logistic quantification of growth variables (21 days, ± 60 mM NaCl) to two rice varieties, salt-sensitive IR29 and tolerant Pokkali. Thus, logistic models determine the maximum response velocities (Vmax) and times of half-maximum (T0) for root border cell (RBC) and growth parameters. Thereof, seven variables show logistic models (0.58 < R ≤ 1) and monotonous responses in both Pokkali and IR29: root to shoot ratio by water content, primary root length, shoot water, adventitious root number, shoot dry and fresh weight, and root dry weight. Moreover, the regression to lognormal distribution (R = 0.99) of these seven Vmax fractionated by T0 represents the rice variety's comprehensive response. Its quotient IR29/Pokkali is peaking at 98-fold higher velocity of IR29, thus capturing the variety's sensitivity. Consequently, our finding of 66-fold higher Vmax of primary root length response of IR29 indicates an essential salt sensor in the root, including RBC. Finally, the effects of salt stress on RBC confirm multi-logistic quantification, showing 36% decrease of RBC mucilage layer in IR29, without change in Pokkali. Inversely, RBC number of Pokkali increases 43% without change in IR29. Briefly, this suggests both RBC and multi-logistic quantification for the screening for salt tolerance in two thousand rice varieties.

Variability and salt tolerance screening of maize (Zea mays L.) inbred lines at seedling stage

Variability and salt tolerance screening of maize (Zea mays L.) inbred lines at seedling stage

Role of active transport of potassium to leaves in the mechanisms of tolerance to salinity in common bean (Phaseolus vulgaris L.)

Biochemical markers are of great utility in screening for salt tolerance of crops. In common beans (Phaseolus vulgaris), lower levels of proline under stress have been associated with a better stress resistance of cultivars. In the present study, the responses to salinity have been analysed in six cultivars of common beans: four local landraces from Spain and two experimental lines from Cuba. Proline was used for ranking the relative tolerance of the cultivars, confirming a previous study which reported as more stress-tolerant two of the Spanish landraces. Total soluble sugars concentrations varied with treatments and between genotypes, but it was difficult to assess their role in stress tolerance of the analysed plants. Sodium concentration in leaves was the lowest in one of the two salt-resistant cultivars, and potassium did not vary or even increased under salt stress in all of them, except for the most susceptible one, where a drop of this cation was registered under 150 mM NaCl. Changes in malondialdehyde (MDA) contents did not indicate salt-induced membrane peroxidation resulting from secondary oxidative stress; consequently, accumulation of total phenolic compounds and flavonoids, as an antioxidant defence mechanism, was not detected. These results highlight the reliability of using proline as a biochemical marker of salt stress in common beans and the importance of the mechanism related to potassium transport to leaves in conferring stress tolerance to some common bean cultivars.

Screening of Rice Lines (Oryza spp L. 1753) for Salinity Tolerance at Vegetative Stage under Senegal River Valley Conditions

Rice (Oryza spp. L., 1753) is the most staple food cereal in Senegal. However, national production is low and cannot cover the country needs. Salinity limits rice production in Senegal River valley which is main rice growing area in Senegal. This study assessed salinity tolerance of 30 rice lines at vegetative stage in station of Senegalese Institute for Agricultural Research (ISRA) at Ndiol in Senegal River valley. Experimental design adopted was alpha lattice with three rehearsals. Observations were performed on plant height, main stem development and number of tillers. The level of salinity and pH in surface water, groundwater and soil were monitored. The results indicate that salinity affects plant height and tillering ability and among 30 lines, four were identified highly tolerant to salinity at vegetative stage. These are the varieties HK11-NDIOL-11-LON-1, D20-ART20-ARS-1, D56-ARS-NCRIB-1-1 and HK72-NIONO-5-1-1. The decision to incorporate these varieties in salinity tolerance breeding programs would depend on salt tolerance screening across all growing stages.

AGRONOMIC AND PHYSIOLOGICAL STUDIES ON SOME EXOTIC AND LOCAL BREAD WHEAT GENOTYPES UNDER SALINE SOIL CONDITIONS IN NORTH DELTA REGION

Soil salinity is the major global limitation to wheat production. Thus, ten bread wheat exotic lines and local cultivars were studied under normal and moderate saline soil conditions during 2017/18 and 2018/19 growing seasons. the objective was to understand the effects of salinity stress on some agronomic and physiological characters and to estimate some selection indices for salt tolerance in wheat. The studied characters were plant height and grain yield and its components in addition to relative water content, contents of chlorophyll a and b, proline and malondialdehyde and catalase activity in the flag leaves. The two seasons and saline conditions behaved differently. Besides, sufficient genetic variability among the studied genotypes was detected. Moreover, the variance due to saline conditions was the most important comparing to the other sources. Most of studied characters were higher in their mean values in the second season than the first one. All mean values of the studied characters decreased under the saline conditions, except for proline and malondialdehyde contents and catalase activity. Genotypic main effect plus genotype by environment interaction (GGE) Biplot analysis revealed that Line 2, Sakha 95, Misr 3 and Sids 14 had high yielding ability and relative tolerance under salinity conditions. Based on correlation coefficients, the high values of relative water content, chlorophyll, proline contents and catalase activity in addition to the low value of malondialdehyde content may be used as physiological selection criteria for salt tolerance screening of wheat genotypes

Role of seed age in screening for salt tolerance of sunflower at germination

Three sunflower hybrid seeds of known age (3, 2 and 1 month old) seeds of DRSH-1, KBSH-44, CO-2respectively were tested for salt tolerance by conducting germination studies in 200, 250, 300, 350 mM NaCl atmonthly intervals. Results differed when seeds of same age were compared with seeds of mixed age. Therefore, for valid comparisons, the seeds should essentially be of same age.

In vitro screening for salt stress tolerance of native and exotic potato genotypes by morphological and physiological parameters

This study was performed on in vitro bioassay screening for salt tolerance of ten native and six exotic potato genotypes in Bangladesh. Single node was used to evaluate salinity tolerance especially on biomass production. Five different concentrations of NaCl (0 = control, 100, 150, 200 and 250 mM) were used in addition to MS medium and evaluated salt tolerant and sensitive genotype by various morphological and physiological parameters e.g. shoot and root length and its thickness, number of leaves and roots, fresh and dry weight of whole plant and water contents. The ANOVA, DMRT and correlation coefficient were found highly significant at p&lt;0.01 among the genotypes. With salt stress condition highly positive correlation, co-efficient were found between stem length and internodal distance, leaves number, roots number, root length, dry weight of whole plant and fresh weight of whole plant. A dendrogram based on relative values of 10 morphological and physiological parameters of growth under salt conditions were led to clustering into four distinct group’s i.e. tolerant, moderately tolerant, sensitive and very sensitive. On the basis of stress tolerance trait indices (STTIs), Arun (92.78) and Ausha (80.27) showed as a highest salt tolerant, Jamalu (56.33) and Chollisha (57.03) showed the most salt sensitive potato cultivars. From this finding it may be concluded that in vitro screening with bioassay are relatively simple, rapid and convenient and these methods can be used for further advance biotechnological research on potato improvement.&#x0D; J. bio-sci. 28: 21-32, 2020

Salt tolerance screening of seven rice landraces

Rice is grown on about one-tenth of the earth’s arable land. It is the single largest source of food energy to more than half of the world population. Salinity confines the efficiency of production at the mature stage. Soil salinity decreases the plant growth rate and can harshly limit the crop production. Salinity tolerance differs extensively between species of plants and within species A pot study was conducted to evaluate the salt tolerance of rice varieties under different salinity cum sodicity levels [S0=2.70dSm-1+ 11.38 (mmol L-1)1/2, S1= 5.16dSm-1 +27.88 (mmol L-1)1/2, S2= 6.15 dSm-1 +30.38 (mmol L-1)1/2 and S3= 6.78 dSm-1 +33.74 (mmol L-1)1/2 ]. Seeds of seven rice varieties namely PB-95, SRI-12, T-05, No 1121, SRI-13, Basmati-515 and Shaheen Basmati were used for screening against salt tolerance in pots with different salinity cum sodicity combinations at green house of Land Resources Research Institute, National Agricultural Research Centre, Islamabad, Pakistan during, 2017. Completely randomized deign was applied with three repeats. Data on grain yield were collected. This study showed significant differences in grain yield with seven rice varieties. At S0 [2.40dSm-1+ 11.38 (mmol L-1)1/2] Basmati-515 rice variety gained the top position in grain yield (4.18 tha-1) and the lowest position was attained by T-05 with grain yield (3.41 tha-1). PB-95 produced the highest paddy yield (3.18tha-1) and Shaheen Basmati attained grain yield (3.06tha-1). All other rice under S1 [5.106dSm-1+27.88 (mmol L-1)1/2] showed the lowest grain yield. Under S2 [6.15dSm-1 +30.38 (mmol L-1)1/2] PB-95 rice variety attained the highest grain yield (2.16 tha-1). Rice line 1121 also received the least position (1.66tha-1) in this salinity level. % decrease at S2 over S0 was indicated salt tolerance of rice varieties. PB-95 rice variety attained the lowest % decrease at S2 over S0 (45.17). PB-95 rice variety attained the highest grain yield (1.08tha-1) at S3 [6.78dSm-1 +33.74 (mmol L-1)1/2]. Rice line 1121 also received the least position (0.62tha-1) in this salinity level. % decrease at S3 over S0 was indicated salt tolerance of rice varieties. PB-95 rice variety attained the lowest % decrease at S3 over S0 (72.58). Therefore, this variety had the maximum salt tolerance than other rice varieties under this experiment.

Variation for Salinity Tolerance During Seed Germination in Diverse Carrot [Daucus carota (L.)] Germplasm

Global carrot production is limited by the crop’s high susceptibility to salinity stress. Not much public research has been conducted to screen for genetic salinity stress tolerance in carrot, and few resources exist to aid plant breeders in improving salinity tolerance in carrot. The objectives of this study were to evaluate the response of diverse carrot germplasm to salinity stress, identify salt-tolerant carrot germplasm that may be used by breeders, and define appropriate screening criteria for assessing salt tolerance in germinating carrot seed. Carrot plant introductions (PIs) (n = 273) from the U.S. Department of Agriculture (USDA) National Plant Germplasm System representing 41 different countries, inbred lines from the USDA Agricultural Research Service (n = 16), and widely grown commercial hybrids (n = 5) were screened for salinity tolerance under salinity stress and nonstress conditions (150 and 0 mm NaCl, respectively) by measuring the absolute decrease (AD) in the percent of germination, inhibition index (II), relative salt tolerance (RST), and salt tolerance index (STI) of germinating seeds. All salt tolerance measurements differed significantly between accessions; AD ranged from −4.2% to 93.0%; II ranged from −8.0% to 100.0%; RST ranged from 0.0 to 1.08; and STI ranged from 0.0 to 1.38. Broad sense heritability calculations for these measurements were 0.87 or more, indicating a strong genetic contribution to the variation observed. Six accessions identified as salt-tolerant or salt-susceptible were evaluated in a subsequent experiment conducted at salt concentrations of 0, 50, 100, 150, 200, and 250 mm NaCl. Variations between mean AD, II, RST, and STI of tolerant and susceptible lines were greatest at 150 mm NaCl, validating the use of 150 mm NaCl concentrations during salt tolerance screening of carrot seed. Wild carrot accessions displayed little tolerance, and PI 256066, PI 652253, PI 652402, and PI 652405 from Turkey were most salt-tolerant.

Screening for Salt Tolerance in Four Local Varieties of Phaseolus lunatus from Spain

This study assessed the responses of four local Spanish cultivars of Phaseolus lunatus (lima bean) to moderate salinity. For three weeks, plants were exposed to increasing salinity (50–150 mM NaCl) under greenhouse conditions. At the end of the experiment, several growth and biochemical parameters were determined. Salt stress reduced the fresh weight of aerial organs, allowing us to rank the four genotypes according to their tolerance to salinity. The concentration of most photosynthetic pigments remained unaltered, except carotenoids that were reduced in the least salt-tolerant cv. (cultivar) VPH-79. Leaf Na+ and Cl− concentrations increased with increased salt concentration of irrigation water, but K+ either remained constant, as in the most tolerant ‘BGV-15410’, or increased in the other cultivars, resulting in an unchanged K+/Na+ ratio under stress in two of the selected cultivars. Moreover, proline increased in all cultivars, most notably in cv. VPH-79, with the highest absolute concentrations registered in the more salt tolerant cultivars. Interestingly, these cultivars already had a relatively higher proline concentration in non-stressed plants. These findings indicate that P. lunatus is moderately salt tolerant and that its main mechanisms to adjust to salinity stress are the maintenance of high concentrations of K+ and proline accumulation in leaves.