Morphophysiological Diversity and Haplotype Analysis of Saltol QTL Region in Diverse Rice Landraces for Salinity Tolerance

Rice is sensitive to salinity stress at both the seedling and reproductive stages.The present study used 145 rice genotypes comprising of 100 landraces and 45 advanced breeding lines collected from different regions of India.These genotypes were evaluated in hydroponics under control[electrical conductivity(ECe)~1.2 dS/m]and saline(ECe~10.0 dS/m)environments along with susceptible(IR29)and tolerant(FL478)checks.The stress susceptibility index for eight morphophysiological traits was estimated.Analysis of variance showed significant differences among the genotypes for all the parameters studied in control,stress and relative stress conditions.We identified 3 landraces(Kuttimanja,Tulasimog and IET-13713I)as tolerant and 14 lines as moderately tolerant to salt stress.Strong correlations in the morphological(root and shoot lengths)and physiological traits(shoot Na^(+),Ca^(2+)and Mg^(2+)contents,and Na^(+)/K^(+)ratio)were observed under all the conditions.The hierarchical cluster analysis grouped the genotypes into five clusters,among which cluster Ⅱ comprised salt-tolerant lines.Haplotyping of Saltol region using 11 simple sequence repeat markers on 17 saline tolerant and moderately tolerant lines was conducted.Markers AP3206F,RM10793 and RM3412b,located close to SKC1 gene(11.23‒12.55 Mb),displayed diverse allelic variations and they were not related to the FL478 type.In this region,tolerant lines like Kuttimanja,IET-13713I and Tulasimog have new alleles.As a result,these lines may be suitable candidates for novel genomic regions governing rice salinity tolerance.Salt-tolerance ability of Kuttimanja,Tulasimog and IET-13713I was validated in two years in three salinity stress environments.These promising lines can be used in breeding programs to broaden the genetic base of salinity tolerance in rice,and it may help to dissect key genomic regions responsible for salinity tolerance.

Thermal and saline tolerance of Antarctic krill Euphausia superba under controlled in-situ aquarium conditions

As a key species of the Southern Ocean ecosystem,the thermal and saline tolerances of Antarctic krill(Euphausia superb a Dana)are relatively unknown because of the challenging environment and complicated situations needed for observation have inhibited in-situ experiments in the field.Hence,the thermal and saline tolerance of krill were examined under in-situ aquarium conditions with different controlled scenarios.According to the experiments,the critical lethal times of krill were 24h,2h and 0.5h under 9℃,12℃,and 15℃,respectively,and the estimated 50%lethal times were about 17.1 h and 1.7 h under 12℃and 15℃,respectively.Additionally,the critical lethal times(the estimated 50%lethal times)of krill were approximately 14h and 0.5h(about 22.9 h and 1.7 h)of salinity under 19.7 and 15.9,respectively.The observed critical and 50%lethal times of krill were 0.5 h and approximately 1.4 h,respectively,salinity under 55.2.The critical and 50%lethal temperatures of krill were 13℃and approximately 14.2℃,respectively.Additionally,the critical and 50%lethal salinity was 19.6 and approximately 17.5 for the lower saline(below normal oceanic salinity[34.4])environment and 50.3 and approximately 53.2 for the higher saline(above 34.4)environment,respectively.The upper thermal and saline preferences of krill can be considered 6℃and 26.8 to 41.2,respectively.These results can provide potential scenarios for predicting the possible fate of this key species in the Southern Ocean.

Effect of Initial Soluble Salt Composition of Saline Soil on Salinity Tolerance of Barley Plant

A pot experiment was carried out on a marine saline soil to study the effect of initial soluble Na/Ca ratio of saline soil on the salinity tolerance of barley plant.The results showed that (1) the Na/Ca ratio affected significantly the dry weight of the plant at an earlier stage of growth,the critical values of initial Na/Ca ratio at which the plant could grow normally on soils containing salts of 2.5,3.5 and 4.5g kg^-1 were 30,20 and 15,respectively;(2)smaller Na/Ca ratio resulted in a considerable decrease in Na accumulation but a great increase in K accumulation in the barley plant;and (3) the plasmallema of barley leaf were badly injured when the Na/Ca ratio was more than 30 and the increase of Na content of plant caused an exudation of K from the leaf cells.Some critical indexes were suggested for the cultivation of barley plant on marine saline soils and could be used as reference in the biological reclamation of marine saline soils.

Seasonal variance of salinity tolerance of a copepod Drepanopus bispinosus in an Antarctic littoral saline lake (Burton Lake)

In Burton Lake (an Antarctic littoral saline lake), as one of the overwinter species, the female Drepanopus bispinosus reach adult form in autumn. and early winter.For the subsequent life period of more than eight months, the animals experience such changing environment as increasing salinities from approximately 33 (in May) to 39 (in November). There is a considerable difference of salinity tolerance of female adults between summer and winter populations.Winter collected copepods survived lower salinities than summer collected copepods in this experiment. The upward shift in their salinity tolerance range is related to the development of field acclimation to salinity. Respiration rates of the summer animals showed a visible increase over those of winter copepods in simitar salinity and temperature conditions, thus supporting the above conclusion.

Overexpression of vacuolar proton pump ATPase(V-H^+-ATPase) subunits B, C and H confers tolerance to salt and saline-alkali stresses in transgenic alfalfa(Medicago sativa L.)

The vacuolar proton pump ATPase（V-H^＋-ATPase）, which is a multi-subunit membrane protein complex, plays a major role in the activation of ion and nutrient transport and has been suggested to be involved in several physiological processes, such as cell expansion and salt tolerance. In this study, three genes encoding V-H^＋-ATPase subunits B（Sc VHA-B, Gen Bank： JF826506）, C（Sc VHA-C, Gen Bank： JF826507） and H（Sc VHA-H, Gen Bank： JF826508） were isolated from the halophyte Suaeda corniculata. The transcript levels of Sc VHA-B, Sc VHA-C and Sc VHA-H were increased by salt, drought and saline-alkali treatments. V-H^＋-ATPase activity was also examined under salt, drought and saline-alkali stresses. The results showed that V-H^＋-ATPase activity was correlated with salt, drought and saline-alkali stress. Furthermore, V-H^＋-ATPase subunits B, C and H（Sc VHA-B, Sc VHA-C and Sc VHA-H） from S. corniculata were introduced separately into the alfalfa genome. The transgenic alfalfa was verified by Southern and Northern blot analysis. During salt and saline-alkali stresses, transgenic lines carrying the B, C and H subunits had higher germination rates than the wild type（WT）. More free proline, higher superoxide dismutase（SOD） activity and lower malondialdehyde（MDA） levels were detected in the transgenic plants under salt and saline-alkali treatments. Moreover, the Sc VHA-B transgenic lines showed greater tolerance to salt and saline-alkali stresses than the WT. These results suggest that overexpression of Sc VHA-B, Sc VHA-C and Sc VHA-H improves tolerance to salt and saline-alkali stresses in transgenic alfalfa.

Nucleus-Encoded Thylakoid Protein,OsY3IP1,Confers Enhanced Tolerance to Saline and Alkaline Stresses in Rice

Abiotic stress confers serious damage to the photosynthetic machinery,often resulting in plant growth inhibition.Hypothetical chloroplast open reading frame 3(Ycf3)-interacting protein 1(Y3IP1)is a nucleus-encoded thylakoid protein and plays an essential role in the assembly of photosystem I.The full-length cDNA over-expresser(FOX)gene-hunting system is an approach using systemically generated gain-of-function mutants.Among the FOX-rice lines,a line CE175 overexpressing rice Y3IP1gene(Os Y3IP1)displayed less inhibition of root growth under saline(NaCl)stress.The expression of Os Y3IP1 was up-regulated under saline and alkaline(Na2CO3)stresses in the rice variety Kitaake.After saline and alkaline treatments,transgenic Kitaake overexpressing OsY3IP1-GFP(OsY3IP1-GFPox/Kit)displayed higher levels of chlorophyll content compared to Kitaake.Under the stress conditions,the maximum quantum yield of photosystem II photochemistry levels was higher in OsY3IP1-GFPox/Kit than in Kitaake.The increased tolerance conferred by OsY3IP1 overexpression correlated with reduced reactive oxygen species accumulation.Our data provide new insights into the possible role of OsY3IP1 in the pathway suppressing photooxidative damage under stress conditions.These features can be further exploited to improve saline and alkaline tolerances of rice plants in future.

Effects of Adaptation to Elevated Salinity on Some Enzymes' Salt_tolerance in Vitro and Physiological Changes of Eelgrass

The eelgrass ( Zostera marina L.) was treated with artificial seawater (ASW) of different salinities ( 100%, 150% and 200% seawater) for 5 d. The activities of two enzymes extracted from the plant leaves were determined under a salinity grade in vitro So were the photosynthesis rates of the plants from the three treatments in the media with different salinities 100%, 150%, 200%, 300% ASW) and Some physiological data. The data showed that under increased salinities (concentrated seawater), Na+, Cl-, MDA (malon dialdehyde) and glucose contents and the osmotic potentials ( absolute value) in the leaves increased with the salinity elevation in the medium (ASW), but both K+ and free amino acid (mainly proline) contents decreased. Malate dehydrogenase (MDH) from the plant leaves under a salinity grade showed its activities (A) as follows: A(100%) (ASW) > A(150%) (ASW) > A(200%) (ASW). Phosphoenolpyruvate carboxylase (PEPC) extracted from the 100% ASW- and 200% ASW-treated plants showed similar activities (both insensitive to salinities) under the salinity grade in vitro, but the activities of PEPC from plants treated with 150% ASW were dependent oil salinity. Whether the plant is stressed at 150% ASW and can stand higher salinity than seawater needs to be studied further. Meantime, die data do not agree with the opinion that the adaptation of the eelgrass to seawater salinity is partly fulfilled by its insensitiveness to salinities in Some metabolic enzymes. It can be inferred that the lack of transpiration may be an important aspect of tire plant's tolerance to seawater salinity.

GsMAPK4,a positive regulator of soybean tolerance to salinity stress

Salt stress is one of the major factors affecting plant growth and yield in soybean under saline soil condition. Despite many studies on salinity tolerance of soybean during the past few decades, the detailed signaling pathways and the signaling molecules for salinity tolerance regulation have not been clarified. In this study, a proteomic technology based on two-dimensional gel electrophoresis(2-DE) and mass spectrometry(MS) were used to identify proteins responsible for salinity tolerance in soybean plant. Real-time quantitative PCR(qRT-PCR) and Western blotting(WB) were used to verify the results of 2-DE/MS. Based on the results of 2-DE and MS, we selected glucosyltransferase(GsGT4), 4-coumarate, coenzyme A ligase(Gs4 CL1), mitogen-activated protein kinase 4(GsMAPK4), dehydration responsive element binding protein(GsDREB1), and soybean cold-regulated gene(GsSRC1) in the salinity tolerant soybean variety, and GsMAPK4 for subsequent research. We transformed soybean plants with mitogen-activated-protein kinase 4(GsMAPK4) and screened the resulting transgenics soybean plants using PCR and WB, which confirmed the expression of GsMAPK4 in transgenic soybean. GsMAPK4-overexpressed transgenic plants showed significantly increased tolerance to salt stress, suggesting that GsMAPK4 played a pivotal role in salinity tolerance. Our research will provide new insights for better understanding the salinity tolerance regulation at molecular level.

Genetic diversity and association mapping for salinity tolerance in Bangladeshi rice landraces

Breeding for salinity tolerance using Bangladeshi rice landraces and understand genetic diversity has been limited by the complex and polygenic nature of salt tolerance in rice genotypes. A genetic diversity and association mapping analysis was conducted using 96 germplasm accessions with variable response to salt stress at the seedling stage. These included86 landraces and 10 indica varieties and lines including Nona Bokra, from southern Bangladesh. A total of 220 alleles were detected at 58 Simple Sequence Repeat(SSR) marker loci randomly distributed on all 12 rice chromosomes and 8 Sequence Tagged Site(STS) markers developed for genes SKC1, DST, and SalT. The average gene diversity was 0.5075 and polymorphism information content value was 0.4426, respectively. Cluster analysis revealed that 68 and 21 accessions were clustered into 2 distinct groups, possibly corresponding to indica and japonica groups, respectively and the remaining 7 landraces were classified as an admixed group. In addition to Wn11463, the STS marker for SKC1, RM22418 on Chr. 8 was significantly associated with salinity tolerance, at the location of a QTL detected in previous studies. Our findings of favorable alleles associated with salinity tolerance in Bangladeshi rice landraces, as well as the development of STS markers for salt tolerance genes, will be helpful in future efforts to breed salinity tolerance in rice.

Genotypic Divergence, Photosynthetic Efficiency, Sodium Extrusion, and Osmoprotectant Regulation Conferred Salt Tolerance in Sorghum

Salt stress is one of the major limitations to modern agriculture that negatively influences plant growth and productivity.Salt tolerant cultivar can provide excellent solution to enhance stress tolerance with plantfitness to unfavorable environments.Therefore,this study was aimed to screen salt tolerant sorghum genotypes through evaluating of different morphological,biochemical,and physiological attributes in response to salinity stress.In this study,we have been evaluated total six sorghum genotypes including Hybrid sorgo,Debgiri,BD-703,BD-706,BD-707,and BD-725 under salt stress(12 dS m^(-1) NaCl).The response variables included length and weight of root and shoot,root:shoot ratio(RSR),photosynthesis(A),transpiration rate(E),elemental concen-trations(K^(+),Na^(+) and K^(+)/Na^(+)),photochemical efficiency of photosystem II(F_(v)/F_(m)),water use efficiency(WUE)and pigment content(chlorophyll a,and b).The results revealed that saline environment significantly reduced all response variables under study of sorghum genotypes,however,Hybrid sorgo remained unmatched by recording the maximum root and shoot traits.The same genotype recorded higher photosynthetic efficiency which was attributed to Na^(+) extrusion,K^(+) uptake and higher K^(+)/Na^(+) ratio(1.8 at stress),while these mechanisms were not fully active in rest of genotypes.Moreover,this study also implies the involvement of proline in imparting tolerance against saline environment in Hybrid sorgo genotype.Overall,BD-703 remained the most salt sensitive genotype as evident from the minimum morphological growth traits and the least biosynthesis of osmoprotectants.Thesefindings open new research avenues for salt stress alleviation by identifying elite salt-to-lerant genotypes of sorghum for breeding programs.

Selection of Rice Genotypes for Salinity Tolerance Through Morpho-Biochemical Assessment

The present study reported the morpho-biochemical evaluation of 15 selected rice genotypes for salt tolerance at the seedling stage. Growth parameters including shoot length, root length, plant biomass, plant turgid weight, plant dry weight along with relative water content were measured after exposure to saline solution （with electrical conductivity value of 12 dS/m）. Genotypes, showing significant differential responses towards salinity in the fields, were assessed through 14 salinity-linked morpho-biochemical attributes, measured at 14 d after exposure of seedling in saline nutrient solution. Relative water content, chlorophyll a/b, peroxidase activity and plant biomass were identified as potential indicators of salt tolerance. Principal component analysis and successive Hierarchical clustering using Euclidean distance revealed that Talmugur, Gheus, Ghunsi, Langalmura, Sabitapalui, and Sholerpona were promising genotypes for further breeding programmes in rice. The maximum Euclidean distance was plotted between Thavallakanan and Talmugur （7.49）, followed by Thavallakanan and Langalmura （6.82）, indicating these combinations may be exploited as parental lines in hybridization programmes to develop salinity tolerant variety.

Selection of Maize Genotypes with Tolerance to Osmotic Stress Associated with Salinity

Thirteen different inbred lines in relation to the type of grain and life cycles were characterized by testing for osmotic stress associated with salinity. The identification of tolerant genotypes would be an effective strategy to overcome the saline stress. Osmotic stress reduces immediately the expansion of the roots and young leaves which determine a reduction in the size of the plant. A completely randomized design was adopted to test seedlings under controlled conditions of light and temperature. Two treatments were used: 0 mM NaCl (as control) and 100 mM NaCl. After 15 days of complete salinization, the seedlings were harvested and several morphological traits were measured. The morphological traits of growth were leaf growth (Ar1, Ar2, Ar3 and Ar4), dry masses of shoot and root (SDM and RDM, respectively). Also, traits associated with water economy were registered: leaf water loss (LWL) and relative water content (RWC). The morphological traits were expressed in relative terms, while the traits associated with the economy of water were expressed in absolute terms. Uni and multivariate techniques were applied to identify genotypes with divergent behaviors to osmotic stress tolerance. Also, a Tolerance Index was employed to identify superior genotypes. Four clusters were obtained after applying a Cluster Analysis and Principal Component Analysis (PCA). The genotypes were compared to each other with a test of DMS. The results obtained with different statistical techniques converged. Some variables presented a differential weight classification of genotypes. The morphological traits like RDM, SDM, Ar3, Ar4 and Ar5 were the most discriminating. Tolerance Index allowed to classify genotypes, thus SC2 and AD3 lines were that reached highest value of the index and therefore would be tolerant lines, while AF3 and LP3 had a low index and were seen as sensible.

Introgression the Salinity Tolerance QTLs <i>Saltol</i>into AS996, the Elite Rice Variety of Vietnam

This study focus on developing new salinity tolerance and high yielding rice lines, using markers assisted backrossing (MABC). Total of 500 SSR markers on 12 rice chromosomes were screened for parental polymorphic markers. Of which, 52 primers in the Saltol region were checked with the two parents varieties to identify polymorphic primers for screening the Saltol region of the breeding populations. For each backcross generation of ASS996/FL478, approx. 500 plants were screened with 63 polymorphic markers distributed on 12 chromosomes. The two BC1F1 plants P284 and P307 which had the highest recipient alleles up to 89.06% and 86.36%, were chosen for the next backcrossing. Three BC2F1 plants with the recipient alleles up to 94.03% and 93.18% were used to develop BC3F1 generation. The best BC3F1 plant was P284-112-209 with all the recipient alleles and Saltol region. The four plants P307-305-21, P284-112-195, P284-112-198, P284-112-213 were the second ranking with only one loci heterozygous (applied 63 markers covered on 12 chromosomes). These five plants were chosen as the breeding lines for result of Saltol-AS996 introgression. The breeding line BC4F1 having 100% genetic background of donor variety is ready for develop new salinity tolerant variety ASS996-Saltol to cope with climate change.

Innovation on Distant Hybridization of Saline-tolerant Mud Flat Spartina and Rice Germplasm

To explore saline-tolerant high yield Spartina and rice germplasm resources,innovate upon distant hybridization technology,and develop new saline-tolerant mud flat Spartina germplasm,autonomous patent for invention was used to study distant hybridization of Spartina and rice in 2005- 2016. The study adopted tidal flat planting screening,phenotypic screening,molecular marker assisted selection,to find biological evidences of new germplasm,and also applied crossbreeding,conventional breeding,and molecular breeding,to select new saline-tolerant Spartina and rice varieties. With 12 years of efforts,the team developed 1498 crossbreeding combinations and established pedigree file and seed bank,tested 307 crossbreeding materials(57 hybrid seeds showed parental genetic components of Spartina and Rice); obtained Spartina/ Rice distant hybridization and seed setting,transplanting,hybridization material economic traits,and molecular biological experimental evidences; Rice♀× Spartina ♂ hybridization success rate of 1. 04- 1. 39%; obtained authorization of patent for invention of Distant Hybridization Methods for Spartina and Rice; formulated procedures for high yield cultivation of Spartina-Rice,planted 33. 33 hm2Spartina-Rice in coastal saline and alkaline land,cultivated 10 new saline-tolerant Spartina-Rice varieties,and the rice yield up to 5. 925- 8. 28 t / hm2. Results indicate that Spartina-Rice is saline-tolerant high yield rice germplasm,developed through sexual hybridization,conventional breeding,and molecular breeding technologies,and is optimal crop for saline and alkaline land. Success of Spartina-Rice solves the problem of saline-tolerant crop badly for transformation of saline and alkaline land,the problem of feeds for herbivores,as well as problem of environmental pollution resulted from straw burning. Besides,it is of essential scientific significance for resource utilization,increase of agricultural efficiency,grain security,and farmland strategy,so it has broad application prospect.

Tolerance, Oxygen Consumption and Ammonia Excretion of Ophiopholis sarsii vadicola in Different Temperatures and Salinities

There are more than 2000 species of brittle stars in the world. For most of them, many scientific questions including basic characteristics of eco-physiology are still unknown. In the present study, Ophiopholis sarsii vadicola acclimated at 15 ℃, salinity 31, were assessed for temperature monia excretion were studied at different temperatures （5, 10, and salinity tolerance. Its oxygen consumption and am- 15, 20, 25℃） and salinities （25, 30, 35）. O. sarsii vadi- cola could tolerate 0-24℃ and no brittle star was dead in the salinity range of 19-48 in the experimental situation. Two-way ANOVA showed that the oxygen consumption and ammonia excretion normalized with both dry mass and wet mass, Q10, which is used to describe the temperature sensitivity of respiration, and moisture content were significantly affected by temperature and salinity, and the combined effects of the two factors were significant. Stepwise multiple regression analysis revealed that logarithmic oxygen consumption and ammonia excretion showed a significant positive relationship with logarithmic temperature and salinity. The logarithmic moisture content of the brittle stars showed an inverse relationship with logarithmic salinity, but a positive relationship with logarithmic temperature. This suggests that the tolerance of temperature and salinity of brittle stars is closely related to their living environment, and that the effects of temperature on oxygen consumption are more significant at higher salinity, and that the ammonia excretion is less affected by salinity at lower temperatures.

Salinity Tolerance and Growth Response of Juvenile Oreochromis mossambicus at Different Salinity Levels

Juveniles of Oreochromis mossambicus with initial wet weights of 0.0382±0.0859 g and initial total lengths of 0.735 ±1.425 cm were tested for their salinity tolerance. The juveniles were subjected to five salinity levels for a period of seventy five days. These salinity levels correspond to the salinities found along the creek and in estuarine regions. Each set of experiments was conducted at a fifteen day intervals. The weight, length and survival rate were calculated. No mortality was observed at salinity levels 0, 5, 10 and 15, while the juveniles faced slight mortality at 20 in the same environmental conditions, including the diet. There was no significant difference in specific growth rate at all salinity levels. The juveniles of O. mossambicus could survive up to 20 salinity. These results suggest that this species can grow and be exploited commercially in brackish waters, rivers and estuarine regions.

Effect of soil salinity on cold tolerance of mangrove Kandelia candel

Analysis of cold tolerance on mangrove Kandelia candel leaf growing in different soil salinity along Jiulong River Estuary in South China showed that the cold tolerance decreased as the increase of soil salinity. The lethal temperatures of K. candel leaf were -10.4, -9.9 and -8.6 ℃ in Liaodong, Baijiao and Aotou, respectively. Under 1–2℃ cold stress treatment on detached leaves of K. candel, their caloric value gradually decreased, while electrolyte leakage gradually increased. The leaf’s caloric value and electrolyte leakage in Aotou with higher soil salinity varied more largely than those in Liaodong with lower soil salinity. In K. candel leaf, total water content lowered a little, bound water content rose significantly and free water content dropped significantly with duration of cold stress. At the same time, reduction sugar, soluble sugar and starch content gradually decreased and sucrose content gradually increased. Bound water, free water and sucrose content in K. candel leaf from Aotou with higher soil salinity changed more slowly than those from Liaodong with lower soil salinity, but reduction sugar, soluble sugar and starch content in K. candel leaf from Aotou had faster variations than those from Liaodong. These data indicated that soil salinity can reduce cold tolerance of K. candel leaf by increasing negative effect of salt ions in cell membrane, inhibiting variations of water content, and aggravating consumption of material and energy.

Maternal salinity improves yield, size and stress tolerance of Suaeda fruticosa seeds

Shrubby seablite or lani(Suaeda fruticosa Forssk)is a perennial euhalophyte with succulent leaves,which could be planted on arid-saline lands for restoration and cultivated as a non-conventional edible or cash crop.Knowledge about the impacts of maternal saline environment on seed attributes of this important euhalophyte is lacking.This study investigated the effects of maternal salinity on yield,size and stress tolerance of S.fruticosa seeds.Seedlings of S.fruticosa were grown in a green net house under increasing maternal salinity levels(0,300,600 and 900 mM NaCl)until seed production.Total yield,size,stress tolerance and germination of the descended seeds under different maternal saline conditions were examined.Plants grown under saline conditions(300,600 and 900 mM NaCl)produce a substantially higher quantity of seeds than plants grown under non-saline condition(0 mM NaCl).Low maternal salinity(300 mM NaCl)improves seed size.Seeds produced under all maternal salinity levels display a higher tolerance to low temperature(night/day thermoperiod of 10℃/20℃),whereas seeds produced under 300 mM NaCl maternal saline condition show a better tolerance to high temperature(night/day thermoperiod of 25℃/35℃)during germination.Seeds from all maternal saline conditions germinate better in the 12 h photoperiod(12 h light/12 h dark)than in the dark(24 h dark);however,seeds produced from low and moderate maternal saline conditions(300 and 600 mM NaCl)show a higher germination in the dark than those from control and high maternal saline conditions(0 and 900 mM NaCl).In general,maternal salinity is found to improve yield,size and stress tolerance of S.fruticosa seeds.

Salinity Tolerance in Argentinean Population of <i>Bromus catharticus</i>. Variability and Direct and Indirect Effects on Seedling Characters

The aim of this research was to evaluate the salinity tolerance in prairie grass populations at the seedling stage quantifying the variability and the influence of physiological traits related to it. Salinity tolerance, in Bromus catharticus Vahl (prairie grass) populations collected in different environments of the Pampean Phytogeography region (Argentine) was evaluated at the seedling stage, using controlled condition of temperature and light. It was adopted a completely randomized design using 3 plots with three plants each one per population and two levels of treatment: 0 mM and 100 mM NaCl. Morphological, biomass and membrane stability root and shoot traits were studied. A factorial ANOVA with interaction was estimated. Then one way ANOVA for all seedling traits in both treatments allowed estimating variance components, coefficient of genotypic determination (CGD) and variation index (VI). Comparisons between populations were made using Tukey test (at 5% of probability). Phenotypic correlations among traits were calculated and then a path coefficient analysis separated direct and indirect effects at 100 and 0 mM NaCl. No significant interactions “Population × Treatment” were found for any character. The saline stress caused a pairing in the population means for the most traits. Coefficients of variation were mainly higher when the seedlings grew without stress (0 mM) because it allowed a greater potential genotypic expression. The absence of significant interactions denotes a good homeostatic capacity of the prairie grass facing that abiotic stress. Leaf length, shoot length and root dry matter were the variables with the largest direct and indirect effects. Our results showed an increase for them at salt and demonstrated intraspecific variation, possibly in relation with the origin sites. Plants under stress showed a marked resilience, in order to quickly restore the same biomass allocation patterns that occur in non-stress environment.

Fine-mapping and characterisation of genes on barley(Hordeum vulgare)chromosome 2H for salinity stress tolerance during germination

Salinity causes a detrimental impact on plant growth,particularly when the stress occurs during germination and early development stages.Barley is one of the most salt-tolerant crops;previously we mapped two quantitative trait loci(QTL)for salinity tolerance during germination on the short arm of chromosome 2 H using a CM72/Gairdner doubled haploid(DH)population.Here,we narrowed down the major QTL to a region of 0.341 or 0.439 Mb containing 9 or 24 candidate genes belonging to 6 or 20 functional gene families according to barley reference genomes v1 and v3 respectively,using two DH populations of CM72/Gairdner and Skiff/CM72,F_(2)and F;generations of CM72/Gairdner/;Spartacus CL,Two Receptorlike kinase 4(RLPK4)v1 or Receptor-like kinase(RLK)v3 could be the candidates for enhanced germination under salinity stress because of their upregulated expression in salt-tolerant variety CM72.Besides,several insertion/deletion polymorphisms were identified within the 3 rd exon of the genes between CM72 and Gairdner.The sequence variations resulted in shifted functional protein domains,which may be associated with differences in salinity tolerance.Two molecular markers were designed for selecting the locus with receptor-like protein kinase 4,and one was inside HORVU2 Hr1 G111760.1 or HORVU.MOREX.r3.2 HG0202810.1.The diagnostic markers will allow for pyramiding of 2 H locus in barley varieties and facilitate genetic improvement for saline soils.Further,validation of the genes to elucidate the mechanisms involved in enhancing salinity tolerance at germination and designing RLPK4 specific markers is proposed.For this publication,all the analysis was based on barley reference genome of2017(v1),and it was used throughout for consistence.However,the positions of the markers and genes identified were updated according to new genome(v3)for reference.