Salt-tolerant Varieties Research Articles

Salinity-induced Changes In Growth, Physiology And Yield Of Soybean Genotypes

Soybean (Glycine max L.) is mostly grown in the coastal region of Bangladesh, where salinity is a threat for potential harvest. So far there is no salt tolerant variety. In order to extricate high salt tolerant soybean genotypes, 13 selected advanced soybean lines, namely BD 2342, AGS 313, G 00207, Galarsum, G 00209, G 00343, G 00028, G 00221, G 00283, AGS 95, G 00062, G 00041 and BD 2330 along with two varieties viz. BU Soybean 2 and Shohag were grown in pots under polyvinyl house at BSMRAU, Gazipur during February to June 2021 following completely randomized design (CRD) with three replications. The plants were exposed to seawater of electrical conductivity (EC) of 5 dSm-1 and 10 dSm-1 from 2nd trifoliate stage till harvest, where control pots were irrigated with tap water (0.3 dSm-1). Results indicated that there was no significant variation in days to first flowering but significant variation was observed in maturity duration among the genotypes. In saline conditions BD 2330, G 00028 and AGS 313 survived longer days which were 96.36%, 80.29%, and 79.53% days to control at 10 dSm-1, respectively compared to other genotypes. Plants of other genotypes died earlier before reaching maturity, especially at 10 dSm-1. The genotype AGS313 expressed maximum leaf relative water content (RWC) at 5 dSm-1 salinity (97.51% of control), while BD2330 showed the highest RWC at 10 dSm-1 salinity (94.76%). The SPAD value showed stable or an increasing trends in BD 2330, AGS 313 and G 00028, where it was in decreasing trend in other genotypes under saline conditions. Unexpectedly, the leaf K-Na ratio did not show any significant relationship with the salt-tolerance among the genotypes. In case of number of filled pods/plant BD2330 produced the maximum (23.33) at 5 dSm-1 salinity, while the genotype AGS313 showed the highest (16.0) at 10 dSm-1 salinity. Genotypes other than BD2330, AGS313 and G00028 did not perform well in pod set, 100-seed weight and grain yield/plant under saline conditions, even at 5 dSm-1. However, even at the highest salinity (10 dSm-1) the genotypes G00028, BD2330 and AGS313 produced 2.0, 1.9 and 1.83 g/plant seeds, respectively. Whereas, most of the genotypes did not produce any seed at 10 dSm-1. It may be concluded that the genotypes BD2330, AGS313 and G00028 were relatively salt tolerant than other tested genotypes, and can be used as potential genetic resources for further field trials. Ann. Bangladesh Agric. (2022) 26 (1) : 29-48

Development of Retrotransposon-Based Molecular Markers for Characterization of Persea americana (Avocado) Cultivars and Horticultural Races

Persea americana (avocado) represents one of the most demanded food products worldwide, with an important impact in several agronomy-based economies. The avocado is one of the most salt-sensitive and valuable crops. It is therefore necessary to use salt-tolerant varieties, such as the West Indian, for cultivation in locations with soil salinity problems, such as the Canary Islands. Therefore, characterization of avocado cultivars is in demand, as well as development of molecular tools able to easily identify the main avocado cultivars and horticultural races. In the present work, inter-Primer Binding Site (iPBS) and Inter-Retrotransposon Amplified Polymorphism (IRAP) techniques, which are based on retrotransposon with Long Terminal Repeats (LTR), have been implemented for the first time in P. americana, allowing the characterization of genetic variation among cultivars from the three main horticultural races and the identification of potential P. americana LTR sequences. The iPBS approach showed clear advantages over its technical implementation, and allowed a better delimitation of horticultural races, especially when focused on West Indian cultivars. However, both techniques generated reproducible genetic fingerprints that not only allowed genetic characterization of each cultivar analyzed, but also revealed potential molecular markers for the identification of avocado cultivars and horticultural races.

Combining GWAS, Genome-Wide Domestication and a Transcriptomic Analysis Reveals the Loci and Natural Alleles of Salt Tolerance in Rice (Oryza sativa L.).

Soil salinity poses a serious threat to the sustainable production of rice (Oryza sativa L.) throughout the world. Thus, the detection of loci and alleles responsible for salt tolerance is fundamental to accelerating the improvement of rice and producing the resilient varieties that will ensure future harvests. In this study, we collected a set of 191 mini-core rice populations from around the world, evaluated their salt tolerance based on plant growth and development phenotypes at the seedling stage, and divided a standard evaluation score (SES) of visual salt injury into five different grades. We used ∼3.82 million single nucleotide polymorphisms (SNPs) to identify 155 significant SNPs and 275 genes associated with salt sensitivity based on a genome-wide association study (GWAS) of SES. In particular, two candidate genes, ZFP179 and OsDSR2, were associated with salt tolerance, and OsHKT1;1 was co-detected in the entire GWAS of all the panels and indica. Additionally, we investigated the transcriptional changes in cultivars 93-11 and PA64s under normal and salinity stress conditions and found 517 co-upregulated and 223 co-downregulated genes. These differentially expressed genes (DEGs) were highly enriched in “response to chemical” and “stress” based on the gene ontology enrichment analysis. Notably, 30 candidate genes that were associated with the salt tolerance analysis were obtained by integrating GWAS and transcriptomic DEG analyses, including 13 cloned genes that had no reports of tolerance to salt and 17 candidate genes whose functions were unknown. To further explore these genes and their alleles, we performed haplotype analysis, genome-wide domestication detection, and transcriptome analysis to breed improved varieties. This data and the genetic resources provided will be valuable for the development of salt tolerant rice varieties.

Genetic analysis and identification of VrFRO8, a salt tolerance-related gene in mungbean

Mungbean (Vigna radiata (L.) R. Wilczek) is an important legume crop of Asia. Salt concentrations typically causes major yield reductions in mungbean. Although the biochemical and genetic basis of salt tolerance-related gene are well studied in Arabidopsis and soybean, limited information concerning the salt tolerance-related genes in mungbean. To address this issue, we mined salt tolerance related genes using the survival rate trait and 160,1405 SNPs in 112 mungbean accessions. As a result, VrFRO8 significantly associated with salt-stress were identified in the GWAS analysis. The candidate gene VrFRO8 was evidenced by comparative genomics, transcriptome and RT-qPCR analysis. The expression level of VrFRO8 was significantly up-regulated (P-value = 0.001) after salt treatment compared with the control group. Moreover, 188 genes and 158 transcription factors related to salt-stress signal transduction pathway were mined, and 18 genes (18/188) had higher expression level in the salt-tolerant varieties than salt-sensitive varieties. And, the function of VrFRO8 was predicted in mungbean, the protein interaction between VrFRO8 and seven related-genes were found by molecular structure analysis. VrFRO8 might reduce SOD contents by influence Fe2+/Fe3+ ratio under the damage of salt stress. This study used multi-omics data to mine a key genes significantly associated with salt tolerance, and constructed a VrFRO8-related PPI network for salt tolerance, which would lay a solid foundation for further molecular biology research of VrFRO8 and mungbean breeding.

The Identification of Broomcorn Millet bZIP Transcription Factors, Which Regulate Growth and Development to Enhance Stress Tolerance and Seed Germination.

Broomcorn millet (Panicum miliaceum L.) is a water-efficient and highly salt-tolerant plant. In this study, the salt tolerance of 17 local species of broomcorn millet was evaluated through testing based on the analysis of the whitening time and the germination rate of their seeds. Transcriptome sequencing revealed that PmbZIP131, PmbZIP125, PmbZIP33, PmABI5, PmbZIP118, and PmbZIP97 are involved in seed germination under salt stress. Seedling stage expression analysis indicates that PmABI5 expression was induced by treatments of high salt (200 mM NaCl), drought (20% W/V PEG6000), and low temperature (4 °C) in seedlings of the salt-tolerant variety Y9. The overexpression of PmABI5 significantly increases the germination rate and root traits of Arabidopsis thaliana transgenic lines, with root growth and grain traits significantly enhanced compared to the wild type (Nipponbare). BiFC showed that PmABI5 undergoes homologous dimerization in addition to forming a heterodimer with either PmbZIP33 or PmbZIP131. Further yeast one-hybrid experiments showed that PmABI5 and PmbZIP131 regulate the expression of PmNAC1 by binding to the G-box in the promoter. These results indicate that PmABI5 can directly regulate seed germination and seedling growth and indirectly improve the salt tolerance of plants by regulating the expression of the PmNAC1 gene through the formation of heterodimers with PmbZIP131.

Differential Responses to Salt Stress in Four White Clover Genotypes Associated With Root Growth, Endogenous Polyamines Metabolism, and Sodium/Potassium Accumulation and Transport

Selection and utilization of salt-tolerant crops are essential strategies for mitigating salinity damage to crop productivity with increasing soil salinization worldwide. This study was conducted to identify salt-tolerant white clover (Trifolium repens) genotypes among 37 materials based on a comprehensive evaluation of five physiological parameters, namely, chlorophyll (Chl) content, photochemical efficiency of PS II (Fv/Fm), performance index on an absorption basis (PIABS), and leaf relative water content (RWC), and to further analyze the potential mechanism of salt tolerance associated with changes in growth, photosynthetic performance, endogenous polyamine metabolism, and Na+/K+ uptake and transport. The results showed that significant variations in salt tolerance were identified among 37 genotypes, as PI237292 and Tr005 were the top two genotypes with the highest salt tolerance, and PI251432 and Korla were the most salt-sensitive genotypes compared to other materials. The salt-tolerant PI237292 and Tr005 not only maintained significantly lower EL but also showed significantly better photosynthetic performance, higher leaf RWC, underground dry weight, and the root to shoot ratio than the salt-sensitive PI251432 and Korla under salt stress. Increases in endogenous PAs, putrescine (Put), and spermidine (Spd) contents could be key adaptive responses to salt stress in the PI237292 and the Tr005 through upregulating genes encoding Put and Spd biosynthesis (NCA, ADC, SAMDC, and SPDS2). For Na+ and K+ accumulation and transport, higher salt tolerance of the PI237292 could be associated with the maintenance of Na+ and Ca+ homeostasis associated with upregulations of NCLX and BTB/POZ. The K+ homeostasis-related genes (KEA2, HAK25, SKOR, POT2/8/11, TPK3/5, and AKT1/5) are differentially expressed among four genotypes under salt stress. However, the K+ level and K+/Na+ ratio were not completely consistent with the salt tolerance of the four genotypes. The regulatory function of these differentially expressed genes (DEGs) on salt tolerance in the white clover and other leguminous plants needs to be investigated further. The current findings also provide basic genotypes for molecular-based breeding for salt tolerance in white clover species.

Different responses of rice cultivars to salt stress and the underlying mechanisms

<p id="C3">The objective of this study is to elucidate the responses of physiological traits and yield with different salt stress to salt-tolerant and salt-susceptible rice cultivars. Five salt-tolerant rice cultivars and two salt-susceptible rice cultivars were grown in pots with five different salt concentration levels including 0, 1, 2, 2.5, and 3 g kg^-1 of per pot for two years. Results showed that the yields of salt-tolerant cultivars were less reduced than that of salt-susceptible cultivars, and salt-tolerant cultivars was able to tolerate higher salt concentration of 2.5 g kg^-1. Salt-tolerant varieties produced higher grain yield mainly due to the greater total spikelets per area and higher filled grain percentage under salt stress. Salt-tolerant rice cultivars also had higher activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), higher contents of osmotic substances such as fructose, trehalose, and sorbitol, and higher K⁺/Na⁺ ratio from mid-tillering to heading. The crop growth rate from tillering to jointing and from heading to maturity, and photosynthetic rate at heading stage were higher in salt-tolerant cultivars than in salt-susceptible cultivars. The above results revealed that the differences in grain yields between salt-tolerant and salt-susceptible rice varieties were mainly due to the performances of physiological traits at mid-tillering, panicle initiation, and heading stages. These growth stages were the key stages that determined the number of panicles, spikelets per panicle, and the percentage of filled grains. The better physiological traits in the salt-tolerant rice varieties during key stages were the basis for higher grain yield. The results of this study could be helpful for the physiological researches and the breeding of salt-tolerant rice.

Study on the Effect of Salt Stress on Yield and Grain Quality Among Different Rice Varieties.

Salt is one of the main factors limiting the use of mudflats. In this study, the yield, quality, and mineral content of rice seeds under salt stress were investigated. A pot experiment was conducted with Yangyugeng2, Xudao9, and Huageng5 under 0, 17.1, 25.6, and 34.2 mM NaCl of salt concentration treatments. The results showed that salt stress can significantly decrease panicle number, grain number per panicle, 1000-grain weight and yield of rice, and the panicle number was among other things the main cause of yield loss under saline conditions. When the salt concentration is less than 34.2 mM NaCl, the salt stress increases the brown rice rate and milled rice rate, thus significant increasing head milled rice rate of salt-sensitive varieties but decreasing in salt-tolerant varieties. In addition, the grain length is more sensitive than grain width to salt stress. This study also indicates that different varieties of rice exhibit different salt tolerance under salt stress, the three rice varieties in this study, in order of salt tolerance, are Xudao9, Huageng5, and Yangyugeng2. Salt stress will increase the appearance, viscosity, degree of balance, and taste value, and decrease the hardness of rice when salt concentration is less than 17.1 mM NaCl in Yangyugeng2 and Huageng5 or 25.6 mM NaCl in Xudao9. The differences in starch pasting properties among rice varieties in this study are larger than those caused by salt stress. The uptake capacity of K, Mg, P, S, and Cu ions in the seeds of different rice varieties significantly vary, and salt stress causes significant differences in the uptake capacity of K, Na, and Cu ions in rice seeds. Rice varieties with high salt tolerance can be selected for the development and utilization of mudflats, and low concentration of salt stress will increase the rice quality, all of which are meaningful to agricultural production.

A REVIEW ON RESPONSE OF RICE (ORYZA SATIVA L.) UNDER SALINITY STRESS IN TERMS OF ITS GROWTH, DEVELOPMENT, CHARACTERISTICS, AND BIOCHEMICAL LEVEL

Salinity is an important environmental factor that limits growth and yield of rice. It currently affects millions of hectares of soils otherwise suitable for rice cultivation in South and Southeast Asia. Attempts to understand the mechanisms of salt tolerance have revealed several key enzymes and altered biochemical pathways to infer crop resistance to salt stress. Over the past few decades, we have witnessed extensive research into the development of salt-tolerant varieties through traditional methods, improvisation with modern molecular tools and techniques. Rice (Oryza sativa L.) is the staple food crop in many countries around the world. Being a glycophyte by nature, its growth can be severely affected in the presence of excessive salt. Rice is particularly susceptible to salinity in the early vegetative and late reproductive stages, and the response of crops to excess salt toxicity at the biochemical and molecular levels as well as at the physiological level has been well studied and documented. This review aims to summarizes the different responses of rice, especially to salt toxicity, exhibited the detailed physiological, morphological, molecular and biochemical changes that occur in the rice plants.

Genetic Mapping to Detect Stringent QTLs Using 1k-RiCA SNP Genotyping Platform from the New Landrace Associated with Salt Tolerance at the Seedling Stage in Rice

Rice is the world’s most important food crop, providing the daily calorie intake for more than half of the world’s population. Rice breeding has always been preoccupied with maximizing yield potential. However, numerous abiotic factors, such as salt, cold, drought, and heat, significantly reduce rice productivity. Salinity, one of the major abiotic stresses, reduces rice yield worldwide. This study was conducted to determine new quantitative trait loci (QTLs) that regulate salt tolerance in rice seedlings. One F2:3 mapping population was derived from a cross between BRRI dhan49 (a popular but sensitive rainfed rice variety) and Akundi (a salt-tolerant rice landrace in Bangladesh used as a donor parent). The 1k-Rice Custom Amplicon (1k-RiCA) single-nucleotide polymorphism (SNP) markers were used to genotype this mapping population. After removing segregation distortion and monomorphic markers, 884 SNPs generated a 1526.8 cM-long genetic linkage map with a mean marker density of 1.7 cM for the 12 linkage groups. By exploiting QGene and ICIM-ADD, a sum of 15 QTLs for nine traits was identified in salt stress on seven chromosomes. Four important genomic loci were identified (qSES1, qSL1, qSUR1 and qRL1) on chromosome 1. Out of these 15 QTLs, 14 QTLs are unique, as no other study has mapped in the same chromosomal location. We also detected 15 putative candidate genes and their functions. The ICIM-EPI approach identified 43 significant pairwise epistasis interactions between regions associated with and unassociated with QTLs. Apart from more well-known donors, Akundi serves as an important new donor source for global salt tolerance breeding initiatives, including Bangladesh. The introgression of the novel QTLs identified in this study will accelerate the development of new salt-tolerant varieties that are highly resistant to salt stress using marker-enabled breeding.

Comparative transcriptomic analysis of the super hybrid rice Chaoyouqianhao under salt stress

BackgroundSoil salinization is a threat to food security. China is rich in saline land resources for potential and current utilization. The cultivation and promotion of salt-tolerant rice varieties can greatly improve the utilization of this saline land. The super hybrid rice Chaoyouqianhao (CY1000) is one of the most salt-tolerant rice varieties and is widely used, but the molecular mechanism underlying its salt tolerance is not clear.ResultsIn this study, the characteristics of CY1000 and its parents were evaluated in the field and laboratory. The results showed that aboveground parts of CY1000 were barely influenced by salt stress, while the roots were less affected than those of its parents. A comparative transcriptomic strategy was used to analyze the differences in the response to salt stress among the male and female parents of CY1000 at the seedling stage and the model indica rice 93–11. We found that the salt tolerance of CY1000 was mainly inherited from its male parent R900, and its female parent GX24S showed hardly any salt tolerance. To adapt to salt stress, CY1000 and R900 upregulated the expression of genes associated with soluble component synthesis and cell wall synthesis and other related genes and downregulated the expression of most genes related to growth material acquisition and consumption. In CY1000 and R900, the expression of genes encoding some novel key proteins in the ubiquitination pathway was significantly upregulated. After treatment with MG-132, the salt tolerance of CY1000 and R900 was significantly decreased and was almost the same as that of the wild type after salt stress treatment, indicating that ubiquitination played an important role in the salt tolerance mechanism of CY1000. At the same time, we found that some transcription factors were also involved in the salt stress response, with some transcription factors responding only in hybrid CY1000, suggesting that salt tolerance heterosis might be regulated by transcription factors in rice.ConclusionOur results revealed that the ubiquitination pathway is important for salt tolerance in rice, and several novel candidate genes were identified to reveal a novel salt tolerance regulation network. Additionally, our work will help clarify the mechanism of heterosis in rice. Further exploration of the molecular mechanism underlying the salt tolerance of CY1000 can provide a theoretical basis for breeding new salt-tolerant rice varieties.

Antioxidative and osmoprotecting mechanisms in carrot plants tolerant to soil salinity

Soil salinization is a growing problem for agriculture worldwide and carrot is one the most salt-sensitive vegetable species. However, some varieties are capable of withstanding high salt concentrations due to unknown genetic and physiological mechanisms. The aim of this work was to reveal protecting mechanisms against osmotic and ionic stresses that contribute to salt tolerance in carrot. For this purpose, changes in biochemical traits due to soil salinity occurring in the salt-tolerant and salt-sensitive plants were determined. The obtained results showed that the tolerance of the salt-tolerant variety was partially determined constitutively, however, the exposition to saline soil triggered a physiological response that was more evident in the root than in the leaves. The most noticeable changes were the high increase in the content of osmoprotective proline and other low molecular antioxidants such as glutathione and ascorbic acid, and the decrease in the ratio of reduced to oxidized glutathione forms. These changes imply an efficient operation of the ascorbate–glutathione cycle that together with a high activity of antioxidative enzymes such as peroxidases, indicate on the induction of mechanisms associated mainly with protection against excessive reactive oxygen species.

Foliar Application of Spermidine Reduced the Negative Effects of Salt Stress on Oat Seedlings.

The effects of foliar application of spermidine (Spd) on the physiological aspects of salt-stressed oat seedlings were studied under greenhouse conditions. At the seedling stage, the salt-sensitive variety, namely, Caoyou 1 and the salt-tolerant variety, namely, Baiyan 2 were treated with 70 and 100 mM of salt, followed by the foliar application of 0.75 mM Spd or distilled water. Results showed that Spd application increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX), and reduced the rate of O2⋅– production and the accumulation of H2O2 and malondialdehyde (MDA). In addition, it increased the level of zeatin riboside (ZR) and the content of endogenous polyamines. The application of Spd increased the contents of soluble sugar, soluble protein, and free proline and helped maintain the osmotic balance of oat leaves. At the same time, foliar Spd treatment helped in maintaining the ion nutrition balance. Specifically, it reduced the content of Na+ and thereby stabilized the ratio of Na+/K+, Na+/Ca2+, and Na+/Mg2+. The effects of Spd application were more obvious for the salt-sensitive cultivar Caoyou 1 and under the lighter 70 mM salt stress.

Genotypic Variation for Salt Tolerance within and between ‘Alamo’ and ‘Kanlow’ Switchgrass (Panicum virgatum L.) Cultivars

Switchgrass tolerates nutrient and water limitations; however, high salt concentrations may inhibit its production. Therefore, the salt tolerance potential of switchgrass needs to be enhanced for economic production. The objective of this study was to determine the differences within and between two lowland cultivars of switchgrass for growth, stomatal morphology, photosynthetic pigments content, and mineral traits. A greenhouse study was conducted on 18 sublines, derived from the cultivars Alamo (A) and Kanlow (K), plus a salt-tolerant and sensitivity check (20 genotypes). A split-plot randomized complete block design was used with three replications per treatment (0, 5, 10, and 20 dS m−1 NaCl). High salt concentrations (10 and 20 dS m−1 NaCl) reduced shoot biomass, stem diameter, and plant height up to 21, 11, and 16%, respectively, compared to the control for all genotypes (p &lt; 0.05). Chlorophyll a and adaxial stomata width were moderately correlated with growth traits under saline conditions (r = 0.49 to 0.56, p &lt; 0.05). The sublines 12A-227, TN13006-04, 12A-259, 12K-247, and TN13009-08 had better growth and accumulated less salt in shoot biomass than both checks. These results indicate that differences exist within and between the Alamo and Kanlow sublines, and it is possible to breed improved cultivars with increased salt tolerance.

Assessment of Salinity Tolerance Deploying Antioxidant Defense Systems in Gerbera Jamesonii

Inconsistency in the environment exposes plants to various abiotic stresses. This results in damage of a plant’s cellular components due to excessive accumulation of unstable reactive oxygen. Besides, it also disrupts enzymatic/non-enzymatic detoxification mechanisms in plants making them more sensitive. Salinity is one such abiotic stress which disrupts regular physiological mechanisms in plants. In this study, we examined the effects of salinity using NaCl in four different genotypes of Gerbera jamesonii cv Bolus, an important ornamental plant of family Compositae. We hypothesized that, upon treatment with NaCl (50, 100, 150 200mM concentration), alterations in the morphological features along with elevated levels of H2O2, MDA, proline, and degradation of chlorophyll will be observed. The enzymatic antioxidant defenses were also hypothesized to differ among genotypes based on their level of tolerance. These parameters were monitored on the 5th and 20th day of NaCl treatment and results were recorded. The observations suggest that 1. the Lattara genotype of Gerbera is sensitive to NaCl and 2. Faith is tolerant, while 3. Alcatras and Basic are moderately tolerant. These findings accompanied by further research on the physiological parameters responsible for attaining salinity tolerance may help in developing salt-tolerant varieties in Gerbera. Future studies on decoding molecular networks associated with the antioxidative defense system in Gerbera can help improve breeding and create novel germplasm in various ornamentally important plants besides Gerbera.

Effect of sodium chloride on physiological and biochemical indices of wheat and maize genotypes

Aim. Study the effect of sodium chloride on the physiological and biochemical characteristics of wheat and maize genotypes, to identify varieties tolerant to salinity. To create new salt-tolerant varieties of wheat and maize, a comparative analysis of the physiological and biochemical parameters of the parental and hybrid plants was carried out. Methods. Physiological parameters such as chlorophyll content, relative water content, and PSII activity have been studied in parental forms and hybrids. Results. Based on the physiological indices determined during the grain filling stage, the highest tolerance was manifested by the parental forms, Garabagh, Gobustan, and the hybrids, ♀Garabagh×♂Gobustan, ♀Garabagh×♂Mirbashir, ♀Garabagh×♂Sharg. The varieties Gurur and Zagatala-68 and hybrid “Gurur×Zagatala-68” were resistant to 200 mmol salt concentration.The varietiesofmaize Gurur and Zagatala-68 were resistant to 200 mmol salt concentration

Comprehensive Transcriptome Analysis Uncovers Distinct Expression Patterns Associated with Early Salinity Stress in Annual Ryegrass (Lolium Multiflorum L.).

Soil salination is likely to reduce crop production worldwide. Annual ryegrass (Lolium multiflorum L.) is one of the most important forages cultivated in temperate and subtropical regions. We performed a time-course comparative transcriptome for salinity-sensitive (SS) and salinity-insensitive (SI) genotypes of the annual ryegrass at six intervals post-stress to describe the transcriptional changes and identify the core genes involved in the early responses to salt stress. Our study generated 215.18 Gb of clean data and identified 7642 DEGs in six pairwise comparisons between the SS and SI genotypes of annual ryegrass. Function enrichment of the DEGs indicated that the differences in lipid, vitamins, and carbohydrate metabolism are responsible for variation in salt tolerance of the SS and SI genotypes. Stage-specific profiles revealed novel regulation mechanisms in salinity stress sensing, phytohormones signaling transduction, and transcriptional regulation of the early salinity responses. High-affinity K+ (HAKs) and high-affinity K1 transporter (HKT1) play different roles in the ionic homeostasis of the two genotypes. Moreover, our results also revealed that transcription factors (TFs), such as WRKYs, ERFs, and MYBs, may have different functions during the early signaling sensing of salt stress, such as WRKYs, ERFs, and MYBs. Generally, our study provides insights into the mechanisms of the early salinity response in the annual ryegrass and accelerates the breeding of salt-tolerant forage.

SALT AND ABA RESPONSE ERF1 improves seed germination and salt tolerance by repressing ABA signaling in rice.

Rice (Oryza sativa) germination and seedling establishment, particularly in increasingly saline soils, are critical to ensure successful crop yields. Seed vigor, which determines germination and seedling growth, is a complex trait affected by exogenous (environmental) and endogenous (hormonal) factors. Here, we used genetic and biochemical analyses to uncover the role of an APETALA2-type transcription factor, SALT AND ABA RESPONSE ERF1 (OsSAE1), as a positive regulator of seed germination and salt tolerance in rice by repressing the expression of ABSCISIC ACID-INSENSITIVE5 (OsABI5). ossae1 knockout lines exhibited delayed seed germination, enhanced sensitivity to abscisic acid (ABA) during germination and in early seedling growth, and reduced seedling salt tolerance. OsSAE1 overexpression lines exhibited the converse phenotype, with increased seed germination and salt tolerance. In vivo and in vitro assays indicated that OsSAE1 binds directly to the promoter of OsABI5, a major downstream component of the ABA signaling pathway and acts as a major regulator of seed germination and stress response. Genetic analyses revealed that OsABI5-mediated ABA signaling functions downstream of OsSAE1. This study provides important insights into OsSAE1 regulation of seed vigor and salt tolerance and facilitates the practical use of OsSAE1 in breeding salt-tolerant varieties suitable for direct seeding cultivation.

Activities of Antioxidant Enzymes in Six Rice (Oryza sativa L.) Varieties at Seedling Stage under Increasing Salinity Stress

Present study deals with the activities of antioxidant enzymes in six rice (Oryza sativa L.) varieties, namely Sadamota, Patnai, Dhoodeshwar, Ghewas, Gontrabidan-2 and Malabati, which were subjected to increasing salinity stress (0.05 M, 0.1 M and 0.15 M NaCl) from germination to seedling stage along with control under laboratory conditions. The main objective of this study was to find out variations in the activities of antioxidant enzymes which can differentiate tolerance to salinity. Increasing salinity stress induced gradual increase in the activity of Superoxide dismutase (SOD), Peroxidase, Catalse (CAT), Glutathione reductase (GR), and Ascorbate peroxidase (APX). High activities of SOD, CAT, GR and APX were observed in Doodeshwar and Malabti under salinity stress. High levels of antioxidant enzymes (SOD, CAT, APX and GR) under salinity stress will contribute to salinity tolerance in rice varieties Doodeshwar and Malabathi. Significant genotype×salt treatment interaction suggested the differential effect of stress on genotype for antioxidant enzymes. Catalse activity showed significant (p&lt;.001) positive correlation with SOD (r=.818), GR (r=.624), and APX (r=.593). High levels of Lipid peroxidation was noticed in Ghewas, Gonrabidan-2 and Sadamota, indicating higher membrane damage when compare to Doodeshwar and Malabathi under salt stress. Doodeshwar and Malabathi can be recommended as salt tolerant varieties for advance evaluation at field level. Analysis of antioxidant enzymes from rice seedlings exposed to salinity stress will provide rapid screening method and time saving. Mass screening will be conducted for preliminary selections which can be used in field conditions.

Weighted average absolute scores of BLUPs (WAASB) based selection of stable Asiatic cotton genotypes for the salt affected Vertisols of India

Cotton is a major cash crop classified as moderately tolerant to salt stress (threshold ECe = 7.7 dS m-1). In the present study, a set of 21 homozygous advanced breeding lines of cotton (Gossypium herbaceum L.), including one salt tolerant variety G Cot 23 was evaluated over three years to identify stable high yielding genotypes under salt stress. Weighted Average Absolute Scores of BLUPs (WAASB) stability index, which is based on single value decomposition of BLUP, was employed for this purpose. Among the 21 genotypes, CSC-025 and CSC-057 showed the highest boll weight (59.67 and 57.33 g/20 boll), seed cotton yield (1818 and 1570 Kg ha-1) and leaf K/Na ratio (9.6 and 5.6) over the check variety G Cot 23. Considering both WAASB stability index and mean trait values, CSC-025, CSC-057 and G Cot 23 were found promising for all traits and can be considered for deployment in salt-affected Vertisols of India.