Variation In Salinity Tolerance Research Articles

The Effects of Exogenous Iron on the Photosynthetic Performance and Transcriptome of Rice under Salt–Alkali Stress

Saline-sodic stress induces iron deficiency in rice, reduces leaf photosynthetic performance, and inhibits yield enhancement. In this study, we investigated the effects of exogenous Fe on the photosynthetic performance and transcriptomics of two different tolerant rice cultivars CB9 (Changbai9: saline tolerant cultivar) and TH899 (Tonghe899: saline sensitive cultivar) with 4-week-old Fe-deficient rice seedlings under saline stress, Fe deficiency stress, and both co-stresses. The results showed that under saline and alkaline stress, spraying exogenous iron favored the growth of the two cultivars of rice, with a 32.68% and 39.82 increase in fresh weight, a 2.20-fold and 2.16-fold increase in pigment, respectively, and an 80.28% and 100.00% increase in net photosynthetic rate, respectively, as compared with the iron-deficiency treatment. Transcriptome analysis showed that we found a higher number of differentially expressed genes (7785 differentially expressed genes) in response to exogenous Fe spraying in the soda-salt sensitive variety TH899. The differentially expressed genes that are common to the two cultivars are primarily enriched in metabolic pathways, including plant hormone signal transduction (map04075) and phenylpropanoid biosynthesis (map00940). Specifically, among these genes, 14 are differentially expressed in the carotenoid biosynthetic metabolic pathway. The differentially expressed genes specific to the salinity-tolerant variety CB9 were mainly enriched in the metabolic pathways of glyoxylate and dicarboxylic acid methyl metabolism (map00630), and carbon fixation in photosynthetic organisms (map00710), among which 20 genes were significantly expressed in the pathway for carbon fixation in photosynthetic organisms (map00710). The research results offer specific theoretical support for enhancing the salt tolerance of rice.

Histological characteristics of the Indigofera zollingeriana mutant 2 (M2) population resulting from gamma-ray irradiation grown in saline soil

Abstract Indigofera zollingeriana plant has been used by Farmers as a feed plant, which contains high protein and is very good as a source of forage to increase livestock productivity. However, its development is constrained by the limited availability of land, so it is necessary to conduct research for its development on marginal land. This study aims to evaluate the effect of salinity on histological diversity of four populations of mutant 2 (M2) I. zollingeriana resulting from gamma-ray irradiation in saline fields. The study was conducted in a randomized block design (RBD) with four treatments of the M2 I. zollingeriana population resulting from gamma-ray irradiation with 6 replications. Plant population were irradiated at 0, 100, 200, and 300 gray. Parameters observed were: characteristics of stomata, tricoma and cuticle. The results showed that the diversity of stomata and cuticles were not significantly different in each treatment. However, the number of tricoma have a significant effect, namely on the parameter number of tricoma. The highest number of tricoma was found in the 200 gray with a number of 17. Significantly different from the other treatments (0, 100 and 300 gray) each obtained a total of 9.83, 12.17 and 11.67. It was concluded that the radiation dose at the 200 gray level has the genetic potential to be continued at the adaptation test stage to further support the formation of new salinity tolerant Indigofera varieties.

Evolution and plasticity of physiological traits in the collembolan Orchesella villosa at fine spatial scales within the city

Abstract Divergent natural selection caused by spatial environmental variation can lead to local adaptation and evolutionary divergence between populations, even those within close proximity to one another. This, however, is only one possibility among other outcomes, such as the evolution of adaptive phenotypic plasticity or local maladaptation. Cities, as fragmented landscapes with high environmental variability across microgeographic scales, present an excellent venue to explore these possible outcomes. Here, we use common garden experiments to explore the potential for microgeographic divergence of physiological traits among populations of a collembolan, Orchesella villosa, living within the footprint of a single city. We assessed if intra-urban variation in the intensity of the heat island effect and soil salinity has led to evolutionary divergence in heat tolerance and salinity tolerance, respectively. While we found little variation in salinity tolerance among populations, there was evidence for both plasticity and evolutionary divergence among populations in response to variation in the urban heat island. Although the adaptive nature of these specific responses is not known, we suggest that cities, and human modified habitats in general, promote evolutionary divergence at small spatial scales by creating barriers to dispersal and imposing divergent selective environments within previously contiguous habitats.

Germination Capacity of Different Wheat Genotypes Under Salt Stress

Salinity stress can negatively impact the growth and productivity of young wheat seedlings, leading to diminished grain yield and quality. Poor salinity management can cause soil sodicity in farming soils, where sodium (Na) binds to negatively charged clay, causing clay swelling and dispersal, subsequently decreasing the crop yield. Thus, the use of salinity tolerant varieties can be a plausible solution. This article investigates the effects of salinity stress on the germination and early seedling growth of 15 wheat genotypes in Bangladesh. The seeds were exposed to four levels of salinity (0, 6, 9, and 12 dS/m) and various germination parameters were measured, such as water imbibition, germination rate, seedling tissue water content, and seedling vigour index. The results showed significant differences among the genotypes and the salinity levels for all the parameters. BARI Gom 25 was found to be the most tolerant genotype, followed by BARI Gom 24, BARI Gom 29, and Binagom-1. The article also discussed the implications of these findings for saline soil remediation and wheat production in coastal areas of Bangladesh

Development of early maturing salt-tolerant rice variety KKL(R) 3 using a combination of conventional and molecular breeding approaches.

Introduction: Soil salinity poses a severe threat to rice production, resulting in stunted growth, leaf damage, and substantial yield losses. This study focuses on developing an early maturing seedling stage salinity tolerant rice variety by integrating conventional breeding methods with marker assisted breeding (MAB) approaches. Methods: Seedling-stage salinity tolerance Quantitative Trait Locus (QTL) "Saltol" from the salt-tolerant parent FL478 was introduced into the high-yielding but salt-sensitive rice variety ADT 45. This was achieved through a combination of conventional breeding and MAB. The breeding process involved rigorous selection, screening, and physiological parameter assessments. Results: KKL(R) 3 (KR 15066) identified as the top performing Recombinant Inbred Line (RIL), consistently demonstrating maximum mean grain yields under both salinity (3435.6kg/ha) and normal (6421.8kg/ha) conditions. In comparison to the early maturing, salt-tolerant national check variety CSR 10, KKL(R) 3 exhibited a substantial yield increase over 50%. Discussion: The notable improvement observed in KKL(R) 3 positions it as a promising variety for release, offering a reliable solution to maximize yields, ensure food security, and promote agricultural sustainability in both saline and non-saline environments. The study highlights the effectiveness of MAB in developing salt-tolerant rice varieties and emphasizes the significance of the Saltol QTL in enhancing seedling stage salinity tolerance. The potential release of KKL(R) 3 has the capacity to revolutionize rice production in salt affected regions, providing farmers with a reliable solution to maximize yields and contribute to food security while ensuring agricultural sustainability.

Impact of Paddy Varietal Demonstrations in Adoption, Knowledge Gain and Economic Perspective of Tiruvallur District, T.N., India

Krishi Vigyan Kendra, Tiruvallur has been instrumental in conducting frontline demonstrations on high yielding, pest and disease resistant, submergence and salinity tolerant paddy varieties like CO 51, TKM 13, CR 1009 Sub 1 and TRY 3 in order to improve the existing yield level, net returns and also to address the specific environment related issues faced by the farmers. The KVK, Tiruvallur and the Department of Agriculture conducted varietal demonstrations and extension activities resulting in the adoption of CO 51 across 11,580 ha (25.7% of short-duration paddy area) and TKM 13 across 8,915 ha (17.29% of mediumduration paddy area). CO 51 provided an additional income of Rs. 24,935/ha over ADT 43, with a cost saving of Rs. 5,510/ha. While TKM 13 yielded Rs. 25,330/ha more than BPT 5204, with a cost saving of Rs. 8,600/ha. Economic impact realized by way of cultivating CO 51 in an area of 11580 ha and TKM 13 in 8915 ha is 28.87 and 22.58 crores respectively. The introduction of CR 1009 Sub 1 in coastal area has helped farmers realize additional income of Rs.24150/ha over the check variety BPT 5204 and cost saving of Rs.5650/ ha with economic gain of Rs. 72.45 lakhs in 300ha. The introduction of TRY 3 variety has gained popularity among the coastal farmers and cultivated in about 215 ha and earned an economic gain of Rs. 7,33,150 to the farmers apart from addressing problems due to salinity like poor establishment and grain sterility. Cost saving of Rs. 3700/ha and additional net income of Rs.3410 over the check variety BPT 5204 has also been realized. This study clearly indicates the higher economic gains attained by the farmers. The area spread of the popular varieties shows an increasing trend and more area coverage is expected in the coming years. The knowledge gain by the farmers of various blocks of Tiruvallur had significantly improved after intervention where 82-86 per cent farmers had more than 50% knowledge about the high yielding varieties.

The Genetic Variability of Indonesian Local Foxtail Millet Accession Based on Agro-morphological Traits and Early Salinity Tolerance Evaluation Utilizing SiDREB2-based SNAP Marker

Foxtail millet (Setaria italica L. Beauv.) is a grain-producing crop with high nutritional benefits and adaptability to broad environmental conditions. Indonesian local foxtail millet accessions are valuable genetic resources for crop improvement of the species. This study aims to assess the biodiversity of Indonesian local foxtail millet accessions and estimate their salinity tolerance level utilizing the SiDREB2-based SNAP marker and early evaluation at the seedling stage. Our results showed that eight Indonesian local foxtail millet accessions, namely Toraja, Mauliru-2, Hambapraing, NTB-1, ICERI-5, ICERI-6, Botok-4, and Botok-10, had high variability based on agro-morphological traits. The Hambapraing and Mauliru-2 were the potential accessions with high yield estimates (2.33 ton.ha-1 and 1.93 ton.ha-1) and early harvest time (<110 DAT). ICERI-6 was indicated as a salinity-tolerant genotype based on the SiDREB2-based marker and early salinity evaluation at the seedling stage, while Toraja, Mauliru-2, NTB-1, and Botok-4 were categorized as sensitive genotypes. Germplasm variability and the estimated salinity tolerance level of Indonesian local foxtail millet accessions presented in this study serve as essential information in the foxtail millet breeding for high productivity, early harvest time, and salinity tolerant variety.

Evaluating salinity effects on transgenic soybean harboring a cytokinin dehydrogenase gene at early growth stage

Soil salinization, along with drought, is a natural threat that has a great impact on agricultural production in many locations throughout the world. The cytokinin oxidases/dehydrogenases (CKXs) play an essential role in determining plant CK levels and several of which have been modulated to improve abiotic stress tolerance. In this study, the aim was to investigate whether there were differential effects of salinity on wild-type (WT) soybean (Glycine max L.) plants and a transgenic soybean line harboring GmCKX13, which had previously been identified as a responsive gene to osmotic stress. The effects of salt stress were monitored by deploying different concentrations of NaCl. According to the obtained results, the transgenic plants could maintain a better germination rate and radicle growth than the WT plants after a 4-day treatment of 200 mM NaCl. In addition, the transgenic seedlings also displayed a more vigorous shoot and root growth with a larger biomass production under the adverse condition. The analytic data revealed that advantages acquired by the transformed plants at least came from the better capacity to reserve water in the tissue and lower stress damage, as indicated by a lower malondialdehyde content. Taking these findings together, it is suggested that modulating the expression of CKX13 could contribute to better salt tolerance in soybeans, providing the foundation for conducting more elaborate studies in the future and paving the pathway for the development of elite salinity-tolerant varieties.

EFFECT OF SALT STRESS ON THE IMBIBITION CURVE OF COWPEA SEEDS

The salinity of soil and water of irrigation can cause negative effects to agriculture by affecting the development and productivity of the cultivated species. These effects can be mitigated with the cultivation of salinity-tolerant varieties. The objective of this study was to evaluate the effect of salinity on the water imbibition curve during the germination process in cowpea seed and the response of different cultivars. An experiment was conducted in a factorial scheme, composed of three cultivars (BRS Marataoã, BRS Pajeu and BRS Tumucumaque) and four levels of salt stress, obtained by NaCl solutions at concentrations of 50, 100 and 150 mM and control, distilled water. The treatments were arranged in a completely randomized design, with four repetitions. The variables analyzed were the pattern of imbibition curve and final seed water content. It was found that the evaluated cultivars do not present the three-phase pattern for the seed soaking curve, in the absence or presence of salinity. There is variability for the pattern of the seed soaking curve among BRS Marataoã, BRS Pajeu and BRS Tumucumaque cowpea cultivars. Salinity acts by reducing the water content of cowpea seeds during the germination process and causes alteration in the pattern of the water soaking curve by the seeds. The cultivar BRS Tumucumaque shows higher tolerance to the reduction of seed water content under salt stress conditions when compared to the cultivars BRS Pajeu and BRS Marataoã.

Soil salinity management practices in coastal area of Bangladesh: a review

Soil salinity is a significant threat to agriculture and livelihood, particularly in the Southern coastal areas of Bangladesh. Soil salinity is extended from 0.833 to 1.056 million hectares (about), with an increase of 26% between 1973 and 2009. Out of about 1.689 million hectares of coastal land, about 1.056 million hectares are affected by soil salinity of various degrees covering 49 Upazila (sub-district) of 19 districts. About 0.328, 0.274, 0.189, 0.161, and 0.101 million hectares of land are affected by very slight (S1), slight (S2), moderate (S3), strong (S4), and very strong salinity (S5), respectively. Data recorded by SRDI manifests new ingression of salinity in Narail (18.71 ha), Jashore (14.99 ha), Barishal (13.96 ha), Gopalgonj (6.27 ha), Jhalakati (4.69 ha), and Madaripur (0.72 ha) districts. Soil salinity also encroached a large area of Bhola (53.84 ha), Patuakhali (40.08 ha), Khulna (27.92 ha), and Bagerhat (23.14 ha), besides minor ingression in other districts. The salinity level is almost double (2.8-18.5 to 4.0-42.8 dS/m) from 1973 to 2009 in Sharankhola Upazila of Bagerhat district, Dumuria Upazila of Khulna district and Shyamnagar Upazila of Satkhira district (SRDI, 2010). Different causes are involved in increasing the water and soil salinity of the coastal area of Bangladesh, like withdrawal of fresh river water from upstream, irregular rainfall, faulty management of sluice gates and polders, regular tidal water flooding in an unprotected area, the capillary rise of soluble salts, decreased surface water availability, lowered ground water table, reduced soil moisture content, the introduction of unplanned shrimp cultivation, lack of drainage facilities. Some of the widespread soil and land management techniques adopted in the saline areas of Bangladesh to cope with the salinity are polder (123), farm-pond (khamar-pokor), sarjan procedure, usage of raised shrimp farm bund for year-round cropping, mulching (keeping land covered in winter and summer months), land leveling, pitcher (kolosh) irrigation to grow watermelon, dibbling method, the addition of organic matter, chemical fertilizers and cultivation of saline tolerant crop varieties, particularly rice. Vol. 10, No. 1, April 2023: 1-7

Evaluation and Selection of Wheat (Triticum aestivum L.) Advanced Lines for Salt Tolerance in Bangladesh

The present study was carried out to investigate the genetic variability in advanced wheat lines and to identify superior advanced lines under salinity stress based on yield and yield-related traits. The evaluated advanced lines were derived through accurate pedigree selection method. Fifty wheat lines were evaluated in 2011-2012 wheat season at Regional Wheat Research Centre, Bangladesh Agricultural Research Institute Gazipur, Bangladesh under salinity stress condition. Various statistical tools were used in analyzing the data. Genetic variability was found among the evaluated wheat genotypes for all the traits studied. The evaluated lines were grouped into five clusters using cluster analysis ranging from high salt-tolerant to salt-sensitive genotypes. High to intermediate broad-sense heritability for measured traits showed their potential to be utilized under salinity stress for identifying salt- tolerant wheat lines. The traits under this study showed highly significant positive relationship with yield in terms of genotypic and phenotypic correlations. This indicated that all traits were important in influencing grain yield and could be exploited as selection criteria for improving grain yield of wheat under saline conditions. Eight wheat lines were selected as high salinity tolerant genotypes that would further be used in the breeding program to develop saline tolerant wheat varieties.

HvNCX, a prime candidate gene for the novel qualitative locus qS7.1 associated with salinity tolerance in barley

Key MessageA major QTL (qS7.1) for salinity damage score and Na+ exclusion was identified on chromosome 7H from a barley population derived from a cross between a cultivated variety and a wild accession. qS7.1 was fine-mapped to a 2.46 Mb physical interval and HvNCX encoding a sodium/calcium exchanger is most likely the candidate gene.Soil salinity is one of the major abiotic stresses affecting crop yield. Developing salinity-tolerant varieties is critical for minimizing economic penalties caused by salinity and providing solutions for global food security. Many genes/QTL for salt tolerance have been reported in barley, but only a few of them have been cloned. In this study, a total of 163 doubled haploid lines from a cross between a cultivated barley variety Franklin and a wild barley accession TAM407227 were used to map QTL for salinity tolerance. Four significant QTL were identified for salinity damage scores. One (qS2.1) was located on 2H, determining 7.5% of the phenotypic variation. Two (qS5.1 and qS5.2) were located on 5H, determining 5.3–11.7% of the phenotypic variation. The most significant QTL was found on 7H, explaining 27.8% of the phenotypic variation. Two QTL for Na+ content in leaves under salinity stress were detected on chromosomes 1H (qNa1.1) and 7H(qNa7.1). qS7.1 was fine-mapped to a 2.46 Mb physical interval using F4 recombinant inbred lines. This region contains 23 high-confidence genes, with HvNCX which encodes a sodium/calcium exchanger being most likely the candidate gene. HvNCX was highly induced by salinity stress and showed a greater expression level in the sensitive parent. Multiple nucleotide substitutions and deletions/insertions in the promoter sequence of HvNCX were found between the two parents. cDNA sequencing of the HvNCX revealed that the difference between the two parents is conferred by a single Ala77/Pro77 amino acid substitution, which is located on the transmembrane domain. These findings open new prospects for improving salinity tolerance in barley by targeting a previously unexplored trait.

Climate Resilient Varietal Development of Diverse Crops through Mutation Breeding in Bangladesh

The capability to quickly generate a considerable range of genetic variation in plants through mutation enables the mutagenesis approach extremely successful in developing climate-resistant cultivars across the entire world. In Bangladesh, plant breeders are confronted with a significant challenge in producing resilient and high-yielding cultivars rapidly capable of adapting to the changing environment in this densely populated region. Based on Mutant varieties data of Bangladesh which are available in the domain of FAO/IAEA Mutant Varieties Database (MVD), this review attempted to highlight the relevance of mutation breeding in crop variety development to adapt to changes occurring in diverse ecosystems of Bangladesh during this era of ongoing climate change. So far, seventy-eight mutant varieties of important crops have been released in Bangladesh, including rice, wheat, mustard, sesame, jute, rapeseed, tomato, black gram, chickpea, grass pea, lentil, mung bean, groundnut, and onion. Significant improvements in agronomic and botanical qualities have been made to maximize crop production. Salinity-tolerant varieties for southern coastal regions, drought-tolerant varieties for drought-prone locations, early mature varieties for flash flood escape in haor regions, submerged tolerant varieties for flooding regions and various major disease and insect resistant varieties have been generated through mutation breeding. These mutant varieties with climate-resilient traits are sustainable under different climatic circumstances, playing a key role in assuring food security in Bangladesh. Therefore, it is anticipated that mutant breeding will contribute significantly to meeting the challenges that food production will confront in the near future due to a changing climate.

Regional Environmental Change, Farmers’ Perceptions and Resilient Farming: Experiences from the Sagar Island of Indian Sundarbans

This research analyzed the patterns of agricultural transformations and adjustments to rapid environmental changes in deltaic island ecosystems by considering the case of Sagar Island of Indian Sundarbans using decadal climatic datasets, geospatial information, and farmers’ perceptions. Farmers’ cognition was considered for identifying crops that were suitable for cultivation in the changing environment. Results indicated that the average annual temperature and precipitation in this region had increased notably since 1980. Similarly, surface soil salinity had also recorded an overall increase throughout the island during the last three decades. In such a scenario, local farmers were only able to profitably cultivate few salinity-tolerant varieties of paddy (e.g., Masoori, Kalma, Santoshi, and Pratiksha) and vegetables (e.g., sunflower, potato, onion, okra, and betel leaf). Brackish water aquaculture had also become popular here in spite of its socio-ecological detriments. Many farmers were found to use their traditional knowledge proficiently alongside modern methods. However, the pressure of local peers, lack of readily investable wealth, and appropriate technological expertise often weakened their adaptive capacity. The findings suggested that effective cropping strategies such as coupled mangrove-shrimp farming and cultivation of salinity as well as waterlogging tolerant crop varieties could be considered as viable strategies toward enhancing resilience.

Identification of a Saltol-Independent Salinity Tolerance Polymorphism in Rice Mekong Delta Landraces and Characterization of a Promising Line, Doc Phung

The Mekong Delta River in Vietnam is facing salinity intrusion caused by climate change and sea-level rise that is severely affecting rice cultivation. Here, we evaluated salinity responses of 97 rice accessions (79 landraces and 18 improved accessions) from the Mekong Delta population by adding 100 mM NaCl to the nutrient solution for up to 20 days. We observed a wide distribution in salinity tolerance/sensitivity, with two major peaks across the 97 accessions when using the standard evaluation system (SES) developed by the International Rice Research Institute. SES scores revealed strong negative correlations (ranging from − 0.68 to − 0.83) with other phenotypic indices, such as shoot elongation length, root elongation length, shoot dry weight, and root dry weight. Mineral concentrations of Na+ in roots, stems, and leaves and Ca2+ in roots and stems were positively correlated with SES scores, suggesting that tolerant accessions lower their cation exchange capacity in the root cell wall. The salinity tolerance of Mekong Delta accessions was independent from the previously described salinity tolerance–related locus Saltol, which encodes an HKT1-type transporter in the salinity-tolerant cultivars Nona Bokra and Pokkali. Indeed, genome-wide association studies using SES scores and shoot dry weight ratios of the 79 accessions as traits identified a single common peak located on chromosome 1. This SNP did not form a linkage group with other nearby SNPs and mapped to the 3′ untranslated region of gene LOC_Os01g32830, over 6.5 Mb away from the Saltol locus. LOC_Os01g32830 encodes chloroplast glycolate/glycerate translocator 1 (OsPLGG1), which is responsible for photorespiration and growth. SES and shoot dry weight ratios differed significantly between the two possible haplotypes at the causal SNP. Through these analyses, we characterize Doc Phung, one of the most salinity-tolerant varieties in the Mekong Delta population and a promising new genetic resource.

Identification and characterization of salt-responsive proteins in mango (Mangifera indica L.)

Increasing salinity is a cause of concern for meeting UN sustainable development goals and needs urgent mitigation strategies. The widespread use of salinity tolerant rootstocks in salt-sensitive fruits provides long-term solutions to the harsh effects of soil salinization. Polyembryonic mango cultivar 13-1, a salinity-tolerant variety from Israel, was used to unravel initial salt adaptive mechanism by imposing a salinity screen at 200mM NaCl. Differentially accumulated proteins were separated through 2-D electrophoresis (pH gradient 4.0-7.0), and identified through properties of pI and molecular weight by annotation against Citrus isoelectric focusing database. Protein spots (309) were detected on Coomassie-stained gels and about 22 spots were found differentially expressed in control and stress. Overproduction of stress-related proteins like polygalacturonase (97 kDa/4.9PI) and alcohol dehydrogenase (38kDa/5.6PI) is linked to enhanced cell wall integrity, transpiration rate regulation and ionic maintenance in adaptability mechanism. The upregulated phenylpropanoid pathway proteins p-coumaroyl ester, Flavanone3-hydroxylase-2 and UDP-glycosyl transferase are also involved in stress alleviation through flavonoid accumulation. Glutathione S-transferase was also identified with 2.21-fold accumulation in plants exposed to salinity stress, thereby elucidating its role in oxidative stress mitigation. Cell wall and cytoskeleton metabolism-related proteins were also found to be associated with salinity adaptation in mango cv 13-1. Differential accumulation of proteins implicated in signal transduction pathway, transcription regulation and hormone signaling were also identified. Thus, role of differentially expressed proteins under initial salinity stress conditions provide new insights molecular adjustment mechanisms orchestrated by mango rootstock variety by hormone signaling, osmotic arrangements, cytoskeleton modifications, phenol accumulation and transcription regulation.

The first long-read nuclear genome assembly of Oryza australiensis, a wild rice from northern Australia

Oryza australiensis is a wild rice native to monsoonal northern Australia. The International Oryza Map Alignment Project emphasises its significance as the sole representative of the EE genome clade. Assembly of the O. australiensis genome has previously been challenging due to its high Long Terminal Repeat (LTR) retrotransposon (RT) content. Oxford Nanopore long reads were combined with Illumina short reads to generate a high-quality ~ 858 Mbp genome assembly within 850 contigs with 46× long read coverage. Reference-guided scaffolding increased genome contiguity, placing 88.2% of contigs into 12 pseudomolecules. After alignment to the Oryza sativa cv. Nipponbare genome, we observed several structural variations. PacBio Iso-Seq data were generated for five distinct tissues to improve the functional annotation of 34,587 protein-coding genes and 42,329 transcripts. We also report SNV numbers for three additional O. australiensis genotypes based on Illumina re-sequencing. Although genetic similarity reflected geographical separation, the density of SNVs also correlated with our previous report on variations in salinity tolerance. This genome re-confirms the genetic remoteness of the O. australiensis lineage within the O. officinalis genome complex. Assembly of a high-quality genome for O. australiensis provides an important resource for the discovery of critical genes involved in development and stress tolerance.

The use of osmoregulators and antioxidants to mitigate the adverse impacts of salinity stress in diploid and tetraploid potato genotypes (Solanum spp.)

BackgroundMany arid and semi-arid areas endure from extensive salinization of agricultural land. Nevertheless, it must either develop salinity-tolerant varieties or use agronomic treatments to alleviate the symptoms of stress. Although the cultivated potato, Solanum tuberosum L., is relatively salt sensitive, salinity tolerance was demonstrated in several Solanum relatives. Knowledge of genetic variation for salinity tolerance across diverse species is required for breeding of salinity-tolerant cultivars. Higher osmotic pressures associated with salinity impede plant development and cause plant death; yet, the exogenous application of cellularly recognized molecules to withstand such stress might be a key method.ResultsIn vitro studies were performed to determine how much genetic variability for salinity tolerance exists in S. tuberosum (tbr), a tetraploid species and S. chacoense (chc), a diploid species in which 13 genotypes were evaluated under 100, 200 or 300 mmol L−1 NaCl and the average tested parameters were compared with the control (no stress). A further experiment was conducted to investigate the effect of exogenous application of osmoregulators and antioxidants, namely, glycine betaine (GB), proline (P) and salicylic acid (SA) at 400, 200 and 100 mg L−1, respectively, which applied solely to counteract the harmful effect of stress on potato plants. The results showed that when plants exposed to salinity, root characteristics, plantlet water content % (PWC), chlorophyll and K+ content, and callus formation all substantially reduced; however, Cl− and Na+ levels, as well as catalase and peroxidase activity, were elevated. In general, chc showed more tolerance compared to tbr with genetic diversity within and among species. Under stress, chc clones, ‘A-6’, ‘C-8’ and ‘D-2’ and tbr cultivars, ‘Diamond’ and ‘Russet Burbank’ were more tolerant and yielded the greatest salinity tolerance index. Under stress but with applied GB, SA and P, the adverse consequences of stress were relieved. GB was found to be a good treatment for enhancing all the examined traits.ConclusionThe results indicated that there is a significant genetic variation in salt tolerance between (tbr) cultivars and (chc) clones. GB followed by SA and P could completely or partly reverse the adverse impact of salinity stress on potato plants.Graphical

Adaptation Strategy with Climate Induced Salinity Disaster in the Coastal Area of Bangladesh

This study examined explanatory responses to saline-water intrusion in the coastal areas of Bangladesh which are renowned for providing ecological and livelihood services. The goal of this study is to look at the different adaption strategies which coastal people have been using to deal with the growing salty water incursion. To this end, the researchers conducted a survey on 100 (one hundred) coastal people (Female 37% & Male 63%) chosen at a random basis from two unions (the lowest tier of local government) namely Perikhali union of Rampal upazila under Bagerhat district and Banishanta union of Dacope upazila under Khulna District at the southwest coast of Bangladesh. Agriculture (30%) and fisheries (27%) were the main livelihoods of the respondents. While looking at their existing problems due to salinity, it is seen that around 65% people are to move 3 - 5 (three to five) kilometres to get water access, low yield from agriculture (47%) and conversion of agricultural land (25%), acute crisis of grazing land (50%), damaged housing of cattle (30%) and fisheries (92%) are being affected due to salinity. Along with the impact, locals also have adaptation like seasonal water storage (31%), desalination (30%) and rainwater harvesting (26%) for water related impact. For agriculture, farmers are rotating crops (32%), cultivating saline tolerant varieties and others have switched from rice cultivation to other crops (30%) and cultivating saline tolerant variety (32%). In livestock, farmers are using better management practices (39%) followed by complete shift of livestock rearing (20%) to other businesses. Shifting from freshwater fish to marine water fish and crab/prawn cultivation (38%) found the most adaptation practices by the communities. For long term resilience to salinity induced disaster, collection of safe water (93%), quality seed (57%), disease control (47%) in livestock and quality hatchlings are the main barriers identified by the communities. For strengthening the current adaptation practices, rainwater harvesting (41%), household filtering of water (34%), ensuring of quality seeds (67%) and interest free loan to women through local NGOs have been stressed by the communities, local government officials as well as civil societies. Changes in land use patterns, use of contemporary technologies in agriculture, crop diversification, growing saline tolerant crops, income sources diversification, cultivating of saline tolerant fishes, utilization of savings, and rainwater harvesting are all prevalent adaptation strategies in the studied area. Moreover, to effectively address salinity in the coastal area of Bangladesh, the study also recommends increasing budget allocation for saline-water intrusion adaptation in the targeted institutions, staff capacity enhancement in water salinity monitoring, and provision of sophisticated equipment and technology.

Agronomical, Physiological and Biochemical Characterization of In Vitro Selected Eggplant Somaclonal Variants under NaCl Stress.

Previously, an efficient regeneration protocol was established and applied to regenerate plants from calli lines that could grow on eggplant leaf explants after a stepwise in vitro selection for tolerance to salt stress. Plants were regenerated from calli lines that could tolerate up to 120 mM NaCl. For further in vitro and in vivo evaluation, four plants with a higher number of leaves and longer roots were selected from the 32 plants tested in vitro. The aim of this study was to confirm the stability of salt tolerance in the progeny of these four mutants (‘R18’, ‘R19’, ‘R23’ and ‘R30’). After three years of in vivo culture, we evaluated the impact of NaCl stress on agronomic, physiological and biochemical parameters compared to the parental control (‘P’). The regenerated and control plants were assessed under in vitro and in vivo conditions and were subjected to 0, 40, 80 and 160 mM of NaCl. Our results show significant variation in salinity tolerance among regenerated and control plants, indicating the superiority of four regenerants (‘R18’, ‘R19’, ‘R23’ and ‘R30’) when compared to the parental line (‘P’). In vitro germination kinetics and young seedling growth divided the lines into a sensitive and a tolerant group. ‘P’ tolerate only moderate salt stress, up to 40 mM NaCl, while the tolerance level of ‘R18’, ‘R19’, ‘R23’ and ‘R30’ was up to 80 mM NaCl. The quantum yield of PSII (ΦPSII) declined significantly in ‘P’ under salt stress. The photochemical quenching was reduced while nonphotochemical quenching rose in ‘P’ under salt stress. Interestingly, the regenerants (‘R18’, ‘R19’, ‘R23’ and ‘R30’) exhibited high apparent salt tolerance by maintaining quite stable Chl fluorescence parameters. Rising NaCl concentration led to a substantial increase in foliar proline, malondialdehyde and soluble carbohydrates accumulation in ‘P’. On the contrary, ‘R18’, ‘R19’, ‘R23’ and ‘R30’ exhibited a decline in soluble carbohydrates and a significant enhancement in starch under salinity conditions. The water status reflected by midday leaf water potential (ψl) and leaf osmotic potential (ψπ) was significantly affected in ‘P’ and was maintained a stable level in ‘R18’, ‘R19’, ‘R23’ and ‘R30’ under salt stress. The increase in foliar Na+ and Cl− content was more accentuated in parental plants than in regenerated plants. The leaf K+, Ca2+ and Mg2+ content reduction was more aggravated under salt stress in ‘P’. Under increased salt concentration, ‘R18’, ‘R19’, ‘R23’ and ‘R30’ associate lower foliar Na+ content with a higher plant tolerance index (PTI), thus maintaining a normal growth, while foliar Na+ accumulation was more pronounced in ‘P’, revealing their failure in maintaining normal growth under salinity stress. ‘R18’, ‘R19’, ‘R23’ and ‘R30’ showed an obvious salt tolerance by maintaining significantly high chlorophyll content. In ‘R18’, ‘R19’, ‘R23’ and ‘R30’, the enzyme scavenging machinery was more performant in the roots compared to the leaves. Salt stress led to a significant augmentation of catalase, ascorbate peroxidase and guaiacol peroxidase activities in the roots of ‘R18’, ‘R19’, ‘R23’ and ‘R30’. In contrast, enzyme activities were less enhanced in ‘P’, indicating lower efficiency to cope with oxidative stress than in ‘R18’, ‘R19’, ‘R23’ and ‘R30’. ACC deaminase activity was significantly higher in ‘R18’, ‘R19’, ‘R23’ and ‘R30’ than in ‘P’. The present study suggests that regenerated plants ‘R18’, ‘R19’, ‘R23’ and ‘R30’ showed an evident stability in tolerating salinity, which shows their potential to be adopted as interesting selected mutants, providing the desired salt tolerance trait in eggplant.