Comprehensive Evaluation of Salt Tolerance in Rice (Oryza sativa L.) Germplasm at the Germination Stage

Salt stress reduces the yield and quality of rice. It is of great significance to screen out salt-tolerant varieties for the development and utilization of saline land. The study was carried out on 114 rice varieties; first, seven varieties were selected and treated with different salt concentrations (0, 50, 85, 120, 155, 190, 225 mM), and seven traits, including germination energy, germination capacity, shoot length, root length, root number, plant fresh weight, and seedling vigor index, were measured. The salt concentration at which the sodium chloride injury index was 50% of the control was considered the optimal salt concentration. Second, 114 rice germplasms were carried out under an optimal salt concentration (120 mM). Then, principal component analysis, fuzzy function analysis, stepwise regression analysis, correlation analysis, and systematic cluster analysis were carried out on each parameter. There was a significant correlation between each parameter and the D-value, and the correlation coefficient between the seedling vigor index and D-value was the highest. D-value = − 0.272 + 1.335 × STI − SVI + 0.549 × STI − RN − 0.617 × STI-RL + 0.073 × STI − GE, R2 = 0.986. Using this equation, the sodium chloride tolerance of rice in the germination experiment could be quickly identified. This study showed that the seedling vigor index was a reliable parameter to identify the salinity tolerance of rice varieties. Five groups were obtained by classification at a Euclidean distance of 5. There were 8 highly salt-tolerant cultivars, 23 salt-tolerant cultivars, 42 cultivars with moderate salt tolerance, 33 salt-sensitive cultivars, and 8 highly salt-sensitive cultivars. In this study, we found that Riguang was the most salt-tolerant rice variety, and Xiangxuejing15 was the most salt-sensitive variety.

Download Full-text

Advances and Challenges in the Breeding of Salt-Tolerant Rice

International Journal of Molecular Sciences ◽

10.3390/ijms21218385 ◽

2020 ◽

Vol 21 (21) ◽

pp. 8385

Author(s):

Hua Qin ◽

Yuxiang Li ◽

Rongfeng Huang

Keyword(s):

Food Security ◽

Salt Tolerance ◽

Quantitative Trait ◽

Molecular Mechanisms ◽

Soil Salinization ◽

Ecological Environment ◽

Salt Tolerant ◽

Salt Stress Tolerance ◽

Rice Varieties ◽

Salt Susceptible

Soil salinization and a degraded ecological environment are challenging agricultural productivity and food security. Rice (Oryza sativa), the staple food of much of the world’s population, is categorized as a salt-susceptible crop. Improving the salt tolerance of rice would increase the potential of saline-alkali land and ensure food security. Salt tolerance is a complex quantitative trait. Biotechnological efforts to improve the salt tolerance of rice hinge on a detailed understanding of the molecular mechanisms underlying salt stress tolerance. In this review, we summarize progress in the breeding of salt-tolerant rice and in the mapping and cloning of genes and quantitative trait loci (QTLs) associated with salt tolerance in rice. Furthermore, we describe biotechnological tools that can be used to cultivate salt-tolerant rice, providing a reference for efforts aimed at rapidly and precisely cultivating salt-tolerance rice varieties.

Download Full-text

Whole genome sequence analysis of rice genotypes with contrasting response to salinity stress

Scientific Reports ◽

10.1038/s41598-020-78256-8 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Prasanta K. Subudhi ◽

Rama Shankar ◽

Mukesh Jain

Keyword(s):

Salt Tolerance ◽

Dna Polymorphisms ◽

Whole Genome Sequence ◽

Whole Genome ◽

Salt Tolerant ◽

Tolerance Mechanisms ◽

Rice Varieties ◽

Genome Wide ◽

Rice Genotypes ◽

Genome Level

AbstractSalinity is a major abiotic constraint for rice farming. Abundant natural variability exists in rice germplasm for salt tolerance traits. Since few studies focused on the genome level variation in rice genotypes with contrasting response to salt stress, genomic resequencing in diverse genetic materials is needed to elucidate the molecular basis of salt tolerance mechanisms. The whole genome sequences of two salt tolerant (Pokkali and Nona Bokra) and three salt sensitive (Bengal, Cocodrie, and IR64) rice genotypes were analyzed. A total of 413 million reads were generated with a mean genome coverage of 93% and mean sequencing depth of 18X. Analysis of the DNA polymorphisms revealed that 2347 nonsynonymous SNPs and 51 frameshift mutations could differentiate the salt tolerant from the salt sensitive genotypes. The integration of genome-wide polymorphism information with the QTL mapping and expression profiling data led to identification of 396 differentially expressed genes with large effect variants in the coding regions. These genes were involved in multiple salt tolerance mechanisms, such as ion transport, oxidative stress tolerance, signal transduction, and transcriptional regulation. The genome-wide DNA polymorphisms and the promising candidate genes identified in this study represent a valuable resource for molecular breeding of salt tolerant rice varieties.

Download Full-text

Salt Tolerance of Three Tree Species Differing in Native Habitats and Leaf Traits

HortScience ◽

10.21273/hortsci.49.9.1194 ◽

2014 ◽

Vol 49 (9) ◽

pp. 1194-1200

Author(s):

Nisa Leksungnoen ◽

Roger K. Kjelgren ◽

Richard C. Beeson ◽

Paul G. Johnson ◽

Grant E. Cardon ◽

...

Keyword(s):

Salt Tolerance ◽

Gas Exchange ◽

Salt Concentration ◽

Leaf Traits ◽

Leaf Damage ◽

Urban Landscapes ◽

Salt Tolerant ◽

Native Habitat ◽

Saline Habitats ◽

Salinity Levels

We investigated if salt tolerance can be inferred from observable cues based on a woody species’ native habitat and leaf traits. Such inferences could improve species selection for urban landscapes constrained by soils irrigated with reclaimed water. We studied the C3 tree species Acer grandidentatum Nutt. (canyon maple; xeric-non-saline habitat) that was hypothesized to have some degree of salt tolerance based on its semiarid but non-saline native habitat. We compared it with A. macrophyllum Pursh. (bigleaf maple) from mesic/riparian-non-saline habitats with much larger leaves and Eucalyptus camaldulensis Dehnh. (eucalyptus/red gum) from mesic-saline habitats with schlerophyllous evergreen leaves. Five levels of increasing salt concentrations (non-saline control to 12 dS·m−1) were applied over 5 weeks to container-grown seedling trees in two separate studies, one in summer and the other in fall. We monitored leaf damage, gas exchange, and hydric behavior as measures of tree performance for 3 weeks after target salinity levels were reached. Eucalyptus was the most salt-tolerant among the species. At all elevated salinity levels, eucalyptus excluded salt from its root zone, unlike either maple species. Eucalyptus maintained intact, undamaged leaves with no effect on photosynthesis but with minor reductions in stomatal conductance (gS). Conversely, bigleaf maple suffered increasing leaf damage, nearly defoliated at the highest levels, with decreasing gas exchange as salt concentration increased. Canyon maple leaves were not damaged and gas exchange was minimally affected at 3 dS·m−1 but showed increasing damage at higher salt concentration. Salt-tolerant eucalyptus and riparian bigleaf maple framed canyon maple’s moderate salt tolerance up to 3 dS·m−1 that appears related to seasonal soil drying in its semiarid native habitat. These results highlight the potential to infer a degree of salt tolerance from either native habitat or known drought tolerance in selecting plant species for urban landscapes limited by soil salinity or brackish irrigation water. Observable cues such as xeri-morphic leaf traits may also provide visual evidence of salt tolerance.

Download Full-text

Salinity Effects on Bentgrass Germination

HortScience ◽

10.21273/hortsci.28.1.15 ◽

1993 ◽

Vol 28 (1) ◽

pp. 15-17 ◽

Cited By ~ 16

Author(s):

L.B. McCarty ◽

A.E. Dudeck

Keyword(s):

Salt Tolerance ◽

Warm Season ◽

Creeping Bentgrass ◽

Salt Tolerant ◽

Salinity Effects ◽

Agrostis Tenuis ◽

Seawater Salinity ◽

Salt Tolerant Cultivars

Duplicate studies were conducted to determine salt tolerance during germination of eight bentgrass (Agrostis spp.) cultivars commonly used for overseeding warm-season turf species, such as bermudagrass (Cynodon spp.) putting surfaces. Bentgrass seeds were germinated on agar salinized with 0, 4000, 8000, 12,000, or 16,000 mg·liter-1, with the highest rate approaching one-half seawater salinity. Total germination decreased linearly or quadratically for specific cultivars as salinity increased. Time necessary to reach 50% germination across all salt concentrations was shortest for `Highland' colonial (Agrostis tenuis Sibth) and `Seaside' creeping (A. palustris Huds.) bentgrass (≈3.7 days); intermediate for `Kingstown' velvet (A. canina L.) and `Streaker' red top (A. alba L.) bentgrass (≈4.5 days); and longest for `Penneagle' creeping, `Penncross' creeping, `Exeter' colonial, and `Pennlinks' creeping bentgrass (≈5.3 days). Salt concentrations necessary to reduce germination to 90%, 75%, and 50% indicated that `Streaker' red top and `Seaside' creeping bentgrass were the most salt-tolerant cultivars. `Kingstown' velvet, `Exeter' colonial, and `Highland' colonial bentgrass were intermediate, while `Pennlinks', `Penncross', and `Penneagle' creeping bentgrass were the most salt-sensitive cultivars.

Download Full-text

Identification and Validation a Major QTL from “Sea Rice 86” Seedlings Conferred Salt Tolerance

Agronomy ◽

10.3390/agronomy10030410 ◽

2020 ◽

Vol 10 (3) ◽

pp. 410 ◽

Cited By ~ 1

Author(s):

Fengling Wu ◽

Jun Yang ◽

Diqiu Yu ◽

Peng Xu

Keyword(s):

Salt Tolerance ◽

Oryza Sativa L ◽

Bulked Segregant Analysis ◽

Indica Rice ◽

Chromosome 1 ◽

Saline Stress ◽

Salt Tolerant ◽

Rice Varieties ◽

Target Region ◽

High Salt Tolerance

Saline stress severely affects rice (Oryza sativa L.) growth and development and reduces crop yield. Therefore, developing salt-tolerant and high-yielding rice using quantitative trait loci (QTLs) and linkage markers is a priority for molecular breeding. Here, the indica rice Sea Rice 86 (SR86) seedlings showed higher tolerance than ordinary rice varieties in saline soil, and a dominant effect on salinity sensitivity was demonstrated by genetic analysis. We constructed bulked segregant analysis pools using F2 populations from parents Dianjingyou 1 as the recipient and SR86 as the donor. We identified a 2.78 Mb region on chromosome 1 as the candidate region. Using simple sequence repeat markers and substitution analysis, we mapped the target region within 5.49 cM in the vicinity of markers RM8904–RM493. We speculated that this QTL, named qST1.1, might contribute significantly to the salt tolerance of SR86. The high salt tolerance of introgression lines obtained by marker assistant selection (MAS) confirmed that the qST1.1 region was associated with salinity tolerance. This newly-discovered QTL will be helpful for the analysis of the salt-tolerant mechanism of rice and breeding high-quality rice varieties using MAS.

Download Full-text

Influence of NaCl Salinity on the Behaviour of Protease, Aminopeptidase and Carboxypeptidase in Rice Seedlings in Relation to Salt Tolerance

Functional Plant Biology ◽

10.1071/pp9900215 ◽

1990 ◽

Vol 17 (2) ◽

pp. 215 ◽

Cited By ~ 23

Author(s):

RS Dubey ◽

M Rani

Keyword(s):

Salt Tolerance ◽

Protease Activity ◽

Leucine Aminopeptidase ◽

Growth Period ◽

Salt Tolerant ◽

Rice Seedlings ◽

Salt Treatment ◽

Nacl Salinity ◽

Salt Susceptible ◽

Salt Tolerant Cultivars

Activities of the enzymes protease, aminopeptidase and carboxypeptidase were determined in seedlings of rice cultivars with different salt tolerances raised under increasing levels of NaCl salinity. Salinity caused a marked increase in protease activity in roots as well as shoots, though activity was higher in roots than in shoots. Salt-tolerant cultivars possessed higher levels of protease activity in control as well as salt-stressed seedlings compared with salt-susceptible cultivars. During a growth period of 5-20 days, leucine aminopeptidase (LAP) activity increased up to days 10-15 and decreased thereafter. Salt treatment caused a sharp increase in LAP activity in roots of both sets of cultivars. The increase was larger in tolerant than in susceptible cultivars. In shoots, unlike roots, higher salinity suppressed LAP activity, and suppression was more marked in susceptible cultivars than in tolerant ones. Carboxypeptidase activity was higher in susceptible cultivars than in tolerant ones under both control as well as salt treatments. Roots maintained higher levels of carboxypeptidase activity than shoots. Results suggest an increased rate of proteolysis in salt-stressed rice seedlings and an association of salt-tolerance ability with higher protease and aminopeptidase activities and lower carboxypeptidase activity under salinisation.

Download Full-text

Biochemical and molecular characterisations of salt tolerance components in rice varieties tolerant and sensitive to NaCl: the relevance of Na+ exclusion in salt tolerance in the species

Functional Plant Biology ◽

10.1071/fp20089 ◽

2021 ◽

Vol 48 (1) ◽

pp. 72

Author(s):

Amber Gupta ◽

Birendra P. Shaw

Keyword(s):

Salt Tolerance ◽

Indica Rice ◽

Constitutive Expression ◽

Initial Study ◽

Cereal Crops ◽

Salt Tolerant ◽

Rice Varieties ◽

Induced Expression ◽

Soil Salinisation ◽

Vacuolar Sequestration

Soil salinisation is a major abiotic stress in agriculture, and is especially a concern for rice production because among cereal crops, rice is the most salt-sensitive. However, the production of rice must be increased substantially by the year 2050 to meet the demand of the ever growing population. Hence, understanding the biochemical events determining salt tolerance in rice is highly desirable so that the trait can be introduced in cultivars of interest through biotechnological intervention. In this context, an initial study on NaCl response in four Indica rice varieties showed a lower uptake of Na+ in the salt-tolerant Nona Bokra and Pokkali than in the salt-sensitive IR64 and IR29, indicating Na+ exclusion as a primary requirement of salt tolerance in the species. This was also supported by the following features in the salt-tolerant, but not in the -sensitive varieties: (1) highly significant NaCl-induced increase in the activity of PM-H+ATPase, (2) a high constitutive level and NaCl-induced threonine phosphorylation of PM-H+ATPase, necessary to promote its activity, (3) a high constitutive expression of 14-3-3 protein that makes PM-H+ATPase active by binding with the phosphorylated threonine at the C-terminal end, (4) a high constitutive and NaCl-induced expression of SOS1 in roots, and (5) significant NaCl-induced expression of OsCIPK 24, a SOS2 that phosphorylates SOS1. The vacuolar sequestration of Na+ in seedlings was not reflected from the expression pattern of NHX1/NHX1 in response to NaCl. NaCl-induced downregulation of expression of HKTs in roots of Nona Bokra, but upregulation in Pokkali also indicates that their role in salt tolerance in rice could be cultivar specific. The study indicates that consideration of increasing exclusion of Na+ by enhancing the efficiency of SOS1/PM-H+ATPase Na+ exclusion module could be an important aspect in attempting to increase salt tolerance in the rice varieties or cultivars of interest.

Download Full-text

Effects of Nitrogen on Seedling Growth of Wheat Varieties under Salt Stress

Journal of Agricultural Science ◽

10.5539/jas.v8n10p131 ◽

2016 ◽

Vol 8 (10) ◽

pp. 131 ◽

Cited By ~ 1

Author(s):

Muhi Eldeen Hussien Ibrahim ◽

Xinkai Zhu ◽

G. Zhou ◽

Eltayib H. M. A. Abidallhaa

Keyword(s):

Salt Tolerance ◽

Root Length ◽

Dry Weight ◽

Saline Soils ◽

Tolerance Index ◽

Seedling Vigor ◽

Wheat Varieties ◽

Vigor Index ◽

Emergence Percentage ◽

Salt Tolerance Index

<p>Wheat growth is hampered by various environmental stresses including salinity. The aim of the present study was to evaluate the nitrogen effect on seedling emergence and growth under salinity conditions. For this reason the seeds of wheat (<em>Triticum aestivum </em>L.) varieties Argine, and Elnilein from Sudan and Xumai 30, and Yang 10-13 from China were cultured under four NaCl solutions containing (0, 100, 150, and 200 mM NaCl) and three nitrogen (N) fertilizer levels (N0 = 0, N1 = 105, and N2 12 = 210 kg N/h). Emergence percentage and early growth were determined. There were significant differences among salinity and N levels for emergence percentage shoot and root length, dry weight, salt tolerance index, and seedling vigor index. At all salinity levels, the varieties showed similar salt resistance, but each responded differently. Nitrogen affected positively on the seedling characteristics under saline soil. Elnilein had a better emergence percentage, shoot and root length, dry weight, salt tolerance index, and seedling vigor index than the other varieties. Elnilein is recommended for saline soils. We suggest that a simple seedling test would be a useful selection tool in order to develop productive new wheat lines on saline soils.</p>

Download Full-text

Stomatal and Photosynthetic Traits Are Associated with Investigating Sodium Chloride Tolerance of Brassica napus L. Cultivars

Plants ◽

10.3390/plants9010062 ◽

2020 ◽

Vol 9 (1) ◽

pp. 62 ◽

Cited By ~ 7

Author(s):

Ibrahim A. A. Mohamed ◽

Nesma Shalby ◽

Chenyang Bai ◽

Meng Qin ◽

Ramadan A. Agami ◽

...

Keyword(s):

Sodium Chloride ◽

Gas Exchange ◽

Salinity Tolerance ◽

Soluble Sugar ◽

Antioxidant Enzyme Activities ◽

Salt Tolerant ◽

Negative Effects ◽

Brassica Napus L ◽

Photosynthetic Gas Exchange ◽

Salt Tolerant Cultivars

The negative effects of salt stress vary among different rapeseed cultivars. In this study, we investigated the sodium chloride tolerance among 10 rapeseed cultivars based on membership function values (MFV) and Euclidean cluster analyses by exposing seedlings to 0, 100, or 200 mM NaCl. The NaCl toxicity significantly reduced growth, biomass, endogenous K+ levels, relative water content and increased electrolyte leakage, soluble sugar levels, proline levels, and antioxidant enzyme activities. SPAD values were highly variable among rapeseed cultivars. We identified three divergent (tolerant, moderately tolerant, and sensitive) groups. We found that Hua6919 and Yunyoushuang2 were the most salt-tolerant cultivars and that Zhongshuang11 and Yangyou9 were the most salt-sensitive cultivars. The rapeseed cultivars were further subjected to photosynthetic gas exchange and anatomical trait analyses. Among the photosynthetic gas exchange and anatomical traits, the stomatal aperture was the most highly correlated with salinity tolerance in rapeseed cultivars and thus, is important for future studies that aim to improve salinity tolerance in rapeseed. Thus, we identified and characterized two salt-tolerant cultivars that will be useful for breeding programs that aim to develop salt-tolerant rapeseed.

Download Full-text

Regulation of enzymatic and non-enzymatic antioxidants contributes to salt tolerance in hitherto unknown upland farmer rice varieties.

Current Botany ◽

10.25081/cb.2020.v11.6019 ◽

2020 ◽

pp. 18-27

Author(s):

Lins Simon ◽

Yusuf Akkara

Keyword(s):

Salt Stress ◽

Salt Tolerance ◽

Stability Index ◽

Monodehydroascorbate Reductase ◽

Enzymatic Antioxidants ◽

Salt Tolerant ◽

Sod Activity ◽

Rice Varieties ◽

Pronounced Increase ◽

Nacl Concentration

Salt tolerance potential of the three upland farmer varieties, koduvelliyan, mullankayama and marathondi was evaluated by comparing with the released salt-tolerant pokkali variety, vytilla-2. The salt tolerance exhibited by the upland varieties was identical with the salt tolerant variety. The superoxide (O2-) content in the upland varieties was lower; however, the hydrogen peroxide (H2O2) content increased with the salt concentration. The lesser malondialdehyde (MDA) content in the koduvelliyan variety was equivalent to the vytilla-2 and slight increase was observed in mullankayama and marathondi. The ascorbate (AsA) content in the upland varieties was comparable to vytilla-2 and upon exposure to increased concentration of NaCl, the AsA level reduced in all the treatments. Reduced glutathione (GSH) content was uniform in all the varieties up to a concentration of 100mM NaCl, however, in 125-150mM NaCl, mullankayama showed a pronounced increase in GSH content. Under salt stress, due to the formation of O2-, the oxidation of GSH was higher, maintaining a stable GSH/GSSG ratio. Superoxide dismutase (SOD) and catalase (CAT) activity of the upland varieties was higher than vytilla-2 up to 100mM NaCl, however, in 125-150mM NaCl the SOD activity increased slightly and the CAT activity decreased. Ascorbate peroxidase (APX) activity increased in upland varieties up to 125mM NaCl, and in 150mM NaCl, maintained a steady level in all the varieties. Glutathione reductase (GR) activity increased proportionate with NaCl concentration; with highest activity in all the upland varieties. Monodehydroascorbate reductase (MDHAR) activity was uniform in all the varieties up to 100mM NaCl, however, in 125 and 150mM NaCl, vytilla-2 showed higher MDHAR activity. Dehydroascorbate reductase (DHAR) activity was lesser in upland varieties under salt stress compared to vytilla-2. The GSH/GSSG ratio decreased in marathondi and koduvelliyan varieties with the increase in NaCl concentration, however, in mullankayama and vytilla-2, the GSH/GSSG ratio was higher. The membrane stability index of all the varieties was uniform in all the concentrations of NaCl used, except marathondi. The Na+ content in all the varieties increased in relation to NaCl concentration and the K+ efflux was higher suggesting a higher Na+/K+ ratio, with increased NaCl concentration.

Download Full-text