Salt Stress Tolerance In Rice Research Articles

Transcriptome analysis of the molecular basis of 11‐eicosenoic acid‐mediated salt stress tolerance in rice

AbstractSalt stress is one of the major abiotic factors severely hampering rice production. Fatty acids play a crucial role in plants response to such stress. Previous studies have demonstrated the potential of unsaturated fatty acid (11‐eicosenoic acid [EA]) to enhance salt tolerance in rice, but the molecular mechanism remains unclear. Our study indicates that the exogenous application of EA could alleviate salt stress‐induced damage as well as improve the survival rate of rice seedlings. Transcriptome analysis was performed following treatment of rice seedlings with EA, NaCl, and NaCl + EA. The results showed that there were 4970, 11, 304, and 4735 differentially expressed genes (DEGs) in NaCl versus CK, EA versus CK, NaCl + EA versus NaCl, and NaCl + EA versus CK, respectively. Notably, pathways such as unsaturated fatty acid metabolism, diterpenoid phytoalexin biosynthesis, and phytohormone signal transduction were significantly enriched in NaCl + EA versus NaCl. Specifically, genes related to ethylene, abscisic acid, jasmonic acid, salicylic acid, gibberellin signaling, and fatty acid metabolism were implicated in the mitigation effect of EA on salt stress in rice. Furthermore, DEGs involved in rice diterpenoid biosynthesis were analyzed in detail, revealing that EA induced the biosynthesis of multiple diterpenoids. Metabolomic analysis showed that the levels of various fatty acids, phytohormones, and terpenes increased. The presented data may serve as a useful guide for further exploration of the various biological functions of EA in enhancing plant resilience to salt stress. Additionally, it offers a valuable list of genes for the development of crop plants with improved salt resistance.

Overexpression of OsDUF6 increases salt stress tolerance in rice

BackgroundSoil salinity is one of the primary environmental stresses faced in rice production. When plants are exposed to salt stress, a series of cellular balances will be disrupted. Dufulin is an immune-induced antiviral agent used in plants. The DUF gene family influences plant response to abiotic stress, and the functional role of OsDUF6(ABA98726.1) in rice response to salt stress is being investigated here.ResultsBased on the transcriptome analysis of Dufulin treatment in inducing salt tolerance in rice, we selected the OsDUF6 protein located on the cell membrane and studied its molecular function by overexpressing OsDUF6. Salt-induced decreases in root, stem, and leaf length and increased leaf yellowing rate and Na+ concentration in the wild-type plant were mitigated in the overexpressed lines. OsDUF6 overexpression increased the enzymatic antioxidant activities of superoxide dismutase, peroxidase, catalase, and phenylalanine ammonia-lyase. OsDUF6 also played a positive role in Na+ transport as reflected by the increased growth of a salt-sensitive yeast mutant complemented with OsDUF6 in the presence of salt stress. In addition, Reverse transcription quantitative PCR analysis confirmed that the overexpression of OsDUF6 significantly changed the expression level of other genes related to growth and stress tolerance.ConclusionsCombined with previously published data, our results supported the observation that OsDUF6 is an important functional factor in Dufulin-induced promotion of salt stress tolerance in rice.

The MYB-CC Transcription Factor PHOSPHATE STARVATION RESPONSE-LIKE 7 (PHL7) Functions in Phosphate Homeostasis and Affects Salt Stress Tolerance in Rice.

Inorganic phosphate (Pi) homeostasis plays an important role in plant growth and abiotic stress tolerance. Several MYB-CC transcription factors involved in Pi homeostasis have been identified in rice (Oryza sativa). PHOSPHATE STARVATION RESPONSE-LIKE 7 (PHL7) is a class II MYC-CC protein, in which the MYC-CC domain is located at the N terminus. In this study, we established that OsPHL7 is localized to the nucleus and that the encoding gene is induced by Pi deficiency. The Pi-responsive genes and Pi transporter genes are positively regulated by OsPHL7. The overexpression of OsPHL7 enhanced the tolerance of rice plants to Pi starvation, whereas the RNA interference-based knockdown of this gene resulted in increased sensitivity to Pi deficiency. Transgenic rice plants overexpressing OsPHL7 produced more roots than wild-type plants under both Pi-sufficient and Pi-deficient conditions and accumulated more Pi in the shoots and roots. In addition, the overexpression of OsPHL7 enhanced rice tolerance to salt stress. Together, these results demonstrate that OsPHL7 is involved in the maintenance of Pi homeostasis and enhances tolerance to Pi deficiency and salt stress in rice.

RNAi-Mediated Suppression of OsBBTI5 Promotes Salt Stress Tolerance in Rice.

This study explores the impact of RNAi in terms of selectively inhibiting the expression of the OsBBTI5 gene, with the primary objective of uncovering its involvement in the molecular mechanisms associated with salt tolerance in rice. OsBBTI5, belonging to the Bowman-Birk inhibitor (BBI) family gene, is known for its involvement in plant stress responses. The gene was successfully cloned from rice, exhibiting transcriptional self-activation in yeast. A yeast two-hybrid assay confirmed its specific binding to OsAPX2 (an ascorbate peroxidase gene). Transgenic OsBBTI5-RNAi plants displayed insensitivity to varying concentrations of 24-epibrassinolide in the brassinosteroid sensitivity assay. However, they showed reduced root and plant height at high concentrations (10 and 100 µM) of GA3 immersion. Enzyme activity assays revealed increased peroxidase (POD) and superoxide dismutase (SOD) activities and decreased malondialdehyde (MDA) content under 40-60 mM NaCl. Transcriptomic analysis indicated a significant upregulation of photosynthesis-related genes in transgenic plants under salt stress compared to the wild type. Notably, this study provides novel insights, suggesting that the BBI gene is part of the BR signaling pathway, and that OsBBTI5 potentially enhances stress tolerance in transgenic plants through interaction with the salt stress-related gene OsAPX2.

The zinc finger protein DHHC09 S-acylates the kinase STRK1 to regulate H2O2 homeostasis and promote salt tolerance in rice.

Soil salinity results in oxidative stress and heavy losses to crop production. The S-acylated protein SALT TOLERANCE RECEPTOR-LIKE CYTOPLASMIC KINASE 1 (STRK1) phosphorylates and activates CATALASE C (CatC) to improve rice (Oryza sativa L.) salt tolerance, but the molecular mechanism underlying its S-acylation involved in salt signal transduction awaits elucidation. Here, we show that the DHHC-type zinc finger protein DHHC09 S-acylates STRK1 at Cys5, Cys10, and Cys14 and promotes salt and oxidative stress tolerance by enhancing rice H2O2-scavenging capacity. This modification determines STRK1 targeting to the plasma membrane or lipid nanodomains and is required for its function. DHHC09 promotes salt signaling from STRK1 to CatC via transphosphorylation, and its deficiency impairs salt signal transduction. Our findings demonstrate that DHHC09 S-acylates and anchors STRK1 to the plasma membrane to promote salt signaling from STRK1 to CatC, thereby regulating H2O2 homeostasis and improving salt stress tolerance in rice. Moreover, overexpression of DHHC09 in rice mitigates grain yield loss under salt stress. Together, these results shed light on the mechanism underlying the role of S-acylation in RLK/RLCK-mediated salt signal transduction and provide a strategy for breeding highly salt-tolerant rice.

The seaweed Ascophyllum nodosum-based biostimulant enhances salt stress tolerance in rice (Oryza sativa L.) by remodeling physiological, biochemical, and metabolic responses

ABSTRACT This study explores the role of a biostimulant derived from the seaweed Ascophyllum nodosum (AN) in mitigating salt stress in rice plants. The weekly (S+W) and biweekly (S+B) biostimulant treatments exhibited enhanced shoot and root biomass, maintained ionic balance, and increased pigment content (total chlorophyll increased by 26.35% and 31%, carotenoids by 11.90% and 16.67% in S+W and S+B treatments, respectively) compared to untreated salt-stressed plants (CS). Improved gas exchange parameters and PSII efficiency were observed in S+W and S+B treatments. AN-biostimulant treatments mitigated salt-induced oxidative stress by positively regulating the antioxidant defense system. Notably, a strong negative correlation was observed between antioxidants and oxidative markers. Furthermore, AN-biostimulant treatments induced key metabolites (organic acids, sugars, amino acids, flavonoids), emphasizing the integrated role of multiple pathways in enhancing salt tolerance in rice. These findings highlight the potential of AN biostimulants as eco-friendly tools for crop enhancement in challenging environments.

MicroRNA2871b of Dongxiang Wild Rice (Oryza rufipogon Griff.) Negatively Regulates Cold and Salt Stress Tolerance in Transgenic Rice Plants.

Cold and salt stresses are major environmental factors that constrain rice production. Understanding their mechanisms is important to enhance cold and salt stress tolerance in rice. MicroRNAs (miRNAs) are a class of non-coding RNAs with only 21-24 nucleotides that are gene regulators in plants and animals. Previously, miR2871b expression was suppressed by cold stress in Dongxiang wild rice (DXWR, Oryza rufipogon Griff.). However, its biological functions in abiotic stress responses remain elusive. In the present study, miR2871b of DWXR was overexpressed to investigate its function under stress conditions. When miR2871b of DWXR was introduced into rice plants, the transgenic lines were more sensitive to cold and salt stresses, and their tolerance to cold and salt stress decreased. The increased expression of miR2871b in rice plants also increased the levels of reactive oxygen species (ROS) and malondialdehyde (MDA); however, it markedly decreased the activities of peroxidase (POD), superoxide dismutase (SOD), and catalase (CAT) and the contents of proline (Pro) and soluble sugar (SS). These data suggested that miR2871b of DXWR has negative regulatory effects on cold and salt stress tolerance. Meanwhile, 412 differentially expressed genes (DEGs) were found in rice transgenic plants using transcriptome sequencing, among which 266 genes were up-regulated and 146 genes were down-regulated. Furthermore, the upstream cis-acting elements and downstream targets of miR2871b were predicted and analyzed, and several critical acting elements (ABRE and TC-rich repeats) and potential target genes (LOC_Os03g41200, LOC_Os07g47620, and LOC_Os04g30260) were obtained. Collectively, these results generated herein further elucidate the vital roles of miR2871b in regulating cold and salt responses of DXWR.

Comparative analysis of microRNA expression profiles in shoot and root tissues of contrasting rice cultivars (Oryza sativa L.) with different salt stress tolerance.

Rice is the second-most important primary crop in the world and one of the most susceptible crops to salt stress. Soil salinization hinders seedling growth and decreases crop yield by inducing ionic and osmotic imbalances, photosynthesis disturbances, cell wall alterations, and gene expression inhibition. Plants have developed a range of defense mechanisms to adapt to salt stress. One of the most effective means is to make use of plant microRNAs (miRNAs) as post-transcriptional regulators to regulate the expression of developmental genes in order to mitigate the detrimental effects of salt stress. In this study, the miRNA sequencing data between two contrasting rice cultivars, salt-tolerant Doc Phung (DP) and salt-sensitive IR28 seedlings, were compared under control and salt stress (150 mM NaCl) conditions to determine the salt stress-responsive miRNAs. Comparative analysis of miRNA sequencing data detected a total of 69 differentially expressed miRNAs in response to salt stress treatment. Among them, 18 miRNAs from 13 gene families, MIR156, MIR164, MIR167, MIR168, MIR171, MIR396, MIR398, MIR1432, MIR1846, MIR1857, MIR1861, MIR3979, and MIR5508, were identified to be specifically and significantly expressed in the shoot and root tissues of DP seedlings. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses further revealed that these detected miRNAs regulate a range of essential biological and stress response processes, including gene transcription, osmotic homeostasis, root formation, ROS scavenger synthesis, and auxin and abscisic acid signaling pathways. Our findings provide more insight into the miRNA-mediated responsive mechanisms of rice under salt stress and should benefit the improvement of salt stress tolerance in rice.

OsLPR5 Encoding Ferroxidase Positively Regulates the Tolerance to Salt Stress in Rice.

Salinity is a major abiotic stress that harms rice growth and productivity. Low phosphate roots (LPRs) play a central role in Pi deficiency-mediated inhibition of primary root growth and have ferroxidase activity. However, the function of LPRs in salt stress response and tolerance in plants remains largely unknown. Here, we reported that the OsLPR5 was induced by NaCl stress and positively regulates the tolerance to salt stress in rice. Under NaCl stress, overexpression of OsLPR5 led to increased ferroxidase activity, more green leaves, higher levels of chlorophyll and lower MDA contents compared with the WT. In addition, OsLPR5 could promote the accumulation of cell osmotic adjustment substances and promote ROS-scavenging enzyme activities. Conversely, the mutant lpr5 had a lower ferroxidase activity and suffered severe damage under salt stress. Moreover, knock out of OsLPR5 caused excessive Na+ levels and Na+/K+ ratios. Taken together, our results exemplify a new molecular link between ferroxidase and salt stress tolerance in rice.

OsJRL40, a Jacalin-Related Lectin Gene, Promotes Salt Stress Tolerance in Rice.

High salinity is a major stress factor affecting the quality and productivity of rice (Oryza sativa L.). Although numerous salt tolerance-related genes have been identified in rice, their molecular mechanisms remain unknown. Here, we report that OsJRL40, a jacalin-related lectin gene, confers remarkable salt tolerance in rice. The loss of function of OsJRL40 increased sensitivity to salt stress in rice, whereas its overexpression enhanced salt tolerance at the seedling stage and during reproductive growth. β-glucuronidase (GUS) reporter assays indicated that OsJRL40 is expressed to higher levels in roots and internodes than in other tissues, and subcellular localization analysis revealed that the OsJRL40 protein localizes to the cytoplasm. Further molecular analyses showed that OsJRL40 enhances antioxidant enzyme activities and regulates Na+-K+ homeostasis under salt stress. RNA-seq analysis revealed that OsJRL40 regulates salt tolerance in rice by controlling the expression of genes encoding Na+/K+ transporters, salt-responsive transcription factors, and other salt response-related proteins. Overall, this study provides a scientific basis for an in-depth investigation of the salt tolerance mechanism in rice and could guide the breeding of salt-tolerant rice cultivars.

Jasmonate signaling controls negative and positive effectors of salt stress tolerance in rice.

Plant responses to salt exposure involve large reconfiguration of hormonal pathways that orchestrate physiological changes towards tolerance. Jasmonate (JA) hormones are essential to withstand biotic and abiotic assaults, but their roles in salt tolerance remain unclear. Here we describe the dynamics of JA metabolism and signaling in root and leaf of rice, a plant species that is highly exposed and sensitive to salt. Roots activate the JA pathway in an early pulse, while 2 nd leaf displays a biphasic JA response with peaks at 1 hour and 3 days post-exposure. Based on higher salt tolerance of a rice JA-deficient mutant (aoc), we examined through kinetic transcriptome and physiological analysis the salt-triggered processes that are under JA control. Profound genotype-differential features emerged that could underlie observed phenotypes. ABA content and ABA-dependent water deprivation responses were impaired in aoc shoots. Moreover, aoc accumulated more Na + in roots, and less in leaf, with reduced ion translocation correlating with root derepression of the HAK4 Na + transporter. Distinct reactive oxygen species scavengers were also stronger in aoc leaf, along with reduced senescence and chlorophyll catabolism markers. Collectively, the data identify contrasted contributions of JA signaling to different sectors of the salt stress response in rice.

The UDP-glucuronic acid decarboxylase OsUXS3 regulates Na+ ion toxicity tolerance under salt stress by interacting with OsCATs in rice

Overly Na+ ion in soil caused by salt stress has a significant negative impact on the growth and production of crops, especially rice (Oryza sativa L.). Therefore, it is vital for us to clarify how salt stress tolerance in rice is caused by Na+ ion toxicity. The UDP-glucuronic acid decarboxylase (UXS) is a critical enzyme in the biosynthesis of UDP-xylose, which is the key substrate of cytoderm synthesis in plants. In this study, we found that OsUXS3, a rice UXS, is a positive regulator to regulate Na+ ion toxicity under salt stress by interacting with OsCATs (Oryza sativa catalase; OsCAT). The expression of OsUXS3 was significantly up-regulated under NaCl and NaHCO3 treatments of rice seedlings. Meanwhile, by the genetic and biochemical evidence, knockout of OsUXS3 significantly increased reactive oxygen species (ROS) levels and decreased CAT activity under NaCl and NaHCO3 treatments in tissue. Furthermore, knockout of OsUXS3 caused excessive accumulation of Na + ion and rapid loss of K+ ion and disrupts Na+/K+ homeostasis under NaCl and NaHCO3 treatments. Based on the results above, we can conclude that OsUXS3 might regulate CAT activity by interacting with OsCATs, which is not only characterized for the first time but also regulating Na+/K+ homeostasis, positively regulating the Na+ ion toxicity tolerance under salt stress in rice.

In vitro selection for drought and salt stress tolerance in rice: an overview

In vitro selection for drought and salt stress tolerance in rice: an overview

Astaxanthin synthesized gold nanoparticles enhance salt stress tolerance in rice by enhancing tetrapyrrole biosynthesis and scavenging reactive oxygen species in vitro

One of the most common abiotic stresses, high salinity stress, has strictly inhibited plant growth all over the world. Rice is a common food crop, while saline soil has a bad impact on its quality and yield. Nanoparticles (NPs) have been found as an alleviation strategy against abiotic stresses, including salt stress. Astaxanthin is a natural antioxidative oxycarotenoid found in a variety of seafood and microorganisms. We first synthesized astaxanthin gold nanoparticles (Ast-AuNPs) using astaxanthin and chloroauric acid, and then found that 100 mg/L Ast-AuNPs effectively reduced the stress of high salinity (150 mM NaCl) for seven days in hydroponically grown 10-days-old rice seedlings to a greater extent than astaxanthin (100 mg/L) alone. We discovered that supplementing with Ast-AuNPs induced tetrapyrrole biosynthesis while decreasing oxidative stress caused by high salinity. Free proline, malondialdehyde, and hydrogen peroxide levels were dramatically reduced by 45.9%∼51.8%, while antioxidant enzyme activities (peroxidase, catalase, and superoxide dismutase) were expressively increased by 1.85∼3.85 fold with the addition of Ast-AuNPs under salt stress. Furthermore, we found that supplementing rice with Ast-AuNPs induced the expression of ROS-scavenging genes (OsCATA, OsCATB, OsPRX65, OsPRX89, OsCu/ZnSOD1, and OsCu/ZnSOD2) by 2.19∼9.92 fold in leaves. Consequently, these results showed that Ast-AuNPs can benefit rice seedlings coping with high salinity stress by inducing tetrapyrrole biosynthesis, scavenging ROS, and increasing antioxidant activity, and it also expanded the use of functional gold nanoparticles in the treatment of high salinity stress in crops.

Rice glycosyltransferase gene UGT2 functions in salt stress tolerance under the regulation of bZIP23 transcription factor.

Rice glycosyltransferase gene UGT2 was identified to play a crucial role in salt tolerance. The transcription factor OsbZIP23 was demonstrated to regulate the UGT2 expression under stress conditions. UDP-glycosyltransferases (UGTs) play key roles in modulating plant responses to environmental challenges. In this study, we characterized a novel glycosyltransferase, UGT2, which plays an important role in salt stress responses in rice (Oryza sativa L). We found that seedlings overexpressing UGT2 exhibited better growth than wild type in shoot and root under hydroponic culture with salt stress treatments, while ugt2ko mutant lines suffered much more growth inhibition. When the soil-grown UGT2 transgenic plants were subjected to salt stress, we also found that ugt2ko mutant lines were severely withered and most of them died, while the overexpression lines grew well and had higher survival rate. Compared with wild-type plants, UGT2 overexpression greatly increased the expression levels of the reactive oxygen species scavenging genes and stress-responsive genes. Furthermore, the upstream regulatory mechanism of the UGT2 gene was identified and we found that a bZIP transcription factor, OsbZIP23, can bind to the UGT2 promoter and enhance the UGT2 transcription levels. This work reveals that OsbZIP23-UGT2 module may play a major role in regulating the salt stress tolerance in rice.

The WRKY Transcription Factor OsWRKY54 Is Involved in Salt Tolerance in Rice.

Salt stress is a critical limiting factor for rice growth and production. Although numerous salt-tolerant genes have been identified, the mechanism underlying salt stress tolerance in rice remains unclear. This study reports the need for an uncharacterized WRKY transcription factor OsWRKY54 for rice salt-tolerance. Salt stress resulted in a rapid induction of OsWRKY54 expression in roots. Immunostaining analysis showed that it was mainly expressed in the stele. The loss of OsWRKY54 resulted in greater Na accumulation in shoots and enhanced sensitivity of rice plants to salt stress. The real-time quantitative PCR (qRT-PCR) and transcriptome analysis revealed that OsWRKY54 regulated the expression of some essential genes related to salt tolerance, such as OsNHX4 and OsHKT1;5. Furthermore, OsWRKY54 was found to regulate OsHKT1;5 expression by directly binding to the W-box motif in its promoter. Thus, these results indicated that OsWRKY54 was a critical regulatory factor in salt tolerance in rice.

Clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated genome-editing toolkit to enhance salt stress tolerance in rice and wheat.

The rice and wheat agricultural system is the primary source of food for billions across the world. However, the productivity and long-term sustainability of rice and wheat are threatened by a large number of abiotic stresses, especially salinity stress. Salinity has a significant impact on plant development and productivity and is one of the leading causes of crop yield losses in agricultural soils worldwide. Over the last few decades, several attempts have been undertaken to enhance salinity stress tolerance, most of which have relied on traditional or molecular breeding approaches. These approaches have so far been insufficient in addressing the issues of abiotic stress. However, due to the availability of genome sequences for cereal crops like rice and wheat and the development of genome editing techniques like clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein9 (Cas9), it is now possible to "edit" genes and influence key traits. Here, we review the application of the CRISPR/Cas9 system in both rice (Oryza sativa L.) and wheat (Triticum aestivum L.) to develop salinity tolerant cultivars. The CRISPR/Cas genome editing toolkit holds great promise of producing cereal crops tolerant to salt stress to increase agriculture resilience with a strong impact on the environment and public health.

OsVDE, a xanthophyll cycle key enzyme, mediates abscisic acid biosynthesis and negatively regulates salinity tolerance in rice.

OsVDE, a lipocalin-like protein in chloroplasts, negatively regulated the ABA biosynthesis and stomatal closure under salt stress in rice seedlings. Violaxanthin de-epoxidase (VDE) is a key enzyme of xanthophyll cycle. It plays a critical role in abscisic acid (ABA) biosynthesis, growth and stress responses in plants. Although functions of several VDE genes have been characterized, it is largely unknown whether OsVDE regulates the ABA biosynthesis and salt stress tolerance in rice. In this study, we generated the OsVDE overexpressing and CRISPR-Cas9-mediated gene-editing transgenic lines, and identified that the gene-editing mutant lines showed the dwarfism, shorter panicle and lower seed-setting rate than the wild type whereas the overexpression lines did not exhibit the difference from the wild type. In addition, the gene-editing transgenic lines were hypersensitive to exogenous ABA during germination. Under salt stress, the gene-editing transgenic seedlings had a higher ABA level, higher stomatal closure percentage and higher survival rate than the wild type. The qRT-PCR analysis confirmed that OsVDE negatively regulated the OsNECD2/4/5 expressions, ABA biosynthesis and salt stress tolerance in rice seedlings. These results provide new evidence that VDE plays an essential role in ABA biosynthesis and salt stress tolerance in plants.

Comparative Transcriptome Analysis Reveals the Mechanisms Underlying Differences in Salt Tolerance Between indica and japonica Rice at Seedling Stage.

Screening and breeding more salt-tolerant varieties is an effective way to deal with the global reduction in rice (Oryza sativa L.) yield caused by salt stress. However, the molecular mechanism underlying differences in salt tolerance between varieties, especially between the subspecies, is still unclear. We herein performed a comparative transcriptomic analysis under salt stress in contrasting two rice genotypes, namely RPY geng (japonica, tolerant variety) and Luohui 9 (named as Chao 2R in this study, indica, susceptible variety). 7208 and 3874 differentially expressed genes (DEGs) were identified under salt stress in Chao 2R and RPY geng, separately. Of them, 2714 DEGs were co-expressed in both genotypes, while 4494 and 1190 DEGs were specifically up/down-regulated in Chao 2R and RPY geng, respectively. Gene ontology (GO) analysis results provided a more reasonable explanation for the salt tolerance difference between the two genotypes. The expression of normal life process genes in Chao 2R were severely affected under salt stress, but RPY geng regulated the expression of multiple stress-related genes to adapt to the same intensity of salt stress, such as secondary metabolic process (GO:0019748), oxidation-reduction process (GO:0009067), etc. Furthermore, we highlighted important pathways and transcription factors (TFs) related to salt tolerance in RPY geng specific DEGs sets based on MapMan annotation and TF identification. Through Meta-QTLs mapping and homologous analysis, we screened out 18 salt stress-related candidate genes (RPY geng specific DEGs) in 15 Meta-QTLs. Our findings not only offer new insights into the difference in salt stress tolerance between the rice subspecies but also provide critical target genes to facilitate gene editing to enhance salt stress tolerance in rice.

Constitutive expression of Ribosomal Protein L6 modulates salt tolerance in rice transgenic plants.

We have functionally characterized the RPL6, a Ribosomal Protein Large subunit gene for salt stress tolerance in rice. The overexpression of RPL6 resulted in tolerance to moderate (150mM) to high (200mM) levels of salt (NaCl). The transgenic rice plants expressing RPL6 constitutively showed better phenotypic and physiological responses with high quantum efficiency, accumulation of higher chlorophyll and proline contents, and an overall increase in seed yield compared with the wild type in salt stress treatments. An iTRAQ-based comparative proteomic analysis revealed the high expression of about 333 proteins among the 4378 DAPs in a selected overexpression line of RPL6 treated with 200mM of NaCl. The functional analysis showed that these highly accumulated proteins (HAPs) are involved in photosynthesis, ribosome and chloroplast biogenesis, ion transportation, transcription and translation regulation, phytohormone and secondary metabolite signal transduction. An in silico network analysis of HAPs predicted that RPL6 binds with translation-related proteins and helicases, which coordinately affect the activities of a comprehensive signaling network, thereby inducing tolerance and promoting growth and productivity in response to salt stress. Our overall findings identified a novel candidate, RPL6, whose characterization contributed to the existing knowledge on the complexity of salt tolerance mechanism in plants.