Developmental Responses to Water and Salinity in Root Systems.

Roots provide the primary mechanism that plants use to absorb water and nutrients from their environment. These functions are dependent on developmental mechanisms that direct root growth and branching into regions of soil where these resources are relatively abundant. Water is the most limiting factor for plant growth, and its availability is determined by the weather, soil structure, and salinity. In this review, we define the developmental pathways that regulate the direction of growth and branching pattern of the root system, which together determine the expanse of soil from which a plant can access water. The ability of plants to regulate development in response to the spatial distribution of water is a focus of many recent studies and provides a model for understanding how biological systems utilize positional cues to affect signaling and morphogenesis. A better understanding of these processes will inform approaches to improve crop water use efficiency to more sustainably feed a growing population.

CmCNIH1 improves salt tolerance by influencing the trafficking of CmHKT1;1 in pumpkin.

Pumpkin is often used as a rootstock for other Cucurbitaceae crops due to its resistance to soil-borne diseases and abiotic stress. Pumpkin rootstocks use a sodium transporter (CmHKT1;1) to promote the transport of Na+ from the shoot to the root effectively and improve the salt tolerance of the scion. However, the molecular regulatory mechanisms that influence the activity of CmHKT1;1 during salt stress response remain unknown. In this study, CmCNIH1, a cornichon homolog, was identified as a potential cargo receptor for CmHKT1;1. Yeast two-hybrid, biomolecular fluorescence complementation and luciferase complementary assays demonstrated that CmCNIH1 and CmHKT1;1 could interact. CmCNIH1 was a key component of the cellular vesicle transport machinery located in the endoplasmic reticulum (ER), ER export site and Golgi apparatus. A CmCNIH1 knockout mutant was more sensitive to salt stress than the wild-type (WT). In addition, ion homeostasis was disrupted in cmcnih1 mutants, which had higher Na+ and lower K+ content in shoots and roots than the WT. Two-electrode voltage-clamp experiment displayed that CmCNIH1 could not influence the Na+ current that passed through the plasma membrane (PM) in CmHKT1;1-expressing Xenopus laevis oocytes. Data from co-localization assays indicated that intact CmCNIH1 protein could alter the subcellular localization of CmHKT1;1 in tobacco leaf, pumpkin root and yeast. In summary, CmCNIH1 may function as a cargo receptor that regulates the localization of CmHKT1;1 to the PM to improve salt tolerance in pumpkin.

Salinity-responsive histone PTMs identified in the gills and gonads of Mozambique tilapia (Oreochromis mossambicus).

BACKGROUND: Histone post-translational modifications (PTMs) are epigenetic marks that can be induced by environmental stress and elicit heritable patterns of gene expression. To investigate this process in an ecological context, we characterized the influence of salinity stress on histone PTMs within the gills, kidney, and testes of Mozambique tilapia (Oreochromis mossambicus). A total of 221 histone PTMs were quantified in each tissue sample and compared between freshwater-adapted fish exposed to salinity treatments that varied in intensity and duration. RESULTS: Four salinity-responsive histone PTMs were identified in this study. When freshwater-adapted fish were exposed to seawater for two hours, the relative abundance of H1K16ub significantly increased in the gills. Long-term salinity stress elicited changes in both the gills and testes. When freshwater-adapted fish were exposed to a pulse of severe salinity stress, where salinity gradually increased from freshwater to a maximum of 82.5 g/kg, the relative abundance of H1S1ac significantly decreased in the gills. Under the same conditions, the relative abundance of both H3K14ac and H3K18ub decreased significantly in the testes of Mozambique tilapia. CONCLUSIONS: This study demonstrates that salinity stress can alter histone PTMs in the gills and gonads of Mozambique tilapia, which, respectively, signify a potential for histone PTMs to be involved in salinity acclimation and adaptation in euryhaline fishes. These results thereby add to a growing body of evidence that epigenetic mechanisms may be involved in such processes.

SOG1 and BRCA1 Interdependently Regulate RAD54 Expression for Repairing Salinity-Induced DNA Double-Strand Breaks in Arabidopsis.

As sessile organisms, land plants experience various forms of environmental stresses throughout their life span. Therefore, plants have developed extensive and complicated defense mechanisms, including a robust DNA damage response (DDR) and DNA repair systems for maintaining genome integrity. In Arabidopsis, the NAC [NO APICAL MERISTEM (NAM), ARABIDOPSIS TRANSCRIPTION ACTIVATION FACTOR (ATAF), CUP-SHAPED COTYLEDON (CUC)] domain family transcription factor SUPPRESSOR OF GAMMA RESPONSE 1 (SOG1) plays an important role in regulating DDR. Here, we show that SOG1 plays a key role in regulating the repair of salinity-induced DNA double-strand breaks (DSBs) via the homologous recombination (HR) pathway in Arabidopsis. The sog1-1 mutant seedlings display a considerably slower rate of repair of salinity-induced DSBs. Accumulation of SOG1 protein increases in wild-type Arabidopsis under salinity stress, and it enhances the expression of HR pathway-related genes, including RAD51, RAD54 and BReast CAncer gene 1 (BRCA1), respectively, as found in SOG1 overexpression lines. SOG1 binds specifically to the AtRAD54 promoter at the 5'-(N)4GTCAA(N)3C-3' consensus sequence and positively regulates its expression under salinity stress. The phenotypic responses of sog1-1/atrad54 double mutants suggest that SOG1 functions upstream of RAD54, and both these genes are essential in regulating DDR under salinity stress. Furthermore, SOG1 interacts directly with BRCA1, an important component of the HR-mediated DSB repair pathway in plants, where BRCA1 appears to facilitate the binding of SOG1 to the RAD54 promoter. At the genetic level, SOG1 and BRCA1 function interdependently in modulating RAD54 expression under salinity-induced DNA damage. Together, our results suggest that SOG1 regulates the repair of salinity-induced DSBs via the HR-mediated pathway through genetic interactions with RAD54 and BRCA1 in Arabidopsis.

Novel underlying regulatory mechanism of the MsDAD2-mediated salt stress response in alfalfa.

Alfalfa (Medicago sativa L.), a crucial and widely grown forage legume, faces yield and quality challenges due to salinity stress. The defender against apoptotic death (DAD) gene, recognized initially as an apoptosis suppressor in mammals, plays a pivotal role in catalyzing N-glycosylation, acting as a positive regulator for protein folding and endoplasmic reticulum (ER) export. Here, we found that the MsDAD2 gene was specially induced in the salt-tolerant alfalfa cultivar (DL) under salinity stress, but not in the salt-sensitive cultivar (SD). Overexpression of MsDAD2 enhanced the salinity resistance of transgenic alfalfa by promoting NAD(P)H-quinone oxidoreductase (NQO1) and cytochrome b6f complex subunit (Cyt b6/f) expression, thereby mitigating reactive oxygen species (ROS) production. ChIP-qPCR analysis suggested that the differential expression of MsDAD2 in DL and SD under salinity stress may be linked to dynamic histone modifications in its promoter. Therefore, our findings elucidate a novel regulatory mechanism of MsDAD2 in alfalfa's response to salinity stress, underscoring its significance as a target for alfalfa breeding to enhance salt tolerance.

Alleviating salinity stress in canola (Brassica napus L.) through exogenous application of salicylic acid.

Canola, a vital oilseed crop, is grown globally for food and biodiesel. With the enormous demand for growing various crops, the utilization of agriculturally marginal lands is emerging as an attractive alternative, including brackish-saline transitional lands. Salinity is a major abiotic stress limiting growth and productivity of most crops, and causing food insecurity. Salicylic acid (SA), a small-molecule phenolic compound, is an essential plant defense phytohormone that promotes immunity against pathogens. Recently, several studies have reported that SA was able to improve plant resilience to withstand high salinity. For this purpose, a pot experiment was carried out to ameliorate the negative effects of sodium chloride (NaCl) on canola plants through foliar application of SA. Two canola varieties Faisal (V1) and Super (V2) were assessed for their growth performance during exposure to high salinity i.e. 0 mM NaCl (control) and 200 mM NaCl. Three levels of SA (0, 10, and 20 mM) were applied through foliar spray. The experimental design used for this study was completely randomized design (CRD) with three replicates. The salt stress reduced the shoot and root fresh weights up to 50.3% and 47% respectively. In addition, foliar chlorophyll a and b contents decreased up to 61-65%. Meanwhile, SA treatment diminished the negative effects of salinity and enhanced the shoot fresh weight (49.5%), root dry weight (70%), chl. a (36%) and chl. b (67%). Plants treated with SA showed an increased levels of both enzymatic i.e. (superoxide dismutase (27%), peroxidase (16%) and catalase (34%)) and non-enzymatic antioxidants i.e. total soluble protein (20%), total soluble sugar (17%), total phenolic (22%) flavonoids (19%), anthocyanin (23%), and endogenous ascorbic acid (23%). Application of SA also increased the levels of osmolytes i.e. glycine betaine (31%) and total free proline (24%). Salinity increased the concentration of Na+ ions and concomitantly decreased the K+ and Ca2+ absorption in canola plants. Overall, the foliar treatments of SA were quite effective in reducing the negative effects of salinity. By comparing both varieties of canola, it was observed that variety V2 (Super) grew better than variety V1 (Faisal). Interestingly, 20 mM foliar application of SA proved to be effective in ameliorating the negative effects of high salinity in canola plants.

Effect of methyl jasmonate and GA3 on canola (Brassica napus L.) growth, antioxidants activity, and nutrient concentration cultivated in salt-affected soils.

Salinity stress is a significant challenge in agricultural production. When soil contains high salts, it can adversely affect plant growth and productivity due to the high concentration of soluble salts in the soil water. To overcome this issue, foliar applications of methyl jasmonate (MJ) and gibberellic acid (GA3) can be productive amendments. Both can potentially improve the plant's growth attributes and flowering, which are imperative in improving growth and yield. However, limited literature is available on their combined use in canola to mitigate salinity stress. That's why the current study investigates the impact of different levels of MJ (at concentrations of 0.8, 1.6, and 3.2 mM MJ) and GA3 (0GA3 and 5 mg/L GA3) on canola cultivated in salt-affected soils. Applying all the treatments in four replicates. Results indicate that the application of 0.8 mM MJ with 5 mg/L GA3 significantly enhances shoot length (23.29%), shoot dry weight (24.77%), number of leaves per plant (24.93%), number of flowering branches (26.11%), chlorophyll a (31.44%), chlorophyll b (20.28%) and total chlorophyll (27.66%) and shoot total soluble carbohydrates (22.53%) over control. Treatment with 0.8 mM MJ and 5 mg/L GA3 resulted in a decrease in shoot proline (48.17%), MDA (81.41%), SOD (50.59%), POD (14.81%) while increase in N (10.38%), P (15.22%), and K (8.05%) compared to control in canola under salinity stress. In conclusion, 0.8 mM MJ + 5 mg/L GA3 can improve canola growth under salinity stress. More investigations are recommended at the field level to declare 0.8 mM MJ + 5 mg/L GA3 as the best amendment for alleviating salinity stress in different crops.

GhVIM28, a negative regulator identified from VIM family genes, positively responds to salt stress in cotton.

The VIM (belonged to E3 ubiquitin ligase) gene family is crucial for plant growth, development, and stress responses, yet their role in salt stress remains unclear. We analyzed phylogenetic relationships, chromosomal localization, conserved motifs, gene structure, cis-acting elements, and gene expression patterns of the VIM gene family in four cotton varieties. Our findings reveal 29, 29, 17, and 14 members in Gossypium hirsutum (G.hirsutum), Gossypium barbadense (G.barbadense), Gossypium arboreum (G.arboreum), and Gossypium raimondii (G. raimondii), respectively, indicating the maturity and evolution of this gene family. motifs among GhVIMs genes were observed, along with the presence of stress-responsive, hormone-responsive, and growth-related elements in their promoter regions. Gene expression analysis showed varying patterns and tissue specificity of GhVIMs genes under abiotic stress. Silencing GhVIM28 via virus-induced gene silencing revealed its role as a salt-tolerant negative regulator. This work reveals a mechanism by which the VIM gene family in response to salt stress in cotton, identifying a potential negative regulator, GhVIM28, which could be targeted for enhancing salt tolerance in cotton. The objective of this study was to explore the evolutionary relationship of the VIM gene family and its potential function in salt stress tolerance, and provide important genetic resources for salt tolerance breeding of cotton.

Zinc oxide nanoparticles mediated salinity stress mitigation in Pisum sativum: a physio-biochemical perspective.

Salinity is the major abiotic stress among others that determines crop productivity. The primary goal is to examine the impact of Zinc Oxide Nanoparticles (ZnO NPs) on the growth, metabolism, and defense systems of pea plants in simulated stress conditions. The ZnO NPs were synthesized via a chemical process and characterized by UV, XRD, and SEM. The ZnO NPs application (50 and 100) ppm and salt (50 mM and 100 mM) concentrations were carried out individually and in combination. At 50 ppm ZnO NPs the results revealed both positive and negative effects, demonstrating an increase in the root length and other growth parameters, along with a decrease in Malondialdehyde (MDA) and hydrogen peroxide concentrations. However, different concentrations of salt (50 mM and 100 mM) had an overall negative impact on all assessed parameters. In exploring the combined effects of ZnO NPs and salt, various concentrations yielded different outcomes. Significantly, only 50 mM NaCl combined with 50 ppm ZnO NPs demonstrated positive effects on pea physiology, leading to a substantial increase in root length and improvement in other physiological parameters. Moreover, this treatment resulted in decreased levels of MAD, Glycine betaine, and hydrogen peroxide. Conversely, all other treatments exhibited negative effects on the assessed parameters, possibly due to the high concentrations of both stressors. The findings offered valuble reference data for research on the impact of salinity on growth parameters of future agriculture crop.

CmDOF18 positively regulates salinity tolerance in Chrysanthemum morifolium by activating the oxidoreductase system.

BACKGROUND: Chrysanthemum, one of the four major cut flowers all over the world, is very sensitive to salinity during cultivation. DNA binding with one finger (DOF) transcription factors play important roles in biological processes in plants. The response mechanism of CmDOF18 from chrysanthemum to salt stress remains unclear. RESULTS: In this study, CmDOF18 was cloned from Chrysanthemum morifolium, and its expression was induced by salinity stress. The gene encodes a 291-amino acid protein with a typical DOF domain. CmDOF18 was localized to the nucleus in onion epidermal cells and showed transcriptional activation in yeast. CmDOF18 transgenic plants were generated to identify the role of this gene in resistance to salinity treatment. Chrysanthemum plants overexpressing CmDOF18 were more resistant to salinity stress than wild-type plants. Under salinity stress, the malondialdehyde content and leaf electrolyte conductivity in CmDOF18-overexpressing transgenic plants were lower than those in wild-type plants, while the proline content, chlorophyll content, superoxide dismutase activity and peroxidase activity were higher than those in wild-type plants. The opposite findings were observed in gene-silenced plants compared with wild-type plants. The gene expression levels of oxidoreductase increased in CmDOF18-overexpressing transgenic plants but decreased in CmDOF18-SRDX gene-silenced transgenic plants. CONCLUSION: In summary, we analyzed the function of CmDOF18 from chrysanthemum, which may regulate salinity stress in plants, possibly due to its role in the regulation of oxidoreductase.

The role of strigolactone in alleviating salinity stress in chili pepper.

Salinity stress can significantly delay plant growth. It can disrupt water and nutrient uptake, reducing crop yields and poor plant health. The use of strigolactone can be an effective technique to overcome this issue. Strigolactone enhances plant growth by promoting root development and improvement in physiological attributes. The current pot study used strigolactone to amend chili under no salinity and salinity stress environments. There were four treatments, i.e., 0, 10µM strigolactone, 20µM strigolactone and 30µM strigolactone. All treatments were applied in four replications following a completely randomized design (CRD). Results showed that 20µM strigolactone caused a significant increase in chili plant height (21.07%), dry weight (33.60%), fruit length (19.24%), fruit girth (35.37%), and fruit yield (60.74%) compared to control under salinity stress. Significant enhancement in chili chlorophyll a (18.65%), chlorophyll b (43.52%), and total chlorophyll (25.09%) under salinity stress validated the effectiveness of 20µM strigolactone application as treatment over control. Furthermore, improvement in nitrogen, phosphorus, and potassium concentration in leaves confirmed the efficient functioning of 20µM strigolactone compared to other concentrations under salinity stress. The study concluded that 20µM strigolactone is recommended for mitigating salinity stress in chili plants. Growers are advised to apply 20µM strigolactone to enhance their chili production under salinity stress.

Impact of cobalt and proline foliar application for alleviation of salinity stress in radish.

Salinity stress ranks among the most prevalent stress globally, contributing to soil deterioration. Its negative impacts on crop productivity stem from mechanisms such as osmotic stress, ion toxicity, and oxidative stress, all of which impede plant growth and yield. The effect of cobalt with proline on mitigating salinity impact in radish plants is still unclear. That's why the current study was conducted with aim to explore the impact of different levels of Co and proline on radish cultivated in salt affected soils. There were four levels of cobalt, i.e., (0, 10, 15 and 20 mg/L) applied as CoSO4 and two levels of proline (0 and 0.25 mM), which were applied as foliar. The treatments were applied in a complete randomized design (CRD) with three replications. Results showed that 20 CoSO4 with proline showed improvement in shoot length (∼ 20%), root length (∼ 23%), plant dry weight (∼ 19%), and plant fresh weight (∼ 41%) compared to control. The significant increase in chlorophyll, physiological and biochemical attributes of radish plants compared to the control confirms the efficacy of 20 CoSO4 in conjunction with 10 mg/L proline for mitigating salinity stress. In conclusion, application of cobalt with proline can help to alleviate salinity stress in radish plants. However, multiple location experiments with various levels of cobalt and proline still needs in-depth investigations to validate the current findings.

The effect of the combined application of elicitors to Salvia virgata Jacq. under salinity stress on physiological and antioxidant defense.

Salinity stress is one of the most important stress barriers to crop production worldwide. Developing and implementing new strategies against salinity stress is critical for increasing agricultural productivity and supporting sustainable farming. Elicitors such as nanoparticles and Salicylic acid have recently been used potentially for better product yield. Therefore, in our research the Salvia virgata plant was exposed to salinity (NaCl) stress, and zinc oxide nanoparticles (ZnONP), salicylic acid (SA), and the ZnONP + SA combination were applied to plants divided into different groups. While salinity stress decreased the amount of chlorophyll a, chlorophyll b, and carotenoid pigments, SA, ZnONP, and SA + ZnONP elicitors combined with salinity stress enhanced the content of all three pigments. While salt stress raised MDA, H2O2, total phenolic, total flavonoid, soluble sugar and proline content, elicitor applications enhanced proline, soluble sugar, total phenolic and total flavonoid content more. Additionally, the application of NaCl + SA + ZnONP increased proline content by 21.55% and sugar content by 15.73% compared to NaCl application, while decreasing MDA content by 42.28% and H2O2 levels by 42.34%, thereby alleviating the plant's salt stress. It was revealed that DPPH, ABTS, and CUPRAC antioxidant activity sequence used to determine the total antioxidant activity displayed similarities, and it was found as NaCI + ZnONP > NaCI + SA > NaCI + SA + ZnONP > NaCI > Control. Furthermore, all elicitor applications increased CAT, GR, APX, and SOD enzyme activities while reducing oxidative stress in S. virgata plants. When all the data were evaluated, it was confirmed that SA and ZnONP had a synergistic effect and that SA and ZnONP have the potential to support plant development and growth under salinity. SA and ZnONP applications may have the capacity to least the detrimental impacts of salinity stress on plants. However, further research is needed to investigate the effectiveness of SA and ZnONPs in ameliorating salinity or different stress factors in various other plants.

Expression profiling of Nuclear Factor-Y (NF-Y) transcription factors during dehydration and salt stress in finger millet reveals potential candidate genes for multiple stress tolerance.

MAIN CONCLUSION: Expression profiling of NF-Y transcription factors during dehydration and salt stress in finger millet genotypes contrastingly differing in tolerance levels identifies candidate genes for further characterization and functional studies. The Nuclear Factor-Y (NF-Y) transcription factors are known for imparting abiotic stress tolerance in different plant species. However, there is no information on the role of this transcription factor family in naturally drought-tolerant crop finger millet (Eleusine coracana L.). Therefore, interpretation of expression profiles against drought and salinity stress may provide valuable insights into specific and/or overlapping expression patterns of Eleusine coracana Nuclear Factor-Y (EcNF-Y) genes. Given this, we identified 59 NF-Y (18 NF-YA, 23 NF-YB, and 18 NF-YC) encoding genes and designated them EcNF-Y genes. Expression profiling of these genes was performed in two finger millet genotypes, PES400 (dehydration and salt stress tolerant) and VR708 (dehydration and salt stress sensitive), subjected to PEG-induced dehydration and salt (NaCl) stresses at different time intervals (0, 6, and 12 h). The qRT-PCR expression analysis reveals that the six EcNF-Y genes namely EcNF-YA1, EcNF-YA5, EcNF-YA16, EcNF-YB6, EcNF-YB10, and EcNF-YC2 might be associated with tolerance to both dehydration and salinity stress in early stress condition (6 h), suggesting the involvement of these genes in multiple stress responses in tolerant genotype. In contrast, the transcript abundance of finger millet EcNF-YA5 genes was also observed in the sensitive genotype VR708 under late stress conditions (12 h) of both dehydration and salinity stress. Therefore, the EcNF-YA5 gene might be important for adaptation to salinity and dehydration stress in sensitive finger millet genotypes. Therefore, this gene could be considered as a susceptibility determinant, which can be edited to impart tolerance. The phylogenetic analyses revealed that finger millet NF-Y genes share strong evolutionary and functional relationship to NF-Ys governing response to abiotic stresses in rice, sorghum, maize, and wheat. This is the first report of expression profiling of EcNF-Ys genes identified from the finger millet genome and reveals potential candidate for enhancing dehydration and salt tolerance.

A glutathione-independent DJ-1/Pfp1 domain containing glyoxalase III, OsDJ-1C, functions in abiotic stress adaptation in rice.

MAIN CONCLUSION: Overexpression of OsDJ-1C in rice improves root architecture, photosynthesis, yield and abiotic stress tolerance through modulating methylglyoxal levels, antioxidant defense, and redox homeostasis. Exposure to abiotic stresses leads to elevated methylglyoxal (MG) levels in plants, impacting seed germination and root growth. In response, the activation of NADPH-dependent aldo-keto reductase and glutathione (GSH)-dependent glyoxalase enzymes helps to regulate MG levels and reduce its toxic effects. However, detoxification may not be carried out effectively due to the limitation of GSH and NADPH in plants under stress. Recently, a novel enzyme called glyoxalase III (GLY III) has been discovered which can detoxify MG in a single step without needing GSH. To understand the physiological importance of this pathway in rice, we overexpressed the gene encoding GLYIII enzyme (OsDJ-1C) in rice. It was observed that OsDJ-1C overexpression in rice regulated MG levels under stress conditions thus, linked well with plants' abiotic stress tolerance potential. The OsDJ-1C overexpression lines displayed better root architecture, improved photosynthesis, and reduced yield penalty compared to the WT plants under salinity, and drought stress conditions. These plants demonstrated an improved GSH/GSSG ratio, reduced level of reactive oxygen species, increased antioxidant capacity, and higher anti-glycation activity thereby indicating that the GLYIII mediated MG detoxification plays a significant role in plants' ability to reduce the impact of abiotic stress. Furthermore, these findings imply the potential of OsDJ-1C in crop improvement programs.

OsRR26, a type-B response regulator, modulates salinity tolerance in rice via phytohormone-mediated ROS accumulation in roots and influencing reproductive development.

MAIN CONCLUSION: OsRR26 is a cytokinin-responsive response regulator that promotes phytohormone-mediated ROS accumulation in rice roots, regulates seedling growth, spikelet fertility, awn development, represses NADPH oxidases, and negatively affects salinity tolerance. Plant two-component systems (TCS) play a pivotal role in phytohormone signaling, stress responses, and circadian rhythm. However, a significant knowledge gap exists regarding TCS in rice. In this study, we utilized a functional genomics approach to elucidate the role of OsRR26, a type-B response regulator in rice. Our results demonstrate that OsRR26 is responsive to cytokinin, ABA, and salinity stress, serving as the ortholog of Arabidopsis ARR11. OsRR26 primarily localizes to the nucleus and plays a crucial role in seedling growth, spikelet fertility, and the suppression of awn development. Exogenous application of cytokinin led to distinct patterns of reactive oxygen species (ROS) accumulation in the roots of both WT and transgenic plants (OsRR26OE and OsRR26KD), indicating the potential involvement of OsRR26 in cytokinin-mediated ROS signaling in roots. The application of exogenous ABA resulted in varied cellular compartmentalization of ROS between the WT and transgenic lines. Stress tolerance assays of these plants revealed that OsRR26 functions as a negative regulator of salinity stress tolerance across different developmental stages in rice. Physiological and biochemical analyses unveiled that the knockdown of OsRR26 enhances salinity tolerance, characterized by improved chlorophyll retention and the accumulation of soluble sugars, K+ content, and amino acids, particularly proline.

Low salinity stress increases the risk of Vibrio parahaemolyticus infection and gut microbiota dysbiosis in Pacific white shrimp.

BACKGROUND: Extreme precipitation events often cause sudden drops in salinity, leading to disease outbreaks in shrimp aquaculture. Evidence suggests that environmental stress increases animal host susceptibility to pathogens. However, the mechanisms of how low salinity stress induces disease susceptibility remain poorly understood. METHODS: We investigated the acute response of shrimp gut microbiota exposed to pathogens under low salinity stress. For comparison, shrimp were exposed to Vibrio infection under two salinity conditions: optimal salinity (Control group) and low salinity stress (Stress group). High throughput 16S rRNA sequencing and real-time PCR were employed to characterize the shrimp gut microbiota and quantify the severity level of Vibrio infection. RESULTS: The results showed that low salinity stress increased Vibrio infection levels, reduced gut microbiota species richness, and perturbed microbial functions in the shrimp gut, leading to significant changes in lipopolysaccharide biosynthesis that promoted the growth of pathogens. Gut microbiota of the bacterial genera Candidatus Bacilliplasma, Cellvibrio, and Photobacterium were identified as biomarkers of the Stress group. The functions of the gut microbiota in the Stress group were primarily associated with cellular processes and the metabolism of lipid-related compounds. CONCLUSIONS: Our findings reveal how environmental stress, particularly low salinity, increases shrimp susceptibility to Vibrio infection by affecting the gut microbiota. This highlights the importance of avoiding low salinity stress and promoting gut microbiota resilience to maintain the health of shrimp.

The signalling pathways, calcineurin B-like protein 5 (CBL5)-CBL-interacting protein kinase 8 (CIPK8)/CIPK24-salt overly sensitive 1 (SOS1), transduce salt signals in seed germination in Arabidopsis.

For plant growth under salt stress, sensing and transducing salt signals are central to cellular Na+ homoeostasis. The calcineurin B-like protein (CBL)-CBL-interacting protein kinase (CIPK) complexes play critical roles in transducing salt signals in plants. Here, we show that CBL5, an ortholog of CBL4 and CBL10 in Arabidopsis, interacts with and recruits CIPK8/CIPK24 to the plasma membrane. Yeast cells coexpressing CBL5, CIPK8/CIPK24 and SOS1 demonstrated lesser Na+ accumulation and a better growth phenotype than the untransformed or SOS1 transgenic yeast cells under salinity. Overexpression of CBL5 improved the growth of the cipk8 or cipk24 single mutant but not the cipk8 cipk24 double mutant under salt stress, suggesting that CIPK8 and CIPK24 were the downstream targets of CBL5. Interestingly, seed germination in cbl5 was severely inhibited by NaCl, which was recovered by the overexpression of CBL5. Furthermore, CBL5 was mainly expressed in the cotyledons and hypocotyls, which are essential to seed germination. Na+ efflux activity in the hypocotyls of cbl5 was reduced relative to the wild-type under salt stress, enhancing Na+ accumulation. These findings indicate that CBL5 functions in seed germination and protects seeds and germinating seedlings from salt stress through the CBL5-CIPK8/CIPK24-SOS1 pathways.

A Novel MsEOBI-MsPAL1 Module Enhances Salinity Stress Tolerance, Floral Scent Emission and Seed Yield in Alfalfa.

Alfalfa (Medicago sativa L.) is an important and widely cultivated forage legume, yet its yield is constrained by salinity stress. In this study, we characterized an R2R3-MYB transcription factor MsEOBI in alfalfa. Its salt tolerance function and regulatory pathways were investigated. The nuclear-localized MsEOBI functions as a transcriptional activator, enhancing salinity tolerance by promoting the biosynthesis of flavonoids and lignin, as well as facilitating the scavenging of reactive oxygen species (ROS). Additionally, MsEOBI promotes pollinator attraction and increases seed yield by activating the biosynthesis of volatile phenylpropanoids. Yeast one-hybrid (Y1H), dual-luciferase reporter and chromatin immunoprecipitation coupled with quantitative PCR (ChIP-qPCR) assays demonstrated that MsEOBI directly binds to the promoter regions of MsPAL1, a key gene in the phenylpropanoid pathway, thereby activating its expression. Overexpression of MsPAL1 enhances salinity tolerance in alfalfa. These findings elucidate the role of the MsEOBI-MsPAL1 regulatory module and provide valuable genetic resources for the future breeding of salt-tolerant alfalfa varieties.

Nucleoporin 50 proteins affect longevity and salinity stress tolerance in seeds.

Nucleoporin 50 (Nup50) is an evolutionarily conserved protein that is a constituent of the nuclear pore complex (NPC); however, its physiological role in plants is unclear. Arabidopsis has two Nup50 proteins, Nup50a and Nup50b, which are highly expressed in developing seeds. Green fluoresceent protein (GFP)-fused Nup50a and Nup50b are localized exclusively in the nucleopolasm, implying an additional function beyond the NPC in the nuclear envelope. To investigate the function of Nup50s, we employed the CRISPR/Cas9 [clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9] system to generate a nup50a nup50b double mutant, which exhibited premature translation termination of both Nup50 proteins. While the mutant showed no significant abnormal phenotype during vegetative growth, the nup50a nup50b seeds had an abnormal shape compared with the wild type. Comparative transcriptomics using immature seeds revealed that Nup50s regulate the expression of various genes, including cell wall-related genes. The nup50a nup50b seeds exhibited reduced seed longevity and salinity stress tolerance. Tetrazolium uptake and mucilage release assays implied that the nup50a nup50b seeds had greater water permeability than the wild type. Taken together, our results imply that Nup50s play a critical role in seed formation by regulating gene expression.