Salt and drought stress signal transduction in plants

The synergistic roles of MsRCI2B and MsRCI2E in the regulation of ion balance and ROS homeostasis in alfalfa under salt stress

Under salt stress, plasma membrane proteins regulate ion homeostasis and the balance between reactive oxygen species (ROS). In this study, we investigated the functions of two small membrane proteins-MsRCI2B (tailless) and MsRCI2E (tailed)-encoded by the RCI2 (Rare Cold Inducible 2) gene family in Medicago sativa (alfalfa). We identified the distinct subcellular localization and expression patterns of these proteins under salt stress. Using yeast two-hybrid (Y2H), GST pull-down, and bimolecular fluorescence complementation (BiFC) assays, we confirmed the physical interactions between MsRCI2B and MsRCI2E. Transgenic alfalfa lines overexpressing MsRCI2(OE#RCI2) and co-expressing both MsRCI2B and MsRCI2E (OE#RCI2E-2B) were developed to explore their roles in salt tolerance. Interestingly, the C-terminal tail of MsRCI2E negatively affects salt tolerance; however, its interaction with MsRCI2B mitigates this adverse effect. To further understand the regulatory mechanisms, we screened for plasma membrane proteins (PMPs) that interact with MsRCI2B or MsRCI2E using a DUALmembrane yeast two-hybrid system. MsCaM1 interacts with MsRCI2B, whereas MsPIP1;4 and MsHVP1 specifically interact with MsRCI2E. Notably, the MsRCI2E-PIP1;4 interaction influenced the intracellular trafficking of PIP1;4, reducing its presence on the plasma membrane and thereby limiting the export of H2O2, which helps maintain ROS homeostasis. Additionally, the interaction between MsRCI2E and HVP1 stabilized ion homeostasis by decreasing Na+ concentration in the cytoplasm under salt stress. Overall, our study provides new insights into the molecular mechanisms through which MsRCI2B and MsRCI2E coordinate the ion and ROS balance under salt stress and offering promising strategies for enhancing crop tolerance to salinity.

Spd-CDs-driven respiratory burst oxidase homolog/polyamine oxidase-dependent H2O2 signaling molecule engineering for salt tolerance in tomato

Carbon dots, are now considered safe, environment-friendly materials. Spermidine carbon dots (Spd-CDs) have been used as new agrochemicals for abiotic stress, but in-depth studies of salt stress remain scarce. Here, foliar application of Spd-CDs improved salt stress tolerance in tomatoes, and the beneficial effects were concentration-dependent. Tomato seedlings supplied with Spd-CDs (3.0 mg/L) had a greater height, a higher maximum quantum yield of PSII, and a higher net photosynthetic rate than controls after being exposed to 120 mM NaCl for 7 d. Molecular evidence showed that Spd-CDs promoted H2O2 molecule production by inducing the expression of respiratory burst oxidase homolog 1 (rboh1) and polyamine oxidase 5 (pao5), thus causing H2O2 molecule production and conferring resistance to salt stress. The role of RBOH1- and PAO5-dependent H2O2 molecule generation was evaluated by manipulating endogenous H2O2 levels and in rboh1 and pao5 mutants. Spd-CDs-meditated H2O2 regulation of salt tolerance could be articulated by reducing iron deficiency, maintaining ion homeostasis, and reducing root-to-shoot Na+ loading. Overall, the ROS signal molecule produced by RBOH1 and PAO5 protein was involved in the control of salt tolerance by Spd-CDs. These findings demonstrate that Spd-CDs are an effective and durable strategy to improve plant performance under salt stress, and to increase food security and quality.

Functional analysis of AtDPBF3, encoding a key member of the ABI5 subfamily involved in ABA signaling, in Arabidopsis thaliana under salt stress

Soil salinization is a major environmental stress limiting plant growth and development, affecting crop yields worldwide. We investigated the role of AtDPBF3, encoding a key member of the ABI5 subfamily, in the response to salt stress. The AtDPBF3 mutant (dpbf3) was significantly more sensitive to salt stress compared with wild type. Compared with leaves of salt-stressed wild type, those of salt-stressed dpbf3 exhibited severe decreases in chlorophyll content and photochemical efficiency (Fv/Fm), and disrupted ion homeostasis (higher Na+ content and lower K+ content). Comparative transcriptome analyses identified 457 genes that were differentially expressed in wild-type plants under salt stress but not in dpbf3 under salt stress. These differentially expressed genes encoded a range of products, including ion channels (e.g., AtCXX5, encoding a high-affinity K⁺ uptake/Na⁺ transporter), regulatory protein [e.g., AtSOS3, encoding Salt Overly Sensitive 3 (SOS3) that regulates SOS1 to reduce cytoplasmic Na⁺ levels through the SOS signaling pathway], sugar transporters [e.g., AtSUT4, encoding sucrose transporter 4 (SUT4)], and proteins involved in the stress response (e.g., AtLEA4-5, encoding LEA family proteins) and hormone signaling. These findings suggest that AtDPBF3 enhances salt tolerance by regulating many genes. qRT-PCR analyses confirmed the reliability of the transcriptome data, supporting the crucial role of AtDPBF3 in the salt stress response. These results lay the foundation for further research on the ABA signaling pathway and stress resistance mechanisms.

Heterologous expression of the durum wheat TdHKT1;4-1 partially complements the mutant athkt1 in Arabidopsis thaliana under severe salt stress

High-affinity K+ (HKT) transporters which mediate Na+-specific transport or Na+-K+ co-transport play a key role in plant salt tolerance. In our previous functional study in Xenopus oocytes, we demonstrated that the durum wheat TdHKT1;4-1 acts as a Na+-selective transporter. Here, we investigated the function of TdHKT1;4-1 and its contribution in salt stress tolerance in the Arabidopsis athkt1 mutant background. Our results revealed that TdHKT1;4-1 partially complements the salt sensitivity phenotype of the athkt1 transgenic lines. Comparative physiological analyses and oxidative stress status under moderate salt stress (50 mM NaCl) showed that both transgenic lines SH3 and SH5 restored the salt stress tolerance comparable to the level observed in Wt plants. Whereas, under severe salt stress treatment (100 mM NaCl), the athkt1 transgenic lines exhibited an intermediate salt stress tolerance between Wt and athkt1 mutant. Moreover, TdHKT1;4-1 was highly expressed in leaves under moderate and severe salt stress, while in roots, it was largely expressed only under severe salt stress. In addition, antioxidant enzymes such as catalase (CAT), peroxidase (POD), and superoxide dismutase (SOD) were significantly expressed in SH3 and SH5 lines compared to athkt1 and Wt under moderate stress. Therefore, TdHKT1;4-1 seems to differ from its Arabidopsis homologous counterpart, as it contributes to salt stress tolerance up to a specific threshold, above which the TdHKT1;4-1 expression may lead to higher root Na+ influx, hence increasing its toxicity during salt stress.

CYTOKININ DEHYDROGENASE suppression increases intrinsic water-use efficiency and photosynthesis in cotton under drought

Drought reduces endogenous cytokinin (CK) content and disturbs plant water balance and photosynthesis. However, the effect of higher endogenous CK levels (achieved by suppressing cytokinin dehydrogenase [CKX] genes) on plant water status and photosynthesis under drought stress is unknown. Here, pot experiments were conducted with wild-type (WT) cotton (Gossypium hirsutum) and 2 GhCKX suppression lines (CR-3 and CR-13) to explore the effect of higher endogenous CK levels on leaf water utilization and photosynthesis under drought stress. The GhCKX suppression lines had a higher leaf net photosynthetic rate (AN) and intrinsic water-use efficiency (iWUE) than WT under drought. This increase was attributed to the decoupling of stomatal conductance (gs) and mesophyll conductance (gm) in the suppression lines in response to drought. GhCKX suppression increased gm but maintained gs relative to WT under drought, and the increased gm was associated with altered anatomical traits, including decreased cell wall thickness (Tcw) and increased surface area of chloroplast-facing intercellular airspaces per unit leaf area (Sc/S), as well as altered cell wall composition, especially decreased cellulose levels. This study provides evidence that increased endogenous CK levels can simultaneously enhance AN and iWUE in cotton under drought conditions and establishes a potential mechanism for this effect. These findings provide a potential strategy for breeding drought-tolerant crops or exploring alternative methods to promote crop drought tolerance.

Salinity induced changes in esterase, peroxidase and alcohol dehydrogenase isozymes and leaf soluble proteins in salinity susceptible and salinity tolerant sugarcane genotypes

The salinity susceptible CoC-671 and salinity tolerant sugarcane genotype CoM-265 were evaluated for Peroxidase (POX), Esterase (EST) and Alcohol Dehydrogenase (ADH) isozymes and soluble protein profiling by SDS and native-PAGE at salinity levels 0.41 dSm-1, 2.31 dSm-1, 4.21 dSm-1, and 8.01 dSm-1 maintained by NaCl solution. The plant height, number of leaves and seedling diameter got reduced in salinity susceptible sugarcane genotype CoC-671 as well as salinity tolerant sugarcane genotype CoM-265 with increase in salinity levels. However, reduction in plant height, number of leaves and seedling diameter was less in salinity tolerant sugarcane genotype CoM-265 as compared to salinity susceptible sugarcane genotype CoC-671. The POX isozyme profiling revealed that salinity susceptible CoC-671 and salinity tolerant sugarcane genotype CoM-265 had variation in soluble protein band intensity at different salinity levels with relative mobility (Rm) 0.137. The present study could be useful for genetic variability analysis in sugarcane genotypes differing in salinity stress tolerance capability.

Beneficial microorganisms: Regulating growth and defense for plant welfare

Beneficial microorganisms (BMs) promote plant growth and enhance stress resistance. This review summarizes how BMs induce growth promotion by improving nutrient uptake, producing growth-promoting hormones and stimulating root development. How BMs enhance disease resistance and help protect plants from abiotic stresses has also been explored. Growth-defense trade-offs are known to affect the ability of plants to survive under unfavourable conditions. This review discusses studies demonstrating that BMs regulate growth-defense trade-offs through microbe-associated molecular patterns and multiple pathways, including the leucine-rich repeat receptor-like kinase pathway, abscisic acid signalling pathway and specific transcriptional factor regulation. This multifaceted relationship underscores the significance of BMs in sustainable agriculture. Finally, the need for integration of artificial intelligence to revolutionize biofertilizer research has been highlighted. This review also elucidates the cutting-edge advancements and potential of plant-microbe synergistic microbial agents.

The Multifaceted Roles of Neutrophil Death in COPD and Lung Cancer

Chronic obstructive pulmonary disease (COPD) and lung cancer are closely linked, with individuals suffering from COPD at a significantly higher risk of developing lung cancer. The mechanisms driving this increased risk are multifaceted, involving genomic instability, immune dysregulation, and alterations in the lung environment. Neutrophils, the most abundant myeloid cells in human blood, have emerged as critical regulators of inflammation in both COPD and lung cancer. Despite their short lifespan, neutrophils contribute to disease progression through various forms of programmed cell death, including apoptosis, necroptosis, ferroptosis, pyroptosis, and NETosis, a form of neutrophil death with neutrophil extracellular traps (NETs) formation. These distinct death pathways affect inflammatory responses, tissue remodeling, and disease progression in COPD and lung cancer. This review provides an in-depth exploration of the mechanisms regulating neutrophil death, the interplay between various cell death pathways, and their influence on disease progression. Additionally, we highlight emerging therapeutic approaches aimed at targeting neutrophil death pathways, presenting promising new interventions to enhance treatment outcomes in COPD and lung cancer.

Genome-wide identification and expression analysis of the lipoxygenase gene family in sesame reveals regulatory networks in response to abiotic stress

BACKGROUND

Plant lipoxygenase (Lox) genes, catalyze polyunsaturated fatty acids and play essential roles in plant growth, development, and stress responses. It is extensively studied under various stresses, their role in abiotic stress responses remains unexplored in sesame.

METHODS AND RESULTS

This study identified seven Lox genes in sesame divided into two subfamilies: 9-Lox (Silox1, Silox2 and Silox3) are likely involved in pathogen defence and signalling and 13-Lox (Type-I: Silox4 and Type-II: Silox5, Silox6 and Silox7) play crucial roles in jasmonic acid biosynthesis and abiotic stress responses. Silox genes have undergone purifying selection, promoting the stability of gene function and prefer codons with A or T in the third position. The chromosomal distribution, sequence similarity, and subcellular localization, with conserved lipoxygenase domains and motifs were analysed. Promoter regions contained 34 cis-acting regulatory elements (e.g. WRKY, ERF, and bHLH) and 35 transcription factors binding sites (TFBS) linked to light, stress (e.g. MYC, W-box, ERE and STRE), phytohormones, and growth. Differential Gene Expression (DGE) analysis showed Lox1 was upregulated in Drought sensitive (DS) and in Drought tolerant (DT) the Lox1 & Lox3 were upregulated when compared to control. In addition, weighted gene co-expression network analysis (WGCNA) of Lox, showed that blue module is positively correlated with drought tolerance. Fourteen hub genes related to stress were identified, which closely associated with Lox1. Gene ontology and KEGG pathway analyses showed that these genes were linked to linoleic acid metabolism, lipid metabolism, and stress response. Quantitative Real-Time PCR (qRT-PCR) analysis confirmed that Silox genes showed time-varying differential expression under drought, salt and a combined drought-salt stress treatments.

CONCLUSION

This research lays the groundwork for future studies on the role of Lox genes in sesame's growth and stress adaptation.

The viscoelastic properties of Nicotiana tabacum BY-2 suspension cell lines adapted to high osmolarity

To survive and grow, plant cells must regulate the properties of their cellular microenvironment in response to ever changing external factors. How the biomechanical balance across the cell's internal structures is established and maintained during environmental variations remains a nurturing question. To provide insight into this issue we used two micro-mechanical imaging techniques, namely Brillouin light scattering and BODIPY-based molecular rotors Fluorescence Lifetime Imaging, to study Nicotiana tabacum suspension BY-2 cells long-term adapted to high concentrations of NaCl and mannitol. The molecular crowding in cytoplasm and vacuoles was examined, as well as tension in plasma membrane. To understand how sudden changes in osmolarity affect cellular mechanics, the response of the control and the already adapted cells to further short-term osmotic stimulus was also examined. The viscoelasticity of protoplasts is altered differently during adaptation processes compared to responses to sudden hyperosmolarity stress. The applied correlative approach provides evidence that adaptation to hyperosmotic stress leads to different ratios of protoplast and environmental qualities that help to maintain cell integrity. The viscoelastic properties of protoplasts are an element of plant cells long-term adaptation to high osmolarity. Moreover, such adaptation has an impact on the response to the hyperosmolarity stress.

The physiological and molecular mechanisms of WRKY transcription factors regulating drought tolerance: A review

WRKY transcription factors (TFs) play crucial roles in responses to abiotic and biotic stresses that significantly impact plant growth and development. Advancements in molecular biology and sequencing technologies have elevated WRKY TF studies from merely determining expression patterns and functional characterization to uncovering molecular regulatory networks. Numerous WRKY TFs regulate drought tolerance in plants through various regulatory networks. This review details the physiological and molecular mechanisms of WRKY TFs regulating drought tolerance. The review focuses on the WRKY TFs involved in the phytohormone and metabolic pathways associated with the drought stress response and the multiple functions of these WRKY TFs, including biotic and abiotic stress responses and their participation in plant growth and development.

Genome-Wide Analyses of the Soybean GmABCB Gene Family in Response to Salt Stress

BACKGROUND

Soybean (Glycine max (L.) Merr.) is a significant economic oilseed crop, and saline-alkali soils restrict soybean yield. Identifying salt-tolerant genes is a key strategy for enhancing soybean productivity under saline-alkali conditions. The roles of the GmABCB gene family in growth, development, and stress resistance remain incompletely understood.

METHODS

Bioinformatics approaches were employed to identify and analyze GmABCB genes. A total of 39 GmABCB genes were identified and analyzed in the soybean genome, focusing on their phylogenetic relationships, chromosomal distribution, gene structure, cis-acting elements, evolutionary history, and expression patterns under salt stress.

RESULTS

A total of 39 GmABCB genes were identified. These genes are unevenly distributed across the soybean genome, with 21 segmental duplication events identified. Several cis-acting elements associated with abiotic stress responses were identified.

CONCLUSIONS

The GmABCB gene family likely regulates growth, development, and stress tolerance in soybean.

Stress Increases Ecological Risk of Glufosinate-Resistant Transgene Located on Alien Chromosomes in Hybrids Between Transgenic Brassica napus and Wild Brassica juncea

When glufosinate-resistant transgenic Brassica napus (transgene PAT located on C chromosome) were backcrossed with wild Brassica juncea, 50% of the progeny expressed PAT under favourable conditions. However, exposure to stress (drought, salt, flooding, and intraspecific competition) increased the proportion of plants expressing the PAT gene (r-e plants) by approximately 20% compared to those under unstressed conditions. In the self-pollinated progeny of the stressed plants, the proportion of r-e plants increased by a nearly 30% compared to that of the unstressed plants. Composite fitness was comparable between plants developed under drought stress at the seedling stage and those grown under favourable conditions. Abscisic acid (ABA) content and expression of the Repressor of Silencing 1 (ROS1) in leaves increased significantly after stress treatment in the progeny, with r-e plants exhibiting higher levels. Exogenous ABA treatment significantly up-regulated ROS1 expression in progeny leaves, and the ABA treatment of seeds increased the survival of progeny exposed to glufosinate by 15%. Results suggest that increasing ABA under stress may enhance the demethylation of PAT's promoter by promoting ROS1 expression, thereby inhibiting transgene silencing of PAT, indicating that transgene located on the C chromosome of transgenic B. napus may pose a higher risk of gene flow to wild B. juncea under stress, especially drought stress.

Evolution of light-dependent functions of GIGANTEA

GIGANTEA (GI) is a multifaceted plant-specific protein that originated in a streptophyte ancestor. The current known functions of GI include circadian clock control, light signalling, flowering time regulation, stomata response, chloroplast biogenesis, accumulation of anthocyanin, chlorophyll, and starch, phytohormone signalling, senescence, and response to drought, salt, and oxidative stress. Six decades since its discovery, no functional domains have been defined, and its mechanism of action is still not well characterized. In this review, we explore the functional evolution of GI to distinguish between ancestral and more recently acquired roles. GI integrated itself into various existing signalling pathways of the circadian clock, blue light, photoperiod, and osmotic and oxidative stress response. It also evolved parallelly to acquire new functions for chloroplast accumulation, red light signalling, and anthocyanin production. In this review, we have encapsulated the known mechanisms of various biological functions of GI, and cast light on the evolution of GI in the plant lineage.

AmbHLH091 is released by AmNAC035 and drives Salt Overly Sensitive 1 and Pyrroline-5-Carboxylate Synthase expression to mediate salt tolerance in mangrove Avicennia marina

Avicennia marina is the pioneer species of mangroves suffering from high-saline environment. bHLH is the second largest family of transcription factors (TFs) in plants, and involves in various stress responses. So far, the bHLH family members are not identified and bio-functionally characterized in A. marina. In this study, the 228 AmbHLH family members were identified from A. marina genome. Through bioinformatics analysis, the AmbHLH091 was specifically chosen to elucidate its biological function in salt tolerance. Expression pattern analysis exhibited AmbHLH091 was mainly expressed in leaf, root, and stem tissues, and AmbHLH091 was significantly up-regulated under salinity treatment. Additionally, subcellular localization analysis showed AmbHLH091 was mainly expressed in cell nucleus. The transient overexpression and protein-DNA interaction analysis revealed AmbHLH091 is likely to promote Na+ transport and proline accumulation by interacting with the promoters of Salt Overly Sensitive 1 (AmSOS1) and Pyrroline-5-Carboxylate Synthase (AmP5CS). In yeast expression analysis, the AmbHLH091 enhanced the salt tolerance via promoting the AmSOS1 and AmP5CS expression. Besides, another TF AmNAC035 interacts with AmbHLH091 and negatively regulates AmbHLH091 transcriptional activity, thereby modulating the expression of AmSOS1 and AmP5CS. Summarily, our results revealed AmbHLH091-AmNAC035 macromolecule participates the salt tolerance of A. marina in the coastal saline intertidal habitats.

Genome-wide identification and expression analysis of orphan genes in twelve Musa (sub)species

Orphan genes (OGs), also known as lineage-specific genes, are species-specific genes that play a crucial role in species-specific adaptations to various stresses. Although OGs have been identified in several plant species, there is no information on OGs in banana genomes. This study aimed to systematically identify OGs in twelve banana (sub)species using comparative genomics. The results showed that OG content varied widely among these (sub)species, from 0.4% in Musa itinerans to 7.3% in Ensete glaucum. Genetic structure analysis showed that banana OGs have significantly shorter protein lengths, smaller molecular weight, fewer exons, and shorter exon lengths than non-orphan genes (NOGs). Subcellular localization predictions showed that banana OGs are mainly found in the chloroplast, nucleus, and cytosol, and are evenly distributed across chromosomes. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses suggested that OGs may be involved in cellular processes, metabolic processes, and molecular transport. The transcriptome analysis of 9 AAA cultivars against 4 M. acuminata subspecies genomes showed the OGs content. Analysis of gene expression in M. acuminata subsp. malaccensis showed 75 differentially expressed (DE) OGs in response to abiotic stresses and 46 DE OGs related to biotic stresses, indicating that these OGs might play important roles in response to abiotic and biotic stresses. This study provides a foundation for further in-depth research into the functions of OGs in bananas.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-025-04213-9.

Tolerance to multiple abiotic stresses is mediated by interacting CNGC proteins that regulate Ca2+ influx and stomatal movement in rice

Members of the cyclic nucleotide-gated channel (CNGC) proteins are reportedly involved in a variety of biotic and abiotic responses and stomatal movement. However, it is unknown if and how a single member could regulate multiple responses. Here we characterized three closely related CNGC genes in rice, OsCNGC14, OsCNGC15 and OsCNGC16, to determine whether they function in multiple abiotic stresses. The loss-of-function mutants of each of these three genes had reduced calcium ion (Ca2+) influx and slower stomatal closure in response to heat, chilling, drought and the stress hormone abscisic acid (ABA). These mutants also had reduced tolerance to heat, chilling and drought compared with the wild-type. Conversely, overexpression of OsCNGC16 led to a more rapid stomatal closure response to stresses and enhanced tolerance to heat, chilling and drought. The tight association of stomatal closure and stress tolerance strongly suggests that tolerance to multiple abiotic stresses conferred by these OsCNGC genes results at least partially from their regulation of stomatal movement. In addition, physical interactions were observed among the three OsCNGC proteins but not with a distantly related CNGC, suggesting the formation of hetero-oligomers among themselves. This study unveils the crucial role of OsCNGC14, 15 and 16 proteins in stomatal response and tolerance to multiple stresses, suggesting a mechanism of tolerance to multiple stresses that involves calcium influx and stomatal movement regulation.

Genomic insights into drought adaptation of the forage shrub Caragana korshinskii (Fabaceae) widely planted in drylands

The Korshinsk peashrub (Caragana korshinskii), known for its exceptional drought tolerance, is widely cultivated in arid and semi-arid regions for vegetation restoration and as a vital forage plant. To elucidate the genomic basis of its drought tolerance, we generated a chromosomal-scale genome sequence of C. korshinskii. Our synteny analysis disputes the previously hypothesized genus-specific whole-genome duplication event, as suggested by earlier transcriptome study of this species and its congeners. We identified that tandem duplications were critical for the expansion of gene families, such as early light-induced protein, heat shock protein 100, and Dehydrin, which are involved in cellular protection processes. These expansions are likely pivotal to the superior drought tolerance observed in C. korshinskii, as evidenced by the elevated gene expression of these genes under drought conditions. Furthermore, overexpression studies of seven tandemly duplicated DHN genes revealed a substantial enhancement in drought survival rates of seedlings, likely attributable to increased gene dosage effects. Conversely, gene silencing via virus-induced gene silencing demonstrated opposing effects. Additionally, we have established the CakorDB, a genomic resource database for C. korshinskii (https://bis.zju.edu.cn/cakordb/), accessible freely to the scientific community. Collectively, our study not only provides a valuable genomic resource for the Korshinsk peashrub but also highlights the genetic adaptations that enable C. korshinskii to thrive in desert environments, positioning its stress-responsive genes as a valuable genetic reservoir for breeding drought-resistant crops.

A small peptide miPEP172b encoded by primary transcript of miR172b regulates salt tolerance in rice

Recent studies have demonstrated that the primary transcript of miRNAs (pri-miRNAs) are able to encode small peptides influencing plant growth and development, as well as responses to various environmental cues. However, their role in plant responses to salt stress is not fully comprehended. Here, we characterized a short peptide encoded by miR172b (miPEP172b) in rice (Oryza sativa L.). By applying synthetic miPEP172b, we observed a significant increase in miR172b abundance and a decrease in the expression of its target gene IDS1. Consequently, plants treated with miPEP172b exhibited enhanced tolerance to salinity stress. Furthermore, we found that miPEP172b was efficiently absorbed by roots and transported to the aerial parts of the plant, thus conferring salt tolerance in the aboveground organs. Overexpression of miPEP172b resulted in reduced levels of reactive oxygen species (ROS), leading to improved performance of rice seedlings under salinity conditions. This was consistent with the observations in miR172-overexpressing plants. Conversely, miPEP172b mutants showed increased sensitivity to salt stress. Further analysis revealed that miPEP172b-miR172-IDS1 improved rice salt tolerance by integrating the ROS scavenging pathway and plant hormone signaling. Our findings highlight the significant role of miPEP172b in regulating miR172 activity and salt tolerance, providing a useful agent for improving crop salt tolerance.

Genome-wide identification and expression analysis of bHLH gene family revealed their potential roles in abiotic stress response, anthocyanin biosynthesis and trichome formation in Glycyrrhiza uralensis

Introduction

Licorice stands out as an exceptional medicinal resource with a long history of application, attributed to its substantial pharmacological potential. The basic helix-loop-helix (bHLH) transcription factors (TFs) gene family, being the second-largest in plants, is vital for plant development and adapting to environmental shifts. Despite this, the comprehensive characteristics of licorice bHLH gene family are not well-documented.

Results

In this study, a detailed and thorough genome-wide identification and expression analysis of Glycyrrhiza uralensis bHLH gene family was carried out, resulting in the identification of 139 licorice bHLH members. Our duplication analysis highlighted the significant contribution of segmental duplications to the expansion of G. uralensis bHLH genes, with GubHLH genes experiencing negative selection throughout evolution. It was discovered that GubHLH64 and GubHLH38 could be importantly linked to the licorice trichome initiation and anthocyanin biosynthesis and GubHLH64 was also involved in the abiotic stress response. Additionally, certain subfamily III (d+e) GubHLH members could be implicated in the licorice drought response. GubHLH108, GubHLH109, and GubHLH116 were suggested to form a tightly related cluster, initiating transcriptional responses via JA signaling pathway.

Discussion

In summary, our findings furnish a foundational understanding for future investigations of GubHLH gene functions and regulation mechanisms, shedding light on the potential applications of licorice in medicine and agriculture.

Identification of EXPA4 as a key gene in cotton salt stress adaptation through transcriptomic and coexpression network analysis of root tip protoplasts

BACKGROUND

Salinity stress impairs cotton growth and fiber quality. Protoplasts enable elucidation of early salt-responsive signaling. Elucidating crop tolerance mechanisms that ameliorate these diverse salinity-induced stresses is key for improving agricultural productivity under saline conditions.

RESULTS

Herein, we performed transcriptome profiling of Gossypium arboreum root tips and root tips-derived protoplasts to uncover salt tolerance genes and mechanisms. Differentially expressed genes (DEGs) were significantly enriched in the plant hormone signal transduction and MAPK signaling pathways. Transcriptome based weighted gene coexpression network analysis (WGCNA) clustered 885 commonly differentially expressed genes into four distinct modules. Black and yellow modules were highly upregulated under salt treatment, containing hub genes integral to signaling and transport, highlighting their importance. Differential expression analysis revealed more dynamic changes in protoplasts, identifying key genes including the Ga-α-expansin 4 (GaEXPA4). Silencing of the GaEXPA4 gene through virus-induced gene silencing heightened cotton's sensitivity to salt stress, leading to increased wilting, elevated lipid peroxidation, and impaired antioxidant activity under salt conditions compared to controls.

CONCLUSION

These findings underscore the functional significance of GaEXPA4 in the salt stress response. Future research should focus on elucidating the precise mechanisms of putative salt tolerance genes like GaEXPA4 and evaluating the potential of signaling pathways, such as MAPK, for engineering enhanced salt resilience in cotton. Integrating multi-omics approaches could further expand the genetic resources available for improving cotton cultivation in saline environments.

Pan-genome analyses of 11 Fraxinus species provide insights into salt adaptation in ash trees

Ash trees (Fraxinus) exhibit rich genetic diversity and wide adaptation to various ecological environments, and several species are highly salt tolerant. Dissecting the genomic basis of salt adaptation in Fraxinus is vital for its resistance breeding. Here, we present 11 high-quality chromosome-level genome assemblies for Fraxinus species, which reveal two unequal subgenome compositions and two recent whole-genome triplication events in their evolutionary history. A Fraxinus pan-genome was constructed on the basis of structural variations and revealed that presence-absence variations (PAVs) of transmembrane transport genes have likely contributed to salt adaptation in Fraxinus. Through whole-genome resequencing of an F1 population from an interspecies cross of F. velutina 'Lula 3' (salt tolerant) with F. pennsylvanica 'Lula 5' (salt sensitive), we mapped salt-tolerance PAV-based quantitative trait loci (QTLs) and pinpointed two PAV-QTLs and candidate genes associated with Fraxinus salt tolerance. Mechanistically, FvbHLH85 enhances salt tolerance by mediating reactive oxygen species and Na+/K+ homeostasis, whereas FvSWEET5 enhances salt tolerance by mediating osmotic homeostasis. Collectively, these findings provide valuable genomic resources for Fraxinus salt-resistance breeding and the research community.

A de novo Gene Promotes Seed Germination Under Drought Stress in Arabidopsis

The origin of genes from noncoding sequences is a long-term and fundamental biological question. However, how de novo genes originate and integrate into the existing pathways to regulate phenotypic variations is largely unknown. Here, we selected 7 genes from 782 de novo genes for functional exploration based on transcriptional and translational evidence. Subsequently, we revealed that Sun Wu-Kong (SWK), a de novo gene that originated from a noncoding sequence in Arabidopsis thaliana, plays a role in seed germination under osmotic stress. SWK is primarily expressed in dry seed, imbibing seed and silique. SWK can be fully translated into an 8 kDa protein, which is mainly located in the nucleus. Intriguingly, SWK was integrated into an extant pathway of hydrogen peroxide content (folate synthesis pathway) via the upstream gene cytHPPK/DHPS, an Arabidopsis-specific gene that originated from the duplication of mitHPPK/DHPS, and downstream gene GSTF9, to improve seed germination in osmotic stress. In addition, we demonstrated that the presence of SWK may be associated with drought tolerance in natural populations of Arabidopsis. Overall, our study highlights how a de novo gene originated and integrated into the existing pathways to regulate stress adaptation.

The StbHLH47 transcription factor negatively regulates drought tolerance in potato (Solanum tuberosum L.)

BACKGROUND

Drought stress is a major environmental constraint affecting crop yields. Plants in agricultural and natural environments have developed various mechanisms to cope with drought stress. Identifying genes associated with drought stress tolerance in potato and elucidating their regulatory mechanisms is crucial for the breeding of new potato germplasms. The bHLH transcription factors involved play crucial roles not only in plant development and growth but also in responsesresponse to abiotic stress.

RESULTS

In this study, the StbHLH47 gene, which is highly expressed in potato leaves, was cloned and isolated. Subcellular localization assays revealed that the gene StbHLH47 performs transcriptional functions in the nucleus, as evidenced by increased malondialdehyde (MDA) content and relative conductivity under drought stress. These findings indicate that overexpressing plants are more sensitive to drought stress. Differential gene expression analysis of wild-type plants (WT) and plants overexpressing StbHLH47 (OE-StbHLH47) under drought stress revealed that the significantly differentially expressed genes were enriched in metabolic pathways, biosynthesis of various plant secondary metabolites, biosynthesis of metabolites, plant hormone signal transduction, mitogen-activated protein kinase (MAPK) signalling pathway-plant, phenylpropanoid biosynthesis, and plant‒pathogen interactions. Among these pathways, the phenylalanine and abscisic acid (ABA) signal transduction pathways were enriched in a greater number of differentially expressed genes, and the expression trends of these differentially expressed genes (DEGs) were significantly different between WT and OE-StbHLH47. Therefore, it is speculated that StbHLH47 may regulate drought resistance mainly through these two pathways. Additionally, RT‒qPCR was used for fluorescence quantification of the expression of StNCED1 and StERD11, which are known for their drought resistance, and the results revealed that the expression levels were much lower in OE-StbHLH47 than in WT plants.

CONCLUSION

RNA-seq, RT‒qPCR, and physiological index analyses under drought conditions revealed that overexpression of the StbHLH47 gene increased the sensitivity of potato plants to drought stress, indicating that StbHLH47 negatively regulates drought tolerance in potato plants. In summary, our results indicate that StbHLH47 is a negative regulator of drought tolerance and provide a theoretical basis for further studies on the molecular mechanism involved.

Amelioration of the growth and physiological responses of Capsicum annum L. via quantum dot-graphene oxide, cerium oxide, and titanium oxide nanoparticles foliar application under salinity stress

Salinity is one of the predominant abiotic stressors that reduce plant growth, yield, and productivity. Ameliorating salt tolerance through nanotechnology is an efficient and reliable methodology for enhancing agricultural crops yield and quality. Nanoparticles enhance plant tolerance to salinity stress by facilitating reactive oxygen species detoxification and by reducing the ionic and osmotic stress effects on plants. This experiment was conducted to study the effects of NaCl salinity stress (0, 100, and 200 mM), and foliar application of quantum dot-graphene oxide, nano-TiO2, and CeO2 (zero and 2 g/l) on the growth and physiological responses of Capsicum annum L. The results revealed that the interaction effects of treatments significantly affected plant and fruit fresh weight, chlorophyll a, total soluble solids, phenolics, malondialdehyde, H2O2, and proline content. Moreover, catalase activity and sodium, and phosphorus content were responded to the treatments. The highest fresh weight of plants and fruits, fruit diameter, and chlorophyll a content were recorded under no-salinity × quantum dot-graphene oxide foliar use. The highest data for total phenolics content was recorded at NaCl100 mM × quantum dot-graphene oxide. In contrast, the maximum flavonoids content belonged to NaCl100 mM × quantum dot-graphene oxide and NaCl100 mM × TiO2. The experimental treatments independently affected the number of fruits, chlorophyll b, carotenoids, and vitamin C content, as well as K/Na ratio. The foliar treatment of quantum dot-graphene oxide nanoparticles improved the carotenoids and vitamin C content, stem diameter, and fruit number. The overall results disclosed that, when plants were exposed to high salinity levels; the foliar treatments were unable to effectively mitigate the negative impacts of salt stress on the plant, except for certain traits such as total phenolics, flavonoids, and TSS levels. However, under the low and mild salinity depression, the foliar treatments were enough capable to overcome the salinity defects.

LcMYB5, an R2R3-MYB family gene from Lonicera caerulea L., enhances drought and salt tolerance in transgenic tobacco and blue honeysuckle

MYB transcription factors exert crucial functions in enhancing plant stress tolerance, which is impacted by soil drought and salinity. In our study, the R2R3-type MYB transcription factor gene LcMYB5 from blue honeysuckle (Lonicera caerulea L.) was successfully cloned and identified, and confirmed its nuclear localization. LcMYB5 overexpression was vastly enhanced drought and salt tolerance in both blue honeysuckle and tobacco seedlings. After drought stress, transgenic tobacco exhibited an average survival rate of 70.30%, while most wild-type (WT) plants perished, resulting in a survival rate of only 15.33%. Following salt stress, the average survival rate for transgenic tobacco reached 77.24%, compared to just 22.47% for WT plants. Measurements indicated, that transgenic tobacco had higher proline content than WT, as well as higher superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activity. Transgenic tobacco decreased chlorophyll content less dramatically than WT tobacco, despite both tobaccos having decreased chlorophyll content. Furthermore, the level of malondialdehyde (MDA) and relative conductivity were lower in transgenic tobacco compared to WT. Furthermore, LcMYB5 overexpression significantly increased the expression levels of key genes related to drought stress (NCED1, NCED2, PYL4, PYL8, and CBL1) and salt stress (NHX1, SOD, CAT1, SOS1, and HSP17.8), thus improving transgenic tobacco's stress tolerance. Compared to WT blue honeysuckle, transiently transformed LcMYB5-expressing blue honeysuckle exhibited milder damage under stress conditions, a significant increase in chlorophyll and proline content was observed, the activities of SOD, POD and CAT were also significantly increased, the increase in MDA content and relative conductivity is relatively small. Additionally, In addition, transient expression of LcMYB5 can also positively regulate the expression of these five key genes of drought stress and five key genes of salt stress, so as to improve the resistance of transgenic blue honeysuckle to drought and salt stress. In summary, our study reveals the important regulatory role of LcMYB5 in plant resistance to drought and salt stress, providing theoretical support and potential application value for further improving crop stress resistance.

Multi-Omics Research Reveals the Effects of the ABA-Regulated Phenylpropanoid Biosynthesis Pathway on the UV-B Response in Rhododendron chrysanthum Pall

The growing depletion of the ozone layer has led to increased ultraviolet B (UV-B) radiation, prompting plants like the alpine Rhododendron chrysanthum Pall. (R. chrysanthum) to adapt to these harsh conditions. This study explored how abscisic acid (ABA) signaling influences R. chrysanthum's metabolic responses under UV-B stress. R. chrysanthum was treated with UV-B radiation and exogenous ABA for widely targeted metabolomics, transcriptomics, and proteomics assays, and relevant chlorophyll fluorescence parameters were also determined. It was observed that UV-B stress negatively impacts the plant's photosynthetic machinery, disrupting multiple metabolic processes. Multi-omics analysis revealed that ABA application mitigates the detrimental effects of UV-B on photosynthesis and bolsters the plant's antioxidant defenses. Additionally, both UV-B exposure and ABA treatment significantly influenced the phenylpropanoid biosynthesis pathway, activating key enzyme genes, such as 4CL, CCR, and HCT. The study also highlighted the MYB-bHLH-WD40 (MBW) complex's role in regulating this pathway and its interaction with ABA signaling components. These findings underscore ABA's crucial function in improving plant resistance to UV-B stress and offer novel insights into plant stress biology.

Transcription factors CpSPL5 and CpSPL8 negatively regulate salt tolerance in Codonopsis pilosula by inhibiting SOS pathway

Environmental stresses such as salt and drought severely affect plant growth and development. SQUAMOSA-promoter binding protein-like (SPL) transcription factors (TFs) play critical roles in the regulation of diverse processes; however, reports describing the SPL regulation of plant responses to abiotic stress are relatively few. In this study, two stress-responsive TFs from Codonopsis pilosula (CpSPL5 and CpSPL8) are reported, which confer salt stress sensitivity. CpSPL5 and CpSPL8 are expressed in almost all tissues and localized in the nucleus, where the CpSPL5 transcript level is relatively higher than that of CpSPL8. Their expression levels are significantly suppressed in hairy roots treated with ABA, NaCl, PEG-6000, and under high temperature stress. Compared with the control, CpSPL5, or CpSPL8-overexpressed hairy roots increased salt stress sensitivity, and exhibited higher levels of O2- and MDA, as well as lower superoxide dismutase and peroxidase activities. Further, the CpSPL5 or CpSPL8 interference transgenic hairy roots enhanced salt tolerance and exhibited contrasting phenotype and antioxidant indices. Although all genotypes revealed significantly increased Na+ and decreased K+ contents under salt stress, the physiological indicators of CpSPL5 or CpSPL8-interference transgenic hairy roots could be partially restored, where CpSPL5 was more sensitive to salt stress than CpSPL8. A yeast one-hybrid and dual-luciferase assay revealed that CpSPL5 and CpSPL8 directly targeted and inhibited the expression of CpSOS2 in the salt overly sensitive (SOS) pathway, which promoted salt stress sensitivity. Our findings suggest that CpSPL5 and CpSPL8 served as negative regulators of salt tolerance, which indicate that members of the SPL family participate in the plant SOS pathway.

Crop root system architecture in drought response

Drought is a natural disaster that profoundly impacts on global agricultural production, significantly reduces crop yields, and thereby poses a severe threat to worldwide food security. Addressing the challenge of effectively improving crop drought resistance (DR) to mitigate yield loss under drought conditions is a global issue. An optimal root system architecture (RSA) plays a pivotal role in enhancing the capacity of crops to efficiently uptake water and nutrients, which consequently strengthens their resilience against environmental stresses. In this review, we discuss the compositions and roles of crop RSA and summarize the most recent developments in augmenting drought tolerance in crops by manipulating RSA-related genes. Based on the current research, we propose the potential optimal RSA configuration that could be helpful in enhancing crop DR. Lastly, we discuss the existing challenges and future directions for breeding crops with enhanced DR capabilities through genetic improvements targeting RSA.

Nei 6 You 7075, a hybrid rice cultivar, exhibits enhanced disease resistance and drought tolerance traits

BACKGROUND

Rice is the main food crop for much of the population in China. Therefore, selecting and breeding new disease resistance and drought tolerance in rice is essential to ensure national food security. The utilization of heterosis has significantly enhanced rice productivity, yet many of the molecular mechanisms underlying this phenomenon remain largely unexplored. 'Nei 6 You 7075' ('N6Y7075') is a novel hybrid rice cultivar with exceptional quality, developed through the crossbreeding of 'Fuhui 7075' ('FH7075') and 'Neixiang 6 A' ('NX6A'). However, the precise mechanisms underlying the disease resistance and drought tolerance in 'N6Y7075' are poorly understood. In this study, we investigated the resistance of hybrid rice 'N6Y7075' to bacterial blight (Xanthomonas oryzae pv. oryzae), rice blast (Magnaporthe oryzae), and drought and identified differentially expressed genes between hybrid rice 'N6Y7075' and its parents through RNA-seq analysis.

RESULTS

Our research found that the hybrid 'N6Y7075' and its female parent 'NX6A' were less susceptible to bacterial blight and rice blast than the male parent 'FH7075', while 'FH7075' showed better drought tolerance than 'NX6A'. The hybrid 'N6Y7075' exhibited heterosis. Clustering results revealed that the expression profiles of the F1 hybrid closely resembled those of its parental lines rather than exhibiting an intermediate profile between the two parental lines. The disease resistance of hybrid rice 'N6Y7075' may be attributed to the plant-pathogen interaction pathways involving Xa21, CDPK, and RPM1-mediated hypersensitive response and WRKY1-induced defense-related gene expression and programmed cell death. The MAPK signaling pathway PR1 could also be associated with plant defense responses. Hybrid rice 'N6Y7075' may enhance drought tolerance by regulating MAPKKK17 and WAK60 in the MAPK signaling pathway. These proteins affect ABA stress adaptation and stomatal development in plants, respectively.

CONCLUSIONS

Our results provide a preliminary exploration of 'N6Y7075' disease resistance and drought tolerance and provide a relevant theoretical basis for its further study and use. This study provides insights into the molecular mechanisms of heterosis in hybrid rice and identifies potential associated genes.

Physiological, Photosynthetic Characteristic and Transcriptome Analysis of PsnWRKY70 Transgenic Populus simonii × Populus nigra Under Salt Stress

The PsnWRKY70 transcription factor (TF) was reported to play an important role in the salt stress response mechanism of Populus simonii × Populus nigra in our previous research, and we also produced several PsnWRKY70 overexpression (OEXs) and RNAi suppression (REXs) P. simonii × P. nigra lines. In order to further compare the photosynthetic and physiological characteristics of NT (non-transgenic line) and transgenic lines under salt stress, the dynamic phenotypic change, Na+ and K+ content in leaf and root tissues, superoxide dismutase (SOD) and peroxidase (POD) activity, malondialdehyde (MDA) content, chlorophyll content (Chl), photosynthesis parameters (net photosynthetic rate, Pn; stomatal conductance, Gs; intercellular CO2 concentration, Ci; transpiration rate, Tr), chlorophyll fluorescence parameters (electron transport rate, ETR; maximum photochemical efficiency of photosystem II (PSII), Fv/Fm; actual efficiency of PSII, ΦPSII; photochemical quenching coefficient, qP; non-photochemical quenching, NPQ; the photosynthetic light-response curves of ΦPSII and ETR) and RNA-seq of NT, OEX and REX lines were detected and analyzed. The phenotypic observation, MDA content and Chl detection results indicate that the stress damage of REXs was less severe than that of NT and OEX lines under salt stress. Photosynthesis parameter (Pn, Gs, Tr and Ci) and chlorophyll fluorescence parameter (ETR, Fv/Fm, ΦPSII qP and NPQ) detection results indicate that the REX lines exhibited much better photosynthetic adaptability than NT and OEX lines during salt stress. The photosynthetic light-response curves of ΦPSII and ETR of NT, OEX and REX lines indicate that REXs exhibited better ability to activate the photosynthetic protection mechanism and adapt to a certain degree of strong light than NT and OEX lines under salt stress. RNA-seq analysis indicates that the DEGs between OEX1 vs. NT and REX1 vs. NT in different tissues (apical bud and fifth functional leaf) were all different in category and change trend. The expression of PsnWRKY70 was significantly up-regulated in both the apical bud and fifth functional leaf of OEX1, and showed no significant change (namely maintained low expression level) in both the apical bud and fifth functional leaf of REX1, thus indicating the negative regulation role of PsnWRKY70 in P. simonii × P. nigra under salt stress. Additionally, there were a lot of stress response-related TF genes (such as bHLH, WRKY, MYB, NAM and AP2/EREBP) and photosynthesis-related genes among all the DEGs. In REX1, the expression of three Photosystem I P700 chlorophyll a apoprotein A1 genes (Potri.003G065200, Potri.013G141800 and Potri.019G028100) and a Photosystem II protein D1 gene (Potri.013G138300) were significantly up-regulated after 6 days of salt stress. In OEX1, the Heterodimeric geranylgeranyl pyrophosphate synthase small subunit gene (Potri.015G043400) and Phospho-2-dehydro-3-deoxyheptonate aldolase 1 gene (Potri.007G095700) were significantly down-regulated after 6 days of salt stress. These photosynthesis-related genes are probably regulated by PsnWRKY70 TF in response to salt stress. In conclusion, the REX lines suffered less severe salt damage and exhibited better photosynthetic adaptability than NT and OEXs under salt stress. The differences among the DEGs between OEX1 vs. NT and REX1 vs. NT in apical bud and fifth functional leaf, and the significantly differentially expressed photosynthesis-related genes are probably the key clues for discovering the photosynthesis adaptability mechanism of PsnWRKY70 transgenic P. simonii × P. nigra under salt stress.

Genome-Wide Analysis of the PYL Gene Family in Betula platyphylla and Its Responses to Abiotic Stresses

Abscisic acid (ABA) is a key phytohormone that participates in various plant biological processes, such as seed germination, senescence, stomatal movement, and flowering. In the ABA signal transduction pathway, Pyrabactin Resistance 1 (PYR1)/PYR1-Like (PYL)/Regulatory Component is the core module for ABA perception. In this study, a total of 12 PYL family members were identified in birch (Betula platyphylla Suk.) from a genome-wide range that can be divided into 3 subgroups according to their evolutionary relationships. The physiochemical properties of the 12 BpPYLs were characterized, and the members of the same subgroups share more similar exon-intron and motif patterns. The results of synteny analysis showed two syntenic gene pairs within BpPYL family members and 12, 8, 19, and 6 syntenic gene pairs between BpPYLs and AtPYLs, OsPYLs, PtPYLs, and ZmPYLs, respectively. Multiple cis-acting elements were identified in the promoters of BpPYLs, including stress response, phytohormone signaling, and growth and development. The results of GO and KEGG enrichment analysis showed that BpPYLs were enriched in the pathways mainly related to ABA signaling and cell communication. The results of RT-qPCR verified the expressional responses of BpPYLs to ABA, salt, and PEG treatments. Furthermore, the positive roles of BpPYL3 and BpPYL11 were proven by using salt-tolerant yeast transformation. This study provides a reference for research on ABA signal transduction and forest tree responses upon abiotic stresses.

OsPUB75-OsHDA716 mediates deactivation and degradation of OsbZIP46 to negatively regulate drought tolerance in rice

Histone deacetylases (HDACs) play crucial roles in plant stress responses via modification of histone as well as nonhistone proteins; however, how HDAC-mediated deacetylation of nonhistone substrates affects protein functions remains elusive. Here, we report that the reduced potassium dependency3/histone deacetylase1-type histone deacetylase OsHDA716 and plant U-box E3 ubiquitin ligase OsPUB75 form a complex to regulate rice drought response via deactivation and degradation of basic leucine zipper (bZIP) transcription factor OsbZIP46 in rice (Oryza sativa). OsHDA716 decreases abscisic acid (ABA)-induced drought tolerance, and mechanistic investigations showed that OsHDA716 interacts with and deacetylates OsbZIP46, a key regulator in ABA signaling and drought response, thus inhibiting its transcriptional activity. Furthermore, OsHDA716 recruits OsPUB75 to facilitate ubiquitination and degradation of deacetylated OsbZIP46. Therefore, the OsPUB75-OsHDA716 complex exerts double restrictions on the transcriptional activity and protein stability of OsbZIP46, leading to repression of downstream drought-responsive gene expression and consequently resulting in reduced drought tolerance. Conversely, OsbZIP46 acts as an upstream repressor to repress OsHDA716 expression, and therefore OsHDA716 and OsbZIP46 form an antagonistic pair to reciprocally inhibit each other. Genetic evidence showed that OsHDA716 works with OsbZIP46 in a common pathway to antagonistically regulate rice drought response, revealing that plants can fine-tune stress responses by the complex interplay between chromatin regulators and transcription factors. Our findings unveil an acetylation-dependent regulatory mechanism governing protein functions and shed light on the precise coordination of activity and stability of key transcription factors through a combination of different posttranslational modifications.

Effects of drought and salt stress on the root phenotype of wheat seedlings and underlying gene expression analysis

In our previous study, three TaPSK genes highly expressed in the roots of wheat were screened. To explore the effects of adverse stresses on the wheat root phenotype and the expression of TaPSK3, TaPSK9 and TaPSK10, we measured the phenotypic parameters of the JM22 root system at the seedling stage after treatment with different concentrations of NaCl and PEG6000. Additionally, the relative expression levels of TaPSK3, TaPSK9, and TaPSK10 were analyzed via RT-qPCR within 72 h of treatment with 150 mM NaCl and 30% PEG6000. The results revealed that drought and salt stress significantly inhibited phenotypic parameters such as total root length, root surface area, root biomass distribution estimation and root tip number in wheat. Notably, salt stress causes wheat roots to germinate more root hairs. The expression of TaPSK3 did not change significantly during salt stress but was upregulated approximately five-fold at 12 h of drought stress. The gene expression levels of TaPSK9 and TaPSK10 were upregulated to varying degrees but gradually returned to normal at 72 h. These results show that when wheat encounters stresses, the expression of TaPSK genes is upregulated to promote root growth and ensure the normal growth and development of plants. This study provides data and theoretical support for further study of TaPSK gene function and cultivation of high-quality wheat plants with strong stress resistance.

Evolution and Function of MADS-Box Transcription Factors in Plants

The MADS-box transcription factor (TF) gene family is pivotal in various aspects of plant biology, particularly in growth, development, and environmental adaptation. It comprises Type I and Type II categories, with the MIKC-type subgroups playing a crucial role in regulating genes essential for both the vegetative and reproductive stages of plant life. Notably, MADS-box proteins can influence processes such as flowering, fruit ripening, and stress tolerance. Here, we provide a comprehensive overview of the structural features, evolutionary lineage, multifaceted functions, and the role of MADS-box TFs in responding to biotic and abiotic stresses. We particularly emphasize their implications for crop enhancement, especially in light of recent advances in understanding the impact on sugarcane (Saccharum spp.), a vital tropical crop. By consolidating cutting-edge findings, we highlight potential avenues for expanding our knowledge base and enhancing the genetic traits of sugarcane through functional genomics and advanced breeding techniques. This review underscores the significance of MADS-box TFs in achieving improved yields and stress resilience in agricultural contexts, positioning them as promising targets for future research in crop science.

Overexpression of rice High-affinity Potassium Transporter gene OsHKT1;5 improves salinity and drought tolerance in Arabidopsis

BACKGROUND

Rice is subjected to various environmental stresses, resulting in significant production losses. Abiotic stresses, particularly drought and salinity, are the leading causes of plant damage worldwide. The High-affinity Potassium Transporter (HKT) gene family plays an important role in enhancing crop stress tolerance by regulating physiological and enzymatic functions.

METHODS AND RESULTS

This study investigates the effect of overexpressing the rice HKT1;5 gene in Arabidopsis thaliana on its tolerance to salinity and drought. The OsHKT1;5 gene was introduced into Arabidopsis under the control of 35 S promoter of CaMV via floral dip transformation method. PCR confirmed the integration of the transgene into the Arabidopsis genome, while qPCR analysis showed its expression. Three transgenic lines of OsHKT1;5 were used for stress treatment and phenotypic studies. The overexpressed lines showed considerably higher germination rates, increased leaf counts, greater fresh and dry weights of the roots and shoots, higher chlorophyll contents, longer root lengths, and reduced Na+ levels together with increased K+ ions levels after salt and drought treatments, in comparison to wild-type plants. Furthermore, overexpressed lines exhibited higher antioxidant levels than wild-type plants under salinity and drought conditions. In addition, transgenic lines showed higher expression levels of the OsHKT1;5 gene in both roots and shoots compared to wild-type plants.

CONCLUSIONS

In conclusion, this study revealed OsHKT1;5 as a promising candidate for enhancing tolerance to salinity and drought stresses in rice, marking a significant step toward developing a new rice variety with improved abiotic stress tolerance.

The varying responses of leaves and roots and the link between sugar metabolic genes and the SWEET family in Dendrobium officinale under salt stress

BACKGROUND

Dendrobium officinale Kimura et Migo is a perennial epiphytic herb in traditional Chinese medicine, showing remarkable resistance to salt stress. Water-soluble sugars serve as important osmoprotectants and play crucial roles in plant stress responses. Previous studies have primarily focused on sugar metabolism in individual tissues under stress, resulting in a limited understanding of the regulatory differences between tissues and the relationship between sugar metabolism and transport.

RESULTS

A variety of salt-responsive genes were identified through transcriptome analysis of D. officinale. GO and KEGG enrichment analyses revealed functional differences among the differentially expressed genes (DEGs) between leaves and roots. Expression analysis indicated that sugar metabolic genes and D. officinale Sugars Will Eventually be Exported Transporters (DoSWEETs) displayed distinct expression patterns in leaves and roots under salt stress. Most sugar metabolic genes were up-regulated in the leaves and down-regulated in the roots in response to salt, while DoSWEETs predominantly responded in the roots. Specifically, DoSWEET2a, 6a, 12a, 14, and 16 were confirmed via RT-qPCR. Additionally, positive correlations were observed between certain genes (scrK, INV, SUS) and DoSWEETs, with INV (LOC110096666) showing a strong positive correlation with all detected DoSWEETs in both leaves and roots.

CONCLUSIONS

Our findings not only illustrated the distinct responses of leaves and roots to salt stress, but also highlighted the relationship between sugar metabolic genes and DoSWEETs in adapting to such stress. This enhances our understanding of the differential responses of plant tissues to salt stress and identified candidate genes for salt-resistance breeding in D. officinale.

Dissection of major QTLs and candidate genes for seedling stage salt/drought tolerance in tomato

BACKGROUND

As two of the most impactful abiotic stresses, salt and drought strongly affect tomato growth and development, especially at the seedling stage. However, dissection of the genetic basis underlying salt/drought tolerance at seedling stage in tomato remains limited in scope.

RESULTS

Here, we reported an analysis of major quantitative trait locus (QTL) and potential causal genetic variations in seedling stage salt/drought tolerance in recombinant inbred lines (n = 201) of S. pimpinellifolium and S. lycopersicum parents by whole genome resequencing. A total of 5 QTLs on chromosome 1, 3, 5, 7 and 12 for salt tolerance (ST) and 15 QTLs on chromosome 1, 3, 4, 8, 9, 10, 12 for drought tolerance (DT) were identified by linkage mapping. The proportion of phenotypic variation explained (PVE%) by these QTLs ranged from 4.91 to 15.86. Two major QTLs qST7 and qDT1-3 were detected in both two years, for which two candidate genes (methionine sulfoxide reductase SlMSRB1 and brassinosteroid insensitive 1-like receptor SlBRL1) and the potential functional variations were further analyzed. Taking advantage of the tomato population resequencing data, the frequency changes of the potential favorable QTL allele for seedling stage ST/DT during tomato breeding were explored.

CONCLUSIONS

These results will be beneficial for the exploration of salt/drought tolerance genes at seedling stages, laying a foundation for marker-assisted breeding for seedling stage salt/drought tolerance.

The ubiquitin E3 ligase RZFP1 affects drought tolerance in poplar by mediating the degradation of the protein phosphatase PP2C-9

Abscisic acid (ABA) signaling has been implicated in plant responses to water deficit-induced osmotic stress. However, the underlying molecular mechanism remains unelucidated. This study identified the RING-type E3 ubiquitin ligase RING ZINC FINGER PROTEIN1 (PtrRZFP1) in poplar (Populus trichocarpa), a woody model plant. PtrRZFP1 encodes an ubiquitin E3 ligase that participates in protein ubiquitination. PtrRZFP1 mainly functions in the nucleus and endoplasmic reticulum and is activated by drought and ABA. PtrRZFP1-overexpressing transgenic poplars (35S:PtrRZFP1) showed greater tolerance to drought, whereas PtrRZFP1-knockdown lines (KD-PtrRZFP1) showed greater sensitivity to drought. Under treatment with polyethylene glycol and ABA, PtrRZFP1 promoted the production of nitric oxide and hydrogen peroxide in stomatal guard cells, ultimately enhancing stomatal closure and improving drought tolerance. Additionally, PtrRZFP1 physically interacted with the clade A Protein Phosphatase 2C protein PtrPP2C-9, a core regulator of ABA signaling, and mediated its ubiquitination and eventual degradation through the ubiquitination-26S proteasome system, indicating that PtrRZFP1 positively regulates the ABA signaling pathway. Furthermore, the PtrPP2C-9-overexpression line was insensitive to ABA and more sensitive to drought than the wild-type plants, whereas the opposite phenotype was observed in 35S:PtrRZFP1 plants. In general, PtrRZFP1 negatively regulates the stability of PtrPP2C-9 to mediate poplar drought tolerance. The results of this study provide a theoretical framework for the targeted breeding of drought-tolerant traits in perennial woody plants.

OsAAH confers salt tolerance in rice seedlings

Soil salinization is becoming a great threat that reduces crop productivity worldwide. In this study, we found that rice allantoate amidohydrolase (OsAAH) expression was significantly upregulated by salt stress, and its overexpression conferred salt tolerance at the seedling stage. Compared to wild type (WT), the contents of ureides (allantoin and allantoate) were significantly increased in Osaah mutants and reduced in OsAAH overexpression lines both before and after salt treatments. Exogenous allantoin significantly promoted salt tolerance in OsAAH overexpression, but not in Osaah mutants. Subcellular localization showed that OsAAH was also localized to the peroxisomes in addition to the previously reported endoplasmic reticulum (ER). The differential expression of peroxisome-related genes was identified between Osaah mutants and WT. Furthermore, the contents of H2O2 and malondialdehyde (MDA) were significantly accumulated in Osaah mutants and reduced in OsAAH overexpression lines. The activities of antioxidant enzymes were significantly reduced in Osaah mutants and enhanced in OsAAH overexpression under NaCl treatment. The transcription factor OsABI5 could directly bind to OsAAH promoter and activate OsAAH expression. Our findings reveal that OsAAH could be induced by salt stress through the activation of OsABI5 and then confer salt tolerance by enhancing the scavenging capacity of reactive oxygen species (ROS), which contributes to rice breeding in salt tolerance.

Apple vacuolar sugar transporters regulated by MdDREB2A enhance drought resistance by promoting accumulation of soluble sugars and activating ABA signaling

Soluble sugars are not only an important contributor to fruit quality, but also serve as the osmotic regulators in response to abiotic stresses. Early drought stress promotes sugar accumulation, while specific sugar transporters govern the cellular distribution of the sugars. Here, we show that apple plantlets accumulate soluble sugars in leaf tissues under drought stress. Transcriptional profiling of stressed and control plantlets revealed differential expression of several plasma membrane-or vacuolar membrane-localized sugar transporter genes. Among these, four previously identified vacuolar sugar transporter (VST) genes (MdERDL6-1, MdERDL6-2, MdTST1, and MdTST2) showed higher expression under drought, suggesting their roles in response to drought stress. Promoter cis-elements analyses, yeast one-hybrid, and dual-luciferase tests confirmed that the drought-induced transcription factor MdDREB2A could promote the expression of MdERDL6-1/-2 and MdTST1/2 by binding to their promoter regions. Moreover, overexpressing of each of these four MdVSTs alone in transgenic apple or Arabidopsis plants accumulated more soluble sugars and abscisic acid (ABA), and enhanced drought resistance. Furthermore, apple plants overexpressing MdERDL6-1 also showed reduced water potential, facilitated stomatal closure, and reactive oxygen species scavenging under drought conditions compared to control plants. Overall, our results suggest a potential strategy to enhance drought resistance and sugar accumulation in fruits through manipulating the genes involved in vacuolar sugar transport.

Salinity Stress Responses and Adaptation Mechanisms of Zygophyllum propinquum: A Comprehensive Study on Growth, Water Relations, Ion Balance, Photosynthesis, and Antioxidant Defense

Zygophyllum propinquum (Decne.) is a leaf succulent C4 perennial found in arid saline areas of southern Pakistan and neighboring countries, where it is utilized as herbal medicine. This study investigated how growth, water relations, ion content, chlorophyll fluorescence, and antioxidant system of Z. propinquum change as salinity levels increase (0, 150, 300, 600, and 900 mM NaCl). Salinity increments inhibited total plant fresh weight, whereas dry weight remained constant at moderate salinity and decreased at high salinity. Leaf area, succulence, and relative water content decreased as salinity increased. Similarly, the sap osmotic potential of both roots and shoots declined as NaCl concentrations increased. Except for a transitory increase in roots at 300 mM NaCl, sodium concentrations in roots and shoots increased constitutively to more than five times higher under saline conditions than in non-saline controls. Root potassium increased briefly at 300 mM NaCl but did not respond to NaCl treatments in the leaf. Photosynthetic pigments increased with 300 and 600 mM NaCl compared to non-saline treatments, although carotenoids appeared unaffected by NaCl treatments. Except for very high NaCl concentration (900 mM), salinity showed no significant effect on the maximum efficiency of photosystem II photochemistry (Fv/Fm). Light response curves demonstrated reduced absolute (ETR*) and maximum electron transport rates (ETRmax) for the 600 and 900 mM NaCl treatments. The alpha (α), which indicates the maximum yield of photosynthesis, decreased with increasing NaCl concentrations, reaching its lowest at 900 mM NaCl. Non-photochemical quenching (NPQ) values were significantly higher under 150 and 300 mM NaCl treatments than under non-saline and higher NaCl treatments. Electrolyte leakage, malondialdehyde (MDA), and hydrogen peroxide (H2O2) peaked only at 900 mM NaCl. Superoxide dismutase and glutathione reductase activities and glutathione content in both roots and shoots increased progressively with increasing salinity. Hence, growth reduction under low to moderate (150-600 mM NaCl) salinity appeared to be an induced response, while high (900 mM NaCl) salinity was injurious.

Okra WRKY Transcription Factor AeWRKY32 and AeWRKY70 Are Involved in Salt Stress Response

Soil salinization is one of the abiotic stresses that inhibit plant growth and development, which seriously restricts global crop production. WRKY transcription factors play an important role in regulating plant responses to stress such as salt stress. In our previous study, two WRKY family genes from okra, AeWRKY32 and AeWRKY70, were significantly up-regulated and down-regulated, respectively, in response to salt stress. In this study, subcellular localization showed that they were localized to the nucleus. The down-regulation of AeWRKY32 and AeWRKY70 via whole plant virus-induced gene silencing (VIGS) increased and decreased plant sensitivity to salt stress, respectively. Ectopic expression of AeWRKY32 and AeWRKY70 led to promoted and reduced salt tolerance in transgenic Arabidopsis, respectively. There was no significant difference between transgenic plants and wild type (WT) without salt treatment. Salt stress significantly inhibited plant growth. The decrease of chlorophyll content and the increase of anthocyanin content in AeWRKY32-overexpressed transgenic plants were lower than those in the WT, while AeWRKY70-overexpressed plants had the opposite effect. Under salt stress, the AeWRKY70-overexpressed plants had the highest malondialdehyde (MDA) content, followed by the WT, and the lowest in AeWRKY32-overexpressed plants. The hydrogen peroxide (H2O2) content and superoxide anion (O2•-) generation rate were only slightly increased. Moreover, salt stress significantly increased plant proline content and antioxidant enzyme activities, which was highest in AeWRKY70-overexpressed plants except superoxide dismutase (SOD). Taken together, these results suggest that AeWRKY32 and AeWRKY70 play positive and negative roles in plant in response to salt stress, respectively.

Advances in Understanding Drought Stress Responses in Rice: Molecular Mechanisms of ABA Signaling and Breeding Prospects

Drought stress is a pivotal environmental factor impacting rice production and presents a significant challenge to sustainable agriculture worldwide. This review synthesizes the latest research advancements in the regulatory mechanisms and signaling pathways that rice employs in response to drought stress. It elaborates on the adaptive changes and molecular regulatory mechanisms that occur in rice under drought conditions. The review highlights the perception and initial transmission of drought signals, key downstream signaling networks such as the MAPK and Ca2+ pathways, and their roles in modulating drought responses. Furthermore, the discussion extends to hormonal signaling, especially the crucial role of abscisic acid (ABA) in drought responses, alongside the identification of drought-resistant genes and the application of gene-editing technologies in enhancing rice drought resilience. Through an in-depth analysis of these drought stress regulatory signaling pathways, this review aims to offer valuable insights and guidance for future rice drought resistance breeding and agricultural production initiatives.

Exploiting light energy utilization strategies in Populus simonii through multitrait-GWAS: insights from stochastic differential models

The photosynthetic phenotype of trees undergoes changes and interactions that reflect their abilities to exploit light energy. Environmental disturbances and genetic factors have been recognized as influencing these changes and interactions, yet our understanding of the underlying biological mechanisms remains limited, particularly in stochastic environments. Here, we developed a high-dimensional stochastic differential framework (HDSD) for the genome-wide mapping of quantitative trait loci (QTLs) that regulate competition or cooperation in environment-dependent phenotypes. The framework incorporates random disturbances into system mapping, a dynamic model that views multiple traits as a system. Not only does this framework describe how QTLs regulate a single phenotype, but also how they regulate multiple phenotypes and how they interact with each other to influence phenotypic variations. To validate the proposed model, we conducted mapping experiments using chlorophyll fluorescence phenotype data from Populus simonii. Through this analysis, we identified several significant QTLs that may play a crucial role in photosynthesis in stochastic environments, in which 76 significant QTLs have already been reported to encode proteins or enzymes involved in photosynthesis through functional annotation. The constructed genetic regulatory network allows for a more comprehensive analysis of the internal genetic interactions of the photosynthesis process by visualizing the relationships between SNPs. This study shows a new way to understand the genetic mechanisms that govern the photosynthetic phenotype of trees, focusing on how environmental stochasticity and genetic variation interact to shape their light energy utilization strategies.

A Critical Review of Recent Advances in Maize Stress Molecular Biology

With the intensification of global climate change and environmental stress, research on abiotic and biotic stress resistance in maize is particularly important. High temperatures and drought, low temperatures, heavy metals, salinization, and diseases are widespread stress factors that can reduce maize yields and are a focus of maize-breeding research. Molecular biology provides new opportunities for the study of maize and other plants. This article reviews the physiological and biochemical responses of maize to high temperatures and drought, low temperatures, heavy metals, salinization, and diseases, as well as the molecular mechanisms associated with them. Special attention is given to key transcription factors in signal transduction pathways and their roles in regulating maize stress adaptability. In addition, the application of transcriptomics, genome-wide association studies (GWAS), and QTL technology provides new strategies for the identification of molecular markers and genes for maize-stress-resistance traits. Crop genetic improvements through gene editing technologies such as the CRISPR/Cas system provide a new avenue for the development of new stress-resistant varieties. These studies not only help to understand the molecular basis of maize stress responses but also provide important scientific evidence for improving crop tolerance through molecular biological methods.

Integrating Morpho-Physiological, Biochemical, and Molecular Genotyping for Selection of Drought-Tolerant Pigeon Pea (Cajanus cajan L.) Genotypes at Seedling Stage

Pigeon pea (Cajanus cajan (L.) Millsp.), a potential legume as an economic source of protein, is commonly cultivated in tropical and subtropical regions of the world. It possesses medicinal properties and acts as a cash crop, benefiting low-income farmers economically. The identification of pigeon peas exhibiting drought tolerance has become crucial in addressing water scarcity issues in the agriculture sector. In addition, exploring the genetic diversity among genotypes is important for conservation, management of genetic resources, and breeding programs. The aim of this study was to evaluate the morpho-physiological and biochemical responses of selected pigeon pea genotypes under pot-induced water stress conditions through different field capacities as well as the genetic diversity using start codon targeted (SCoT) markers. A significant variation was observed for the physiological traits studied. The accumulation of fresh weight (FW) and dry weight (DW) was significantly reduced in moderate and severe drought stress conditions. The lowest % DW decrease was found in LM (35.39%), KAT (39.43%), and SM (46.98%) than other genotypes at severe drought stress. Analyses of physiological responses including the photosynthetic efficiency (Phi2), the chlorophyll content (SPAD), and the relative water content (RWC) revealed positive and negative correlations with various parameters, reflecting the impact of drought stress on the chlorophyll content. The results revealed that biochemical traits including the total phenolic content, soluble sugars, proline, total protein, total amino acids, and free amino acids were variably and significantly increased under water stress. Antioxidant enzyme activity levels, specifically ascorbate peroxidase (APX) and catalase, varied among the genotypes and in response to severe water stress, offering further insights into adaptive responses. The eight genotypes analysed by use of 20 SCoT markers revealed 206 alleles and an average of 10.3 alleles per locus. Genetic similarity ranged from 0.336 to 0.676, clustering the pigeon pea genotypes into two major groups by the unweighted pair group method of arithmetic averages (UPGMA) cluster analysis. Principal coordinate analysis (PCoA) explained 43.11% of genetic variation and based on analysis of molecular variance, a high genetic variation (80%) within populations was observed, emphasizing the potential for genetic improvement. Among the eight genotypes studied, LM and KAT were drought tolerant and genetically diverse and therefore could be used as parents for developing drought tolerance in pigeon pea.

An LRR-RLK protein modulates drought- and salt-stress responses in maize

Maize (Zea mays), which is a vital source of food, feed, and energy feedstock globally, has significant potential for higher yields. However, environmental stress conditions, including drought and salt stress, severely restrict maize plant growth and development, leading to great yield losses. Leucine-rich repeat receptor-like kinases (LRR-RLKs) function in biotic and abiotic stress responses in the model plant Arabidopsis (Arabidopsis thaliana), but their roles in abiotic stress responses in maize are not entirely understood. In this study, we determine that the LRR-RLK ZmMIK2, a homolog of the Arabidopsis LRR-RK MALE DISCOVERER 1 (MDIS1)-INTERACTING RECEPTOR LIKE KINASE 2 (MIK2), functions in resistance to both drought and salt stress in maize. Zmmik2 plants exhibit enhanced resistance to both stresses, whereas overexpressing ZmMIK2 confers the opposite phenotypes. Furthermore, we identify C2-DOMAIN-CONTAINING PROTEIN 1 (ZmC2DP1), which interacts with the intracellular region of ZmMIK2. Notably, that region of ZmMIK2 mediates the phosphorylation of ZmC2DP1, likely by increasing its stability. Both ZmMIK2 and ZmC2DP1 are mainly expressed in roots. As with ZmMIK2, knockout of ZmC2DP1 enhanced resistance to both drought and salt stress. We conclude that ZmMIK2-ZmC2DP1 acts as a negative regulatory module in maize drought- and salt-stress responses.

Transcriptional Profiling Analysis Providing Insights into the Harsh Environments Tolerance Mechanisms of Krascheninnikovia arborescens

Krascheninnikovia arborescens, an endemic shrub in China, thrives in desertification-prone environments due to its robust biomass, hairy leaves, and extensive root system. It is vital for ecological restoration and serves as a valuable forage plant. This study explored the molecular mechanisms underlying K. arborescens' adaptation to desert conditions, focusing on its physiological, biochemical, and transcriptomic responses to drought, salt, and alkali stresses. The results revealed that the three stresses have significant impacts on the photosynthetic, antioxidant, and ion balance systems of the plants, with the alkali stress inducing the most pronounced changes and differential gene expression. The clustering and functional enrichment analyses of differentially expressed genes (DEGs) highlighted the enrichment of the induced genes in pathways related to plant hormone signaling, phenylpropanoid biosynthesis, and transcription factors following stress treatments. In these pathways, the synthesis and signal transduction of abscisic acid (ABA) and ethylene, as well as the flavonoid and lignin synthesis pathways, and transcription factors such as MYB, AP2/ERF, bHLH, NAC, and WRKY responded actively to the stress and played pivotal roles. Through the WGCNA analysis, 10 key modules were identified, with the yellow module demonstrating a high correlation with the ABA and anthocyanin contents, while the turquoise module was enriched in the majority of genes related to hormone and phenylpropanoid pathways. The analysis of hub genes in these modules highlighted the significant roles of the bHLH and MYB transcription factors. These findings could offer new insights into the molecular mechanisms that enable the adaptation of K. arborescens to desert environments, enhancing our understanding of how other desert plants adapt to harsh conditions. These insights are crucial for exploring and utilizing high-quality forage plant germplasm resources and ecological development, with the identified candidate genes serving as valuable targets for further research on stress-resistant genes.

An ABA biosynthesis enzyme gene OsNCED4 regulates NaCl and cold stress tolerance in rice

Rice (Oryza sativa L.) is susceptible to various abiotic stresses, such as salt, cold, and drought. Therefore, there is an urgent need to explore the relevant genes that enhance tolerance to these stresses. In this study, we identified a gene, OsNCED4 (9-cis-epoxycarotenoid dioxygenase 4), which regulates tolerance to multiple abiotic stresses. OsNCED4 encodes a chloroplast-localized abscisic acid (ABA) biosynthetic enzyme. The expression of OsNCED4 gene was significantly induced by 150 mM NaCl and cold stress. Disruption of OsNCED4 by CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9-mediated mutagenesis resulted in significant sensitivity to NaCl and cold stress. The salt and cold sensitivity of osnced4 mutant was due to the reduction of ABA content and the excessive accumulation of reactive oxygen species (ROS) under stress. Moreover, OsNCED4 also regulates drought stress tolerance of rice seedlings. Taken together, these results indicate that OsNCED4 is a new regulator for multiple abiotic stress tolerance in rice, and provided a potential target gene for enhancing multiple stress tolerance in the future.