Search Results (237)

Arsenic (As) contamination has significantly increased in recent decades due to anthropogenic activities. This is a serious challenge for human health, environmental quality, and crop productivity. Biochar (BC) is an important practice used globally to remediate polluted soils. Likewise, melatonin (MT) has also shown tremendous results in mitigating metal toxicity and improving crop productivity. Nevertheless, the mechanism of combined BC and MT in alleviating As toxicity in rice (Oryza sativa L.) remains unexplored. In this study, we investigated how As affected rice and how the combined BC and MT facilitated As tolerance. The study comprised a control, As stress (100 mg kg⁻¹), As stress (100 mg kg⁻¹) + BC (2%), As stress (100 mg kg⁻¹) + MT (100 µM) and As stress (100 mg kg⁻¹) + BC (2%) + MT (100 µM). Arsenic significantly decreased rice growth and yield by increasing electrolyte leakage (EL), malondialdehyde (MDA), and hydrogen peroxide (H₂O₂). Co-applying BC and MT substantially enhanced rice growth and yield by increasing chlorophyll synthesis (48.12–92.42%) leaf water contents (40%), antioxidant activities (ascorbate peroxide: 56.43%, catalase: 55.14%, peroxidase: 57.77% and superoxide dismutase: 57.52%), proline synthesis (41.35%), MT synthesis (91.53%), and phytochelatins synthesis (125%) nutrient accumulation in rice seedlings and soil nutrient availability. The increased rice yield with BC + MT was also linked with reduced H₂O₂ production, As accumulation, soil As availability, and an increase in OsAPx6, OsCAT, OsPOD, OsSOD OsASMT1, and OsASMT2 and a decrease in expression of OsABCC1. Biochar + MT enhanced residual OM- and Fe, ((Fe₂As) and Mn (Mn₃(AsO₄)₂) bound forms of As leading to a substantial increase in rice growth and yield. Thus, the combination of BC and MT is an eco-friendly approach to mitigate As toxicity and improve rice productivity. Full article

Soil salinization constitutes a major constraint on global agricultural production, with marked divergence in salt adaptation strategies between salt-tolerant barley (Hordeum vulgare) and salt-sensitive rice (Oryza sativa). This study systematically investigated the evolution and functional specialization of the C3HC4-type RING zinc finger gene family, known to mediate abiotic stress responses through E3 ubiquitin ligase activity, in these contrasting cereal species. Through comparative genomics, we identified 123 HvC3HC4 genes and 90 OsC3HC4 genes, phylogenetically classified into four conserved subgroups. Differences in C3HC4 genes in phylogenetic relationships, chromosomal distribution, gene structure, motif composition, gene duplication events, and cis-elements in the promoter region were observed between barley and rice. Moreover, HvC3HC4s in barley tissues preferentially adopted an energy-conserving strategy, which may be a key mechanism for barley’s higher salt tolerance. Additionally, we found that C3HC4 genes were evolutionarily conserved in salt-tolerant species. The current results reveal striking differences in salt tolerance between barley and rice mediated by the C3HC4 gene family and offer valuable insight for potential genetic engineering applications in improving crop resilience to salinity stress. Full article

Drought stress poses a major constraint on global crop productivity. Although aspartic proteases (APs) are primarily characterized in plant disease resistance, their roles in abiotic stress adaptation remain largely unexplored. Here, we demonstrate that rice (Oryza sativa) OsAP4 critically regulates drought stress tolerance at the seedling stage. Genetic manipulation through overexpression (OsAP4-OE) or CRISPR knockout (OsAP4-KO) resulted in significantly reduced or enhanced stress tolerance compared to wild-type plants, respectively. Through integrated approaches including yeast two-hybrid, bimolecular fluorescence complementation, pull-down, co-immunoprecipitation, and protein degradation assays, we established that OsAP4 physically interacts with and destabilizes OsCATA/OsCATC, two catalase enzymes responsible for reactive oxygen species (ROS) scavenging. Importantly, OsAP4 modulates ROS production under drought stress treatment conditions. Together, these findings reveal a novel OsAP4-OsCATA/OsCATC regulatory module governing rice drought stress responses. Full article

Calcium-dependent protein kinases (CDPKs) are crucial regulators in calcium-mediated signal transduction pathways, playing a pivotal role in plant response to abiotic stresses. However, there is still limited knowledge regarding the genes of the Populus tomentosa CDPK family and their underlying functions in response to arsenic (As) stress and arbuscular mycorrhizal fungi (AMF) colonization. In our study, 20 PtCDPKs were identified in the P. tomentosa genome. Phylogenetic analysis categorized these PtCDPK genes into four subgroups based on sequence homology. Motif analysis revealed that PtCDPK genes within the same group share a similar exon–intron structure, conserved domains, and composition. The promoters of PtCDPK genes were found to contain a multitude of cis-acting elements, including light-response elements, phytohormone-response elements, and stress-response elements. The analysis of genes provided insights into the evolutionary dynamics and expansion of the PtCDPK gene family within P. tomentosa. The PtCDPK genes exhibited a strong collinear relationship with the CDPK genes of two model plants, namely, Arabidopsis thaliana and Oryza sativa L. Specifically, 10 gene pairs showed collinearity with Arabidopsis; in contrast, 14 gene pairs were collinear with rice. Transcriptome analysis of gene expression levels in P. tomentosa roots under both As stress and arbuscular mycorrhizal fungi (AMF) colonization conditions revealed that 20 PtCDPK genes had differential expression patterns. Under As stress, AMF inoculation led to the upregulation of 11 PtCDPK genes (PtCDPKSK5, X2, 1-3, 20-1, 24, 26-X1-1, 26-X1-2, 29-1, 29-2, 32, and 32-X1) and the downregulation of 8 PtCDPK genes, including PtCDPK1-1, 1-2, 8-X1, 10-X4, 13, 20-2, 26-X2, and 26-X3. The RT-qPCR results for 10 PtCDPK genes were consistent with the transcriptome data, indicating that AMF symbiosis plays a regulatory role in modulating the expression of PtCDPK genes in response to As stress. The principal findings of this study were that PtCDPK genes showed differential expression patterns under As stress and AMF colonization, with AMF regulating PtCDPK gene expression in response to As stress. Our study contributes to developing a deeper understanding of the function of PtCDPKs in the Ca²⁺ signaling pathway of P. tomentosa under As stress and AMF inoculation, which is pivotal for elucidating the molecular mechanisms underlying As tolerance in AMF-inoculated P. tomentosa. Full article

Rice (Oryza sativa L.), a staple food for over half of the global population, plays a pivotal role in food security. Among its two primary groups, japonica and indica, temperate japonica varieties are particularly valued for their high-quality grain and culinary uses. Although some of these varieties are adapted to cooler climates, they often suffer from reduced productivity or increased disease susceptibility when cultivated in warmer productive environments. These limitations underscore the need for breeding programs to incorporate biotechnological tools that can enhance the adaptability and resilience of the plants. However, New Genomic Techniques (NGTs), including CRISPR-Cas9, require robust in vitro systems, which are still underdeveloped for temperate japonica genotypes. In this study, we developed a reproducible and adaptable protocol for protoplast isolation and regeneration from the temperate japonica cultivars ‘Ónix’ and ‘Platino’ using somatic embryos as the starting tissue. Protoplasts were isolated via enzymatic digestion (1.5% Cellulase Onozuka R-10 and 0.75% Macerozyme R-10) in 0.6 M AA medium over 18–20 h at 28 °C. Regeneration was achieved through encapsulation in alginate beads and coculture with feeder extracts in 2N6 medium, leading to embryogenic callus formation within 35 days. Seedlings were regenerated in N6R and N6F media and acclimatized under greenhouse conditions within three months. The isolated protoplast quality displayed viability rates of 70–99% within 48 h and supported transient PEG-mediated transfection with GFP. Additionally, the transient expression of a gene editing CRISPR-Cas9 construct targeting the DROUGHT AND SALT TOLERANCE (OsDST) gene confirmed genome editing capability. This protocol offers a scalable and genotype-adaptable system for protoplast-based regeneration and gene editing in temperate japonica rice, supporting the application of NGTs in the breeding of cold-adapted cultivars. Full article

C2H2 zinc finger proteins (C2H2-ZFPs) constitute one of the largest transcription factor families in plants, playing crucial roles in growth, development, and stress responses. Here, we performed a comprehensive genome-wide analysis of C2H2-ZFPs in foxtail millet (Setaria italica v2.0), identifying 67 members that were unevenly distributed across all nine chromosomes. Most SiC2H2 proteins were predicted to be alkaline, stable, and nuclear-localized, with the exception of SiC2H2-11 and SiC2H2-66, which were chloroplast-targeted. Phylogenetic analysis with Arabidopsis thaliana and Oryza sativa (rice) homologs classified these genes into seven distinct subfamilies, each containing the characteristic motif1 domain. Evolutionary studies revealed 14 segmental duplication events and strong syntenic conservation with Triticum aestivum (wheat, 163 orthologous pairs), suggesting conserved functions during evolution. Promoter analysis identified multiple cis-acting elements associated with light responsiveness, hormone signaling, and stress adaptation. Transcriptome profiling and qPCR validation in the YuGu 56 cultivar identified several stress-responsive candidates, including SiC2H2-35 and SiC2H2-58 (salt tolerance), as well as SiC2H2-23 (5.19-fold induction under salt stress) and SiC2H2-32 (5.47-fold induction under drought). This study provides some valuable insights into the C2H2-ZFP family in foxtail millet and highlights potential genetic markers for improving stress resilience through molecular breeding approaches. Full article

Drought stress is a predominant abiotic constraint adversely affecting global rice (Oryza sativa) production and threatening food security. While the transcriptional and post-transcriptional regulation of drought-responsive pathways has been widely investigated, the emerging field of epitranscriptomics, particularly RNA chemical modifications such as N6-methyladenosine (m⁶A), adds a new dimension to gene regulation under stress. The most prevalent internal modification in eukaryotic messenger RNA influences RNA metabolism by interacting dynamically with enzymes that add, remove, or recognize the modification. Recent studies in rice reveal that m⁶A deposition is not static but dynamically regulated in response to water-deficit conditions, influencing transcript stability, splicing, nuclear export, and translation efficiency of key drought-responsive genes. This review critically synthesizes current findings on the distribution and functional implications of m⁶A and other epitranscriptomic marks (e.g., 5-methylcytosine [m⁵C], pseudouridine [Ψ]) in modulating rice responses to drought. We discuss the regulatory circuitry involving m⁶A effectors such as OsMTA, OsFIP37, and YTH domain proteins and their integration with known drought-signaling pathways including ABA and reactive oxygen species (ROS) cascades. We also highlight emerging high-resolution technologies such as m⁶A-seq, direct RNA sequencing, and nanopore-based detection that facilitate epitranscriptomic profiling in rice. Finally, we propose future directions for translating epitranscriptomic knowledge into crop improvement, including CRISPR/Cas-based modulation of RNA modification machinery to enhance drought tolerance. Full article

Salinity and heavy metal stress significantly reduce agricultural productivity in arable lands, particularly affecting crops like rice (Oryza sativa L.). This study aimed to evaluate the efficacy of heavy metal-tolerant plant growth-promoting rhizobacteria (HMT-PGPR) in mitigating the harmful effects of salt (NaCl), chromium (Cr), and combined NaCl + Cr stress on rice plants. Two pre-isolated and well-characterized heavy metal-tolerant epiphytic (Ochrobactrum pseudogrignonense strain P14) and endophytic (Arthrobacter woluwensis strain M1R2) PGPR were tested. The LSD test (p ≤ 0.05) was used to assess the statistical significance between treatment means. Stresses caused by NaCl, Cr, and their combination were found to impair plant growth and biomass accumulation through mechanisms, including osmotic stress, oxidative damage, ionic imbalance, reduced photosynthetic pigment, lowered relative water content, and compromised antioxidant defense systems. Conversely, inoculation with HMT-PGPR alleviated these adverse effects by reducing oxidative stress indicators, including malondialdehyde (MDA), hydrogen peroxide (H₂O₂) content and electrolyte leakage (EL) and enhancing plant growth, osmolyte synthesis, and enzymatic antioxidant activity under single- and dual-stress conditions. The application of HMT-PGPR notably restricted Na⁺ and Cr⁶⁺ uptake, with an endophytic A. woluwensis M1R2 demonstrating superior performance in reducing Cr⁶⁺ translocation (38%) and bioaccumulation (42%) in rice under dual stress. The findings suggest that A. woluwensis effectively mitigates combined salinity and chromium stress by maintaining ion homeostasis and improving the plant’s antioxidant defenses. Full article

With the continuous rise in global temperatures, heat stress has become a significant threat to rice (Oryza sativa L.) growth and yield. MYB transcription factors, the largest family of genes in plants, play a crucial role in mediating responses to various abiotic stresses. However, the specific functions of MYB genes in rice under heat stress remain largely unexplored. In this study, we conducted a comprehensive genome-wide characterization of the MYB transcription factor family and performed an RNA-seq analysis to identify OsMYB genes that are responsive to heat stress. We identified 229 MYB genes in rice, 134 of which exhibited significant expression changes under heat treatment. An RT-qPCR analysis validated the RNA-seq results for 15 MYB genes, confirming significant expression changes, such as the upregulation of Os02g0685200 after heat stress and the downregulation of Os05g0579600. Six highly responsive genes were selected for further analysis. Cis-acting elements associated with hormone response and abiotic stress were identified in the promoter regions of these genes. A subcellular localization analysis revealed that, except for Os05g0579600, which located to both the nucleus and cytoplasm, the other MYB genes (Os01g0192300, Os02g0685200, Os06g0637500, Os06g0669700, and Os09g0106700) were predominantly located in the nucleus. In yeast, Os01g0192300, Os06g0637500, and Os06g0669700 exhibited transcriptional activation activity, while Os02g0685200 and Os09g0106700 showed transcriptional repression activity. Notably, these genes responded not only to heat stress but also to other abiotic stresses, such as cold, salt, and heavy metal cadmium. This study provides valuable insights into the functional roles of OsMYB family genes in the heat stress response, identifying Os01g0192300, Os02g0685200, Os05g0579600, Os06g0637500, Os06g0669700, and Os09g0106700 as potential key genes involved in heat tolerance in rice. Full article

Rice (Oryza sativa L.) is a staple crop that provides essential nutrients and energy; however, it is sensitive to heat stress, posing a threat to sustainable productivity. Heat stress can cause delayed germination in progeny, increased oxidative stress, reduced biomass accumulation, and excessive water loss. Notably, heat stress memory induced through heat priming can be inherited, potentially strengthening heat tolerance in subsequent generations. This study examined the effects of heat priming and heat stress on delayed germination, shoot length, and shoot fresh and dry weight under elevated-temperature conditions. The results showed that while heat stress delayed germination in progeny, heat priming significantly accelerated germination rates. Furthermore, heat stress elevated oxidative stress levels, thereby hindering biomass synthesis. In contrast, heat priming helped maintain low levels of reactive oxygen species (ROS) and malondialdehyde (MDA), contributing to greater biomass accumulation. These findings suggest that heat priming enhances transgenerational heat tolerance in rice, leading to faster germination, higher biomass accumulation, and improved ROS homeostasis in progeny. Full article

Oxidative stress, arising from environmental challenges such as drought, salinity, extreme temperatures, and pathogen attack, significantly impairs rice (Oryza sativa) growth, yield, and grain quality. This review provides a comprehensive synthesis of the mechanisms underlying oxidative stress in rice, with a focus on the generation of reactive oxygen species (ROS), their physiological and molecular impacts, and the antioxidant defense systems employed for mitigation. The roles of enzymatic and non-enzymatic antioxidants, along with key transcription factors, signaling pathways, and stress-responsive genes, are explored in detail. This study further highlights varietal differences in oxidative stress tolerance, emphasizing traditional, modern, and genetically engineered rice cultivars. Recent advances in breeding strategies, gene editing technologies, and multi-omics integration are discussed as promising approaches for enhancing stress resilience. The regulatory influence of epigenetic modifications and small RNAs in modulating oxidative stress responses is also examined. Finally, this paper identifies critical research gaps—including the need for multi-stress tolerance, long-term field validation, and deeper insights into non-coding RNA functions—and offers recommendations to inform the development of climate-resilient rice varieties through integrative, sustainable strategies. Full article

Heat stress is one of the major factors affecting crop growth and yield. However, the molecular mechanisms underlying rice heat stress tolerance remain largely unclear. In this study, we identified and characterized the rice high temperature sensitive 2 (hts2) mutant, which is highly susceptible to heat stress. Map-based cloning revealed that the HTS2 encodes a cytochrome P450 protein (CYP71P1) involved in serotonin biosynthesis. HTS2 is ubiquitously expressed across plant tissues and shows strong upregulation in response to heat stress. The HTS2 mutation significantly impairs basal serotonin synthesis in rice, and the heat-sensitive phenotype of the hts2 mutant is completely rescued by exogenous serotonin supplementation. Compared to the wild type, the hts2 mutant exhibits reduced antioxidant capacity, leading to excessive reactive oxygen species (ROS) accumulation and severe oxidative damage, ultimately reducing heat stress tolerance. Furthermore, disruption of HTS2 significantly affects the rice heat shock response, with the heat-induced expression of HsfA2s and their downstream target genes, such as HSP18.0 (heat shock protein 18.0) and OsAPX2 (ascorbate peroxidase 2), markedly depressed in hts2 mutant. Our results suggest a pivotal role of HTS2 in modulating serotonin metabolism and maintaining ROS homeostasis during heat stress, offering new perspectives on the mechanisms underlying heat tolerance and potential strategies to enhance rice resilience to heat stress. Full article

Worldwide, cadmium (Cd) contamination severely threatens rice production and public health. Jasmonic acid (JA) is recognized to be involved in rice Cd stress responses, but the underlying mechanism remains unclear. In this study, we show that JA positively regulates Cd tolerance in rice by repressing Cd uptake and root-to-shoot translocation. Cd exposure rapidly elevated the endogenous JA in rice roots, which was associated with increased expression of JA synthesis and JA-responsive genes. Moreover, silencing the expression of either allene oxide synthase (OsAOS; active in JA biosynthesis) or CORONATINE INSENSITIVE1 (OsCOI1; active in JA perception) resulted in aggravated Cd toxicity and increased Cd accumulation in both the roots and shoots, as well as increased translocation from the root to the shoots. A short-term uptake experiment revealed that silencing of OsAOS and OsCOI1 enhanced root Cd uptake ability. Furthermore, the elevated transcript levels of genes for Cd uptake (OsNramp5, OsNramp1, and OsIRT1) and root-to-shoot translocation (OsHMA2) were observed in OsAOS and OsCOI1 RNAi plants in comparison with wild-type plants. Taken together, our findings suggest that JA enhances rice cadmium tolerance by suppressing Cd uptake and translocation. Full article

Rice (Oryza sativa L.) serves as a staple food for over half the global population, but its cultivation faces significant challenges from abiotic stresses such as drought, salinity, temperature extremes, and heavy metal toxicity. These stresses adversely impact rice growth, yield, and quality, posing a threat to global food security. This review comprehensively explores the physiological, biochemical, and molecular responses of rice to abiotic stresses, highlighting key functional genes and signaling pathways. Advanced breeding strategies, including molecular marker-assisted selection (MAS), genome-wide association studies (GWASs), and CRISPR/Cas9-based genome editing, offer innovative solutions for enhancing stress tolerance. Integrated approaches combining traditional breeding, modern molecular techniques, and exogenous applications such as plant hormones and beneficial microorganisms are discussed. These methods aim to develop rice varieties resilient to multiple stresses, ensuring sustainable production. Future prospects emphasize the integration of multi-omics technologies and the establishment of stress-resistant germplasm banks to accelerate breeding programs. This review provides some support for the development of stress-tolerant rice varieties to help address agricultural challenges in the context of climate change. Full article

Auxin plays a versatile role in regulating plant growth and development. The auxin efflux carrier PIN-FORMED (PIN) proteins dictate the distribution and maximum of auxin within various tissues. Despite extensive research on OsPINs in recent years, their functions in abiotic stress resistance, particularly cold tolerance, remain poorly understood. Here, we investigated the role of OsPIN5b in rice (Oryza sativa L.) growth and development, as well as its contribution to cold tolerance using overexpression technology. Overexpression of OsPIN5b (OE) resulted in reduced shoot height and a lower number of adventitious roots at the seedling stage. Transgenic rice plants exhibited an earlier heading date, stunted growth, and compromised agronomic traits, including shortened panicle length, decreased grain number per panicle, reduced seed size, and lower seed setting rate during the reproductive stage. Auxin content in the transgenic lines was significantly elevated, as indicated by the upregulation of the auxin-responsive gene OsIAA20 and increased auxin levels quantified using a newly developed method. Compared with wild-type plants, the cold tolerance of OE plants was markedly reduced, as evidenced by lower survival rates, higher levels of electrolyte leakage, and increased malondialdehyde (MDA) production following cold treatment. In line with this, the transgenic lines produced less soluble sugar and proline, while accumulating more hydrogen peroxide (H₂O₂) and superoxide anion radicals (${\mathrm{O}}_2^{-}$) after cold treatment. Furthermore, the activities of antioxidant enzymes, including catalase (CAT), superoxide dismutase (SOD), and peroxidase (POD), were notably decreased upon cold treatment compared with those in WT plants. Additionally, OsRBOHH, which plays a role in ROS production, was significantly upregulated in transgenic lines both before and after chilling stress, suggesting that OsRBOHH plays a potential role in regulating ROS production. Collectively, overexpression of OsPIN5b substantially disturbs auxin homeostasis, resulting in impaired plant architecture and agronomic traits. More importantly, the upregulation of OsPIN5b compromises rice cold tolerance by perturbing ROS homeostasis and adversely influencing the accumulation of soluble sugar and proline. Full article