Search Results (135)

Fusarium oxysporum f. sp. radicis-lycopersici (Forl) is the etiological agent of tomato Fusarium crown and root rot (FCRR), a devastating soil-borne disease that severely compromises global tomato production. The pathogenicity of Forl has been increasingly linked to its capacity to produce phytotoxic isocassadiene-type diterpenoids. In this study, Forl was cultured in rice medium to obtain Forl cultures, which were used for the separation and identification of secondary metabolites. After removing the known metabolites, two new isocassadiene-type diterpenoid compounds, namely fusariumic acids I (1) and J (2), were isolated from the ethyl acetate extract. Their structures were identified using spectroscopic data analyses and quantum chemical calculations. This is the first report of the fusariumic acid analogs containing a hydroxyl group at position C–1 in the molecule. Fusariumic acids I (1) and J (2) exhibited significantly inhibitory activities on the hypocotyl elongation of tomato (Solanum lycopersicum) and sesame (Sesamum indicum) seedlings, as well as on the coleoptile elongation of rice (Oryza sativa var. japonica) seedlings at concentrations from 10 to 100 µg/mL. The discovery of two new phytotoxic isocassadiene-type diterpenoids expanded the diversity of secondary metabolites of Forl. Meanwhile, it provided critical insights into Forl-tomato interactions and the candidate lead compounds for the development of new herbicides as well. Full article

Fusarium head blight (FHB), caused by Fusarium graminearum, is a fungal disease that severely affects wheat. The mycotoxins it produces, such as deoxynivalenol (DON), pose serious risks to human and animal health. In this study, a biocontrol strain, LYH8, was isolated from local sources in Jingzhou, Hubei Province. Plate confrontation assays demonstrated that LYH8 effectively inhibited the mycelial growth of F. graminearum, with an inhibition rate of 43%, and induced morphological abnormalities such as hyphal swelling and shrinkage. Based on 16S rRNA and gyrB gene sequencing and phylogenetic analysis, LYH8 was identified as Bacillus velezensis. In vivo experiments showed that disease severity in wheat coleoptiles and spikes was significantly reduced by treatment with LYH8 by 75–85%, and the accumulation of DON and its deoxynivalenol-3-glucoside (D3G) in grains was decreased by 20–22%. Further transcriptome analysis revealed that it affects pathogen growth by regulating amino acid biosynthesis, ribosomal biosynthesis, carbon metabolism pathways, and the catalytic activities of related genes. In summary, LYH8 significantly controlled FHB through multiple mechanisms, including inhibiting mycelial growth, reducing infection, and blocking toxin synthesis, demonstrating strong biocontrol potential. Full article

Salinity stress constitutes a major environmental constraint impeding crop establishment by limiting water uptake and disrupting osmotic homeostasis during seed germination and early growth. Plant growth-promoting bacteria (PGPB) offer as a sustainable and cost-effective strategy to mitigate these limitations in agricultural systems. In this study, whole-genome analysis of the salt-tolerant PGPB Priestia aryabhattai WJ45 identified its genomic potential for PGP and salinity adaptation, alongside evaluations of wheat germination under saline conditions. Genome analysis revealed that strain WJ45 harbors a coordinated set of genes associated with key plant growth-promoting traits, including exopolysaccharide production, phosphate solubilization, and siderophore biosynthesis, as well as genes involved in Na⁺/K⁺ transport and osmolyte metabolism. Consistent with these genomic predictions, germination assays demonstrated that WJ45 treatment increased the germination rate by 13.1%, under salt stress compared with the non-inoculated control, while coleoptile, radicle lengths, and fresh weight were enhanced by 17.0%, 15.7%, and 53.2%, respectively, indicating improved early seedling establishment. Collectively, these findings demonstrate that WJ45 possesses a genome-encoded capacity to facilitate crop establishment under saline conditions. While further seedling and large-scale evaluations are warranted, this study underscores the potential of this genome-informed microbial resource to enhance early plant growth and resilience in salt-affected environments. Full article

Drought stress is one of the most severe abiotic constraints limiting wheat productivity worldwide, particularly during early developmental stages that determine crop establishment and yield potential. Sustainable, biologically based strategies that enhance drought tolerance without environmental cost are therefore urgently needed. In this study, we evaluated the individual and combined effects of chitosan (Cs), microalgae (Ma) (Nostoc linckia, MACC-612), and a chitosan–microalgae nanoparticle formulation (Cs-Ma) on germination performance, early seedling growth, and molecular stress responses in two wheat (Mehregan and MV Nádor) cultivars with contrasting drought sensitivity under polyethylene glycol (PEG)-induced osmotic stress (−2 and −4 MPa). Drought stress significantly reduced germination percentage, germination rate, and radicle and coleoptile development in both cultivars, especially at −4 MPa. Application of Cs and microalgae individually partially alleviated these negative effects; however, the combined Cs-Ma treatment consistently produced the strongest improvements in seedling vigor and biomass accumulation under both moderate and severe drought stress. Evaluation of drought tolerance using tolerance index (TOL), stress tolerance index (STI), and stress intensity (SI) demonstrated that Cs-Ma markedly increased STI and reduced SI across most germination traits, indicating enhanced drought tolerance and lower stress sensitivity, particularly in MV Nádor. These physiological responses were supported by transcriptional reprogramming in radicle tissues, including upregulation of genes involved in polyamine biosynthesis (TaSPDS, TaSAMDC), phenylpropanoid metabolism (TaPAL), and protein protection (TaHSP70), along with moderated induction of polyamine catabolism (TaPXPAO). Overall, the results reveal a synergistic interaction between chitosan nanoparticles and microalgae biomass, highlighting Cs-Ma as an effective, eco-friendly biostimulant for improving early-stage drought tolerance in wheat. Full article

Delayed chilling stress is a frequent meteorological disaster in the spring maize-growing region of Northern China. Understanding the physiological responses and key characteristics of cold-tolerant maize varieties under such stress is crucial for their selection and utilization. This study compared the physiological and biochemical responses of a cold-tolerant variety (XY335) and a conventional variety (KH8) to simulated delayed chilling stress induced by early field sowing. Results showed that the emergence percentage and emergence uniformity of the cold-tolerant variety were 9.6% and 2.8% higher than those of the conventional variety, respectively. Under chilling stress, the root diameter of the cold-tolerant variety remained stable, while root length decreased by 24.5%. In contrast, the conventional variety exhibited the opposite response. Growth of the cold-tolerant variety slowed during stress but accelerated significantly after temperature recovery, achieving 1–2 more leaf ages than the conventional variety. The SPAD value (chlorophyll content) of the cold-tolerant variety was less affected, remaining 14.3% higher than the conventional variety, thereby maintaining higher photosynthetic efficiency. The enhanced stress tolerance of XY335 correlated with a robust antioxidant system: leaf peroxidase (POD) activity was 60.7% higher, and malondialdehyde (MDA) content was 42.4% lower compared to KH8. In summary, under delayed chilling stress, the cold-tolerant variety ensured higher emergence and seedling uniformity by reducing coleoptile length, maintained root diameter and absorption capacity by shortening root length, preserved chlorophyll synthesis and photosynthetic performance under the protection of a POD-dominated enzyme system, and employed a “standby mode” with compensatory leaf growth to ensure adequate dry matter accumulation and yield formation. Full article

Direct seeded rice, being less water- and labor-intensive, can be an alternative approach to conventional rice planting methods. However, uneven and poor stand establishment caused by deep sowing in the field is one of the major hurdles in the adoption of direct seeding technology. Varieties with the potential to emerge from deeper layers of soil may have a positive impact on crop establishment. To evaluate the behavior of ten rice cultivars against their potential to emerge from different soil depths (0, 2.5, and 5.0 cm), a pot experiment was conducted under semi-controlled conditions at the PARC Rice Programme, Kala Shah Kaku, Lahore. Data on different seedling parameters were collected. The results showed that the highest mean seedling emergence percentage (95%) was achieved by the tested genotypes at a 2.5 cm seeding depth, while surface sowing and placement of seeds at a 5 cm depth demonstrated a similar mean emergence percentage (89%). Seeding depth, genotypes, and their interactions significantly affected mean emergence time, mesocotyl and coleoptile lengths, and root and shoot lengths. Sowing seeds at a 5 cm depth increased mean emergence time by 28%. However, increasing sowing depth increased the coleoptile length, mesocotyl length, first leaf sheath length, and shoot length of rice seedlings. Mesocotyls and coleoptile lengths showed a linear relationship with mean emergence time. Mesocotyl and coleoptile are key structures of the apical–basal axis in grasses that elongate to facilitate the emergence of germinating seeds under deep sowing. The longest coleoptiles (1.47 cm) and mesocotyls (3.27 cm) were measured from seedlings sown at a depth of 5 cm. Among genotypes, PK-1121 exhibited maximum coleoptile elongation (2.10 cm) under deep sowing (5 cm), while the longest mesocotyls were recorded from deep-sown (5 cm) seedlings of Chenab Basmati. Root length was found to be inversely proportional to sowing depth. PK-1121 aromatic, Kisan Basmati, Punjab Basmati, and Chenab Basmati produced longer shoots (22.61, 23.37, 23.32, and 21.05 cm, respectively) and took a relatively short time for emergence when sown deep. These varieties may have better potential to emerge from deeper soil layers, which may have a positive impact on even germination and better crop stand establishment. Full article

The infestation of Echinochloa crus-galli (L.) P.Beauv. in crop fields results in significant yield loss in many agricultural systems. Currently, the most effective strategy for controlling E. crus-galli is the application of synthetic herbicides. However, biotypes of E. crus-galli that are resistant to different modes of herbicide action often emerge. Thus, it is necessary to develop alternative control methods and address ecological concerns about synthetic herbicides. During the field survey, we observed diseased E. crus-galli exhibiting symptoms of leaf blight. These symptoms indicate a potential pathogen infection and subsequent phytotoxin production during the pathogenesis. Therefore, we aimed to isolate and identify the phytotoxic substances present in the diseased leaves. Aqueous extracts of the diseased leaves exhibited phytotoxicity, suppressing the growth of Echinochloa crus-galli seedlings in a concentration-dependent manner. A phytotoxic substance was isolated from the leaf extracts through a bioassay-guided separation process using the E. crus-galli bioassay. Spectrum analysis revealed that the phytotoxic substance was monocerin. Monocerin inhibited the growth of coleoptiles and roots of E. crus-galli seedlings at concentrations greater than 30 and 10 μM, respectively, and inhibited germination at concentrations greater than 100 μM. Therefore, monocerin may be involved in the phytotoxic activity exhibited by the extracts of E. crus-galli leaves with blight symptoms. Creating bioherbicides based on the monocerin structure could be an environmentally friendly approach to weed management. Full article

Low temperature during early spring severely impairs maize germination, leading to significant yield losses. To elucidate the mechanisms underlying cold tolerance at the germination stage, we compared two cold-tolerant maize inbred lines (AM and CM) with a cold-sensitive line (BM) under control (25 °C) and chilling (6 °C) conditions. Phenotypic observations showed that AM and CM maintained high germination rates and exhibited enhanced coleoptile elongation under cold stress, whereas BM displayed substantial growth inhibition. Cold-tolerant lines accumulated less malondialdehyde and showed markedly higher SOD and POD activities, indicating a stronger antioxidant defense. Transcriptome profiling revealed that cold tolerance is associated with a more robust transcriptional response in AM and CM, characterized by significant activation of the phenylpropanoid and flavonoid biosynthesis pathways. Among the differentially expressed genes, the class III peroxidase gene ZmPER5 was strongly upregulated in AM and CM but only weakly induced in BM, suggesting its central role in reinforcing the cell wall structure and enhancing ROS-scavenging capacity under chilling conditions. Other lignin- and flavonoid-related genes, including ZmHCT4 and ZmCYP75, also exhibited genotype-specific induction patterns consistent with cold tolerance. qRT-PCR validation confirmed the RNA-seq expression trends. These results demonstrate that maize cold tolerance during germination relies on the coordinated enhancement of antioxidant enzyme activity, activation of phenylpropanoid-derived lignin biosynthesis, and accumulation of protective flavonoids. The identified candidate genes, especially ZmPER5, provide valuable targets for improving cold tolerance in maize breeding. Full article

Fusarium head blight (FHB), caused by Fusarium graminearum, poses a serious threat to wheat production and grain security. In this study, a strain of Bacillus velezensis was isolated from the plant Polygonatum sibiricum and designated FXJ. FXJ inhibited the mycelial growth of F. graminearum by 52% and induced hyphal abnormalities including swelling and shrinkage. In vivo experiments demonstrated that FXJ treatment significantly reduced disease severity in wheat coleoptiles and spikes, decreased deoxynivalenol accumulation in grains, and down-regulated the expression. Transcriptomic analysis further revealed that FXJ suppressed fungal growth by interfering with energy metabolism and essential biosynthetic processes, particularly pathways related to fatty acid degradation and sugar metabolism. Overall, B. velezensis FXJ shows strong potential for integrated management of wheat Fusarium head blight through combined mechanisms, including the inhibition of mycelial growth, disruption of hyphal morphology, reduction in pathogen infection, and suppression of toxin synthesis. Full article

CSN2, a highly conserved subunit of the COP9 signalosome (CSN), serves as the primary binding site for Cullin in the CSN complex. This interaction, dependent on lysine residues, positions CSN2 as a key player in approximately 20% of CRL-mediated ubiquitination reactions, a critical regulatory pathway for growth, development, and cellular processes in eukaryotes. While the role of CSN2 in human cells has been partially characterized, its function in rice (OsCSN2) remains poorly understood. Building on our previous findings regarding OsCSN2 function under natural light, this study investigates its regulatory mechanisms in rice seedlings under red and far-red light conditions. We demonstrate that under natural light, OsCSN2 mainly affects rice GA homeostasis by regulating the expression of SLR1 and influences rice photomorphogenesis by regulating the expression of the COP1-HY5 complex, thereby controlling rice growth through two pathways. Unlike under natural light, under red light, OsCSN2 promotes the expression of OsGID1, enhances the interaction between OsGID1 and OsSLR1, and promotes GA accumulation and OsPIL14 expression, leading to rice stem growth and inhibition of coleoptile elongation. Under far-red light, OsCSN2 mainly promotes the expression of OsCOP1, increasing the formation of the COP1-HY5 complex, which inhibits photomorphogenesis and coleoptile elongation. Lysine site mutations in OsCSN2 affect the interaction between the OsCSN complex and CRLs, regulating CRL-mediated ubiquitination reactions, promoting the ubiquitin-mediated degradation of OsSLR1 and OsCOP1, and thus promoting rice growth. These findings not only elucidate the functional roles of OsCSN2 in rice growth regulation but also provide valuable genetic resources for breeding rice varieties with enhanced agronomic traits. Full article

This study aims to compare the transcriptional responses of japonica and indica rice genotypes with contrasting submergence tolerance and to functionally validate the role of OsEXPB3. Flooding is a major abiotic stress limiting stable rice production, and different genotypes show substantial variation in submergence tolerance. However, the transcriptional and molecular regulatory mechanisms underlying subspecies-specific responses remain poorly understood. Here, RNA-seq analysis of japonica and indica accessions with contrasting tolerance levels was performed to construct molecular response networks and identify key tolerance-related genes. Comparative analysis revealed that both subspecies activate biological processes such as stimulus response, redox homeostasis, carbon metabolism, and hormone signaling under submergence. In the analyzed japonica genotypes, plants relied more on integrated hormone-regulated signaling, whereas in the analyzed indica genotypes, metabolic homeostasis was more prominent. Among the identified genes, OsEXPB3, a β-expansin gene, was consistently upregulated in tolerant accessions, whereas osexpb3 mutants displayed suppressed coleoptile and seedling elongation and reduced tolerance. Hormone profiling revealed a 0.1–0.3-fold increase in ethylene (ETH) and a 50–70% reduction in gibberellin (GA) in mutants after submergence. Defense-related hormones, including jasmonic acid (JA) and salicylic acid (SA), were initially higher but declined markedly under stress conditions. Given that the OsEXPB3 promoter contains multiple ETH-, GA-, ABA-, JA- and SA-responsive cis-elements, we propose that OsEXPB3 may coordinate the balance between growth- and defense-related hormones to mediate adaptive responses to flooding. This study reveals conserved and divergent molecular responses between subspecies and suggests that OsEXPB3 may contribute to submergence tolerance in rice, although its regulatory role requires further validation. Full article

Freshwater scarcity in arid regions forces farmers to use saline water, reducing durum wheat (Triticum turgidum L. subsp. durum) productivity, particularly during early growth stages. This study evaluated two Moroccan varieties, Faraj and Nachit, on silty clay soil under five salinity levels (0.2, 4, 8, 12, and 16 dS m⁻¹) in a randomized complete block design with three replications, aiming to identify tolerance thresholds and characterize physiological and agronomic responses. Key traits measured included germination percentage, germination stress index, mean germination time, root and coleoptile length, plant height, leaf number, chlorophyll fluorescence, grain yield, weight of 200 grains, and straw yield. Germination percentage declined from 8 dS m⁻¹, with delayed germination and inhibited vegetative growth at higher salinity. Both varieties maintained grain yield up to 8 dS m⁻¹ and weight of 200 grains and straw yield up to 12 dS m⁻¹, with Nachit showing higher tolerance. Multivariate analyses, including principal component analysis and heatmaps, linked soil sodium, chloride, and electrical conductivity negatively to growth and yield, whereas potassium, calcium, and magnesium supported plant growth and physiological activity. These findings provide insights for breeding and irrigation strategies to sustain durum wheat under salinity stress. Full article

Submergence during germination is a major barrier to the adoption of direct-seeded rice (DSR). Despite its importance in overcoming this barrier, the genetic architecture underlying the rapid coleoptile elongation under submergence remains largely elusive. Through screening among 20 different rice cultivars, a submergence-tolerant cultivar Xian133 and a sensitive cultivar Chang15 were obtained. Comparative transcriptomics and whole-genome resequencing were conducted between these two cultivars. The results show that rapid germination under flooding is driven primarily by transcriptional reprogramming rather than by antagonistic gene regulation. Transcriptome-wide analyses revealed a significant enrichment of the amino sugar and nucleotide sugar metabolism pathway in tolerant cultivar. This was further supported by the fact that promoter variants at the key loci OscPGM and OsAGPL1 modulate the expression of these genes and emerge as principal determinants of coleoptile elongation capacity under hypoxia. The identified single-nucleotide polymorphisms (SNPs) within these regulatory regions provide promising molecular targets for marker-assisted breeding of DSR cultivars. Full article

Fusarium crown rot (FCR), caused by Fusarium pseudograminearum, is a devastating wheat disease leading to significant yield losses worldwide. However, the pathogenic mechanism of F. pseudograminearum and its resistance to fungicides remain poorly understood. In this study, we identified a hypothetical gene encoding GPI-anchored protein, designated FpPer1, by screening a T-DNA insertion mutant library of F. pseudograminearum for tebuconazole resistance. The ΔFpper1 mutant exhibited increased sensitivity to the triazole antifungal drugs and fludioxonil. Additionally, the deletion of FpPER1 impaired fungal growth, conidiation, and pathogenicity in barley leaves and wheat coleoptiles. Furthermore, the ΔFpper1 mutant displayed enhanced susceptibility to various environmental stresses, including NaCl, CR, sorbitol, H₂O₂, and SDS. The mutant also showed reduced penetration peg formation and impaired reactive oxygen species (ROS) scavenging ability during infection. Subcellular localization analysis revealed that FpPer1-GFP co-localized with the endoplasmic reticulum (ER) marker RFP-HDEL in both conidia and hyphae, indicating its localization in the ER. In summary, our findings demonstrate that FpPER1 plays an important role in pathogenicity and fungicide resistance in F. pseudograminearum. This study not only provides a theoretical foundation for understanding fungal virulence mechanisms but also offers practical insights for developing novel fungicide strategies. Full article

Neo-tetraploid rice is a highly fertile variety created from autotetraploid rice. It demonstrates stronger heterosis and produces stable hybrid progeny. However, there is insufficient data regarding abiotic stress in neo-tetraploid hybrid progeny, especially in relation to salt stress. Two hybrid progenies, high salt-resistance tetraploid rice hybrid progeny (HSRTH) and low salt-resistance tetraploid rice hybrid progeny (LSRTH), were generated by crossing the neo-tetraploid rice cultivars ‘Huaduo 3’ and ‘Huaduo 8’ with the autotetraploid rice Huanghuazhan-4x. Here, we assessed the germination characteristics and seedling growth of two neo-tetraploid hybrids at six NaCl concentrations: 0, 50, 100, 150, 200, and 250 mmol/L. HSRTH demonstrated a higher tolerance to salt stress, achieving a grain germination rate of 48.00 ± 2.63% compared to LSRTH, which reached only 5.00 ± 1.41% under a 250 mmol/L NaCl treatment. Cytological observations showed that the root tip differentiation zone and coleoptiles of HSRTH were less affected by NaCl stress treatment, resulting in fewer cortical cell abnormalities, decreased stele issues, and fewer rhizodermis cell problems, such as shrinkage. Gene expression analysis revealed nine genes that showed differential expression in HSRTH compared to LSRTH. Our study demonstrated that HSRTH showed strong salt stress tolerance, providing a basis for selecting salt-resistant rice germplasm and offering insights for developing salt-tolerant rice varieties using neo-tetraploid resources. Full article