The yield of wheat (Triticum aestivum L.), an important crop, is adversely affected by heat stress in many regions of the world. However, the molecular mechanisms underlying thermotolerance are largely unknown. A novel ferritin gene, TaFER, was identified from our previous heat stress-responsive transcriptome analysis of a heat-tolerant wheat cultivar (TAM107). TaFER was mapped to chromosome 5B and named TaFER-5B. Expression pattern analysis revealed that TaFER-5B was induced by heat, polyethylene glycol (PEG), H2O2 and Fe-ethylenediaminedi(o-hydroxyphenylacetic) acid (Fe-EDDHA). To confirm the function of TaFER-5B in wheat, TaFER-5B was transformed into the wheat cultivar Jimai5265 (JM5265), and the transgenic plants exhibited enhanced thermotolerance. To examine whether the function of ferritin from mono- and dico-species is conserved, TaFER-5B was transformed into Arabidopsis, and overexpression of TaFER-5B functionally complemented the heat stress-sensitive phenotype of a ferritin-lacking mutant of Arabidopsis. Moreover, TaFER-5B is essential for protecting cells against heat stress associated with protecting cells against ROS. In addition, TaFER-5B overexpression also enhanced drought, oxidative and excess iron stress tolerance associated with the ROS scavenging. Finally, TaFER-5B transgenic Arabidopsis and wheat plants exhibited improved leaf iron content. Our results suggest that TaFER-5B plays an important role in enhancing tolerance to heat stress and other abiotic stresses associated with the ROS scavenging.

Heat stress is one of the most crucial environmental factors, which reduces crop yield worldwide. In plants, the MYB family is one of the largest families of transcription factors (TFs). Although some wheat stress-related MYB TFs have been characterized, their involvement in response to high-temperature stress has not been properly studied. Six novel heat-induced MYB genes were identified by comparison with previously established de novo transcriptome sequencing data obtained from wheat plants subjected to heat treatment; genomic and complete coding sequences of these genes were isolated. All six TaMYBs were localized in the nucleus of wheat protoplasts. Transactivation assays in yeast revealed that all six proteins acted as transcriptional activators, and the activation domains were attributed to the C-termini of the six wheat MYB proteins. Phylogenetic analysis of the six TaMYBs and R2R3-MYBs from Arabidopsis revealed that all six proteins were in clades that contained stress-related MYB TFs. The expression profiles of TaMYB genes were different in wheat tissues and in response to various abiotic stresses and exogenous abscisic acid treatment. In transgenic Arabidopsis plants carrying TaMYB80 driven by the CaMV 35S promoter, tolerance to heat and drought stresses increased, which could be attributed to the increased levels of cellular abscisic acid. We identified six heat-induced MYB genes in wheat. We performed comprehensive analyses of the cloned MYB genes and their gene products, including gene structures, subcellular localization, transcriptional activation, phylogenetic relationships, and expression patterns in different wheat tissues and under various abiotic stresses. In particular, we showed that TaMYB80 conferred heat and drought tolerance in transgenic Arabidopsis. These results contribute to our understanding of the functions of heat-induced MYB genes and provide the basis for selecting the best candidates for in-depth functional studies of heat-responsive MYB genes in wheat.

Salt stress severely restricts pepper growth and productivity. Although AP2/ERF transcription factors are widely involved in plant responses to environmental stress, their functions in salt tolerance in pepper remain largely unknown. In this study, transcriptome-based screening identified CaERF3 (Capana07g002313) as a primary-candidate salt-responsive ERF transcription factor. Functional analyses of CaERF3 knockout (KOERF3) and overexpression (OEERF3) lines demonstrated that CaERF3 positively regulated both seedling growth and salt tolerance. Under salt stress, OEERF3 plants exhibited higher SOD, POD, and CAT activities, lower TBARS accumulation, and a more favorable Na⁺/K⁺ balance, whereas KOERF3 plants showed the opposite phenotype. Integrated metabolomic and transcriptomic analyses indicated that CaERF3-mediated salt tolerance was associated with amino sugar and nucleotide sugar metabolism and galactose metabolism. The knockout of CaERF3 reduced the expression of the galactinol synthase genes CaGolS1-1 and CaGolS1-2, accompanied by decreased galactinol and stachyose accumulation, suggesting impaired raffinose-family oligosaccharide biosynthesis. In addition, genes associated with Golgi function, vesicle trafficking, and cell wall modification (CaLAC, CaVSR, CaUNC-1, and CaCHIEP3-1) were coordinately downregulated. Furthermore, CaERF3 functioned as a nuclear transcriptional activator and directly activated the endochitinase gene CaCHIEP3-1 by binding the GCC-box in its promoter. These findings establish CaERF3 as a positive regulator of salt tolerance in pepper and provide new insights into the transcriptional regulation of carbohydrate metabolism and glycan biosynthesis during salt stress.

Sunflower (Helianthus annuus) can potentially be used for uranium (U) phytoremediation. However, the influence of arbuscular mycorrhizal fungi (AMF) on key rhizosphere processes and plant U uptake remains insufficiently researched. We hypothesized that AMF inoculation could enhance sunflower tolerance to U stress by improving plant physiological performance and modifying rhizosphere properties. To test this hypothesis, this study examined the effects of AMF (Funneliformis mosseae, Glomus etunicatum, and their co-inoculation) on sunflowers under U stress, encompassing plant growth and physiological traits, rhizosphere properties, enzyme activities in the rhizosphere soil, uranium speciation in the rhizosphere soil, and the accumulation and distribution of uranium within the plant. Results showed that AMF successfully colonized the roots, enhancing plant growth, biomass, and gas exchange, while improving photosynthetic efficiency and reducing non-photochemical quenching. In the rhizosphere, AMF elevated soil respiration, organic matter, dissolved organic carbon, and microbial biomass carbon; improved phosphatases, urease, catalase, and sucrase activities; also reshaped U speciation, increasing exchangeable and carbonate-bound fractions while decreasing those bound to organic matter, Fe/Mn oxides, and residual phases. Moreover, AMF reduced U concentration in leaves and stems, promoted U retention in belowground tissues, and significantly lowered the U translocation factor. These findings demonstrate that AMF inoculation improves sunflower tolerance to U stress by enhancing physiological performance, modifying rhizosphere properties, and immobilizing U in roots, supporting its potential use in phytoremediation strategies for U-contaminated environments.