Excessive application of phosphorus (P) fertilizers does not alleviate P deficiency in soils and may cause water eutrophication. The available P in acidic soils is bound to minerals, such as iron and aluminum, in forms that are difficult to utilize by plants. The low availability of P is detrimental to soil health and crop growth. To address the P imbalance in the soil, different bioremediation techniques, such as phosphate-solubilizing bacteria (PSB) application, have been employed. However, the systematic analysis of the effects of composite inoculation of PSB on crops remains elusive. In this study, the effects of composite-inoculated PSB on plant growth were systematically evaluated by two scales: plate experiment and soil test. This study employed six different strains of PSB including Lelliottia amnigena 1-1 (A), Kluyvera intermedia 1-2 (B), Pseudomonas tolaasii 1-6 (C), Burkholderia cepacia 2-5 (D), Pseudomonas frederiksbergensis 2-11 (E), and Pseudomonas rhodesiae 2-47 (F). Among the 57 different combinations of these strains, four combinations (AE, AF, ADF, and AEF) indicated higher phosphate-solubilizing abilities than the single strains. These combinations were used for subsequent experiments. The plate experiment revealed that composite strains were more effective than single strains in promoting the growth and development of seedlings and roots of oilseed rape. Furthermore, AE, AF, and AEF combinations indicated excellent growth-promoting effects. Moreover, the soil test revealed that the composite inoculation of AE and AEF significantly enhanced biomass accumulation and root development in oilseed rape. The increased growth-promoting effects of the composite strains were observed to be associated with to their phosphate-solubilizing capacities. Both scales confirmed that compared to single inoculation, composite inoculation of PSB is more beneficial for plant growth. This study provides composite inoculation materials and foundational data to support the bioremediation of P imbalance in soil.

Members of the heat shock protein 20 (HSP20) family of proteins play an important role in responding to various forms of stress. Here, the expression of ClaHSP17.4 was induced by heat stress in watermelon. Then, a floral dipping approach was used to introduce the pCAMBIA1391b-GFP overexpression vector encoding the heat tolerance-related gene ClaHSP17.4 from watermelon into Arabidopsis thaliana, and we obtained ClaHSP17.4-overexpressing Arabidopsis plants. Under normal conditions, the phenotypes of transgenic and wild-type (WT) Arabidopsis plants were largely similar. Following exposure to heat stress, however, the germination rates (96%) of transgenic Arabidopsis plants at the germination stages were significantly higher than those of wild-type idopsis (17%). Specifically, the malondialdehyde (MDA) content of transgenic Arabidopsis was half that of the control group, while the activities of peroxidase (POD) and superoxide dismutase (SOD) were 1.25 times those of the control group after exposure to high temperatures for 12 h at the seedling stages. The proline content in ClaHSP17.4-overexpressing transgenic Arabidopsis increased by 17% compared to WT plants (* p < 0.05), while the soluble sugar content rose by 37% (* p < 0.05). These results suggest that ClaHSP17.4 overexpression indirectly improves the antioxidant capacity and osmotic regulatory capacity of Arabidopsis seedlings, leading to improved survival and greater heat tolerance. Meanwhile, the results of this study provide a reference for further research on the function of the ClHSP17.4 gene and lay a foundation for breeding heat-tolerant watermelon varieties and advancing our understanding of plant adaptation to environmental stress.

Members of the CCT gene family have been shown to play roles in photoperiodic flowering and environmental adaptation under a range of conditions. In this study, 29 CCT genes from watermelon were categorized into three distinct subfamilies. The ClCCT genes were systematically analyzed, focusing on their physicochemical properties, gene duplication, motifs, structural divergence, promoter regions, and collinearity with genes from other species. The responsiveness of these genes to abiotic stressors, hormone treatments, and photoperiod prolongation was also examined. Segmental duplication (gene amplification) significantly influenced the evolution of these genes, with most ClCCT genes containing light-, hormone-, and/or abiotic stimulus-responsive elements. In response to abiotic and hormonal stresses, 5 genes responded to cold, 1 gene to drought, and 4 genes to salt. 6 genes were responsive to ABA, and 13 genes to MeJA. Strikingly, ClCCT17, ClCCT4, and ClCCT28 responded to multiple stressors. A majority of these ClCCT genes and their homologs in other species were responsive to prolonged daylight exposure. The varying expression patterns of these genes suggested a key role for watermelon CCT genes in the regulation of both abiotic stress responses and flowering. Functional diversity was also evident among CCT family genes within a given species as well as among species attributable to changes in the structural features and expression patterns of the genes and the encoded proteins.

Rice (Oryza sativa L.) root system plays a critical role in water and nutrient uptake, influencing overall plant growth and crop yield. In this study, we characterized the Osdrp2b mutant, which exhibits a short-root phenotype and was identified through map-based cloning. The Osdrp2b mutation was traced to the gene encoding a dynamin-related protein, and the mutant displayed reduced cell elongation and impaired cell division in the root tip. Further analysis revealed that ROS (reactive oxygen species) accumulation was elevated in the mutant roots, and treatment with ROS inhibitors restored root elongation in the Osdrp2b mutant, indicating that altered ROS homeostasis is associated with the phenotype. Transcriptomic analysis highlighted the differential expression of genes involved in cell wall organization and hydrogen peroxide catabolism. Agronomic evaluations of the Osdrp2b mutant demonstrated compromised shoot growth, reduced tiller number, and lower seed setting rates, indicating the impact of the mutation on rice yield. Overall, these results suggest that OsDRP2B is involved in regulating root growth, potentially through effects on ROS homeostasis and associated signaling networks. These findings provide a basis for future studies on improving rice root development and agronomic performance.

FAR1/FHY3 transcription factors are key regulators of plant growth and development, but their identification and functions in strawberries (Fragaria × ananassa) remain largely unexplored. In this study, 47 FaFAR1/FHY3 genes in cultivated strawberries were systematically identified, which were categorized into six subfamilies and randomly distributed across 15 chromosomes, with segmental duplication as the main driver of the expansion of this gene family. Integration of phylogenetic relationships, gene structure, and conserved motif composition uncovered distinct divergences among the subfamilies. A cis-acting element analysis of promoters and gene expression profiles showed that these genes responded to various abiotic and biotic stresses, phytohormones, and far-red light signals, with FaFAR1-7 and FaFAR1-44 strongly responding to multiple stresses, including temperature, drought, and pathogen infection. Additionally, FaFAR1-12 and FaFAR1-18 exhibited positive correlations with anthocyanin accumulation and the expression of key anthocyanin biosynthesis genes during fruit development. Dual-luciferase reporter assays further confirmed that FaFAR1-12 and FaFAR1-18 significantly activated the promoters of key structural genes related to anthocyanin biosynthesis, indicating that these two TFs exert vital regulatory functions in anthocyanin accumulation during strawberry fruit development. This study comprehensively identifies and characterizes the FaFAR1/FHY3 genes in cultivated strawberries, laying a foundation for their functional analysis and for screening out the key regulatory genes for strawberry fruit quality improvement.