Drought stress is one of the crucial factors affecting plant growth and development in turfgrass species, especially during the summer season. Exogenous plant growth regulators are an effective and convenient approach to mitigating the adverse effects of drought stress on plant growth. The objectives of this study were to reveal the effects of exogenous carnosine or chitosan on turf performance and physiological indexes in bermudagrass (Cynodon transvaalensis × C. dactylon) in response to drought stress. Bermudagrass was foliar sprayed with carnosine or chitosan, and dose-dependent effects on turf quality were observed under drought stress. Under drought stress, foliar application of either carnosine (0.03%) or chitosan (10 mg L⁻¹) significantly increased turf quality, chlorophyll content, leaf relative water content, and decreased electrolyte leakage, malonaldehyde, and hydrogen peroxide content in comparison with untreated control in bermudagrass. Moreover, exogenous carnosine treatment significantly enhanced the activities of both catalase and peroxidase, but chitosan application only increased catalase activity. The results of this experiment were beneficial to the development of new plant growth regulators and would provide helpful insights for turf management under drought-stressed conditions.

Nitrogen (N) is a critical macronutrient for plant growth, and nitrogen deficiency severely limits turfgrass and forage productivity. Nuclear Factor Y (NF-Y) is a conserved transcription factor family known to regulate plant development and stress responses. Tall fescue (Festuca arundinacea) is a perennial grass widely used as turf and forage due to its strong stress tolerance and low input requirements, making it an ideal model for studying adaptation to nitrogen limitation. However, the NF-Y family and its involvement in nitrogen responsiveness remain largely unexplored in perennial grasses. In this study, ten NF-Y genes (FaNF-Ys) were identified from the tall fescue transcriptome, including two FaNF-YA, six FaNF-YB, and two FaNF-YC members. The expansion of the FaNF-YB subfamily suggests potential functional diversification. Phylogenetic and conserved motif analyses revealed high conservation of NF-Y proteins among grasses and distinct structural characteristics among subfamilies. Expression profiling showed that most FaNF-Y genes were responsive to nitrogen availability and exhibited strong tissue specificity, with many preferentially expressed in lateral roots. Among them, FaNF-YB8 displayed a unique expression pattern, being predominantly expressed in mature leaves and showing a bidirectional response to nitrogen supply, with expression peaks at 6–12 h under low nitrogen stress and significant induction under high nitrogen conditions. This study represents the first systematic characterization of the NF-Y genes family in tall fescue and provides valuable candidate genes for understanding nitrogen adaptation and improving nitrogen use efficiency in turfgrass breeding.

The BRI1-EMS suppressor/Brassinazole-resistant (BES/BZR) transcription factors (TFs) act as regulators of the Brassinosteroid (BR) signaling pathway and play key roles in modulating plant growth, development, and abiotic stress tolerance. However, the function of BES/BZR TFs remains unknown in warm-season turfgrass species. In this study, ZjBZR2, a BES/BZR TF in Zoysia japonica was identified and shared the closest evolutionary relationship with OsBZR2 from Oryza sativa. ZjBZR2 was a nuclear-localized protein and had transcriptional activation activity. ZjBZR2 was predominantly expressed in roots, stems, and lamina joints, and could be significantly induced by BR treatment and osmotic stresses including PEG and salinity. ZjBZR2-overexpressing rice lines increased leaf angle compared with wild-type plants. Furthermore, overexpression of ZjBZR2 enhanced osmotic stress (PEG and salt) tolerance which is associated with the upregulation of stress-responsive and ROS-scavenging genes. These findings provide the first functional characterization of ZjBZR2 in rice and offer excellent genetic resources for the improvement of turfgrass cultivars.

Low nitrogen (LN) availability is a major constraint limiting plant vegetative growth and reproductive development. To investigate the physiological and molecular mechanisms underlying LN stress in tall fescue (Festuca arundinacea), a comprehensive analysis of phenotypic, physiological, and transcriptional responses was conducted. The results showed that LN stress significantly reduced shoot height, tiller number, leaf length, and shoot biomass. In addition, root system architecture was markedly altered, with increased total root length but decreased root number and root volume. Physiological assays revealed that total chlorophyll content, photochemical efficiency, and net photosynthetic rate were significantly reduced. Concurrently, nitrate reductase activity, NO₃⁻ concentration, and N content were significantly reduced, while soluble sugar content was significantly enhanced. Transcriptomic analysis identified a total of 1185 differential expression genes (585 upregulated and 600 downregulated), with significant changes in genes involved in N transport, N assimilation, glycolysis, and the tricarboxylic acid cycle. In addition, 27 transcription factor genes across seven distinct families were significantly differentially expressed. Three bHLH transcription factors, FaIRO2, FabHLH69, and FabHLH062, were identified as candidate regulators of the LN response in tall fescue based on their expression patterns under LN stress. Collectively, this study provides integrated physiological and transcriptional insights into tall fescue responses to LN stress and highlights potential target genes for genetic improvement of perennial forage and turf grasses with high N use efficiency.