Urban green spaces serve as critical but highly heterogeneous components of carbon (C) sinks in urban ecosystems, yet substantial uncertainty persists regarding soil organic carbon (SOC) sequestration and stabilization across different species. This study examined the effects of four common turfgrass species (zoysia grass, bluegrass, tall fescue, and bentgrass) on SOC pool distribution and stability in surface (0–10 cm) and subsurface (10–20 cm) soil following eight years of cultivation. Soil organic matter was fractionated into particulate organic matter (POM) and mineral-associated organic matter (MAOM), with chemical composition analyzed via solid-state 13C-NMR. All species increased SOC content, though the magnitude of enhancement varied 2.4-fold. Zoysia and tall fescue achieved the highest gains, significantly outperforming bentgrass. While MAOM fractions were all significantly elevated, only zoysia grass enriched both POM and MAOM, with its recalcitrant alkyl-C compounds enhancing chemical stability. Soil under tall fescue exhibited higher microbial biomass carbon content, along with significantly greater surface soil respiration compared to the control. These differences in microbial activity and carbon pool distribution drove SOC stabilization and decomposition. For urban carbon management, we recommend prioritizing zoysia grass for long-term carbon stabilization and tall fescue for maximizing total carbon stocks, while noting that management-sensitive species like bentgrass may provide unreliable C-sink functions.

Type-B Arabidopsis Response Regulators (ARRs) are essential transcription factors in cytokinin signaling pathway, regulating plant growth, development, and stress responses. However, the type-B ARRs gene family has not been fully characterized in the model legume Medicago truncatula. Here, we systematically identified and functionally analyzed 15 type-B MtARR genes distributed across six chromosomes of the M. truncatula genome. Phylogenetic analysis classified these genes into four distinct clades, with all members containing conserved response regulator and MYB-like DNA-binding domains. Comprehensive promoter analysis identified abundant cis-acting elements associated with abiotic stress responses and developmental processes, suggesting complex regulatory networks. Expression profiling across different tissues demonstrated widespread MtARR activity in various tissues, with distinct induction patterns under drought, salt, and cold stress. Notably, MtARR4/10 exhibited coordinated upregulation across multiple stresses, while MtARR15 displayed an opposite response. Hormone treatment experiments revealed differential responses to ABA, MeJA, SA, IAA, ETH, and 6-BA, indicating multifaceted roles in phytohormone signaling networks. Functional validation through heterologous expression in yeast confirmed that MtARR7/10 enhance stress tolerance, while MtARR15 reduces it. Transcriptional autoactivation assays verified the transcription factor activity of MtARR10, with both N-terminal domains contributing to autoactivation. Collinearity analysis revealed four gene pairs involved in duplication events, with Ka/Ks ratios below 1.0 indicating purifying selection pressure. These findings provide the first comprehensive characterization of the type-B MtARR gene family and establish a foundation for understanding their roles in legume stress adaptation and hormone signaling, with potential applications for improving stress tolerance in forage crops.

Sports turf, the foundation for athletic activities, faces the risk of degradation because of the influence of global climate change and intensive usage. This degradation compromises sports safety and event quality. Stitched hybrid turf technology (stitched technology) is an emerging, long-term solution. However, the inadequate understanding and disputes among users regarding its technical characteristics cause limited exploitation of technical advantages and increased application costs. In this paper, Chinese and international research advances and limitations were systematically analysed, and the effects of stitched technology on turf stability, sports performance, growth status, and soil water and nutrient dynamics were quantified. Stitched technology significantly enhanced the shear strength, tensile strength, and soil compactness by 18.1%, 18.3%, and 34.4%, respectively. In terms of sports performance, stitched technology significantly increased pivoting friction by 18.4% and decreased the ball bounce rate by 2.9%. However, sports performance may exceed acceptable thresholds under heavy traffic. Moreover, the use of stitched technology had a significant effect on turf coverage (6.3%), root growth (41.9%), stable infiltration rate (55.1%), and soil nutrients (25.1%). Linear regression revealed that turf stability and sports performance correlated more closely with stitched depth, whereas turf coverage and root growth correlated significantly with density and depth, respectively. Future efforts should focus on the development of eco-friendly fibres, the standardization of parameters, long-term performance monitoring, and the establishment of intelligent assessment systems. This review provides new ideas and directions for the improvement, development, and application of stitched hybrid turf technology in sports pitches and public open green spaces.

IntroductionThe roof structures of professional enclosed stadiums often cause shading problems on the turf, posing a major challenge to maintaining turf quality and efficient management. Artificial lighting has been applied to address this issue, particularly light-emitting diode (LED). MethodsTo evaluate the efficacy of LED with a specific wavelength in alleviating the adverse effects of shade stress on turfgrasses, we conducted a systematic and multi-dimensional assessment of Seashore paspalum (Paspalum vaginatum Sw.) and Zoysia japonica (Zoysia japonica Steud.) turf under three light conditions: natural lighting, shading, and LED, within a stadium. ResultsThe results demonstrated that LED effectively alleviated shade-induced light limitation. It maintained turf normalized difference vegetation index (NDVI) and chlorophyll content at levels comparable to those under natural light. Furthermore, LED treatment improved physiological responses associated with shade stress, as indicated by enhanced cell membrane stability, reduced membrane lipid peroxidation, and altered antioxidant-related responses, including increased superoxide dismutase (SOD) activity and dynamic changes in peroxidase (POD) activity. Regarding root morphology, LED treatment reduced the shade-induced increases in specific root length (SRL) and specific root surface area (SRA), suggesting a modification of shade-induced root morphological responses. Principal component analysis (PCA) revealed distinct multivariate response patterns associated with different light environments. Correlation analysis further indicated significant associations among NDVI, chlorophyll content, and antioxidant-related traits across different light environments. These associations suggested that turf performance under LED lighting was related to concurrent variation in chlorophyll content and antioxidant-related traits. DiscussionIn conclusion, applying LED lighting can effectively improve turf recovery-related traits and physiological status through improvements in canopy characteristics, chlorophyll status, antioxidant-related responses, and root morphological traits. This study demonstrated under a real stadium environment that specific LED lighting can serve as an effective supplemental light source for improving turf performance in shaded areas, providing practical guidance for stadium turf management.

Zoysia japonica (Zoysia japonica Steud.) is a perennial warm-season grass widely used for soil and water conservation due to its extensive root system and resilience in lands, which has a huge potential in enhancing carbon sinks, restoring degraded ecosystems, and improving the living environment. However, Z. japonica will lose color and go into withering prematurely in late fall and winter compared with cool-season grass in the transition zone and the northern regions, which limits the application of Z. japonica. In this study, we successfully cultivated a “G” single-base deletion mutant of ZjSGR (STAY-GREEN) in Z. japonica (sgr-mutant) by CRISPR/Cas9 transient expression without exogenous genes. Based on the experiments of the sgr-mutant and the wild-type plant (WT-plant) under dark and low temperature stresses, the study demonstrates that CRISPR/Cas9-mediated novel single-base deletion of ZjSGR in Z. japonica exhibits not only prolonged chlorophyll retention but also superior stress tolerance under both dark and low temperature stress treatments. The mechanism of the improved stress tolerance of the sgr-mutant includes the accumulation of chlorophyll and carotenoid, providing a foundational buffer against oxidative damage, and a flexible regulation of key antioxidant enzymes in an energy-efficient way with a lower transcriptional burden compared to the WT-plant. Therefore, our study demonstrates that SGR plays a vital role in both leaf color and stress tolerance in grass, providing a new breeding strategy for developing green-persistence, stress-tolerance and low-maintenance grass applications.

Light quality regulates plant carbon assimilation and partitioning, but how turfgrass coordinates photosynthetic carbon input with leaf carbon-fraction formation remains unclear. We examined tall fescue (Festuca arundinacea) under white, red, blue, green, and red–blue light, integrating growth, photosynthetic, carbon-fraction, transcriptomic, and metabolomic analyses. Blue light showed high photosynthetic carbon assimilation and relatively high whole-plant carbon accumulation, but this enhancement was not accompanied by corresponding increases in leaf non-structural carbon or in cellulose, hemicellulose, and lignin concentrations. Red light was associated with relatively high turf quality and greater accumulation of structure-related fractions, especially hemicellulose and lignin. Red–blue light showed the highest sucrose content and a reduced SC/NSC ratio, mainly associated with lower structural carbon accumulation rather than a balanced carbon-fraction status. Green light limited photosynthetic performance and overall growth. Multi-omics analyses identified UDP-glucose-related sugar metabolism as a key link between sucrose cleavage, nucleotide-sugar supply, and cell wall precursor formation. Red light showed enhanced responses in this pathway toward structural precursor formation, whereas red–blue light was mainly associated with active upstream carbon supply; blue and green light showed limited downstream structural precursor responses. These findings provide physiological and molecular evidence for light-quality-dependent carbon partitioning in turfgrass.

Biochar holds considerable potential as a soil amendment for turfgrass, but its effects are highly species-specific. To investigate this, a pot experiment compared two cool-season turfgrasses: tall fescue (Festuca arundinacea) and Kentucky bluegrass (Poa pratensis L.). We measured growth traits, physiological parameters, and plant/ rhizosphere nutrients, analyzing the data via response ratio (RR), correlation analysis, and partial least squares path modeling (PLS-PM). The results revealed contrasting responses. In tall fescue, biochar positively affected plant height, leaf morphology, and chlorophyll content, while reducing aboveground biomass allocation and stress markers like malondialdehyde (MDA). Conversely, Kentucky bluegrass exhibited negative responses in these same traits. Furthermore, although biochar uniformly enhanced multiple rhizosphere soil nutrients (e.g., total C, N, P, K and available fractions) and altered C–N–P stoichiometry in both species, nutrient uptake diverged markedly. Tall fescue showed increased contents for most nutrients in leaves, whereas Kentucky bluegrass displayed negative uptake for several elements, such as Ca, Mg, Zn. Partial least squares path modeling (PLS-PM) further revealed distinct regulatory mechanisms between the two species. In tall fescue, biochar-induced changes in soil nutrient status were strongly linked to plant nutrient status, while physiological responses negatively regulated growth traits. In Kentucky bluegrass, growth was more closely associated with positive physiological adjustment, whereas changes in soil nutrient status were not directly translated into enhanced plant nutrient status or aboveground growth. Overall, tall fescue showed more favorable responses in leaf expansion, chlorophyll-related traits and nutrient acquisition, suggesting that it may be more responsive to biochar-based management than Kentucky bluegrass under the present experimental conditions.

As a widely cultivated perennial turfgrass, seashore paspalum (Paspalum vaginatum Sw.) exhibits plasticity in biomass allocation and stress tolerance phenotypes, with growth-resistance trade-offs critically influenced by light intensity. In this study, four light intensity treatments of 100, 300, 500, and 700 mu mol.m(-2).s(-1) (L100, L300, L500, and L700, respectively) were applied to investigate the mechanisms underlying turf responses to increasing light intensity. Under L500, starch, cellulose, hemicellulose, leaf structural traits, leaf dry weight, ascorbate peroxidase (APX) and peroxidase (POD) activities reached their highest levels, achieving a synergistic enhancement of growth and resistance. In contrast, soluble sugars, malondialdehyde (MDA), root structural traits, and root dry weight peaked under L700. L700 also significantly decreased leaf nitrogen (N) concentration by 52.2 % and increased the carbon-to-nitrogen (C/N) ratio by 51.5 % compared with L100. Principal component analysis identified growth components (turf quality, dry matter accumulation, and morphological structure) and resistance components (antioxidant capacity: APX, CAT, POD, SOD and MDA; leaf anatomical structure: vascular bundle, leaf and xylem thickness). Optimal light treatments for growth and resistance were L700 and L500, respectively. Correlation and structural equation modeling (SEM) revealed that N concentration was negatively correlated with starch, cellulose, SOD, and MDA, while C/N ratio was also negatively correlated with these traits. Further analysis identified three pathways through which light intensity mediates growth-resistance trade-offs: photosynthetic capacity (net photosynthetic rate, transpiration rate, stomatal conductance), carbohydrate metabolism (starch, soluble sugars, cellulose), and carbon-nitrogen relationship (N concentration and C/N ratio). Escalating light intensity enhanced resistance via photosynthesis, carbohydrate metabolism, and C/N regulation, whereas the carbon-nitrogen relationship could constrain growth. Overall, moderate light intensity (L500) maximized photosynthetic capacity and carbohydrate metabolism, achieving synergistic improvement of growth and resistance, while high light intensity (L700) disrupted C/N homeostasis, leading to reduced stress tolerance. These findings provide a theoretical basis for optimizing light management in seashore paspalum turf.

Cytokinin oxidases/dehydrogenases (CKXs) are key enzymes regulating cytokinin homeostasis and plant development, yet their transcriptional regulation remains poorly characterized, especially in legumes. Here, we combined promoter truncation, transgenic analysis, and DNA-protein interaction assays to dissect the regulatory mechanism of MtCKX1 in Medicago truncatula. A 1789 bp promoter region was identified, harboring multiple cis-elements responsive to hormones (CK, IAA, ABA, JA, GA) and stresses. Truncation analysis and GUS assay revealed a core cytokinin-responsive region (− 1789 to − 1125 bp), with one construct (CKXp2) functioning as a strong, specific cytokinin-inducible promoter throughout plant development. Using DNA pull-down mass spectrometry, yeast one-hybrid assays, and dual-luciferase reporter, we further demonstrated that C2H2 and GRF transcription factors directly bind to the MtCKX1 promoter. These findings provide novel insights into the transcriptional regulation of CKX genes and highlight the potential of engineered promoters for precise spatiotemporal control of gene expression in biotechnology applications.

Light quality is widely recognized as a crucial environmental factor mediating the trade-off between plant growth and defense, with important implications for turfgrass production. However, the regulatory mechanism of the growth and physiology of perennial ryegrass to light quality, as well as its growth-defense trade-off remains unclear. Therefore, this study investigated how different light quality combinations affected turf quality, morphogenesis, photosynthetic characteristics, and metabolic processes in perennial ryegrass, using red-blue light (BR) as the control and red-blue light supplemented with far-red (BRFR), UV-A (BRUVA), and green (BRG) light as treatment conditions. The results showed that BRFR and BRG treatments could promote leaf expansion, aboveground biomass accumulation, and turf quality improvement, while increasing the IAA content and decreasing the ABA level, promoting a growth-oriented strategy in perennial ryegrass. In contrast, the BRUVA treatment suppressed belowground growth but increased leaf thickness, total nitrogen content, and ABA concentration, while reducing the C/N ratio and enhancing antioxidant responses, thereby inducing a stress-response-oriented physiological state in perennial ryegrass. Furthermore, carbohydrates were positively associated with growth, whereas hormones were negatively associated with defense-related physiological responses. Moreover, the fluctuations in hormonal levels and carbohydrate metabolism may be related to the carbon-nitrogen balance. In summary, our findings uncover the intrinsic processes that mediate how perennial ryegrass modulates its growth and physiological status under diverse light environments, thereby facilitating the precision application of light-quality regulation in modern turfgrass agronomic operations.

Abstract Elemental composition influences the dynamic balance between plant growth and community succession, thereby influencing the synergistic recovery of vegetation and soil on exposed slopes. However, existing research lacks a systematic understanding of the dynamic patterns in elemental allocation strategies and multi-element coupling mechanisms during artificial vegetation restoration. This theoretical gap constrains the transition from short-term community reconstruction to long-term functional stability. In this study, we comprehensively investigated the coupling relationships of 30 elemental indices in roots and leaves across five restoration stages (1, 3, 7, 12, and 17 years). We analysed single-element, element-element relationships, and multi-element networks to uncover patterns in elemental allocation and interactions. Restoration duration significantly affected the concentration changes and accumulation rates of N, K, and Zn in both roots and leaves, reflecting functional specialization-driven allocation strategies between organs. Notably, plant element networks showed a critical shift in hubs from root to leaf elements at 7 years, primarily driven by soil organic carbon, total nitrogen, and nitrate nitrogen. Furthermore, soil available potassium and ammonium nitrogen exhibited significantly decreased with network edge density, thereby highlighting their regulatory roles in elemental coordination. In short, restoration age shapes root-leaf elemental accumulation and allocation strategies, while the interaction network architecture between root and leaf elements is predominantly governed by soil nutrient availability. Understanding multi-element coupling mechanisms helps identify stage-specific limiting factors, optimize phased vegetation management, and accelerate functional recovery in degraded ecosystems. Integrating plant elemental dynamics into restoration planning can enhance long-term vegetation stability and resilience, supporting sustainable land rehabilitation.

Saline‒alkali soil is widespread and pose a major constraint to crop production. Nevertheless, as a substantial reserve of cultivable land, their reclamation plays a pivotal role in mitigating land scarcity, safeguarding food security, and promoting sustainable ecological development. With the development of irrigated agriculture, flood irrigation, drip irrigation and other water conservation methods are often used to ameliorate saline‒alkali soils. Nevertheless, an insufficient understanding of the efficacy, limitations, and contextual applicability of these methods when used indiscriminately, may render these interventions ineffective and trigger secondary soil salinization and alkalization processes. We employed a meta-analysis and linear regression to quantify the effects of typical water conservation methods (included various forms of drip and flood irrigation, with or without salinity or drainage) on soil properties (salinity, alkalinity, nutrient) and crop yield in saline–alkali soils across China, and to clarify the relationships among these effects. The results indicated that water conservation methods significantly reduced the soil electrical conductivity (EC, −10.0%), soil salt content (SSC, −65.0%), pH (−4.2%), and sodium adsorption ratio (SAR, −42.3%) while notably increasing the soil nutrient content (73.1%) and crop yield (13.3%). Among these methods, conventional drip irrigation and film-mulched drip irrigation reduced soil salinity and alkalinity and increased crop yield the most. Notably, saline water irrigation exhibited unstable ameliorative effects with potential secondary salinization risks, accompanied by yield suppression. The impoundment method decreased the SSC (−56.4%), pH (−7.3%), establishing a viable pathway for the amelioration of saline–alkali soil. However, the combination of flood irrigation with drainage method had a more positive effect on saline–alkali soils than the combination of drip irrigation with drainage. The results of regression analysis revealed that the reduction of soil salinity and alkalinity by water conservation methods improved soil fertility, thereby enhancing crop yields. This study provides theoretical support for the formulation of site-specific strategies to develop resource-efficient and eco-friendly agriculture.

As droughts become longer and more intense, impacts on terrestrial primary productivity are expected to increase progressively. Yet, some ecosystems appear to acclimate to multiyear drought, with constant or diminishing reductions in productivity as drought duration increases. We quantified the combined effects of drought duration and intensity on aboveground productivity in 74 grasslands and shrublands distributed globally. Ecosystem acclimation with multiyear drought was observed overall, except when droughts were extreme (i.e., ≤1-in-100-year likelihood of occurrence). Productivity losses after four consecutive years of extreme drought increased by ~2.5-fold compared with those of the first year. These results portend a foundational shift in ecosystem behavior if drought duration and intensity increase, from maintenance of reduced functioning over time to progressive and profound losses of productivity when droughts are extreme.

Light intensity, duration, and spectral composition play critical roles in influencing the growth, and establishment quality of plants. However, the effects of continuous light emitting diode (LED) lighting and various light intensities on the morphological development, turf quality, physiological processes, elemental accumulation, and photodamage mechanisms of tall fescue (Festuca arundinacea) remain unclear. Understanding the response mechanisms of the growth and turf quality of tall fescue to different light intensities under continuous LED lighting is crucial for the efficient application of continuous lighting in turfgrass cultivation such as plant factories. In this experiment, normal light period (NL) of 16 (light)/8 (dark) h (300 mu mol center dot m-2 center dot s-1), together with continuous light treatments at different intensities (150 mu mol center dot m-2 center dot s-1, 300 mu mol center dot m-2 center dot s-1, and 450 mu mol center dot m-2 center dot s-1, namely CL150, CL300 and CL450), were conducted to assess the effect of continuous lighting exposure at varying intensities on the morphology, physiological characteristics, and quality traits of tall fescue. The results showed that compared to NL, CL300 significantly enhanced the turf quality of tall fescue, whereas CL450 did not exhibit a significant improvement with increasing light intensity. In the ultrastructure of tall fescue chloroplasts, the number of chloroplasts was higher under CL300 and CL450 treatments, while a significant increase in the number and size of starch granules was observed specifically in CL450. With the increase in continuous light intensity, the degree of photo-oxidation induced by reactive oxygen species (ROS) in the leaves gradually intensified, leading to a substantial accumulation of malondialdehyde (MDA). Moreover, the reduction in mineral element content in the leaves due to increased light intensity further exacerbated the plant's damage under continuous lighting. In summary, CL300 can improve the turf quality of tall fescue while causing less damage to the plants. In addition, it is indicated that the factors including accumulation of carbohydrate, the damage of photooxidation and the reduction of mineral element content in leaves may be the main reasons for the quality decline of tall fescue under excessive continuous light intensities.

As China's cornerstone lucerne production region, Gansu Province plays a pivotal role in sustaining national forage security and livestock systems, yet the climate resilience of this strategic crop remains critically unassessed. Here we present a multi-objective optimization framework integrating process-based modeling and climate change projections under SSP245 and SSP585 scenarios to reconcile lucerne biomass and protein production, irrigation water productivity, and global warming potential from field (GWP-field) trade-offs. We project that lucerne biomass and protein production in Gansu will increase 5.7 %-25.3 % by the 2090 s, but with a 6.0 %-10.1 % decrease in protein concentration, primarily as temperature-affected biomass increases mask the declines in protein concentration. Strategic spatial restructuring of cultivation could achieve synergistic benefits-elevating biomass and protein yield by 1.4 %-2.0 % while simultaneously diminishing irrigation and GWP-field by 1.4 %-3.9 %. The new planting patterns identified 4238-5521 ha of priority expansion in Longzhong and Longdong, where phased cultivar deployment could maximize benefits of production (1.4-2.0 % increase), resource use (3.4-3.9 % decrease), and environmental impact (1.4-1.9 % decrease). However, increasing lucerne production to expand cattle and sheep feeding would result in an additional 17.9-20.0 thousand CO2-eq of emissions due to enteric fermentation and manure management, even taking into account the benefits of restructuring lucerne planting and irrigation saving on GWP. Our findings underscore the imperative of multidimensional optimization in balancing agronomic gains against environmental impacts in cropping systems of arid regions.

BACKGROUND: MYB transcription factors play a crucial regulatory role in plant growth and stress response. The gene EpMYB, obtained from Endocarpon pusillum, a dominant lichen in the Tengger Desert, was transferred to creeping bentgrass to explore its effects on plant growth and response to abiotic stress. RESULTS: Compared to wild-type (WT), transgenic (TG) plants exhibited a faster growth rate, a significantly higher number of leaves per tiller, increased internode length, and longer maximum leaf length. However, some of the leaves were severely twisted. Additionally, the antioxidant enzyme content, lignin content and drought tolerance of the TG plants was significantly enhanced. RNA-seq analysis revealed that differentially expressed genes (DEGs) in the TG-vs-WT were primarily associated with pathways such as photosynthesis, wax biosynthesis, lipid metabolism, and flavonoid biosynthesis. By comparing the TG (Drought treatment)-vs-TG and WT (Drought treatment)-vs-WT groups, numerous DEGs related to growth, development, and stress tolerance were identified, including aldehyde decarbonylase gene(CER1), lignin synthesis gene (HCT), adenylate dimethylallyltransferase gene (IPT), peroxin-10 gene (PEX10), among others. These results suggest that the EpMYB gene enhances the drought tolerance of transgenic creeping bentgrass by regulating photosynthesis, antioxidant enzyme activity, lignin synthesis, wax synthesis, and lipid metabolism. CONCLUSION: These findings suggest that the EpMYB gene functions as a positive regulator of plant growth and development, while also playing a crucial role in the plant’s response to drought stress. Furthermore, this study demonstrates the feasibility of selecting specific functional genes from stress-tolerant microorganisms and applying them to plants to enhance stress resistance.

Zoysiagrass stands out as a crucial native turfgrass due to its exceptional abiotic stress tolerance, extensive adaptability, and high ornamental value. In this study, we generated a high-quality chromosome-level genome assembly of Compadre (COM) zoysiagrass, leveraging PacBio SMRT sequencing and Hi-C scaffolding technologies. The resulting genome assembly (312.42 Mb) is anchored on 20 chromosomes, with a Scaffold N50 of 18.72 Mb. In total, 49,074 genes and 306,768 repeat sequences were annotated in the assembled genome. The first chromosome-scale genome of Zoysia japonica ‘Compadre’ provides a critical genetic resource for cold-tolerant turfgrass breeding through identifying stress-responsive candidate genes. Additionally, we have successfully established a cell nucleus extraction and library construction protocol tailored for zoysiagrass ATAC-seq technology, and a total of 80 low temperature tolerance candidate genes were preliminarily identified via ATAC-seq and RNA-seq profiling, thereby initiating the exploration of turfgrass epigenomics.

Abscisic acid (ABA) is a pivotal phytohormone involved in regulating various aspects of plant growth, development, and responses to environmental stress. The Cytochrome P450 family member ABA 8'-hydroxylase (8'OH-ABA) is proposed to play a central role in the catabolic degradation of ABA. In the present study, the 8'OH-ABA gene from Medicago truncatula was isolated and functionally characterized using transgenic overexpression approaches. Under non-stress conditions, plants overexpressing 8'-OH-ABA displayed notable phenotypic variations compared to wild-type plants, including altered leaf morphology, an extended lifespan, and delayed flowering. Scanning electron microscopy (SEM) analysis revealed a reduction in cell spacing and curvature at the leaf margins, which was attributed to the smaller size of epidermal cells in the stem, ultimately contributing to a slower growth rate. Furthermore, these overexpressing plants exhibited heightened sensitivity to drought stress, an effect closely associated with 8'OH-ABA expression. Transcriptome analysis revealed 3,814 differentially expressed genes (DEGs), with 13 genes enriched in the "abscisic acid-activated signaling pathway" and 29 in the "carotenoid biosynthesis" pathway. Notably, we identified genes directly linked to ABA responses, including the ABA 8'-hydroxylase CYP707A2, the transcription factor gene MYC2, and the cytochrome P450 enzyme CYP78A5, which regulates organ size and leaf development. Collectively, these findings indicated the regulatory role of 8’OH-ABA in plant development and drought stress response, thereby highlighting the importance of ABA signaling in these biological processes.

Background Zoysiagrass is renowned for its drought resistance and serves as an exceptional domestic turfgrass in China. However, the changes in chromatin accessibility during drought in zoysiagrass are not well understood. Methods We assessed the drought tolerance of six ecotypes zoysiagrass varieties based on their growth characteristics and physiological traits under drought conditions. Additionally, we utilized an integrated multi-omics strategy, encompassing whole-genome sequencing (WGS), RNA sequencing (RNA-seq), Assay for Transposase Accessible Chromatin using high-throughput sequencing (ATAC-seq), and RT-qPCR verification experiments, to gain a deeper understanding of the chromatin accessibility patterns linked to gene expression in response to drought stress in zoysiagrass. Results The correlation analysis between proline levels and drought tolerance in zoysiagrass revealed that the variety 'X4' exhibited notably high drought resistance compared to the other six zoysiagrass varieties. The KEGG pathway enrichment analysis revealed that zoysiagrass responded to environmental stress by regulating stress response and antioxidant defense pathways. Notably, the expression levels of genes Zja03G031540 and Zja11G000860 were notably increased in the 'X4' zoysiagrass genotype with improved drought tolerance compared to the 'X1' zoysiagrass genotype with reduced drought tolerance. This study suggested that 63 high-confidence genes related to drought stress and 6 motifs regulating drought responses were unearthed. The study discovered a positive correlation between ATAC-seq peak intensity and gene expression levels. The expression of high-confidence genes was linked to zoysiagrass resistance evaluation and phenotypic traits, implying that these genes are involved in responding to external drought stress. Conclusions This study combined ATAC-seq and RNA-seq technologies for the first time to identify drought-related genes expression in zoysiagrass, elucidating the grass adaptation to environmental stress and the regulatory mechanisms underlying stress responses, and laying the groundwork for zoysiagrass improvement and breeding.