Paspalum Vaginatum Research Articles

Posphoproteomics profiling reveals the regulatory role of a phosphorylated protein PvFBA1 in cadmium tolerance in seashore paspalum

Seashore paspalum (Paspalum vaginatum) is a warm-season and perennial turfgrass and is known for its cadmium (Cd)-stress tolerance. Here, a Phosphoproteomics analysis was performed to examine the key proteins relating to Cd tolerance in seashore paspalum. Fructose 1,6-biphosphate aldolase, PvFBA1, was identified for its phosphorylated state after exposure to Cd stress. Specifically, the phosphorylation of PvFBA1 was enhanced in several metabolic pathways, including pentose phosphate pathway (PPP), carbon fixation and biosynthesis of amino acids under Cd stress. By transforming PvFBA1 into Arabidopsis, the PvFBA1-OE plants exhibited longer roots, greater FBA activity and higher soluble sugar content than WT under 100µM CdCl2 treatment. By expressing the PvFBA1 in yeast, a serine 50 phosphorylation site was identified as functional site. By microscale thermophoresis experiment, we indicted that PvFBA1can bind Cd directly enhancing its phosphorylation level to alleviate the damage of Cd. This finding may provide new insights into the molecular mechanisms of plants Cd tolerance.

Root-sourced H2O2 is essential for maintaining jasmonic acid and Na+/K+ homeostasis to delay leaf senescence during salt stress in Paspalum vaginatum

Improving salt tolerance and mitigating senescence in the presence of high salinity are crucial for sustaining agricultural productivity. Previous research has demonstrated that hydrogen peroxide (H2O2), specifically H2O2 derived from roots and mediated by the respiratory burst oxidase homolog (NADPH), plays a significant role in regulating ion and plant hormone homeostasis in glycophytic plants, such as Arabidopsis. However, the extent to which root-derived H2O2 fulfils similar functions in halophytic plants remains uncertain. Therefore, our study aimed to explore the potential contribution of root-sourced H2O2 in delaying leaf senescence induced by high salinity, utilizing seashore paspalum as a model halophytic plant. The application of the NADPH-oxidase inhibitor DPI, coupled with a series of leaf senescence analyses, we revealed that root-derived H2O2 significantly retards salt-induced leaf senescence. Furthermore, through the application of hormone analysis, lipidomics, ionomics, Non-invasive Micro-test Technology (NMT), and transcriptomics, we established that NADPH-dependent H2O2 induced by salt stress in the roots was indispensable for maintaining the balance of the aging hormone, jasmonic acid (JA), and sodium ion homeostasis within this halophytic plant. Finally, by utilizing AtrbohD Arabidopsis mutants and virus-induced gene silencing (VIGs) in Paspalum vaginatum, we demonstrated the pivotal role played by root-sourced H2O2 in upholding JA homeostasis and regulating JA-triggered leaf senescence in P. vaginatum. This study offers novel insights into the mechanisms that govern plant leaf senescence and its response to salinity-induced stress.

Chloroplast-localized PvBASS2 regulates salt tolerance in the C4 plant seashore paspalum.

SODIUM SYMPORTER FAMILY PROTEIN 2 (BASS2) is localized within chloroplast membranes, facilitating the translocation of pyruvate and Na+ from the cytosol to the plastid, where pyruvate supports isopentenyl diphosphate (IPP) synthesis via the methylerythritol phosphate pathway in C3 plants. Nevertheless, the biological function of BASS2 in C4 plants has not been well defined. This study unveils a previously unidentified role of PvBASS2 in Na+ and pyruvate transport in seashore paspalum (Paspalum vaginatum), a halophytic C4 grass, indicating a specific cellular function within this plant species. Data showed that overexpression of PvBASS2 in seashore paspalum attenuated salt tolerance, whereas its RNAi lines exhibited enhanced salt resistance compared to wild-type plants, suggesting a negative regulatory role of PvBASS2 in seashore paspalum salt tolerance. The constitutive overexpression of PvBASS2 was also found to reduce salt tolerance in Arabidopsis. Further study revealed that PvBASS2 negatively regulates seashore paspalum salt tolerance, possibly due to elevated Na+/K+ ratio, disrupted chloroplast structure, and reduced photosynthetic efficiency following exposure to salinity. Importantly, our subsequent investigations revealed that modulation of PvBASS2 expression in seashore paspalum influenced carbon dioxide assimilation, intermediary metabolites of the tricarboxylic acid cycle, and enzymatic activities under salinity treatment, which in turn led to alterations in free amino acid concentrations. Thus, this study reveals a role for BASS2 in the C4 plant seashore paspalum and enhances our comprehension of salt stress responses in C4 plants.

Low-cost and reliable substrate-based phenotyping platform for screening salt tolerance of cutting propagation-dependent grass, paspalum vaginatum

BackgroundSalt tolerance in plants is defined as their ability to grow and complete their life cycle under saline conditions. Staple crops have limited salt tolerance, but forage grass can survive in large unexploited saline areas of costal or desert land. However, due to the restriction of self-incompatible fertilization in many grass species, vegetative propagation via stem cuttings is the dominant practice; this is incompatible with current methodologies of salt-tolerance phenotyping, which have been developed for germination-based seedling growth. Therefore, the performance of seedlings from cuttings under salt stress is still fuzzy. Moreover, the morphological traits involved in salt tolerance are still mostly unknown, especially under experimental conditions with varying levels of stress.ResultsTo estimate the salt tolerance of cutting propagation-dependent grasses, a reliable and low-cost workflow was established with multiple saline treatments, using Paspalum vaginatum as the material and substrate as medium, where cold stratification and selection of stem segments were the two variables used to control for experimental errors. Average leaf number (ALN) was designated as the best criterion for evaluating ion-accumulated salt tolerance. The reliability of ALN was revealed by the consistent results among four P. vaginatum genotypes, and three warm-season (pearl millet, sweet sorghum, and wild maize) and four cold-season (barley, oat, rye, and ryegrass) forage cultivars. Dynamic curves simulated by sigmoidal mathematical models were well-depicted for the calculation of the key parameter, Salt50. The reliability of the integrated platform was further validated by screening 48 additional recombinants, which were previously generated from a self-fertile mutant of P. vaginatum. The genotypes displaying extreme ALN-based Salt50 also exhibited variations in biomass and ion content, which not only confirmed the reliability of our phenotyping platform but also the representativeness of the aerial ALN trait for salt tolerance.ConclusionsOur phenotyping platform is proved to be compatible with estimations in both germination-based and cutting propagation-dependent seedling tolerance under salt stresses. ALN and its derived parameters are prone to overcome the species barriers when comparing salt tolerance of different species together. The accuracy and reliability of the developed phenotyping platform is expected to benefit breeding programs in saline agriculture.

Patch growth of seashore paspalum (Paspalum vaginatum) treated with inorganic fertilizer and organic biostimulant

Inorganic fertilizers are often used in the United States in golf courses putting green maintenance. We used milled plant biomass on putting greens to test the hypothesis that organic biostimulants used in putting green maintenance can achieve similar results as inorganic fertilizers. Dilapidated putting greens, #4 and #14, with conspicuous patches at the L.E. Ramey Golf Course in Kingsville, TX, were selected for the study. Each green was split in half with one half selected for treatment and the other half maintained as the control and treated with NPK. Milled Medicago sativa L. mixed with milled high auxin-containing plant species in a ratio of 10:1 was used to test the hypothesis. The mixture was applied in the bio-treated section of the two greens while the golf course management continued to apply inorganic fertilizers on the control section of the study greens. Patch count on the greens was conducted once a week utilizing a randomly placed 1 by 1 m quadrant. Also, soil moisture measurement was taken twice a week on the greens to understand soil moisture retention due to the treatments. Patch count indicates that the bio-treated sections grew and filled significantly faster than the sections treated with inorganic fertilizers. Regression analysis of data collected between July 13th and July 27th indicates a strong linear biostimulant/patch growth relationship (R2 = 0.75 and 0.92) on Greens #4 and #14 respectively. Also, soil moisture data indicates significantly higher moisture retention on the putting green sections treated with the biostimulant.

Waste-green infrastructure nexus: Green roof promotion by digestate and digestate biochar from food waste

Waste—Green Infrastructure Nexus is crucial to mitigate carbon emissions in waste disposal and promote eco-functions of green infrastructure in a circular bio-economy. Our purpose is to verify the feasibility of the nexus via “food waste anaerobic digestion — digestate/digestate biochar — green roof promotion”. The results found that food waste digestate and digestate biochar significantly promoted green roof plant growth, evapotranspiration, rainwater retention, runoff reduction, and prevention of nutrient leaching. Digestate treatments were better than digestate biochar for the green roof promotion. The promotion ranked consistently with 20 % digestate > 10 % digestate > 20 % digestate biochar > 10 % digestate biochar > control in stolon growth, leaf emergence, branching of Paspalum vaginatum, green roof establishment, rainwater retention, runoff reduction, and the leaching of nitrogen, phosphorus, potassium. This study demonstrated that food waste could be regenerated to promote urban green infrastructure to form a circular bio-economy by the Waste—Green Infrastructure Nexus.

A calmodulin-like protein PvCML9 negatively regulates salt tolerance

Calmodulin-like proteins (CMLs) are unique Ca2+ sensors and play crucial roles in response to abiotic stress in plants. A salt-repressed PvCML9 from halophyte seashore paspalum (Paspalum vaginatum O. Swartz) was identified. PvCML9 was localized in the cytoplasm and nucleus and highly expressed in roots and stems. Overexpression of PvCML9 led to reduced salt tolerance in rice and seashore paspalum, whereas downregulating expression of PvCML9 showed increased salt tolerance in seashore paspalum as compared with the wild type (WT), indicating that PvCML9 regulated salt tolerance negatively. Na+ and K+ homeostasis was altered by PvCML9 expression. Lower level of Na+/K+ ratio in roots and shoots was maintained in PvCML9-RNAi lines compared with WT under salt stress, but higher level in overexpression lines. Moreover, higher levels of SOD and CAT activities and proline accumulation were observed in PvCML9-RNAi lines compared with WT under salt stress, but lower levels in overexpression lines, which altered ROS homeostasis. Based on the above data, mutation of its homolog gene OsCML9 in rice by CRISPR/Cas9 was performed. The mutant had enhanced salt tolerance without affecting rice growth and development, suggesting that OsCML9 gene is an ideal target gene to generate salt tolerant cultivars by genome editing in the future.

Dose-dependent physiological effects of UV-C radiation on seashore paspalum

Positive effects of ultraviolet-C (UV–C) radiation on plants have been documented in previous literature with a focus on extending shelf life and reducing disease development. However, its effect on plant growth habits has been scarcely explored, especially in turfgrass where a compact shoot growth is a desirable trait. Seashore paspalum (Paspalum vaginatum) is a warm-season perennial turfgrass requiring low fertilizer and pesticide inputs. This project aimed to test the effects of different doses of UV-C radiation on growth and performance of seashore paspalum cv. Seastar. Here, we provide evidence of dose-dependent effects. Lower UV-C doses (6 s and 1 min daily) improved the performance of seashore paspalum, as manifested by higher tiller density, reduced clipping yields, increased chlorophyll level on selected dates as well as enhanced photosynthetic efficiency compared to control. Contrastingly, higher doses (6 min and 30 min daily) resulted in severe damage with 30-min treatment being lethal to seashore paspalum, causing marked declines in all measured parameters. This is the first time that UV-C-induced growth response was reported in turf. Conclusions drawn from this study would shed light into the effects of UV-C radiation on the growth and performance of seashore paspalum and offer exciting potential for the utilization of UV-C at non-lethal dosage in turfgrass management.

Warm‐season turfgrass species genotype‐by‐environment interaction for turfgrass quality under drought

AbstractOne of the biggest challenges the turfgrass industry is currently facing is limitations of available water for irrigation of turfgrass areas. Efforts on breeding for drought resistance have increased over the past several years across the United States. Thus, the objectives of this study were to evaluate the performance of bermudagrass (Cynodon spp. Rich.), St. Augustinegrass (Stenotaphrum secundatum (Walter) Kuntze), seashore paspalum (Paspalum vaginatum Swartz) and zoysiagrass (Zoysia spp. Willd.) breeding lines from five different breeding programs under drought and estimate genetic parameters in order to increase selection efficiency for drought resistance improvement in these breeding programs. The germplasm sources were bermudagrass from Oklahoma State University and University of Georgia (UGA); St. Augustinegrass from North Carolina State University, Texas A&M University System (TAMUS) and University of Florida (UF); zoysiagrass from UF and TAMUS; seashore paspalum from UGA. Field trials were conducted from 2016 to 2019 at research facilities in Citra, FL and Dallas, TX. The response variables evaluated were per cent living ground cover (%GC), and turfgrass quality under normal or non‐drought (TQND) and drought conditions (TQD). The genetic variance was significant for TQND and TQD in bermudagrass, TQD in St. Augustinegrass and all traits in zoysiagrass. The heritability estimates were higher for TQD than for TQND in bermudagrass and St. Augustinegrass. Genetic correlation estimates showed that indirect selection can be effective to select drought‐resistant genotypes. Several genotypes performed better than all commercial cultivars in both St. Augustinegrass and zoysiagrass.

Overexpression of PvWAK3 from seashore paspalum increases salt tolerance in transgenic Arabidopsis via maintenance of ion and ROS homeostasis

Seashore paspalum (Paspalum vaginatum O. Swartz) is an important warm-season turfgrass species with extreme salt tolerance, but investigations on its salt tolerance mechanism are limited. A salt induced PvWAK3 from halophyte seashore paspalum was identified in this study. Overexpression of PvWAK3 in Arabidopsis led to increased salt tolerance. Transgenic plants had higher levels of seed germination rate, root length, number of lateral roots, shoot weight, survival rate, Fv/Fm, ETR, and NPQ compared with the wild type (WT) under salt stress. Na+ content was increased and K+ content was decreased after salinity treatment, with lower levels of Na+ and Na+/K+ ratio but higher level of K+ in transgenic plants than in WT under salt stress. The improved maintenance of Na+ and K+ homeostasis was associated with the higher transcript levels of K + -Uptake Permease 4 (KUP4), Potassium Transport 2/3 (AKT2), Salt Overly Sensitive 1 (SOS1) and High-Affinity K + Transporter 5 (HAK5) in transgenic plants compared with WT. Superoxide dismutase (SOD), catalase (CAT) and ascorbate-peroxidase (APX) activities, proline concentration, and P5CS1 transcript were increased after salinity treatment, with higher levels in transgenic lines compared with WT, which led to reduced accumulation of O2·− and H2O2 under salt stress. It is suggested that PvWAK3 regulates salt tolerance positively, which is associated with promoted Na+ and K+ homeostasis, activated antioxidant enzymes, and proline biosynthesis under salt stress.

The specialized parenchyma in the Paspalum vaginatum stem as a strategy to water deficit and salinity

Abstract Paspalum vaginatumis a halophyte plant found along coastal plains, which presents cells with atypically thickened walls in the ground tissue of the stem stele (GTS). The tolerance of this species to high salinity and water stress led us to investigate whether the thickened walls could be related to adaptation to the coastal environment. Thus, we sought to characterize the cell walls that make up the GTS ofP. vaginatum, describe the tissue, and verify the influence of the water resource on the thickening of the walls and a possible function related to the reserve of substances. For this, analyses were carried out using light microscopy, transmission electronic microscopy, and histochemical tests. The samples were collected in the field during low and high rainfall periods.Paspalum vaginatumGTS cells have pectic-cellulosic primary walls. In most basal internodes, these cells presented thickened walls formed in two to three layers. Statistical analysis demonstrated that the level of precipitation is directly related to cell wall thickening. The data suggest the storage and mobilization of substances through the cell wall of the specialized parenchyma.

Green roof heat transfer coefficient measurement and impact of plant species and moisture

Green roofs attract wide attention for building energy conservation and sustainable development. However, the heat transfer coefficient of green roofs is not well defined. In this study, we developed a non-contact steady-state method for green roof heat transfer coefficient measurement. The apparatus required 16 min to reach the steady state, with a measurement variation of 2.84 ∼ 3.47 %. The impacts of plant species and substrate moisture on the heat transfer coefficient of green roofs were defined. The green roof with Sedum lineare (a CAM plant) performed the widest variation of heat transfer coefficient, from 2.847 W/m2 K (at the wilting point) to 5.401 W/m2 K (at the field capacity). The green roof with Paspalum vaginatum (a C4 plant) performed the least variation of heat transfer coefficient, with only 2.807 ∼ 3.069 W/m2 K from the wilting point to the field capacity. The green roof with Festuca arundinacea showed mediate variation in heat transfer coefficient, with 2.849 ∼ 4,372 W/m2 K. This work provides a method to determine green roof heat transfer coefficient and defined dynamics of heat transfer coefficients in three different green roofs, which is crucial to further elucidate the green roof heat transfer mechanism and the impact factors.

Improving the Treatment of Saline Wastewater from Shrimp Farms Using Hybrid Constructed Wetlands Models toward Sustainable Development

This study investigated a feasible model for treating actual shrimp farm wastewater at a pilot scale that could be applied to farms in the Mekong Delta area. The research was carried out using a hybrid constructed wetlands (HCWs) model, which included a floating constructed wetland (FCW, total area of 1,500 m2) and a horizontal sub-surface constructed wetland (HSCW, total area of 400 m2). The HCWs were cultivated with native plants including: Scirpus littoralis Schrab, Cyperus alternifolius, and Paspalum vaginatum. These plants are all adapted to the high salinity levels of shrimp farm wastewater. The system was operated for 30 days to treat shrimp farm effluent. Results indicated that the model effectively removed organic matter and nitrogen compounds from the wastewater. The treated wastewater had low concentrations of COD (10.0-15.4 mg/L), BOD5 (7.1-12.5 mg/L), NH4+-N (0.04-1.11 mg/L), and TN (0.17-1.83 mg/L), which met the reliable conditions for reuse or safety requirements for discharge to aquatic systems. The findings of this study have significant implications for the sustainable management of shrimp farm wastewater in the Mekong Delta area. The HCWs model is a feasible and effective way to treat this type of wastewater, and it could be adapted to other regions facing similar challenges.

Comparative genomics and transcriptome analysis reveals potential pathogenic mechanisms of Microdochium paspali on seashore paspalum.

The sparse leaf patch of seashore paspalum (Paspalum vaginatum Sw.) caused by Microdochium paspali seriously impacts the landscape value of turf and poses a challenge to the maintenance and management of golf courses. Little is known about the genome of M. paspali or the potential genes underlying pathogenicity. In this study, we present a high-quality genome assembly of M. paspali with 14 contigs using the Nanopore and Illumina platform. The M. paspali genome is roughly 37.32 Mb in size and contains 10,365 putative protein-coding genes. These encompass a total of 3,830 pathogen-host interactions (PHI) genes, 481 carbohydrate-active enzymes (CAZymes) coding genes, 105 effectors, and 50 secondary metabolite biosynthetic gene clusters (SMGCs) predicted to be associated with pathogenicity. Comparative genomic analysis suggests M. paspali has 672 species-specific genes (SSGs) compared to two previously sequenced non-pathogenic Microdochium species, including 24 species-specific gene clusters (SSGCs). Comparative transcriptomic analyses reveal that 739 PHIs, 198 CAZymes, 40 effectors, 21 SMGCs, 213 SSGs, and 4 SSGCs were significantly up-regulated during the process of infection. In conclusion, the study enriches the genomic resources of Microdochium species and provides a valuable resource to characterize the pathogenic mechanisms of M. paspali.

Establishment of warm‐season turfgrasses in a Mediterranean transition zone under simulated waterlogging

AbstractThe Mediterranean region is expected to experience increased extreme precipitation events with the risk of inland flooding because of climate change. This may adversely affect the establishment of warm‐season turf species, usually selected for low water consumption. A simulated waterlogging experiment was conducted at the University of Padua in northeastern Italy during the summers of 2017 and 2018. Four bermudagrass (Cynodon spp.) cultivars (La Paloma, Transcontinental, SR 9554, and Jackpot), ‘Pure Dynasty’ seashore paspalum (Paspalum vaginatum Swartz), and ‘SWI 2000’ buffalograss [Buchloë dactyloides (Nutt.) Engelm.] were compared under waterlogging conditions. The response of the three warm‐season species to four waterlogging events during establishment at two different seeding rates was investigated. The number of seedlings, percentage green coverage, and NDVI were measured. At the end of the experimental periods, the dry weights of the above‐ground biomass and roots were also determined. All the cultivars tested demonstrated high tolerance to waterlogging in the early stages of establishment. Moreover, they produced a significantly higher number of seedlings per unit area when sown at the higher seeding rate.

Turfgrass Use on US Golf Courses

Golf facilities account for 2.3 million acres in the United States. Numerous turfgrass species are managed on US golf facilities, but golf facilities may change turfgrasses depending on numerous variables. Knowing which turfgrasses are grown and how turfgrass selection has changed would provide important information to scientists, turfgrass managers, and policymakers. The objective of this survey was to measure turfgrass use on US golf facilities in 2021 and to determine whether changes in turfgrass selection have occurred since 2005. A survey was developed and distributed via e-mail to 13,938 US golf facilities, with 1861 responding. From 2005 to 2021, the total projected area of maintained turfgrass on US golf facilities decreased by 14.2%, which was likely a result of course closures and maintenance operations. Nationally, bermudagrass (Cynodon sp.) and Kentucky bluegrass (Poa pratensis) remained the most common warm- and cool-season turfgrasses, respectively. The area of winter-overseeded turfgrass declined by 60% between 2005 and 2021. The percentage of golf facilities that used zoysiagrass (Zoysia sp.) and seashore paspalum (Paspalum vaginatum) increased depending on region and specific playing surface, albeit a pragmatically minor increase. In general, turfgrass selection on golf facilities in northern climates did not change, whereas turfgrass selection in southern climates favored a change from cool- to warm-season species, depending on the playing surface. Whether in historically cool-season or warm-season regions, it appears that many golf facilities are exploring alternatives to their traditional turfgrass species.

Microorganisms and Biochar Improve the Remediation Efficiency of Paspalum vaginatum and Pennisetum alopecuroides on Cadmium-Contaminated Soil.

Phytoremediation can help remediate potential toxic elements (PTE) in soil. Microorganisms and soil amendments are effective means to improve the efficiency of phytoremediation. This study selected three microorganisms that may promote phytoremediation, including bacteria (Ceratobasidium), fungi (Pseudomonas mendocina), and arbuscular-mycorrhizal fungi (AMF, Funneliformis caledonium). The effects of single or mixed inoculation of three microorganisms on the phytoremediation efficiency of Paspalum vaginatum and Pennisetum alopecuroides were tested under three different degrees of cadmium-contaminated soil (low 10 mg/kg, medium 50 mg/kg, and high 100 mg/kg). The results showed that single inoculation of AMF or Pseudomonas mendocina could significantly increase the biomass of two plants under three different degrees of cadmium-contaminated soil, and the growth-promoting effect of AMF was better than Pseudomonas mendocina. However, simultaneous inoculation of these two microorganisms did not show a better effect than the inoculation of one. Inoculation of Ceratobasidium reduced the biomass of the two plants under high concentrations of cadmium-contaminated soil. Among all treatments, the remediation ability of the two plants was the strongest when inoculated with AMF alone. On this basis, this study explored the effect of AMF combined with corn-straw-biochar on the phytoremediation efficiency of Paspalum vaginatum and Pennisetum alopecuroides. The results showed that biochar could affect plant biomass and Cd concentration in plants by reducing Cd concentration in soil. The combined use of biochar and AMF increased the biomass of Paspalum vaginatum by 8.9-48.6% and the biomass of Pennisetum alopecuroides by 8.04-32.92%. Compared with the single use of AMF or biochar, the combination of the two is better, which greatly improves the efficiency of phytoremediation.

Lipid metabolism and antioxidant system contribute to salinity tolerance in halophytic grass seashore paspalum in a tissue-specific manner

Soil salinization is a growing issue that limits agriculture globally. Understanding the mechanism underlying salt tolerance in halophytic grasses can provide new insights into engineering plant salinity tolerance in glycophytic plants. Seashore paspalum (Paspalum vaginatum Sw.) is a halophytic turfgrass and genomic model system for salt tolerance research in cereals and other grasses. However, the salt tolerance mechanism of this grass largely unknown. To explore the correlation between Na+ accumulation and salt tolerance in different tissues, we utilized two P. vaginatum accessions that exhibit contrasting tolerance to salinity. To accomplish this, we employed various analytical techniques including ICP-MS-based ion analysis, lipidomic profiling analysis, enzyme assays, and integrated transcriptomic and metabolomic analysis. Under high salinity, salt-tolerant P. vaginatum plants exhibited better growth and Na+ uptake compared to salt-sensitive plants. Salt-tolerant plants accumulated heightened Na+ accumulation in their roots, leading to increased production of root-sourced H2O2, which in turn activated the antioxidant systems. In salt-tolerant plants, metabolome profiling revealed tissue-specific metabolic changes, with increased amino acids, phenolic acids, and polyols in roots, and increased amino acids, flavonoids, and alkaloids in leaves. High salinity induced lipidome adaptation in roots, enhancing lipid metabolism in salt-tolerant plants. Moreover, through integrated analysis, the importance of amino acid metabolism in conferring salt tolerance was highlighted. This study significantly enhances our current understanding of salt-tolerant mechanisms in halophyte grass, thereby offering valuable insights for breeding and genetically engineering salt tolerance in glycophytic plants.

Use of a Dielectric Sensor for Salinity Determination on an Extensive Green Roof Substrate.

The irrigation of extensive green roofs with recycled or saline water could contribute to the conservation of valuable drinking water supplies. In such cases, the continuous monitoring of substrate electrical conductivity (ECsw) is of immense importance for the sustainable growth of the plants growing on the green roof. The present study aimed to estimate the ECsw (pore water EC) of an extensive green roof substrate in lysimeters with the use of the WET-2 dielectric sensor. Half of the 48 lysimeters that simulated extensive green roofs had a substrate depth of 7.5 cm, while the other half had a 15 cm substrate depth. The warm season turfgrass Paspalum vaginatum 'Platinum TE' was established at the lysimeters, and during the summer period, it was irrigated every two days at a rate of 14 mm with NaCl solutions of various electrical conductivities (ECi): (a) 3 dS m-1, (b) 6 dS m-1, and (c) 12 dS m-1, while potable water of 0.3 dS m-1 ECi served as the control. The relation between bulk electrical conductivity, σb, and bulk dielectric permittivity, εb, of the substrate was observed to be linear for all ECi levels up to σb values of 2-2.5 dS m-1. The ECsw was predicted by employing the salinity index method which was modified to be applied to the particular case of a green roof substrate. Knowing the salinity index and organic portion (%, v/v) for a given green roof substrate, we could calculate the ECsw. It was found that the use of the salinity index method predicts reliably the ECsw up to 10-11 dS m-1, while the method overestimates ECsw at very low levels of electrical conductivity.

Spraying Zinc Sulfate to Reveal the Mechanism through the Glutathione Metabolic Pathway Regulates the Cadmium Tolerance of Seashore Paspalum (Paspalum vaginatum Swartz).

Cadmium (Cd) is considered to be one of the most toxic metals, causing serious harm to plants' growth and humans' health. Therefore, it is necessary to study simple, practical, and environmentally friendly methods to reduce its toxicity. Until now, people have applied zinc sulfate to improve the Cd tolerance of plants. However, related studies have mainly focused on physiological and biochemical aspects, with a lack of in-depth molecular mechanism research. In this study, we sprayed high (40 mM) and low (2.5 mM) concentrations of zinc sulfate on seashore paspalum (Paspalum vaginatum Swartz) plants under 0.5 mM Cd stress. Transcriptome sequencing and physiological indicators were used to reveal the mechanism of Cd tolerance. Compared with the control treatment, we found that zinc sulfate decreased the content of Cd2+ by 57.03-73.39%, and that the transfer coefficient of Cd decreased by 58.91-75.25% in different parts of plants. In addition, our results indicate that the antioxidant capacity of plants was improved, with marked increases in the glutathione content and the activity levels of glutathione reductase (GR), glutathione S-transferase (GST), and other enzymes. Transcriptome sequencing showed that the differentially expressed genes in both the 0.5 Zn and 40 Zn treatments were mainly genes encoding GST. This study suggests that genes encoding GST in the glutathione pathway may play an important role in regulating the Cd tolerance of seashore paspalum. Furthermore, the present study provides a theoretical reference for the regulation mechanism caused by zinc sulfate spraying to improve plants' Cd tolerance.