Trans-zeatin Riboside Research Articles

Mitigation of microplastic toxicity in soybean by synthetic bacterial community and arbuscular mycorrhizal fungi interaction: Altering carbohydrate metabolism, hormonal transduction, and genes associated with lipid and protein metabolism

Microplastics (MPs) have become ubiquitous environmental pollutants, eliciting concerns about their negative impacts on terrestrial and agroecosystems. However, employing sustainable remediation approaches holds the potential to mitigate these negative impacts and bolster MPs tolerance in both the seeds and vegetative structures of plants. The current investigation explores the impact of arbuscular mycorrhizal fungi (AMF) and synthetic bacterial community (SynCom) as potential alleviators of MP-induced stress. Results exhibited that co-applied SynCom and AMF, resulted in the highest plant biomass, leaf area, pod per plant, and 100-seed weight under control (no MPs) and MPs stress. The combined application of SynCom and AMF enhanced colonization, association, and arbuscule abundance in the non-stressed plants (no MPs) as compared to stressed plants. The sole or co-application of SynCom and AMF enhanced the primary metabolites content and mitigated the MPs-induced reduction in soluble sugars, lipids, protein, and oil contents. Soybean inoculation stimulated the genes expression involved in lipid and protein biosynthesis, while a contradictory drift was noted for genes associated with lipid and protein degradation, underpinning the observed increment in protein and lipid content. Soybean inoculated with AMF exhibited the utmost α-amylase and β-amylase activities, demonstrating enhanced osmolyte (soluble sugar) production, mainly under MPs stress. Remarkably, sole or co-application further reinforces the positive effect of MPs stress on the osmoprotectants and antioxidant levels, for instance, phenol, flavonoid, glycine betaine contents, and glutathione-S-transferase (GST) activities. Subsequent to the stress release, a stress hormones known as abscisic acid (ABA) reduced in the seeds of inoculated soybean while gibberellin (GA), trans-zeatin riboside (ZR), and indole acetic acid (IAA) were increased. Therefore, it is concluded that the combined application of SynCom and AMF protected the soybean plants from MPs-induced oxidative damage by upregulating osmoprotectants and antioxidant levels. This study provides insights into the potential of sustainable remediation approaches in alleviating the complex impact of MPs on soybean, contributing to future strategies for environmental sustainability. Future studies could explore the optimization of SynCom and AMF formulations for different crops and environmental conditions, potentially leading to practical applications in sustainable agriculture and pollution management.

Dynamic Changes of Phytohormone Concentrations during <i>Prunella vulgaris</i> L. Development and Impact of Rosmarinic Acid Accumulation through Exogenous ABA Application

Background: Plant hormones not only participate in regulating the growth and development process of plants, but also play an important regulatory role in the synthesis of secondary metabolites. Prunella vulgaris L. (P. vulgaris) is a perennial herb that has a long history for use as a kind of medicinal and edible plant. In order to understand the relationship between plant hormones and Prunella vulgaris L. (P. vulgaris) development. Methods: The quantification of indoleacetic acid (IAA), salicylic acid (SA), jasmonates (JAs), abscisic acid (ABA), 1-aminocyclopropane-1-carboxylic acid (ACC) and cytokinins (CKs) of P. vulgaris during development was performed by a liquid chromatography-mass spectrometry (LC-MS). Furthermore, the effect of exogenous ABA on rosmarinic acid (RA) accumulation was verified. Results: Nuts formation was related to the concentrations of IAA, ABA and ACC in the green-fruit stage, and IAA and ABA levels increased rapidly in this stage. High IAA concentrations can promote an increase in ACC. SA, JAs, ethylene (ET) and ABA were related to the defence response of plants to pathogens. SA concentrations increased sharply after the turning stage, while the concentration of JAs, which are antagonistic to SA, was low. The decrease in ABA concentration after this period may be related to the antagonistic effect of IAA or SA. The CKs trans-zeatin (tZ) and trans-zeatin riboside (tZR) promoted the growth and development of early P. vulgaris, and their concentrations decreased in the late period, leading to withering and senescence of P. vulgaris. The CKs cis-zeatin (cZ) and N6-(2-isopentenyl) adenine (iP) were presumed to be present in nuts. After elicitation with 10 μg/mL ABA, an increase of RA content was observed (p < 0.05). Conclusion: This study can provide an improved basis for elucidating the growth and development mechanism of P. vulgaris in the future, as well as a better understand of the effects of ABA application on RA accumulations.

Role of cytokinins in the regulation the chilling stress response in Triticum aestivum and Triticum spelta

The research is devoted to the study of the effect of chilling (+4 °C, 2 h) on cytokinin homeostasis in 14-day stressed and 21-day restored plants of winter wheat (Triticum aestivum L.) cv. “Podolyanka” and spelt wheat (Triticum spelta L.) cv. “Frankenkorn”. Our study revealed that chilling induces complex changes in the content and distribution of cytokinins in plants that are species- and organ-specifi c. After chilling, the total cytokinin content in the roots of winter wheat cv. “Podolyanka” increased threefold due to the accumulation of trans-zeatin-O-glucoside, trans-zeatin, isopentenyladenine and isopentenyladenosine. Stress did not aff ect trans-zeatin riboside accumulation in roots but induced a fourfold increase in its content in the shoots of winter wheat cv. “Podolyanka”. The total content of cytokinin in the roots of spelt wheat cv. “Frankenkorn” decreased by 1.4 times due to decline in trans-zeatin-O-glucoside and trans-zeatin riboside content, while in shoots, it decreased by 1.2 times owing to reduced trans-zeatin-O-glucoside and isopentenyladenine levels. Prolonged exposure to chilling was manifested by an increase in hormone levels in both 21-day-old species. Our data revealed common and distinct traits in cytokinin homeostasis between winter wheat cv. “Podolyanka” and spelt wheat cv. “Frankenkorn” during rapid adaptation and the recovery period, providing new insights into the response of these species to chilling.

Endogenous cytokinins in plants of Secale cereale (Poaceae) under the effects of soil drought

Due to ongoing global climate changes and anthropogenic stress, soil drought has emerged as a significant threat, hindering plant growth, development, and resulting in crop losses. While phytohormones play a vital role in the formation of stress resistance mechanisms, cytokinins, in particular, remain poorly understood in cultivated cereals. The objective of our study was to investigate the impact of soil drought on plant growth and the homeostasis of endogenous cytokinins in both the aerial parts and roots of winter rye (Secale cereale) during the initial stages of vegetation. We aimed to elucidate the relationship between growth processes and the balance of these phytohormones. The plants were cultivated in a phytochamber using sand culture, and drought stress was induced by withholding water from nine-day-old plants for a period of eight days. The shoots and roots of 17-day-old plants were collected when dehydrated plants reached the critical wilting point. The content of endogenous cytokinins was analyzed using HPLC-MS. Our findings revealed that the inhibition of shoot growth and root elongation in stressed plants coincided with a reduction in the content of trans-zeatin riboside. This observation suggests that trans-zeatin riboside acts as a growth regulator in winter rye under soil drought conditions. Moreover, we observed an elevation in the levels of trans-zeatin and isopentenyladenine in the shoots and roots of stressed rye plants, indicating the involvement of these hormones in the formation of a "protective anti-stress block." These results highlight the multifunctional activity of cytokinins and demonstrate their role in regulating various components of the water deficit response. Consequently, our study expands our understanding of the role of cytokinins in the development of stress resistance in cereals.

Physiological and molecular responses of strawberry plants to Cd stress

Cadmium (Cd), a toxic metal element, can be absorbed by plants via divalent metal ion transporters, thereby retarding plant growth and posing a threat to human health. Strawberries are popular and economically valuable berry species that are sensitive to soil pollutants, especially Cd. However, the mechanisms underlying Cd stress responses in strawberry plants remain largely unclear. Here, we investigated the physiological and molecular basis of Cd stress responses in strawberry plants using the diploid strawberry ‘Yellow Wonder’ as a material. The results indicated that Cd stress induced oxidative damage, repressed photosynthetic efficiency, and interfered with the accumulation and redistribution of trace elements. Furthermore, Cd stress reduced the concentrations of indoleacetic acid, trans-zeatin riboside and gibberellic acid while increasing the concentration of abscisic acid, thus altering the phytohormone signaling pathway in strawberry plants. Cd stress also inhibited the expression of genes involved in nitrogen uptake and assimilation while promoting the energy supply for plant survival under Cd toxicity. Moreover, the flavonoid biosynthesis pathway was induced, and the anthocyanin concentration increased, thereby improving the free radical scavenging capacity of strawberry plants under Cd toxicity. Additionally, we identified several transcription factors and functional genes as hub genes based on a weighted gene coexpression network analysis. These results collectively provide a theoretical foundation for strawberry breeding and ensuring agriculture and food safety.

Investigating the synergistic effects of biochar, trans-zeatin riboside, and Azospirillum brasilense on soil improvement and enzymatic activity in water-stressed wheat

BackgroundWater stress is a major danger to crop yield, hence new approaches to strengthen plant resilience must be developed. To lessen the negative effects of water stress on wheat plants, present study was arranged to investigate the role of synergistic effects of biochar, trans-zeatin riboside (t-ZR), and Azospirillum brasilense on soil improvement and enzymatic activity in water-stressed wheat.ResultsIn a three-replication experiment comprising of four treatments (T0: Control, T1: Drought stress (DS), T2: DS + t-ZR with biochar, T3: DS + A. brasilense with biochar), we observed notable improvements in soil quality and enzymatic activities in water-stressed wheat plants with the application of t-ZR and A. brasilense with biochar. In drought stress, Treatment having the application of A. brasilense with biochar performs best as compared to the other and significant increased the enzymatic activities such as peroxidase (7.36%), catalase (8.53%), superoxide dismutase (6.01%), polyphenol oxidase (14.14%), and amylase (16.36%) in wheat plants. Different enzymatic activities showed different trends of results. Soil organic C, dissolved organic C, dissolved organic N also enhanced 29.46%, 8.59%, 22.70% respectively with the application of A. brasilense with biochar under drought stress condition.ConclusionsThe synergistic action of A. brasilense and biochar creates an effective microbiological environment that supports essential plant physiological processes during drought stress. This enhancement is attributed to improved soil fertility and increased organic matter content, highlighting the potential of these novel strategies in mitigating water stress effects and enhancing crop resilience.

Physiological, Metabolic, and Transcriptomic Analyses Reveal Mechanisms of Proliferation and Somatic Embryogenesis of Litchi (Litchi chinensis Sonn.) Embryogenic Callus Promoted by D-Arginine Treatment.

D-arginine (D-Arg) can promote embryogenic callus (EC) proliferation and increase the rate of somatic embryo induction of litchi (Litchi chinensis Sonn.), yet the mechanism underlying the processes is incompletely understood. To investigate the mechanism, physiological responses of polyamines (PAs) [putrescine (Put), spermidine (Spd), and spermine (Spm)] were investigated for D-Arg-treated litchi EC and enzyme activity related to polyamine metabolism, plant endogenous hormones, and polyamine- and embryogenic-related genes were explored. Results showed that the exogenous addition of D-Arg reduces the activity of diamine oxidase (DAO) and polyamine oxidase (PAO) in EC, reduces the production of H2O2, promotes EC proliferation, and increases the (Spd + Spm)/Put ratio to promote somatic embryo induction. Exogenous D-Arg application promoted somatic embryogenesis (SE) by increasing indole-3-acetyl glycine (IAA-Gly), kinetin-9-glucoside (K9G), and dihydrozeatin-7-glucoside (DHZ7G) levels and decreasing trans-zeatin riboside (tZR), N-[(-)-jasmonoyl]-(L)-valine (JA-Val), jasmonic acid (JA), and jasmonoyl-L-isoleucine (Ja-ILE) levels on 18 d, as well as promoting cell division and differentiation. The application of exogenous D-Arg regulated EC proliferation and somatic embryo induction by altering gene expression levels of the WRKY family, AP2/ERF family, C3H family, and C2H2 family. These results indicate that exogenous D-Arg could regulate the proliferation of EC and the SE induction of litchi by changing the biosynthesis of PAs through the alteration of gene expression pattern and endogenous hormone metabolism.

Supplementary Low Far-Red Light Promotes Proliferation and Photosynthetic Capacity of Blueberry In Vitro Plantlets.

Far-red light exerts an important regulatory influence on plant growth and development. However, the mechanisms underlying far-red light regulation of morphogenesis and photosynthetic characteristics in blueberry plantlets in vitro have remained elusive. Here, physiological and transcriptomic analyses were conducted on blueberry plantlets in vitro supplemented with far-red light. The results indicated that supplementation with low far-red light, such as 6 μmol m-2 s-1 and 14 μmol m-2 s-1 far-red (6FR and 14FR) light treatments, significantly increased proliferation-related indicators, including shoot length, shoot number, gibberellin A3, and trans-zeatin riboside content. It was found that 6FR and 14 FR significantly reduced chlorophyll content in blueberry plantlets but enhanced electron transport rates. Weighted correlation network analysis (WGCNA) showed the enrichment of iron ion-related genes in modules associated with photosynthesis. Genes such as NAC, ABCG11, GASA1, and Erf74 were significantly enriched within the proliferation-related module. Taken together, we conclude that low far-red light can promote the proliferative capacity of blueberry plantlets in vitro by affecting hormone pathways and the formation of secondary cell walls, concurrently regulating chlorophyll content and iron ion homeostasis to affect photosynthetic capacity.

Seasonal variation of two floral patterns in Clematis ‘Vyvyan Pennell’ and its underlying mechanism

BackgroundFloral patterns are crucial for insect pollination and plant reproduction. Generally, once these patterns are established, they exhibit minimal changes under natural circumstances. However, the Clematis cultivar’ Vyvyan Pennell’, the apetalous lineage in the Ranunculaceae family, produces two distinct types of flowers during different seasons. The regulatory mechanism responsible for this phenomenon remains largely unknown. In this study, we aim to shed light on this floral development with shifting seasonal patterns by conducting extensive morphological, transcriptomic, and hormone metabolic analyses. Our findings are anticipated to contribute valuable insights into the diversity of flowers in the Ranunculaceae family.ResultsThe morphological analysis revealed that the presence of extra petaloid structures in the spring double perianth was a result of the transformation of stamens covered with trichomes during the 5th developmental stage. A de novo reference transcriptome was constructed by comparing buds and organs within double and single perianth from both seasons. A total of 209,056 unigenes were assembled, and 5826 genes were successfully annotated in all six databases. Among the 69,888 differentially expressed genes from the comparative analysis, 48 genes of utmost significance were identified. These critical genes are associated with various aspects of floral development. Interestingly, the A-, B-, and C-class genes exhibited a wider range of expression and were distinct within two seasons. The determination of floral organ identity was attributed to the collaborative functioning of all the three classes genes, aligning with a modified “fading border model”. The phytohormones GA3, salicylic acid, and trans-zeatin riboside may affect the formation of the spring double perianth, whereas GA7 and abscisic acid may affect single flowers in autumn.ConclusionsWe presumed that the varying temperatures between the two seasons served as the primary factor in the alteration of floral patterns, potentially affecting the levels of plant hormones and expressions of organ identity genes. However, a more thorough investigation is necessary to fully comprehend the entire regulatory network. Nonetheless, our study provides some valuable informations for understanding the underlying mechanism of floral pattern alterations in Clematis.

Slow-release fertilizer deep placement increased rice yield and reduced the ecological and environmental impact in Southeast China: A life-cycle perspective

An unreasonable application of nitrogen fertilizer leads to increased agricultural greenhouse gas (GHG) emissions and carbon footprint (CF). To solve this issue, slow-release fertilizer and deep placement of nitrogen fertilizer are recommended, and have been proven effective in improving nitrogen utilization efficiency and reducing nitrogen loss. However, the deep placement of fertilizer increases the cost of mechanical fuel and labor, especially in the hilly and mountainous areas of southeast China and the comprehensive effects throughout the life cycle of crop production, including economic benefits, energy flow, and environmental and ecological advantages, resulting from different application strategies for nitrogen fertilizer, are still largely unknown. In this work, a two-year field trial was conducted in Fujian Province, China, from 2021 to 2022. The main objectives of the study were to investigate the yield and GHG emissions resulting from the deep placement of slow-release fertilizer (DSK) and to assess the carbon footprint, energy use efficiency, and net economic and ecological benefits from a life-cycle perspective. The results showed that compared with deep placement of urea (DCK), slow-release fertilizer broadcasting (SK), and the traditional fertilization mode practiced by farmers (CK), the average annual yield of rice under DSK treatment significantly increased by 8.78%, 15.18%, and 23.54% respectively. Compared with CK, the contents of indole-3-acetic acid (IAA) and trans-Zeatin Riboside (t-ZR) under DSK were significantly increased and the dry matter translocation amount, Non-Structural Carbohydrates (NSC) translocation amount and Nitrogen translocation amount were significantly increased by 22.79%, 49.60% and 41.47% respectively. GHG emissions were indirectly reduced by the transport of above-ground substances to grains. The average cumulative CH4 emissions were significantly reduced by 25.34% in the DSK treatment, compared to the CK treatment, primarily as a result of decreased methanogenic gene abundance of mcra gene. Additionally, N2O emissions decreased significantly by 48.97%, compared to the CK, mainly due to a decrease in nirK gene abundance and an increase in nosZ gene abundance in denitrifying bacteria. Furthermore, the carbon footprint of the DSK treatment significantly decreased by 38.74% compared to the CK treatment, while net energy income and net ecological and economic benefits increased by 43.83% and 76.43%, respectively. Comprehensive analysis showed that deep placement of slow-release fertilizer is a sustainable nitrogen fertilizer management mode that helps to balance grain yield, environmental footprint, and economic benefits in southeast China.

Exogenous GR24 Inhibits Strawberry Tillering by Affecting the Phytohormone Signaling and Sugar Metabolism Pathways

Tillering is an important part in strawberry growth, and strawberries can reproduce nutritionally through stolons to generate genetically stable offspring. However, excessive tillering during the fruit-growing stage can negatively impact fruit yield and quality. In this study, different concentrations of exogenous rac-GR24 (GR24) are used to treat the strawberry plants. It was found that GR24 effectively inhibited the sprouting of strawberry stolons, while promoting the growth of the stems and leaves. Among the treatments, the most effective concentration was found to be 5 μmol/L GR24. This treatment resulted in a decrease in the glucose content in the strawberry crowns and also caused changes in the contents of two endogenous phytohormones, gibberellic acid (GA3) and trans-zeatin riboside (tZR). Transcriptome data further suggested that exogenous GR24 may inhibit strawberry plant tillering by affecting various phytohormone signaling pathways and the sugar metabolism pathway. In 5 μmol/L GR24-treated plants, the expression level of type-B response regulator (B-ARR) was down-regulated and the expression level of CYTOKININ RESPONSE 1 (CRE1), histidine-containing phosphotransfer protein (AHP), and type-A response regulator (A-ARR) were up-regulated, suggesting the inhibition of the cytokinin (CTK) signaling pathway. The down-regulation of auxin (AUX) and auxin response factor (ARF), as well as the up-regulation of auxin/indole-3-acetic acid (AUX/IAA), led to the inhibition of the indole-3-acetic acid (IAA) signaling pathway. Additionally, the up-regulation of pyrabactin resistance 1/ pyrabactin resistance 1-like (PYR/PYL), non-fermenting 1-related protein kinase 2 (SnRK2), and ABRE binding factors (ABF) and the down-regulation of protein phosphatase 2C (PP2C) were observed in the up-regulated abscisic acid (ABA) signaling pathways. In the sugar metabolism pathway, the up-regulation of invertase (INV), hexokinase (HK), and fructokinase (FRK) and the down-regulation of trehalase (TREH) and beta-amylase (BMY) led to a decreased glucose synthesis and an increased glucose consumption. Therefore, GR24 can effectively inhibit strawberry plant tillering through these pathways, making it an effective reagent for tillering inhibition.

Associations between endogenous spike cytokinins and grain-number traits in spring wheat genotypes

Genetic variation in grain number has been positively associated with levels of cytokinins in inflorescences in cereals, although studies quantifying endogenous levels in the field are currently lacking. The present study, using a spring wheat association mapping panel (HiBAP II) of 150 lines, quantified associations between spike hormone levels and grain number and associated traits. The HiBAP II panel was grown in the field in NW Mexico under irrigated conditions for one year and a subset of ten genotypes in the glasshouse under well-watered conditions for three years. The spike levels of four cytokinins (trans-zeatin riboside, trans-zeatin, isopentenyladenosine, and isopentenyladenine) were measured by using ultra-high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. In the glasshouse experiments, spike hormone levels were measured at booting and anthesis, and in the field experiment at anthesis. In the glasshouse experiments, cytokinin levels were also measured in the basal, central, and apical spikelets separately in addition to at the whole spike level. The spike cytokinin levels did not differ significantly between the basal, central and apical sections of the spike. or show a spike position × genotype interaction. In the glasshouse experiments, significant genetic variation was detected for the expression of the four cytokinins in spikes at booting. At booting, spike trans-zeatin concentration ranged amongst genotypes from 4.5 to 16.0 ng g−1 FW and was positively correlated with grain number per main shoot (r = 0.77, P < 0.05). In the field at anthesis, the spike levels of each of trans-zeatin, trans-zeatin riboside and isopentenyl adenosine were positively correlated with grains per m2 (r = 0.17–0.19, P < 0.05). Our results indicated that selection for high spike cytokinin levels in wheat germplasm offers scope to raise grain number and yield potential in wheat.

Physiological and molecular bases of the boron deficiency response in tomatoes

Abstract Boron is an essential microelement for plant growth. Tomato is one of the most cultivated fruits and vegetables in the world, and boron deficiency severely inhibits its yield and quality. However, the mechanism of tomato in response to boron deficiency remains largely unclear. Here, we investigated the physiological and molecular bases of the boron deficiency response in hydroponically grown tomato seedlings. Boron deficiency repressed the expression of genes associated with nitrogen metabolism, while it induced the expression of genes related to the pentose phosphate pathway, thereby altering carbon flow to provide energy for plants to cope with stress. Boron deficiency increased the accumulation of copper, manganese and iron, thereby maintaining chlorophyll content and photosynthetic efficiency at the early stage of stress. In addition, boron deficiency downregulated the expression of genes involved in cell wall organization and reduced the contents of pectin and cellulose in roots, ultimately retarding root growth. Furthermore, boron deficiency markedly altered phytohormone levels and signaling pathways in roots. The contents of jasmonic acid, jasmonoy1-L-isoleucine, trans-zeatin riboside, abscisic acid, salicylic acid, and SA glucoside were decreased; in contrast, the contents of isopentenyladenine riboside and ethylene precursor 1-aminocyclopropane-1-carboxylic acid were increased in the roots of boron-deficient tomato plants. These results collectively indicate that tomato roots reprogram carbon/nitrogen metabolism, alter cell wall components and modulate phytohormone pathways to survive boron deficiency. This study provides a theoretical basis for further elucidating the adaptive mechanism of tomato in response to boron deficiency.

Cytokinin Translocation to, and Biosynthesis and Metabolism within, Cereal and Legume Seeds: Looking Back to Inform the Future.

Early in the history of cytokinins, it was clear that Zea mays seeds contained not just trans-zeatin, but its nucleosides and nucleotides. Subsequently, both pods and seeds of legumes and cereal grains have been shown to contain a complex of cytokinin forms. Relative to the very high quantities of cytokinin detected in developing seeds, only a limited amount appears to have been translocated from the parent plant. Translocation experiments, and the detection of high levels of endogenous cytokinin in the maternal seed coat tissues of legumes, indicates that cytokinin does not readily cross the maternal/filial boundary, indicating that the filial tissues are autonomous for cytokinin biosynthesis. Within the seed, trans-zeatin plays a key role in sink establishment and it may also contribute to sink strength. The roles, if any, of the other biologically active forms of cytokinin (cis-zeatin, dihydrozeatin and isopentenyladenine) remain to be elucidated. The recent identification of genes coding for the enzyme that leads to the biosynthesis of trans-zeatin in rice (OsCYP735A3 and 4), and the identification of a gene coding for an enzyme (CPN1) that converts trans-zeatin riboside to trans-zeatin in the apoplast, further cements the key role played by trans-zeatin in plants.

Tomato growth and physiology as well as soil physicochemical and biological properties affected by ozonated water in a saline agroecosystem

Current trends in agriculture are focused on implementing sustainable practices that avoid the use of chemical compounds. It is important to propose environmentally friendly methods, which may enhance plant growth physiology and yield without affecting soil microbial community as much. In this context, irrigation with ozonated water could be a potential strategy to reduce some chemical compounds in soils due to the degradative power of ozone. Here, we studied the impact of irrigation with ozonated water on the microbial community of a Mediterranean soil, and on Solanum lycopersicum L. agro-physiology and productivity in a greenhouse experiment. To this end, we evaluated: i) soil physicochemical properties, soil enzyme activities, microbial biomass via fatty acid analysis, microbial diversity (via amplicon sequencing), and ii) the nutrient content, physiology, phytohormone content, yield, and fruit quality of tomato plants. Our results indicate that soil physicochemical properties were significantly affected by the irrigation with ozonated water (OZ). We observed an increase in the content of total organic carbon (TOC), water-soluble nitrogen (WSN) and ammonium, and a decrease in soil pH due to the OZ treatment. In addition, a significant increase in alkaline phosphatase and fungal and bacterial biomass was also observed in the OZ treatment. It was observed that the prokaryotic community structure was affected by the OZ treatment, while that of fungi was undisturbed. The OZ treatment increased the photosynthetic rates of tomato plants and maintained water conditions when compared to control plants. The increased trans-Zeatin riboside (tZ-Rib) could provide rapid apical and root growth allowing adaptation to the new growing conditions. However, a more in-depth study on the physiological response of the plant to this treatment would be of interest, as it would help with the implementation of this strategy in agricultural fields in a safe manner, and with obtaining higher plant yields.

Metabolomic Analysis ofthe Desert Moss Syntrichia caninervis Provides Insights into Plant Dehydration andRehydration Response.

Desiccation-tolerant (DT) plants can survive extreme dehydration and tolerate the loss of up to 95% of their water content, making them ideal systems to determine the mechanism behind extreme drought stress and identify potential approaches for developing drought-tolerant crops. The desert moss Syntrichia caninervis is an emerging model for extreme desiccation tolerance that has benefited from high-throughput sequencing analyses, allowing identification of stress-tolerant genes; however, its metabolic response to desiccation is unknown. A liquid chromatography-mass spectrometry analysis of S. caninervis at six dehydration-rehydration stages revealed 912 differentially abundant compounds, belonging to 93 metabolic classes. Many (256) metabolites accumulated during rehydration in S. caninervis, whereas only 71 accumulated during the dehydration period, in contrast to the pattern observed in vascular DT plants. During dehydration, nitrogenous amino acids (l-glutamic acid and cysteinylglycine), alkaloids (vinleurosine) and steroids (physalin D) accumulated, whereas glucose 6-phosphate decreased. During rehydration, γ-aminobutyric acid, glucose 6-phosphate and flavonoids (karanjin and aromadendrin) accumulated, as did the plant hormones 12-oxo phytodienoic acid (12-OPDA) and trans-zeatin riboside. The contents ofl-arginine, maltose, turanose, lactulose and sucrose remained high throughout dehydration-rehydration. Syntrichia caninervis thus accumulates antioxidants to scavenge reactive oxygen species, accumulating nitrogenous amino acids and cytoprotective metabolites and decreasing energy metabolism to enter a protective state from dehydration-induced damage. During subsequent rehydration, many metabolites rapidly accumulated to prevent oxidative stress and restore physiological activities while repairing cells, representing a more elaborate rehydration repair mechanism than vascular DT plants, with a faster and greater accumulation of metabolites. This metabolic kinetics analysis in S. caninervis deepens our understanding of its dehydration mechanisms and provides new insights into the different strategies of plant responses to dehydration and rehydration.

Dynamic changes in the levels of metabolites and endogenous hormones during the germination of Zanthoxylum nitidum (Roxb.) DC. Seeds

ABSTRACT Accumulating experimental data have shown that endogenous hormones play important roles in regulating seed dormancy and germination. Zanthoxylum nitidum is a medicinal plant that propagates via seeds, which require a long dormancy period for normal germination, and complex changes in metabolites occur during the germination process. However, the regulatory network of endogenous hormones and metabolites during the germination of Z. nitidum seeds remains unclear. This study investigated the dynamic changes in the levels of metabolites and endogenous hormones during the germination of Z. nitidum seeds. The results revealed an increase in the levels of gibberellin 3 (GA3), 12-oxophytodienoic acid (OPDA), 1-aminocyclopropane-1-carboxylic acid (ACC) and trans-zeatin (TZ) and decrease in the levels of abscisic acid (ABA), jasmonic acid (JA), N-[(-)-jasmonoyl]-(S)-isoleucine (JA-Ile) and trans-zeatin riboside (TZR). Overall, 112 differential metabolites (DAMs) were screened from 3 seed samples (Sa, Sb and Sc), most of which are related to primary metabolism. A total of 16 DAMs (including 3 monosaccharides, 3 phosphate lipids, 3 carboxylic acids, 1 amino acid, 2 pyrimidines, and 4 nucleotides) were identified in the three sample comparison pairs (Sa vs Sb, Sa vs Sc, and Sb vs Sc); these DAMs were significantly enriched in purine metabolism; glycerophospholipid metabolism, citrate cycle (TCA cycle), alanine, aspartate and glutamate metabolism and pyruvate metabolism. OPDA, ACC and GAs were significantly positively correlated with upregulated metabolites, whereas ABA and JA were significantly positively correlated with downregulated metabolites. Finally, a hypothetical metabolic network of endogenous hormones that regulate seed germination was constructed. This study deepens our understanding of the importance of endogenous hormonal profiles that mediate seed germination.

Effect of Exogenous Plant Growth Regulators and Rejuvenation Measures on the Endogenous Hormone and Enzyme Activity Responses of Acer mono Maxim in Cuttage Rooting.

The cuttage rooting method for Acer species is difficult to achieve a good efficacy as trees maintain good characteristics at the rejuvenation stage, thus improving the rooting of Acer species. The addition of exogenous hormones and rejuvenation can improve the rooting effect of cuttings; however, the specific regulatory mechanism is still unclear. Here, Acer mono Maxim rejuvenation and non-rejuvenation cuttings were used as test subjects, to investigate the effects of exogenous hormones on the activities of endogenous hormones and antioxidant enzymes in the rooting process of young cuttings. The results showed that exogenous growth-regulating substances significantly improved the rooting rate of A. mono. Exogenous hormones naphthylacetic acid (NAA) + indolebutyric acid (IBA) increased the initial levels of the endogenous hormones, indoleacetic acid (IAA) and abscisic acid (ABA), and the enzyme activities of peroxidase (POD) and polyphenol oxidase (PPO). Rejuvenation treatment prolonged the time of increase in ABA content and indoleacetic acid oxidase (IAAO) activity at the root primordium induction stage, while increasing trans-zeatin riboside (ZR) content and decreasing POD enzyme activity in cuttings. These results demonstrate that A. mono cuttings can achieve the purpose of improving the rooting rate by adding the exogenous hormone (NAA + IBA), which is closely related to the changes of endogenous hormone content and enzyme activity, and these changes of A. mono rejuvenation cuttings are different from non-rejuvenation cuttings.

Halostachys caspica pathogenesis-related protein 10 acts as a cytokinin reservoir to regulate plant growth and development.

Pathogenesis-related class 10 (PR-10) proteins play a role in plant growth and development, but the underlying molecular mechanisms are unclear. Here, we isolated a salt-induced PR-10 gene from the halophyte Halostachys caspica and named it HcPR10. HcPR10 was constitutively expressed during development and HcPR10 localized to the nucleus and cytoplasm. HcPR10-mediated phenotypes including bolting, earlier flowering, increased branch number and siliques per plant are highly correlated with increased cytokinin levels in transgenic Arabidopsis. Meanwhile, increased levels of cytokinin in plants is temporally correlated with HcPR10 expression patterns. Although the expression of cytokinin biosynthesis genes validated was not upregulated, cytokinin-related genes including chloroplast-related genes, cytokinin metabolism and cytokinin responses genes and flowering-related genes were significantly upregulated in the transgenic Arabidopsis compared to the wild type by transcriptome deep sequencing. Analysis of the crystal structure of HcPR10 revealed a trans-zeatin riboside (a type of cytokinin) located deep in its cavity, with a conserved conformation and protein-ligand interactions, supporting HcRP10 acts as a cytokinin reservoir. Moreover, HcPR10 in Halostachys caspica predominantly accumulated in vascular tissue, the site of long-distance translocation of plant hormones. Collectively, we draw that HcPR10 as a cytokinin reservoir induces cytokinin-related signal transduction in plants, thereby promoting plant growth and development. These findings could provide intriguing insights into the role of HcPR10 proteins in phytohormone regulation in plants and advance our understanding of cytokinin-mediated plant development and could facilitate the breeding of transgenic crops with earlier mature, higher yielding agronomic traits.

Mowing Improves Chromium Phytoremediation in Leersia hexandra Swartz

To improve the efficiency of chromium (Cr) phytoextraction by Leersia hexandra Swartz, the effects of mowing on Cr accumulation in L. hexandra were investigated using hydroponic experiments. Mowing heights (0, 5, and 10 cm), mowing interval (30, 60, 90 and 120 days), and mowing frequencies (1, 2, and 3 times) were optimized. Mowing at 10 cm above roots significantly increased shoot biomass of L. hexandra (32.9 g/pot). The 90 days mowing interval achieved the highest shoot biomass (62.8 g/pot). The shoot biomass with thrice mowing (67.0 g/pot) was higher than those with one and twice mowing, as well as no mowing (CK). The increases in biomass might ascribe to the changes in endogenous hormone balance by mowing. Proper mowing significantly increased contents of Gibberellin 3 (GA3), 6-Benzylaminopurine (6-BA), 6-Kinetin (6-KT), and trans-Zeatin-riboside (TZR) in leaves, and 3-Indolepropionic acid (IPA) in stems, but decreased Jasmonic acid (JA) in the leaves and stems, thereby enhancing the regeneration of plant. The enhancement of plant regeneration resulted in the increases of biomass and Cr accumulation. Compared to CK, the optimal mowing method (10 cm, 90 days, 3 times) increased shoot biomass and Cr accumulation by 91.4% and 36.0%, respectively. These findings suggested that proper mowing had application potential to promote efficiency of Cr phytoextraction by L. hexandra.