Search Results (30)

The universal stress protein (USP) family is a large but poorly studied group of plant proteins whose roles are considered primarily in the context of stress tolerance. This study demonstrates that the functions of USPs are not limited to the stress response but also influence plant developmental processes, namely, the regulation of seed germination and seedling establishment. Using reverse genetics, we found that disruption of the Arabidopsis thaliana At3g58450 gene, encoding germination-related USP (GRUSP), results in delayed germination and abscisic acid (ABA) hypersensitivity in the mutant the GABI-kat 115C08 (grusp-115) knockout line. This hypersensitivity was only partially rescued by the application of fluridone, an ABA biosynthesis inhibitor. Altered ABA content and expression patterns of genes involved in ABA metabolism and signaling, along with a decrease in the mRNA levels of gibberellin (GA) oxidases in dry and either Murashige and Skoog (MS)- or ABA-imbibed mutant seeds, indicate that GRUSP function is primarily associated with seed imbibition and early germination stages. Furthermore, the grusp-115 mutant showed upregulation of ABI5 transcripts in imbibed seeds and seedlings as well as an accumulation of ABI5 protein level under excess GA conditions, indicating a functional relationship between these proteins. Hence, GRUSP is a novel component of the GA and ABA pathways whose function is initiated during seed germination. Full article

Drought is a major limiting factor for apple growth and development. Abscisic acid (ABA) is a key hormone in plant abiotic stress responses, playing a vital role in mediating adaptation to drought. Malus sieversii, the wild ancestor of cultivated apple, exhibits superior drought tolerance. However, the specific ABA-dependent regulatory module underlying its exceptional drought tolerance remains to be elucidated. In this study, we investigated the role of ABA in the drought response of M. sieversii seedlings using a combination of exogenous ABA and the ABA biosynthesis inhibitor fluridone. Plants were subjected to four treatments: CK, PEG (20% PEG-6000), PEG+ABA (100 μM ABA) and PEG+FLU (100 μM fluridone). The results showed that ABA application significantly reduced the wilting rate by 45.53% and electrolyte leakage by 20.50% compared to the PEG treatment. Furthermore, it alleviated the decline in fresh weight and relative water content while reducing the accumulation of starch, sucrose, glucose, and fructose after seven days of stress. Conversely, FLU application intensified the adverse effects of drought. RNA-Seq analysis of the PEG+ABA vs. PEG comparison identified 5642 differentially expressed genes (DEGs), with significant enrichment in the starch and sucrose metabolism pathway, photosynthesis, carbon fixation, and MAPK signaling pathways. Exogenous ABA up-regulated BGLU23 while down-regulating BAM1. In contrast, no significant changes in their expression were observed under FLU treatment, suggesting their likely regulation in an ABA-dependent manner. In summary, ABA enhances osmotic-stress tolerance in M. sieversii through multiple pathways, among which starch and sucrose metabolism may represent a core and highly responsive regulatory pathway. Functional validation of key candidate genes BAM1 and BGLU23 remains an important direction for future investigation. These findings provide a theoretical basis for breeding drought-resistant apple rootstocks and for understanding ABA-mediated osmotic-stress tolerance mechanisms. Full article

Climate change-driven abiotic stresses threaten global potato production, yet stress-specific adaptive mechanisms remain poorly defined. We demonstrate that heat, drought and salt stresses induce fundamentally distinct physiological and biochemical responses in potato plants. Photosynthetic performance and gas exchange showed stress-specific patterns, with heat stress (HS) maintaining elevated carbon metabolism, drought stress (DS) causing severe photosynthetic suppression and water deficit, while salt stress (SS) exhibited intermediate physiological impairment. Secondary metabolite (SM) profiling revealed a corresponding stress-specific signature, where sesquiterpenes (caryophyllene, copaene, humulene) were dramatically elevated under HS but suppressed under DS (which specifically enhanced 1-hexanol and trans-sesquisabinene hydrate), while SS induced copaene and cis-β-farnesene but reduced caryophyllene. Phytohormone analysis demonstrated differential accumulation patterns across stresses: JA, JA-Ile, SA and ABA were maximally elevated under HS, moderately increased under DS, while SS uniquely maintained basal JA/JA-Ile with enhanced SA and ABA. Pharmacological intervention using hormone biosynthesis inhibitors (DIECA, SHAM, Jarin-1, AIP, ABT, fluridone) and exogenous ABA confirmed stress-specific regulatory networks. These findings establish a stress-specific hormone–metabolite regulatory framework, providing a molecular basis for developing climate-resilient potato genotypes. Full article

Zephyranthes tubispatha is an Amaryllidaceae species with high ornamental potential, whose seed dispersal coincides with periods of high temperatures (HTs) and long photoperiods. While supraoptimal temperatures (>28 °C) have been shown to induce thermoinhibition, the effect of light on germination dynamics has not yet been explored. The aim was to study the effect of different exposure times to white light (WL) and different light qualities, as well as the interaction with HT, on seed germination. Changes in the endogenous levels of several phytohormones, responses to pharmacological treatments, and O₂^.− production in the embryo were analyzed to gain an understanding of the underlying physiological mechanisms. Our results suggest the presence of a negative photoblastic response of the high-irradiance (HIR) type. Fluridone (an ABA synthesis inhibitor) restored germination in light-exposed seeds to levels close to the dark control, highlighting the importance of ABA content for photoinhibition. The preincubation period at HT (33 °C) significantly influenced germination behavior and photosensitivity at optimal temperature (20 °C). Thermoinhibition depends on changes in phytohormone balance and/or sensitivity, rather than on their absolute concentration. Unlike thermoinhibition, photoinhibition was not associated with the suppression of O₂^.− production in the embryonic root pole, confirming that these environmental signals utilize different regulatory pathways. Full article

Fluridone is a pyrrolidone soil-sealing herbicide that has been widely used in cotton fields in Xinjiang in recent years. The purpose of this study was to establish a method for determining fluridone residues in cotton fields and to perform residue digestion tests, final residue analysis, and dietary risk assessment. Samples were extracted with acetonitrile, purified with primary secondary amine (PSA) and multi-walled carbon nanotubes (MWCNTs), and analyzed by high-performance liquid chromatography (HPLC). The results showed that in a certain concentration range, the concentration and peak area of fluridone showed a good linear relationship (R² > 0.99), with limit of detection (LOD) and limit of quantification (LOQ) values of 0.00090–0.00108 mg·kg⁻¹ and 0.0030–0.0033 mg·kg⁻¹, respectively. The relative standard deviation (RSD) values of fluridone were 0.46% to 4.57% at the spiked level of 0.1, 0.5, and 1.0 mg·kg⁻¹, respectively. The average daily recovery rate of fluridone was 85.08% to 95.07%. The residual levels of fluridone in cottonseed oil were below the safety threshold, indicating no significant dietary risk to consumers. Full article

1, 2, 4-triazole derivatives, including tebuconazole, have been reported to show positive physiological effects in cereals apart from fungicidal activity and to increase plants’ tolerance against temperature stress. This study investigates the mechanisms of increasing frost resistance of etiolated winter wheat (Triticum aestivum L., “Irkutskaya” variety) seedlings by tebuconazole-based seed dresser “Bunker” (1.5 μL g⁻¹ of seeds) and tebuconazole (30 μg g⁻¹ of seeds). To identify ABA-dependent and ABA-independent pathways of frost resistance, we used fluridone (FLD, 5 mg L⁻¹), an inhibitor of endogenous abscisic acid (ABA) synthesis. FLD effectively inhibited the accumulation of carotenoids in the shoots and prevented the formation of carotenoids caused by the “Bunker” and tebuconazole. In non-hardened seedlings, FLD stimulated coleoptile and first leaf growth, but did not suppress the growth inhibitory effects of “Bunker” and tebuconazole. In shoots of hardened seedlings, FLD reduced the retarding effect of tebuconazole. Regardless of seedling age, temperature, and the protectant treatment, FLD had no effect on the sugar content in the shoots. FLD did not essentially influence frost resistance induced by “Bunker” and tebuconazole in cold-hardened seedlings. Fluridone increased H₂O₂ content and guaiacol peroxidase activity under control conditions (both with tebuconazole and without tebuconazole) and during cold hardening (in seedlings from seeds treated with tebuconazole). ABA levels in cold-hardened seedlings treated with FLD alone, tebuconazole alone, or a combination of the two were two to three times lower than in untreated hardened seedlings. Changes in indole-3-acetic and salicylic acids in response to FLD and tebuconazole treatment indicate complex interactions with signaling cellular systems. Our results suggest that tebuconazole activates ABA-independent pathways more strongly than ABA-dependent pathways in enhancing frost resistance. The potential mechanisms of tebuconazole action in plant cells are discussed. Full article

The herbicide fluridone (1-methyl-3-phenyl-5-[3-trifluoromethyl (phenyl)]-4(1H)-pyridone) interferes with carotenoid biosynthesis in plants by inhibiting the conversion of phytoene to phytofluene. Fluridone also indirectly inhibits the biosynthesis of abscisic acid and strigolactones, and therefore, our study indirectly addresses the effect of reduced ABA on the roots and leaf buds development in stem cuttings of Salix babylonica L. ‘Tortuosa’. The stem cuttings were kept in distilled water (control) or in a solution of fluridone (10 mg/L) in natural greenhouse light and temperature conditions. During the experiments, morphological observations were carried out on developing roots and leaf buds, as well as their appearance and growth. After three weeks of continuous treatments, adventitious roots and leaf buds were collected and analysed. Identification and analysis of anthocyanins were carried out using micro-HPLC-MS/MS-TOF, while HPLC-MS/MS was used to analyse phenolic acids, flavonoids and salicinoids. The fluridone applied significantly inhibited root growth, but the number or density of roots was higher compared to the control. Contents of salicortin and salicin were several dozen times higher in leaf buds than in roots of willow. Fluridone increased the content of salicortin in roots and leaf buds and declined the level of salicin in buds. Fluridone also declined the content of most anthocyanins in roots but enhanced their content in buds, especially cyanidin glucoside, cyanidin galactoside and cyanidin rutinoside. Besides, fluridone markedly decreased the level of chlorophylls and carotenoids in the leaf buds. The results indicate that applied fluridone solution reduced root growth, caused bleaching of leaf buds, and markedly affected the content of secondary metabolites in the adventitious roots and leaf buds of S. babylonica stem cuttings. The paper presents and discusses in detail the significance of fluridone’s effects on physiological processes and secondary metabolism. Full article

Rice (Oryza sativa L.) is a main food crop in China and is crucial for the maintenance of national food security. The growth of rice seedling roots is regulated by a variety of genes and is closely related to abscisic acid (ABA) metabolism and ABA signaling pathways. In this study, we found that OsABT could increase the length of rice root tip meristem cells and upregulate root development-related genes, thereby alleviating ABA’s inhibitory effects on rice root growth and seed germination. The overexpression of OsABT reduced the ABA content by downregulating ABA synthesis genes (OsNCED3 and OsNCED5) and upregulating the ABA catabolic gene (OsABA8ox2). In addition, OsABT interacted with OsPYL4, OsPYL10, and OsABIL2 via the ABA signal transduction pathway. By inhibiting the expression of positive regulatory genes (OsPYL9 and Rab16a) and increasing the expression of a negative regulatory gene (OsABIL1), OsABT negatively regulates the ABA signal transduction pathway. Transcriptome analysis revealed that OsABT inhibited the activity of Gene Ontology entries in response to ABA. Thus, OsABT increased the length of the rice root meristem, reduced the accumulation of ABA in the roots, and negatively regulated the ABA signal transduction pathway by interacting with key proteins in this pathway, ultimately relieving the inhibitory effect of ABA on rice root length and seed germination. Full article

Abscisic acid (ABA) is one of the many naturally occurring phytohormones widely found in plants. This study focused on refining APAn, a series of previously developed agonism/antagonism switching probes. Twelve novel APAn analogues were synthesized by introducing varied branched or oxygen-containing chains at the C-6′ position, and these were screened. Through germination assays conducted on A. thaliana, colza, and rice seeds, as well as investigations into stomatal movement, several highly active ABA receptor antagonists were identified. Microscale thermophoresis (MST) assays, molecular docking, and molecular dynamics simulation showed that they had stronger receptor affinity than ABA, while PP2C phosphatase assays indicated that the C-6′-tail chain extending from the 3′ channel effectively prevented the ligand–receptor binary complex from binding to PP2C phosphatase, demonstrating strong antagonistic activity. These antagonists showed effective potential in promoting seed germination and stomatal opening of plants exposed to abiotic stress, particularly cold and salt stress, offering advantages for cultivating crops under adverse conditions. Moreover, their combined application with fluridone and gibberellic acid could provide more practical agricultural solutions, presenting new insights and tools for overcoming agricultural challenges. Full article

Chinese cork oak (Quercus variabilis Blume) is a widespread tree species with high economic and ecological values. Chinese cork oak exhibits epicotyl dormancy, causing emergence heterogeneity and affecting the quality of seedling cultivation. Gibberellic acid-stimulated transcript (GAST) is a plant-specific protein family that plays a crucial regulatory role in plant growth, development, and seed germination. However, their evolution in Chinese cork oak and roles in epicotyl dormancy are still unclear. Here, a genome-wide identification of the GAST gene family was conducted in Chinese cork oak. Ten QvGAST genes were identified, and nine of them were expressed in seed. The physicochemical properties and promoter cis-acting elements of the selected Chinese cork oak GAST family genes indicated that the cis-acting elements in the GAST promoter are involved in plant development, hormone response, and stress response. Germinated seeds were subjected to gibberellins (GAs), abscisic acid (ABA), and fluridone treatments to show their response during epicotyl dormancy release. Significant changes in the expression of certain QvGAST genes were observed under different hormone treatments. QvGAST1, QvGAST2, QvGAST3, and QvGAST6 exhibited upregulation in response to gibberellin. QvGAST2 was markedly upregulated during the release of epicotyl dormancy in response to GA. These findings suggested that QvGAST2 might play an important role in epicotyl dormancy release. This study provides a basis for further analysis of the mechanisms underlying the alleviation of epicotyl dormancy in Chinese cork oak by QvGASTs genes. Full article

Rhodotypos scandens (Thunb.) Makino is known to have a seed dispersal that is thick and stony (endocarp + seeds) and has potential as a landscaping tree seed. In several Rosaceae species, seeds are covered with a hard endocarp, making the internal seeds water-impermeable and germination difficult. Here, we analyzed the morphoanatomical traits and germination properties of R. scandens seeds. To identify ideal seed propagation conditions, we immersed R. scandens seeds in sulfuric acid for varying durations and subjected them to phytohormone (gibberellic acid A3 and fluridone) and a cold stratification (CS) (5 °C) treatment after endocarp removal (ER). The R. scandens stony seeds did not increase in mass by ≥25.0%. Following ER, the seed mass increased by ≥50.0% with water absorption when compared to the initial dry mass. Seed surfaces showed damage and cracks through scarification after 1 h of immersion in sulfuric acid, failing to germinate. A combination of ER, phytohormone treatment, and CS improved seed germination compared to ER alone (26.0 ± 5.3%). Overall, R. scandens seeds showed a dispersal with a hard endocarp from the parent plant, and a pre-treatment with ER, phytohormones, and CS was required for effective seed propagation. Full article

Prunus spachiana (Lavallée ex Ed.Otto) Kitam. f. ascendens (Makino) Kitam leaves exert natural anti-inflammatory effects by inhibiting nitric oxide formation. P. spachiana flowers bloom earlier than other Prunus spp. and thus could serve as a valuable resource for the horticulture and pharmaceutical industries. However, its seed dormancy class and germination traits remain uncharacterized. Thus, this study aimed to characterize the seed dormancy and germination of P. spachiana. Imbibition, phenological, and move-along experiments were performed, and the effects of H₂SO₄ treatment, hormone soaking, warm/cold stratification, and endocarp removal on germination were explored. Observation revealed that ripe seeds of P. spachiana contain developed embryos and are water permeable. Radicle and shoot emergence began in March and April, respectively, under natural conditions in the year following production. No seed germination was observed after 30 days of incubation at 4, 15/6, 20/10, or 25/15 °C under light/dark conditions, indicating the physiological dormancy of the seeds. Germination increased with prolonged stratification and was affected by incubation temperature. Seed scarification by H₂SO₄ and soaking with gibberellic acid (GA₃) and fluridone were ineffective in breaking dormancy. However, GA₃ soaking of the seeds after endocarp removal effectively induced germination (100%). These results indicate that P. spachiana seeds exhibit intermediate physiological dormancy. Full article

Light provides seeds with information that is essential for the adjustment of their germination to the conditions that are most favorable for the successful establishment of the future seedling. The promotion of germination depends mainly on environmental factors, like temperature and light, as well as internal factors associated with the hormonal balance between gibberellins (GA) and abscisic acid (ABA), although other hormones such as auxins may act secondarily. While transcriptomic studies of light-germinating Arabidopsis thaliana seeds suggest that auxins and auxin transporters are necessary, there are still no functional studies connecting the activity of the auxin transporters in light-induced seed germination. In this study, we investigated the roles of two auxin efflux carrier (PIN3 and PIN7) proteins and one auxin influx (AUX1) carrier protein during Arabidopsis thaliana seed germination. By using next-generation sequencing (RNAseq), gene expression analyses, hormonal sensitivity assays, and the quantification of indole-3-acetic acid (IAA) levels, we assessed the functional roles of PIN3, PIN7, and AUX1 during light-induced seed germination. We showed that auxin levels are increased 24 h after a red-pulse (Rp). Additionally, we evaluated the germination responses of pin3, pin7, and aux1 mutant seeds and showed that PIN3, PIN7, and AUX1 auxin carriers are important players in the regulation of seed germination. By using gene expression analysis in water, fluridone (F), and ABA+F treated seeds, we confirmed that Rp-induced seed germination is associated with auxin transport, and ABA controls the function of PIN3, PIN7, and AUX1 during this process. Overall, our results highlight the relevant and positive role of auxin transporters in germinating the seeds of Arabidopsis thaliana. Full article

There is increasing interest in the production and consumption of tea (Camellia sinensis L.) processed from purple–leaved cultivar due to their high anthocyanin content and health benefits. However, how and why seasonal changes affect anthocyanin accumulation in young tea leaves still remains obscured. In this study, anthocyanin and abscisic acid (ABA) contents in young leaves of Zifuxing 1 (ZFX1), a cultivar with new shoots turning to purple in Wuyi Mountain, a key tea production region in China, were monitored over four seasons. Young leaves produced in September were highly purplish, which was accompanied with higher anthocyanin and ABA contents. Among the environmental factors, the light intensity in particular was closely correlated with anthocyanin and ABA contents. A shade experiment also indicated that anthocyanin content significantly decreased after 168 h growth under 75% shade, but ABA treatment under the shade conditions sustained anthocyanin content. To confirm the involvement of ABA in the modulation of anthocyanin accumulation, anthocyanin, carotenoids, chlorophyll, ABA, jasmonic acid (JA), and salicylic acid (SA) in the young leaves of four cultivars, including ZFX1, Zijuan (ZJ), wherein leaves are completely purple, Rougui (RG) and Fudingdabaicha (FDDB) wherein leaves are green, were analyzed, and antioxidant activities of the leaf extracts were tested. Results showed that ABA, not other tested hormones, was significantly correlated with anthocyanin accumulation in the purple–leaved cultivars. Cultivars with higher anthocyanin contents exhibited higher antioxidant activities. Subsequently, ZFX1 plants were grown under full sun and treated with ABA and fluridone (Flu), an ABA inhibitor. ABA treatment elevated anthocyanin level but decreased chlorophyll contents. The reverse was true to those treated with Flu. To pursue a better understanding of ABA involvement in anthocyanin accumulation, RNA–Seq was used to analyze transcript differences among ABA– or Flu–treated and untreated ZFX1 plants. Results indicated that the differentially expressed genes in ABA or Flu treatment were mainly ABA signal sensing and metabolism–related genes, anthocyanin accumulation-related genes, light–responsive genes, and key regulatory MYB transcription factors. Taking all the results into account, a model for anthocyanin accumulation in ZFX1 cultivar was proposed: high light intensity caused reactive oxygen stress, which triggered the biosynthesis of ABA; ABA interactions with transcription factors, such as MYB-enhanced anthocyanin biosynthesis limited chlorophyll and carotenoid accumulation; and transport of anthocyanin to vacuoles resulting in the young leaves of ZFX1 with purplish coloration. Further research is warranted to test this model. Full article

The plant-specific transcription factor family YABBY plays important roles in plant responses to biotic and abiotic stresses. Although the function of YABBY has been identified in many species, systematic analysis in lotus (Nelumbo nucifera) is still relatively lacking. The present study aimed to characterize all of the YABBY genes in lotus and obtain better insights into NnYABBYs in response to salt stress by depending on ABA signaling. Here, we identified nine YABBY genes by searching the whole lotus genome based on the conserved YABBY domain. Further analysis showed that these members were distributed on six different chromosomes and named from YABBY1 to YABBY9, which were divided into five subgroups, including YAB1, YAB2, YAB5, INO, and CRC. The analysis of cis-elements in promotors revealed that NnYABBYs could be involved in plant hormone signaling and plant responses to abiotic stresses. Quantitative real-time PCR (qRT-PCR) showed that NnYABBYs could be up-regulated or down-regulated by ABA, fluridone, and salt treatment. Subcellular localization indicated that NnYABBY4, NnYABBY5, and NnYABBY6 were mainly localized in the cell membrane and cytoplasm. In addition, the intrinsic trans-activity of NnYABBY was tested by a Y2H assay, which revealed that NnYABBY4, NnYABBY5, and NnYABBY6 are deprived of such a property. This study provided a theoretical basis and reference for the functional research of YABBY for the molecular breeding of lotus. Full article