Search Results (9)

Nitric oxide (NO) breaks a seed’s dormancy and stimulates germination by signaling. However, the key physiological metabolic pathways and molecular regulatory mechanisms are still unclear. Therefore, this study used physiological, transcriptomic, and metabolomics methods to analyze the key genes and metabolites involved in the NO regulation of plant embryo germination and their potential regulatory mechanisms. The physiological analysis results indicate that the appropriate concentration of NO increased the content of NO and hydrogen peroxide (H₂O₂) in cells, stimulated the synthesis of ethylene and jasmonic acid (JA), induced a decrease in abscisic acid (ABA) content, antagonistic to the gibberellin (GA₃) effect, and promoted embryo germination and subsequent seedling growth. However, the high concentrations of NO caused excessive accumulation of H₂O₂, destroyed the reactive oxygen species (ROS) balance, and inhibited embryo germination and seedling growth. The combined analysis of transcriptomics and metabolomics showed that the genes related to phenylpropanoid (phenylalanine ammonia-lyase, trans-cinnamate 4-monooxygenase, ferulate-5-hydroxylase, coniferyl-alcohol glucosyltransferase), and flavonoid synthesis (10 genes such as CHS) were significantly up-regulated during embryo germination. The high concentration of exogenous NO inhibited embryo germination by up-regulating the expression of 4-coumaric acid coenzyme A ligase (4CL) and negatively regulating the expression of flavonoid synthesis genes. This suggests that NO concentration-dependently regulates phenylpropanoid and flavonoid biosynthesis, thereby affecting ROS metabolism and hormone levels, and ultimately regulates the dormancy and germination of Sorbus pohuashanensis embryos. Full article

Polyethylene glycol can abrogate plant seed dormancy and alleviate salt–alkali stress damage to plants, but its role in embryonic dormancy abrogation and germination in Sorbus pohuashanensis is not yet clear. The mechanism by which polyethylene glycol promotes the release of embryonic dormancy may be related to the synthesis and metabolism of endogenous hormones, reactive oxygen species and reactive nitrogen. In this article, germination in indoor culture dishes was used, and the most suitable conditions for treating S. pohuashanensis embryos, with polyethylene glycol (PEG) and sodium carbonate (Na₂CO₃), were selected. Germination was observed and recorded, and related physiological indicators such as endogenous hormones, reactive oxygen species and reactive nitrogen were measured and analyzed to elucidate the mechanism of polyethylene glycol in alleviating salt–alkali stress in S. pohuashanensis embryos. The results showed that soaking seeds in 5% PEG for 5 days is the best condition to promote germination, which can increase the germination rate of embryos under salt–alkali stress by 1–2 times and improve indicators such as germination speed and the germination index. Polyethylene glycol led to an increase in gibberellin (GA), indole-3-acetic acid (IAA), ethylene (ETH), cytokinin (CTK), nitric oxide (NO), soluble protein and soluble sugar in the embryos under salt–alkali stress; increased activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), nitrate reductase (NR) and nitric oxide synthase (NOS) in the embryos; a reduction in the accumulation of abscisic acid (ABA), hydrogen peroxide (H₂O₂) and malondialdehyde (MDA). Therefore, it is suggested that the inhibitory effect of polyethylene glycol on the salt–alkali-stress-induced germination of S. pohuashanensis embryos is closely related to the response of endogenous hormones, reactive oxygen species and nitric oxide signalling. Full article

To investigate resource allocation and adaptation strategies of Sorbus spp. under different environment and soil conditions, four Sorbus L. species (Sorbus hupehensis C. K. Schneid, Sorbus pohuashanensis (Hance) Hedl, Sorbus discolor (Maxim.) Maxim, Sorbus koehneana C. K. Schneid) were selected as the study materials. Phenotypic traits including seed mass, fruit mass, and fruit colour were measured and analyzed. Linear Mixed-Effects Models were employed to analyze the associations between phenotypic traits and the environment, and the Maxent model was used to predict the potential distribution areas. Our study reveals that Sorbus spp. tend to prioritize seed production to increase their survival ability in nutrient-poor environments, while they tend to lean towards fruit production in nutrient-rich environments. Specifically, S. pohuashanensis has fruit skin rich in carotenoids and anthocyanins, with the degree of fruit colouration being positively correlated with the environmental suitability. However, the other three spp. demonstrate the opposite pattern. S. pohuashanensis is found to be most suitable for growth in mountainous areas around 40° N, and it is adapted to low temperatures. S. hupehensis prefers warm regions and is distributed in southern Shanxi, while S. discolor has a wider range of adaptability. These results provide a scientific basis for the protection and rational utilization of Sorbus spp. by elucidating their ecological adaptation abilities. Full article

Sorbus pohuashanensis (Hance) Hedl. is an important forestry species valued for its ornamental, medicinal, and ecological properties. Polyploidy breeding is an important method of germplasm innovation; however, polyploidy induction and phenotypic variation caused by chromosome doubling in S. pohuashanensis are poorly understood. In this study, S. pohuashanensis seeds were used to explore the effects of different colchicine concentrations, cold stratification times, and seeds from different sources on polyploidy induction. Ploidy levels of the regenerated plants were determined by flow cytometry. The results showed that the tetraploid induction effect of S. pohuashanensis seeds was significantly affected by colchicine concentration, and the highest tetraploid induction rate of 24.75% was achieved by immersion in 0.2% (w/v) colchicine for 48 h. After 2 years of induction, 77 tetraploid plants were obtained. Compared to diploids, tetraploid plants showed significant variations in plant height, leaf morphology (apical leaflet width, middle leaflet width), and diameter of the middle petiole. The stomatal size and chloroplast number increased with chromosome doubling whereas the stomatal number and density decreased. In addition, significant differences in the percentage of sunburn associated with ploidy changes were observed. This study provides a technique for tetraploid induction of S. pohuashanensis seeds, showing the variation in traits caused by polyploidization and the effect of chromosome doubling on sunburn resistance. Tetraploidy induction provides a new direction for S. pohuashanensis germplasm innovation. Full article

Saline-alkali stress is a major environmental stress affecting the growth and development of plants such as Sorbus pohuashanensis. Although ethylene plays a crucial role in plant response to saline-alkaline stress, its mechanism remains elusive. The mechanism of action of ethylene (ETH) may be related to the accumulation of hormones, reactive oxygen species (ROS), and reactive nitrogen species (RNS). Ethephon is the exogenous ethylene donor. Therefore, for the present study we initially used different concentrations of ethephon (ETH) to treat S. pohuashanensis embryos and identified the best treatment concentration and method to promote the release of dormancy and the germination of S. pohuashanensis embryos. We then analyzed the physiological indexes, including endogenous hormones, ROS, antioxidant components, and reactive nitrogen, in embryos and seedlings to elucidate the mechanism via which ETH manages stress. The analysis showed that 45 mg/L was the best concentration of ETH to relieve the embryo dormancy. ETH at this concentration improved the germination of S. pohuashanensis by 183.21% under saline-alkaline stress; it also improved the germination index and germination potential of the embryos. Further analysis revealed that ETH treatment increased the levels of 1-aminocyclopropane-1-carboxylic acid (ACC), gibberellin (GA), soluble protein, nitric oxide (NO), and glutathione (GSH); increased the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), nitrate reductase (NR), and nitric oxide synthase (NOS); and decreased the levels of abscisic acid (ABA), hydrogen peroxide (H₂O₂), superoxide anion, and malondialdehyde (MDA) of S. pohuashanensis under saline-alkali stress. These results indicate that ETH mitigates the inhibitory effects of saline-alkali stress and provides a theoretical basis by which to establish precise control techniques for the release of seed dormancy of tree species. Full article

Small heat shock proteins (HSP20s) are a significant factor in plant growth and development in response to abiotic stress. In this study, we investigated the role of HSP20s’ response to the heat stress of Sorbus pohuashanensis introduced into low-altitude areas. The HSP20 gene family was identified based on the genome-wide data of S. pohuashanensis, and the expression patterns of tissue specificity and the response to abiotic stresses were evaluated. Finally, we identified 38 HSP20 genes that were distributed on 16 chromosomes. Phylogenetic analysis of HSP20s showed that the closest genetic relationship to S. pohuashanensis (SpHSP20s) is Malus domestica, followed by Populus trichocarpa and Arabidopsis thaliana. According to phylogenetic analysis and subcellular localization prediction, the 38 SpHSP20s belonged to 10 subfamilies. Analysis of the gene structure and conserved motifs indicated that HSP20 gene family members are relatively conserved. Synteny analysis showed that the expansion of the SpHSP20 gene family was mainly caused by segmental duplication. In addition, many cis-acting elements connected with growth and development, hormones, and stress responsiveness were found in the SpHSP20 promoter region. Analysis of expression patterns showed that these genes were closely related to high temperature, drought, salt, growth, and developmental processes. These results provide information and a theoretical basis for the exploration of HSP20 gene family resources, as well as the domestication and genetic improvement of S. pohuashanensis. Full article

Plant stress memory can provide the benefits of enhanced protection against additional stress exposure. Here, we aimed to explore the responses of recurrent and non-recurrent yeast extract (YE) stresses in Sorbus pohuashanensis suspension cells (SPSCs) at metabolomics and transcriptional levels. Biochemical analyses showed that the cell wall integrity and antioxidation capacity of SPSCs in the pretreated group were evidently improved. Metabolic analysis showed that there were 39 significantly altered metabolites in the pretreated group compared to the non-pretreated group. Based on the transcriptome analysis, 219 differentially expressed genes were obtained, which were highly enriched in plant–pathogen interaction, circadian rhythm–plant, oxidative phosphorylation, and phenylpropanoid biosynthesis. Furthermore, the correlation analysis of the transcriptome and metabolome data revealed that phenylpropanoid biosynthesis involved in the production of biphenyl phytoalexins may play a critical role in the memory response of SPSC to YE, and the key memory genes were also identified, including PAL1, BIS1, and BIS3. Collectively, the above results demonstrated that the memory responses of SPSC to YE were significant in almost all levels, which would be helpful for better understanding the adaptation mechanisms of medicinal plants in response to biotic stress, and laid a biotechnological foundation to accumulate favorable antimicrobial drug candidates from plant suspension cells. Full article

Biphenyls are unique phytoalexins de novo synthesized in plants in response to pathogen attack. These compounds are found in Maloideae, a subfamily of the Rosaceae. The anti-microbial activities of biphenyls have been reported in a number of studies and they appear to represent an important defense strategy against pathogens common in the Maloideae, such as species in Malus, Pyrus, Sorbus, and Chaenomeles. Here, cell suspension cultures of Sorbus pohuashanensis were established to study biphenyl phytoalexins formation after yeast extract (YE) treatment. An ultra-performance liquid chromatography (UPLC) method coupled with quadrupole time of flight mass spectrometry (Q-TOF-MS) LC−MS/MS was applied to determine the time course of these biphenyl biomarkers accumulation in YE-treated S. pohuashanensis suspension cells. The results of quantitative analyses show the content of Noraucuparin, 2′-Hydroxyaucuparin, and their glycosides initially increased, then decreased over time. The Noraucuparin content reached its highest (225.76 μg·g⁻¹) at 18 h after treatment, 6 hours earlier than that of Noraucuparin 5-O-β-d-glucopyranoside. The content of 2′-Hydroxyaucuparin reached its highest (422.75 μg·g⁻¹) at 30 h after treatment, also earlier than that of its glycoside. The understanding of phytoalexin metabolism in this study may provide a basis for improving Maloideae resistance to pathogens. Full article

In order to find new sources of natural antioxidants, the antioxidant potential of 70% methanolic extracts from the inflorescences and leaves of 16 species from the genus Sorbus s.s. was evaluated using two complementary in vitro test systems: the DPPH (2,2-diphenyl-1-picrylhydrazyl) radical-scavenging assay and the AAPH [2,2¢-azobis-(2-amidinopropane)dihydrochloride]-induced linoleic acid (LA) peroxidation test. The radical-scavenging capacities of the extracts towards the DPPH radical were in the range of 0.25-0.86 millimolar Trolox^® equivalents/g dry weight. They were significantly correlated (r = -0.8089, p < 0.001) with the results of the LA-peroxidation test, indicating the Sorbus extracts to be universal antioxidants. Significant linear correlations were also found between the different antioxidant potentials and total phenolic contents as estimated by the Folin-Ciocalteu method and further verified by serial determinations of proanthocyanidins, chlorogenic acid isomers and flavonoids (çrêin the range of 0.71-0.95, p < 0.001). Cluster analysis of the data matrix identified the ten samples (inflorescences of S. aucuparia, S. pohuashanensis, S. decora, S. koehneana, S. commixta, S. gracilis, and S. sitchensis, and the leaves of S. wilfordii, S. pogonopetala, and S. gracilis) exhibiting the highest antioxidant activity and total phenolic levels and therefore the greatest potential as effective sources for natural health products. Full article