MYB Transcription Factors and Its Regulation in Secondary Cell Wall Formation and Lignin Biosynthesis during Xylem Development.

The secondary wall is the main part of wood and is composed of cellulose, xylan, lignin, and small amounts of structural proteins and enzymes. Lignin molecules can interact directly or indirectly with cellulose, xylan and other polysaccharide molecules in the cell wall, increasing the mechanical strength and hydrophobicity of plant cells and tissues and facilitating the long-distance transportation of water in plants. MYBs (v-myb avian myeloblastosis viral oncogene homolog) belong to one of the largest superfamilies of transcription factors, the members of which regulate secondary cell-wall formation by promoting/inhibiting the biosynthesis of lignin, cellulose, and xylan. Among them, MYB46 and MYB83, which comprise the second layer of the main switch of secondary cell-wall biosynthesis, coordinate upstream and downstream secondary wall synthesis-related transcription factors. In addition, MYB transcription factors other than MYB46/83, as well as noncoding RNAs, hormones, and other factors, interact with one another to regulate the biosynthesis of the secondary wall. Here, we discuss the biosynthesis of secondary wall, classification and functions of MYB transcription factors and their regulation of lignin polymerization and secondary cell-wall formation during wood formation.

miR-30a-5p inhibits osteogenesis and promotes periodontitis by targeting Runx2.

BACKGROUND: Periodontitis is the most extensive chronic inflammatory bone resorption disease. MiRNAs offer a potential way for potential therapy. Indeed, miR-30a-5p had an increasing expression in periodontitis gingivae, but whether it promotes osteogenesis and inhibits inflammation remains unknown. METHODS: Periodontitis model was exhibited by wire ligation and verified by micro-CT and HE staining; qPCR was used to detect the expression of miR-30a-5p; miR-30a-5p inhibitors and mimics were transfected into MC3T3-E1 cell line by lipofectamine 3000; The dual luciferase reporter gene experiment and RIP experiment were used to detect the relationship between miR-30a-5p and Runx2; Rescue experiment was used to verify the relationship between miR-30a-5p and Runx2. RESULTS: Periodontitis model was exhibited successfully and miR-30a-5p was overexpressed at the bone and gingival tissues of this model. miR-30a-5p inhibitors not only promoted the osteogenesis but also relieved inflammation. Runx2 is a target of miR-30a-5p by dual luciferase reporter gene experiment and RIP experiment. Rescue experiments revealed that miR-30a-5p inhibitors would promote osteogenesis and relieve inflammation by targeting Runx2 in inflammation of MC3T3-E1 cell line. CONCLUSIONS: That all suggested that miR-30a-5p-mediated-Runx2 provided a novel understanding of mechanism of periodontitis.

Histone Deacetylase HDT1 is Involved in Stem Vascular Development in Arabidopsis.

Histone acetylation and deacetylation play essential roles in eukaryotic gene regulation. HD2 (HD-tuins) proteins were previously identified as plant-specific histone deacetylases. In this study, we investigated the function of the HDT1 gene in the formation of stem vascular tissue in Arabidopsis thaliana. The height and thickness of the inflorescence stems in the hdt1 mutant was lower than that of wild-type plants. Paraffin sections showed that the cell number increased compared to the wild type, while transmission electron microscopy showed that the size of individual tracheary elements and fiber cells significantly decreased in the hdt1 mutant. In addition, the cell wall thickness of tracheary elements and fiber cells increased. We also found that the lignin content in the stem of the hdt1 mutants increased compared to that of the wild type. Transcriptomic data revealed that the expression levels of many biosynthetic genes related to secondary wall components, including cellulose, lignin biosynthesis, and hormone-related genes, were altered, which may lead to the altered phenotype in vascular tissue of the hdt1 mutant. These results suggested that HDT1 is involved in development of the vascular tissue of the stem by affecting cell proliferation and differentiation.

Effect of cadmium and polystyrene nanoplastics on the growth, antioxidant content, ionome, and metabolism of dandelion seedlings.

Cadmium is the most prevalent heavy metal pollutant in the environment and can be readily combined with micro/nanoplastics (M/NPs) to change their bioavailability. In the present study, we comprehensively investigated the effect of polystyrene (PS) NPs on dandelion plants grown under Cd stress. Cd exposure significantly inhibited the growth of dandelion seedlings, resulting in a decrease in seedling elongation from 26.47% to 28.83%, a reduction in biomass from 29.76% to 54.14%, and an exacerbation of lipid peroxidation and oxidative stress. The interaction between PS NPs and Cd resulted in the formation of larger aggregates, with the Cd bioavailability reduced by 12.56%. PS NPs affect ion absorption by regulating reactive oxygen production and increasing superoxide dismutase activity, thereby mitigating the adverse effects of Cd. PSCd aggregates induced significant changes in the metabolic profiles of dandelions, affecting various carbohydrates related to alcohols, organic acids, sugar metabolism, and bioactive components related to flavonoids and phenolic acids. Furthermore, based on a structural equation model, exposure to PSCd activated oxidative stress and nutrient absorption, thereby affecting plant growth and Cd accumulation. Overall, our study provides valuable insights into the effects of PS NPs on Cd bioavailability, accumulation, and plant growth, which are crucial for understanding the food safety of medicinal plants in a coexistence environment.

Effects of polyethylene and biodegradable microplastics on the physiology and metabolic profiles of dandelion.

Biodegradable plastics, such as poly(butylene adipate terephthalate) (PBAT) and polylactic acid (PLA), are potential alternatives to conventional polyethylene (PE), both of which are associated with the production of microplastics (MPs). However, the toxicity of these compounds on medicinal plants and their differential effects on plant morphophysiology remain unclear. This study supplemented soils with MPs sized at 200 µm at a rate of 1% w/w and incubated them for 50 days to investigate the impact of MPs on the growth and metabolites of dandelion (Taraxacum mongolicum Hand.-Mazz.). The results demonstrated that the investigated MPs decreased the growth of dandelion seedlings, induced oxidative stress, and altered the activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase). Based on the comprehensive toxicity assessment results, the ecological toxicity was in the following order: PE MPs > PBAT MPs > PLA MPs. Metabolomics analyses revealed metabolic reprogramming in dandelion plants, leading to the enrichment of numerous differentially accumulated metabolites (DAMs) in the leaves. These pathways include carbohydrate metabolism, energy metabolism, and biosynthesis of secondary metabolites, suggesting that dandelions respond to MP stress by enhancing the activity of sugar, organic acid, and amino acid metabolic pathways. In addition, phenolic acids and flavonoids are critical for maintaining the balance in the antioxidant defense system. Our results provide substantial insights into the toxicity of biodegradable MPs to plants and shed light on plant defense and adaptation strategies. Further assessment of the safety of biodegradable MPs in terrestrial ecosystems is essential to provide guidance for environmentally friendly management.

Transcriptome mechanisms of dandelion under stress of polystyrene and dibutyl phthalate and quantitative tracing of nanoplastics.

Polystyrene nanoplastics (PS NPs) and dibutyl phthalate (DBP) pollution pose significant risks to ecosystems and contribute to bioaccumulation in plants, yet uptake mechanisms and combined toxicity are poorly understood. We used fluorescent labeling and europium-doped PS NPs to reveal the absorption and translocation of NPs by dandelions and conducted a transcriptomic analysis under PS NPs and DBP exposure. The results indicated that NPs are transported horizontally through the intercellular gaps at the root tips and primary root-lateral root junctions via the apoplastic pathway, followed by longitudinal transport through the xylem vessels under the transpiration stream. Co-exposure significantly reduced the bioconcentration factors of dandelion seedlings by 113 % but increased the NP transfer factors by 33.8 %. Transcriptomic analysis confirmed that exposure to PS NPs and DBP activated gene expression in dandelion shoots and roots. The differentially expressed genes were primarily involved in the photosynthesis, plant hormone signal transduction, and phenylpropanoid biosynthesis pathways. Weighted gene co-expression network analysis identified key genes and hub transcription factors playing crucial roles in regulating dandelion's response to combined stress. Our study provides new insights into the plant toxicity mechanism underlying the interaction between PS NPs and DBP, highlighting the adverse effects of the combined pollution on plant health.

Effect of super activated platelet lysate on cell proliferation, repair and osteogenesis.

BACKGROUND: Platelet lysate (PL) is considered as an alternative to fetal bovine serum (FBS) and facilitates the proliferation and differentiation of mesenchymal cells. OBJECTIVE: The aim of this study is to explore whether super activated platelet lysate (sPL), a novel autologous platelet lysate, has the ability to inhibit inflammation and promote cell proliferation, repair and osteogenesis as a culture medium. METHODS: Different concentrations of sPL on human fetal osteoblastic 1.19 cell line (hFOB1.19) proliferation and apoptotic repair were investigated; And detected proliferative capacity, inflammatory factor expressions and osteogenic differentiation of human dental pulp cells (hDPCs) stimulated by LPS under 10% FBS and 5% sPL mediums. RESULTS: sPL promoted hFOB1.19 proliferation and had repairing effects on apoptotic cells. No significant difference in proliferation and IL-1α, IL-6 and TNF-α expressions of hDPCs in FBS and sPL medium stimulated by LPS. hDPCs in sPL osteogenic medium had higher osteogenic-related factor expressions and ALP activity. LPS promoted osteogenic-related factor expressions and ALP activity of hDPCs in FBS osteogenic medium, but opposite effect showed in sPL medium. CONCLUSION: sPL promoted osteoblast proliferation and had restorative effects. Under LPS stimulation, sPL did not promote hDPCs proliferation or inhibit inflammation. sPL promotes osteogenic differentiation of hDPCs.

Phytotoxicity assessment of dandelion exposed to microplastics using membership function value and integrated biological response index.

Microplastic (MP) pollution is a critical environmental issue. Dandelions could be used as a biomonitor of environmental pollution. However, the ecotoxicology of MPs in dandelions remains unclear. Therefore, the toxic effects of polyethylene (PE), polystyrene (PS), and polypropylene (PP) at concentrations of 0, 10, 100, and 1000 mg L-1 on the germination and early seedling growth of dandelion were investigated. PS and PP inhibited seed germination and decreased root length and biomass while promoting membrane lipid peroxidation, increasing O2•-, H2O2, SP, and proline contents, and enhancing the activities of SOD, POD, and CAT. Principal component analysis (PCA) and membership function value (MFV) analysis indicated that PS and PP could be more harmful than PE in dandelion, especially at 1000 mg L-1. In addition, according to the integrated biological response (IBRv2) index analysis, O2•-, CAT, and proline were sensitive biomarkers of dandelion contamination by MPs. Here we provide evidence that dandelion has the potential to be a biomonitor to assess the phytotoxicity of MPs pollution, especially PS with high toxicity. Meanwhile, we believe that if dandelion is to be used as a biomonitor for MPs, attention should also be paid to the practical safety of dandelion.

Revealing the metabolomics and biometrics underlying phytotoxicity mechanisms for polystyrene nanoplastics and dibutyl phthalate in dandelion (Taraxacum officinale).

Micro/nanoplastics (M/NPs) and phthalates (PAEs) are emerging pollutants. Polystyrene (PS) MPs and dibutyl phthalate (DBP) are typical MPs and PAEs in the environment. However, how dandelion plants respond to the combined contamination of MPs and PAEs remains unclear. In this study, we evaluated the individual and combined effects of PS NPs (10 mg L-1) and DBP (50 mg L-1) on dandelion (Taraxacum officinale) seedlings. The results showed that compared to control and individual-treated plants, coexposure to PS NPs and DBP significantly affected plant growth, induced oxidative stress, and altered enzymatic and nonenzymatic antioxidant levels of dandelion. Similarly, photosynthetic attributes and chlorophyll fluorescence kinetic parameters were significantly affected by coexposure. Scanning electron microscopy (SEM) results showed that PS particles had accumulated in the root cortex of the dandelion. Metabolic analysis of dandelion showed that single and combined exposures caused the plant's metabolic pathways to be profoundly reprogrammed. As a consequence, the synthesis and energy metabolism of carbohydrates, amino acids, and organic acids were affected because galactose metabolism, the citric acid cycle, and alanine, aspartic acid and glutamic acid metabolism pathways were significantly altered. These results provide a new perspective on the phytotoxicity and environmental risk assessment of MPs and PAEs in individual or coexposures.

Effects of Super-Activated Platelet Lysate on Early Healing of Tooth Extraction Sockets in Rats.

Purpose: To evaluate the effect of super-activated platelet lysate (sPL) on wound healing of tooth extraction sockets in rats. Methods: Rat models of the tooth extraction socket were established. Thirty-six rats were divided into control and sPL groups and sacrificed on days 7, 14, and 28 after tooth extraction. Bone formation in tooth extraction sockets were observed by microscopic computed tomography (micro-CT) and hematoxylin and eosin (HE) staining; osteoprotegerin (OPG), receptor activator of nuclear factor kappa-Β ligand (RANKL), interleukin 6(IL-6), and tumor necrosis factor-alpha (TNF-α) proteins were detected by immunohistochemistry; and chemokine and osteogenic gene expressions were detected by polymerase chain reaction (PCR). Results: sPL accelerated soft tissue wound healing in the extraction socket of rats. Micro-CT showed that the amount of bone formation and bone volume fraction were higher in the sPL group than the control 14 days after extraction. HE staining showed promotion of the formation of bony trabeculae by sPL in the apical third of the extraction socket 7 days after extraction and more mature and organized bony trabeculae in the sPL group than the control 14 days after extraction; mature bony trabeculae filling most of the fossa with lesser bone porosity in the socket in the sPL group than the control 28 days after extraction. Immunohistochemistry showed that sPL induced OPG expressions 7 and 14 days after tooth extraction but did not affect the RANKL expression while transiently promoting the IL-6 expression 7 days after extraction. PCR showed that sPL promoted chemokine expressions 7 and 14 days after extraction. The expressions of osteogenesis-related factors were higher in the sPL group than the control 7 and 28 days after extraction, while the opposite trend was observed 14 days after extraction. Conclusion: sPL has a transient pro-inflammatory effect and promotes soft tissue healing and bone formation during early wound healing of extraction sockets in rats.

PtomtAPX is an autonomous lignification peroxidase during the earliest stage of secondary wall formation in Populus tomentosa Carr.

At present, a cooperative process hypothesis is used to explain the supply of enzyme (class III peroxidases and/or laccases) and substrates during lignin polymerization. However, it remains elusive how xylem cells meet the needs of early lignin rapid polymerization during secondary cell wall formation. Here we provide evidence that a mitochondrial ascorbate peroxidase (PtomtAPX) is responsible for autonomous lignification during the earliest stage of secondary cell wall formation in Populus tomentosa. PtomtAPX was relocated to cell walls undergoing programmed cell death and catalysed lignin polymerization in vitro. Aberrant phenotypes were caused by altered PtomtAPX expression levels in P. tomentosa. These results reveal that PtomtAPX is crucial for catalysing lignin polymerization during the early stages of secondary cell wall formation and xylem development, and describe how xylem cells provide autonomous enzymes needed for lignin polymerization during rapid formation of the secondary cell wall by coupling with the programmed cell death process.

PtrLAC16 plays a key role in catalyzing lignin polymerization in the xylem cell wall of Populus.

Plant laccases have been proposed to participate in lignin biosynthesis. However, there is no direct evidence that individual laccases in Populus can polymerize lignin monomers and alter cell wall structure. Here, a Populus laccase, PtrLAC16, was expressed and purified in a eukaryotic system. Enzymatic analysis of PtrLAC16 showed that it could polymerize lignin monomers in vitro. PtrLAC16 preferred sinapyl alcohol, and this preference is associated with an altered S/G ratio in transgenic Populus lines. PtrLAC16 was localized exclusively in the cell walls of stem vascular tissue, and a reduction in PtrLAC16 expression led to a significant decrease in lignin content and altered cell wall structure. There was a direct correlation between the inhibition of PtrLAC16 expression and structural changes in the stem cell wall of Populus. This study provides direct evidence that PtrLAC16 plays a key role in the polymerization of lignin monomers, especially for sinapyl lignin, and affects the formation of xylem cell walls in Populus.

[Studies on purification of total glycosides of paeony (TGP) from Paeonia lactiflora by ethanol gradient combined with resin processing].

OBJECTIVE: To study the purification technology of TGP from Paeonia lactiflora by ethanol gradient combined with resin processing and determine the optimum technological conditions and parameters. METHODS: Using orthogonal test design to investigate the effect of ethanol gradient treatment on the content of TGP. Moreover, from the static and dynamic adsorption nine types of macroporous adsorption resin were evaluated to select the best resin type and the optimum separation and purification conditions. RESULTS: The best technology of Paeonia lactiflora ethanol precipitation was concentration of 1 g crude drug/mL precipitated by 95% ethanol to 90% concentration and then frozen for 10 h. HPD300 resin was the optimal model for the separation and purification of TGP from Paeonia lactiflora, with 5BV of 50% ethanol eluenting and the ratio of herb to resin was 2:1 . CONCLUSION: This technology is suitable and advanced for industry production and it is simple and convenient, rapid, accurate, etc.