Non-coding RNAs: targets for Chinese herbal medicine in treating myocardial fibrosis.

Cardiovascular diseases have become the leading cause of death in urban and rural areas. Myocardial fibrosis is a common pathological manifestation at the adaptive and repair stage of cardiovascular diseases, easily predisposing to cardiac death. Non-coding RNAs (ncRNAs), RNA molecules with no coding potential, can regulate gene expression in the occurrence and development of myocardial fibrosis. Recent studies have suggested that Chinese herbal medicine can relieve myocardial fibrosis through targeting various ncRNAs, mainly including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). Thus, ncRNAs are novel drug targets for Chinese herbal medicine. Herein, we summarized the current understanding of ncRNAs in the pathogenesis of myocardial fibrosis, and highlighted the contribution of ncRNAs to the therapeutic effect of Chinese herbal medicine on myocardial fibrosis. Further, we discussed the future directions regarding the potential applications of ncRNA-based drug screening platform to screen drugs for myocardial fibrosis.

Genome-Wide Analysis of Nuclear factor-YC Genes in the Tea Plant (Camellia sinensis) and Functional Identification of CsNF-YC6.

Nuclear factor Y (NF-Y) is a class of transcription factors consisting of NF-YA, NF-YB and NF-YC subunits, which are widely distributed in eukaryotes. The NF-YC subunit regulates plant growth and development and plays an important role in the response to stresses. However, there are few reports on this gene subfamily in tea plants. In this study, nine CsNF-YC genes were identified in the genome of 'Longjing 43'. Their phylogeny, gene structure, promoter cis-acting elements, motifs and chromosomal localization of these gene were analyzed. Tissue expression characterization revealed that most of the CsNF-YCs were expressed at low levels in the terminal buds and at relatively high levels in the flowers and roots. CsNF-YC genes responded significantly to gibberellic acid (GA) and abscisic acid (ABA) treatments. We further focused on CsNF-YC6 because it may be involved in the growth and development of tea plants and the regulation of response to abiotic stresses. The CsNF-YC6 protein is localized in the nucleus. Arabidopsis that overexpressed CsNF-YC6 (CsNF-YC6-OE) showed increased seed germination and increased root length under ABA and GA treatments. In addition, the number of cauline leaves, stem lengths and silique numbers were significantly higher in overexpressing Arabidopsis lines than wild type under long-day growth conditions, and CsNF-YC6 promoted primary root growth and increased flowering in Arabidopsis. qPCR analysis showed that in CsNF-YC6-OE lines, flowering pathway-related genes were transcribed at higher levels than wild type. The investigation of the CsNF-YC gene has unveiled that CsNF-YC6 plays a pivotal role in plant growth, root and flower development, as well as responses to abiotic stress.

Anti-atherosclerosis mechanisms associated with regulation of non-coding RNAs by active monomers of traditional Chinese medicine.

Atherosclerosis is the leading cause of numerous cardiovascular diseases with a high mortality rate. Non-coding RNAs (ncRNAs), RNA molecules that do not encode proteins in human genome transcripts, are known to play crucial roles in various physiological and pathological processes. Recently, researches on the regulation of atherosclerosis by ncRNAs, mainly including microRNAs, long non-coding RNAs, and circular RNAs, have gradually become a hot topic. Traditional Chinese medicine has been proved to be effective in treating cardiovascular diseases in China for a long time, and its active monomers have been found to target a variety of atherosclerosis-related ncRNAs. These active monomers of traditional Chinese medicine hold great potential as drugs for the treatment of atherosclerosis. Here, we summarized current advancement of the molecular pathways by which ncRNAs regulate atherosclerosis and mainly highlighted the mechanisms of traditional Chinese medicine monomers in regulating atherosclerosis through targeting ncRNAs.

Epigallocatechin-3-Gallate Alleviates Liver Oxidative Damage Caused by Iron Overload in Mice through Inhibiting Ferroptosis.

Ferroptosis, a form of regulated cell death, has been widely explored as a novel target for the treatment of diseases. The failure of the antioxidant system can induce ferroptosis. Epigallocatechin-3-Gallate (EGCG) is a natural antioxidant in tea; however, whether EGCG can regulate ferroptosis in the treatment of liver oxidative damage, as well as the exact molecular mechanism, is unknown. Here, we discovered that iron overload disturbed iron homeostasis in mice, leading to oxidative stress and damage in the liver by activating ferroptosis. However, EGCG supplementation alleviated the liver oxidative damage caused by iron overload by inhibiting ferroptosis. EGCG addition increased NRF2 and GPX4 expression and elevated antioxidant capacity in iron overload mice. EGCG administration attenuates iron metabolism disorders by upregulating FTH/L expression. Through these two mechanisms, EGCG can effectively inhibit iron overload-induced ferroptosis. Taken together, these findings suggest that EGCG is a potential ferroptosis suppressor, and may be a promising therapeutic agent for iron overload-induced liver disease.

N6-methyladenosine-associated prognostic pseudogenes contribute to predicting immunotherapy benefits and therapeutic agents in head and neck squamous cell carcinoma.

Rationale: N6-methyladenosine (m6A) is involved in critical cancerous processes. Pseudogenes play various roles in carcinogenesis and progression. However, the functional roles of m6A-associated pseudogenes in head and neck squamous cell carcinoma (HNSCC) are largely unknown. Methods: We systematically analyzed the mRNA profile of 24 m6A regulators and 13931 pseudogenes from The Cancer Genome Atlas HNSCC dataset and ultimately identified 10 m6A-associated prognostic pseudogenes, which were validated in the Gene Expression Omnibus and our hospital datasets. Based on the risk score of m6A-associated pseudogenes, comprehensive analytical frameworks and experimental validation were implemented among pseudogene-defined low-/high-risk subtypes. Results: Here, we found expression pattern of m6A-associated pseudogenes was significantly associated with infiltrating immune cell compositions, and the expression of antitumor immune response markers, including T cell exhaustion, antigen presentation, interferon, and kinase genes. The m6A-associated pseudogenes, which had dramatic m6A peaks and higher m6A levels, could regulate the expression of targeted immune-involved genes through miRNAs. We experimentally validate the oncogene PDIA3P1, and tumor-suppressor RRN3P3, which promote the RNA and protein expression of their targeted immune-involved genes AKT1 and EZH2 via miR-34a-5p and miR-26b-5p, respectively. Moreover, HNSCC patients in the high-risk subtype could benefit more from immune checkpoint inhibitors therapy. Furthermore, doxorubicin and topotecan were considered to hold the most promising therapeutic potential robustly in silico evidence and in vitro experiments for HNSCC patients in the high-risk subtype. Conclusions: Our discovery revealed that the 10 m6A-associated prognostic pseudogenes significantly contribute to predicting immunotherapy benefits and therapeutic agents, which might bring some potential implications for both immunotherapy and chemotherapy in HNSCC.

Microbial Community Analysis in Sichuan South-road Dark Tea Piled Center at Pile-Fermentation Metaphase and Insight Into Organoleptic Quality Development Mediated by Aspergillus niger M10.

Microbes are critical in the Sichuan South-road Dark Tea (SSDT) organoleptic quality development during pile-fermentation. Piled tea center at fermenting metaphase is crucial for the conversion of its quality components. In this study, we investigated the microbial community of piled SSDT center below the stacked tea surface of 15 cm (SSDTB), 50 cm (SSDTX), and 85 cm (SSDTH) on the second turning time of pile-fermentation, respectively. Results showed that SSDTH and SSDTB had a higher similarity in the microbial community. Pantoea (36.8%), Klebsiella (67.7%), and Aspergillus (35.3%) were the most abundant in SSDTH, SSDTB, and SSDTX, respectively. We found 895 species were common among all samples, but 86, 293, and 36 species were unique to SSDTB, SSDTX, and SSDTH, respectively. Aspergillus niger showed high co-occurrence and was positively correlated with numerous microbes in SSDT samples, and Aspergillus niger M10 isolated from SSDTX was excellent at enhancing soluble sugar (SS), amino acids (AAs), theaflavin (TF), and thearubigins (TR) contents, while decreasing catechin (Cat), tea polyphenols (TPs)/AA, Caf/SS, Cat/SS, TPs/SS, and (TPs + Caf)/SS levels in AM10 post-fermentation, as compared with the control. Moreover, it also produced a noticeable difference in the CIELab parameters in dried, liquor, and infused tea colors between AM10 and control during fermentation. When it was further inoculated on differential mediums, we detected glycoside hydrolases, namely, ß-glucosidase, mannosidase, pectinase, cellulase, amylase, and α-galactosidase being secreted by Aspergillus niger M10. Taken together, SSDXT presented a more unique microbial community. Aspergillus niger M10 probably improved the sweet and mellow taste, and the yellow brightness and red color of SSDT during fermentation. It also provided new insights into the microbial profile and organoleptic quality development mechanism of SSDT during pile-fermentation.

Genetic analysis of the early bud flush trait of tea plants (Camellia sinensis) in the cultivar 'Emei Wenchun' and its open-pollinated offspring.

The timing of bud flush (TBF) in the spring is one of the most important agronomic traits of tea plants (Camellia sinensis). In this study, we designed an open-pollination breeding program using 'Emei Wenchun' (EW, a clonal tea cultivar with extra-early TBF) as a female parent. A half-sib population (n = 388) was selected for genotyping using specific-locus amplified fragment sequencing. The results enabled the identification of paternity for 294 (75.8%) of the offspring, including 11 (2.8%) from EW selfing and 217 (55.9%) assigned to a common father, 'Chuanmu 217' (CM). The putative EW × CM full-sib population was used to construct a linkage map. The map has 4244 markers distributed in 15 linkage groups, with an average marker distance of 0.34 cM. A high degree of collinearity between the linkage map and physical map was observed. Sprouting index, a trait closely related to TBF, was recorded for the offspring population in 2020 and 2021. The trait had moderate variation, with coefficients of variation of 18.5 and 17.6% in 2020 and 2021, respectively. Quantitative trait locus (QTL) mapping that was performed using the linkage map identified two major QTLs and three minor QTLs related to the sprouting index. These QTLs are distributed on Chr3, Chr4, Chr5, Chr9, and Chr14 of the reference genome. A total of 1960 predicted genes were found within the confidence intervals of QTLs, and 22 key candidate genes that underlie these QTLs were preliminarily screened. These results are important for breeding and understanding the genetic base of the TBF trait of tea plants.

Global burden of oropharyngeal cancer attributable to human papillomavirus by anatomical subsite and geographic region.

BACKGROUND: Oropharynx is the anatomical site with the highest human papillomavirus (HPV) infection in head and neck. Many studies on HPV prevalence and p16INK4a positivity in oropharyngeal cancer have been published in recent years. We aimed to update the global burden estimates of oropharyngeal cancer attributable to HPV with the latest data and estimate global burden of tonsillar cancer and base of tongue cancer attributable to HPV by region and country. METHODS: We calculated the number of new cancer cases using the Cancer Incidence in Five Continents Volume XI (CI5XI) and country-specific population in 2012 issued by the United Nations. Estimates of HPV prevalence and p16INK4a positivity were obtained from literature search and pooled analyses where necessary. RESULTS: Globally the number of oropharyngeal cancer and tonsillar cancer attributable to HPV were 42,000 and 20,000 in 2012, corresponding to AFs of 42.7% and 52.7%. The number of cancer cases attributable to HPV among males was about 4-fold greater than that among females. For both oropharyngeal cancer and tonsillar cancer, AFs were higher in more developed countries. Among HPV positive oropharyngeal cancer cases, 86.7%, 87.8%, and 92.5% could have been prevented by bivalent (2v), quadrivalent (4v), and nonavalent (9v) HPV vaccines. CONCLUSIONS: It is worth considering the inclusion of HPV immunization in males, especially in the regions where oropharyngeal cancer is highly prevalent.

Positive natural selection of N6-methyladenosine on the RNAs of processed pseudogenes.

BACKGROUND: Canonical nonsense-mediated decay (NMD) is an important splicing-dependent process for mRNA surveillance in mammals. However, processed pseudogenes are not able to trigger NMD due to their lack of introns. It is largely unknown whether they have evolved other surveillance mechanisms. RESULTS: Here, we find that the RNAs of pseudogenes, especially processed pseudogenes, have dramatically higher m6A levels than their cognate protein-coding genes, associated with de novo m6A peaks and motifs in human cells. Furthermore, pseudogenes have rapidly accumulated m6A motifs during evolution. The m6A sites of pseudogenes are evolutionarily younger than neutral sites and their m6A levels are increasing, supporting the idea that m6A on the RNAs of pseudogenes is under positive selection. We then find that the m6A RNA modification of processed, rather than unprocessed, pseudogenes promotes cytosolic RNA degradation and attenuates interference with the RNAs of their cognate protein-coding genes. We experimentally validate the m6A RNA modification of two processed pseudogenes, DSTNP2 and NAP1L4P1, which promotes the RNA degradation of both pseudogenes and their cognate protein-coding genes DSTN and NAP1L4. In addition, the m6A of DSTNP2 regulation of DSTN is partially dependent on the miRNA miR-362-5p. CONCLUSIONS: Our discovery reveals a novel evolutionary role of m6A RNA modification in cleaning up the unnecessary processed pseudogene transcripts to attenuate their interference with the regulatory network of protein-coding genes.

AtSTP8, an endoplasmic reticulum-localised monosaccharide transporter from Arabidopsis, is recruited to the extrahaustorial membrane during powdery mildew infection.

Biotrophic pathogens are believed to strategically manipulate sugar transport in host cells to enhance their access to carbohydrates. However, mechanisms of sugar translocation from host cells to biotrophic fungi such as powdery mildew across the plant-haustorium interface remain poorly understood. To investigate this question, systematic subcellular localisation analysis was performed for all the 14 members of the monosaccharide sugar transporter protein (STP) family in Arabidopsis thaliana. The best candidate AtSTP8 was further characterised for its transport properties in Saccharomyces cerevisiae and potential role in powdery mildew infection by gene ablation and overexpression in Arabidopsis. Our results showed that AtSTP8 was mainly localised to the endoplasmic reticulum (ER) and appeared to be recruited to the host-derived extrahaustorial membrane (EHM) induced by powdery mildew. Functional complementation assays in S. cerevisiae suggested that AtSTP8 can transport a broad spectrum of hexose substrates. Moreover, transgenic Arabidopsis plants overexpressing AtSTP8 showed increased hexose concentration in leaf tissues and enhanced susceptibility to powdery mildew. Our data suggested that the ER-localised sugar transporter AtSTP8 may be recruited to the EHM where it may be involved in sugar acquisition by haustoria of powdery mildew from host cells in Arabidopsis.

Expression pattern of m6A regulators is significantly correlated with malignancy and antitumor immune response of breast cancer.

More than 24 regulators have been revealed to dynamically participant in N6-methyladenosine (m6A) RNA methylation, and play critical roles in tumorigenesis and development of cancers. However, their functional roles have not been comprehensively clarified in breast cancer. Here we systematically analyzed the RNA sequencing data of 24 main m6A RNA methylation regulators in 775 breast cancer patients from The Cancer Genome Atlas dataset. Consensus clustering of the 24 m6A regulators was carried out and identified two patient subgroups, RNA methylation 1/2 (RM1/2). RM1 demonstrated generally lower RNA methylation modification than that of RM2, and had significantly shorter overall survival. The hallmarks of PI3K/AKT signaling in cancer, KRAS signaling and angiogenesis were significantly enriched in RM1. Moreover, the association between m6A regulators and antitumor immune response was also investigated in this study and revealed that RM2 was associated with significantly higher expressions of HLA-A, higher numbers of tumor-infiltrating CD8+ T cells, helper T cells and activated NK cells, but lower expressions of PD-L1, PD-L2, TIM3, and CCR4 than RM1. In conclusion, the expression pattern of m6A regulators was significantly correlated with the malignancy, prognosis and antitumor immune response in breast cancer, which might serve as potential targets and biomarkers for immunotherapy.

Identification of a 15-pseudogene based prognostic signature for predicting survival and antitumor immune response in breast cancer.

Pseudogenes are noncoding RNAs that have been revealed to play critical roles in oncogenesis and tumor progression. However, their functional roles have not been comprehensively clarified in breast cancer. Here, we systematically analyzed the RNA sequencing data of 13931 pseudogenes in 775 breast cancer patients from The Cancer Genome Atlas dataset, and ultimately identified 15 prognostic pseudogenes by univariate Cox proportional hazard regression. A risk score model was constructed based on the prognostic pseudogenes via LASSO analysis and dichotomized patients into low- and high-risk subgroups. Patients in the high-risk group had a significantly shorter overall survival than those in the low-risk group. The prognostic value of these 15 pseudogenes and the risk score model were further validated in the European Genome-Phenome Archive dataset. Furthermore, we performed consensus clustering of the 15 prognostic pseudogenes and found that their expression pattern was significantly associated with tumor malignancy and host antitumor immune response, in terms of infiltrating immune cell compositions, antigen presenting genes expression, cytolytic activity and T-cell exhausted markers. This study indicated that these 15 prognostic pseudogenes were significantly correlated with tumor malignancy and host antitumor immune response in breast cancer, and might serve as potential targets for immunotherapy.

Inheritance and quantitative trait loci analyses of the anthocyanins and catechins of Camellia sinensis cultivar 'Ziyan' with dark-purple leaves.

Owing to the potential health benefits, anthocyanin-rich teas (Camellia sinensis) have attracted interest over the past decade. Previously, we developed the cultivar 'Ziyan,' which has dark-purple leaves because of the accumulation of a high amount of anthocyanins. In this study, we performed a genetic analysis of this anthocyanin-rich tea cultivar and 176 of its naturally pollinated offspring. For two consecutive years, we quantified the anthocyanins and catechins of 'Ziyan' and the offspring population. While >60% of the offspring accumulated less than half of the amount of anthocyanins of 'Ziyan,' 17 (2018) and 15 (2019) individuals exceeded 'Ziyan' in anthocyanin content. A negative correlation between anthocyanin and total catechin content (r = -0.59, P < 0.001) was observed. The population was genotyped with 131 SSR markers spanning all linkage groups of the C. sinensis genome. Kruskal-Wallis tests identified 10 markers significantly associated with anthocyanins, catechins and their ratios in both years. Quantitative trait locus (QTL) analyses using the interval mapping method detected 13 QTLs, suggesting the dark-purple trait of 'Ziyan' is because of the pyramiding of anthocyanin-promoting alleles on at least five linkage groups. Two genetic loci reversely related to anthocyanin and total catechin contents were identified. This study provides valuable information for genetic improvement of purple tea cultivars and for fine-mapping related genes.

The Effects of Ultraviolet A/B Treatments on Anthocyanin Accumulation and Gene Expression in Dark-Purple Tea Cultivar 'Ziyan' (Camellia sinensis).

'Ziyan' is a novel anthocyanin-rich tea cultivar with dark purple young shoots. However, how its anthocyanin accumulation is affected by environmental factors, such as ultraviolet (UV), remains unclear. In this study, we observed that UV light treatments stimulated anthocyanin accumulation in 'Ziyan' leaves, and we further analyzed the underlying mechanisms at gene expression and enzyme activity levels. In addition, the catechins and chlorophyll contents of young shoots under different light treatments were also changed. The results showed that the contents of total anthocyanins and three major anthocyanin molecules, i.e., delphinidin, cyanidin, and pelargonidin, were significantly higher in leaves under UV-A, UV-B, and UV-AB treatments than those under white light treatment alone. However, the total catechins and chlorophyll contents in these purple tea plant leaves displayed the opposite trends. The anthocyanin content was the highest under UV-A treatment, which was higher by about 66% than control. Compared with the white light treatment alone, the enzyme activities of chalcone synthase (CHS), flavonoid 3',5'-hydroxylase (F3'5'H), and anthocyanidin synthase (ANS) under UV treatments increased significantly, whereas the leucoanthocyanidin reductase (LAR) and anthocyanidin reductase (ANR) activities reduced. There was no significant difference in dihydroflavonol 4-reductase (DFR) activity under all treatments. Comparative transcriptome analyses unveiled that there were 565 differentially expressed genes (DEGs) of 29,648 genes in three pair-wise comparisons (white light versus UV-A, W vs. UV-A; white light versus UV-B, W vs. UV-A; white light versus UV-AB, W vs. UV-AB). The structural genes in anthocyanin pathway such as flavanone 3-hydroxylase (F3H), F3'5'H, DFR, and ANS, and regulatory gene TT8 were upregulated under UV-A treatment; F3'5'H, DFR, ANS, and UFGT and regulatory genes EGL1 and TT2 were upregulated under UV-AB treatment. However, most structural genes involved in phenylpropanoid and flavonoid pathways were downregulated under UV-B treatment compared with control. The expression of LAR and ANR were repressed in all UV treatments. Our results indicated that UV-A and UV-B radiations can induce anthocyanin accumulation in tea plant 'Ziyan' by upregulating the structural and regulatory genes involved in anthocyanin biosynthesis. In addition, UV radiation repressed the expression levels of LAR, ANR, and FLS, resulting in reduced ANR activity and a metabolic flux shift toward anthocyanin biosynthesis.

Systematic studies on the binding of metal ions in aggregates of humic acid: Aggregation kinetics, spectroscopic analyses and MD simulations.

The binding of metal ions with humic acid (HA) plays an important role in the aggregation of HA and the migration of metal ions in the environments. The effects of common cations (Na+, Mg2+, Ca2+ and Al3+) and heavy metal ions (Ag+, Cd2+, Cu2+, Cr3+ and Eu3+) on the aggregation of HA were investigated systematically by aggregation kinetics, spectroscopic techniques and molecular dynamic (MD) simulations. The critical coagulation concentration (CCC) of mono-, di- and trivalent cations could be predicted by the Schulze-Hardy rule. The aggregation of HA in the presence of Na+ and Ag+ was mainly due to the reduction of repulsive force and the hydrogen bonds between HA molecules. While the complexation of di- and trivalent cations with carboxylic/phenolic groups, or the cation-π interactions enhanced the intra- or inter-molecular bridges in HA and then contributed greatly to the aggregation of HA. Heavy metal ions could easily pass through the electric double-layer of HA compared with common cations. MD simulations further signified the strong aggregation ability of HA molecules in solutions containing high valence metal ions. These findings are important for understanding not only how the influence of metal ions on the aggregation of HA, but also the conditions which ions more efficient for aggregation.

Effect of co-existing Co2+ ions on the aggregation of humic acid in aquatic environment: Aggregation kinetics, dynamic properties and fluorescence spectroscopic study.

The fate and transport of humic substances in the aquatic environments depend significantly on their interactions with co-existing ions. Herein, we employed dynamic light scattering (DLS) measurement, molecular dynamic (MD) simulation and fluorescence spectrometry to investigate the aggregation of humic acid (HA) in the presence of Co2+ ions. The aggregation kinetics was depicted by hydrodynamic diameter () and the attachment efficiency (α) of HA aggregates. α increases gradually in the reaction-limited (slow) regime due to the decrease of the double layer repulsion, and the energy barrier is eliminated to a certain extent in the diffusion-limited reaction while α close to unity. The complexation between functional groups (i.e. carboxylic and phenolic groups) of HA and Co2+ ions contributes significantly to the aggregation process of HA. MD simulation and density functional theory (DFT) calculation demonstrate that the aggregation process of HA can be promoted by Co2+ through several inter- or intra-molecular interactions between HA and the Co2+ ions. The results provide a pathway for insight into the interactions between HA and metal ions, which is important for deeply understanding the environmental behaviors of HA in natural aqueous systems.

High-density SNP linkage map construction and QTL mapping for flavonoid-related traits in a tea plant (Camellia sinensis) using 2b-RAD sequencing.

BACKGROUND: Flavonoids are important components that confer upon tea plants a unique flavour and health functions. However, the traditional breeding method for selecting a cultivar with a high or unique flavonoid content is time consuming and labour intensive. High-density genetic map construction associated with quantitative trait locus (QTL) mapping provides an effective way to facilitate trait improvement in plant breeding. In this study, an F1 population (LJ43×BHZ) was genotyped using 2b-restriction site-associated DNA (2b-RAD) sequencing to obtain massive single nucleotide polymorphism (SNP) markers to construct a high-density genetic map for a tea plant. Furthermore, QTLs related to flavonoids were identified using our new genetic map. RESULTS: A total of 13,446 polymorphic SNP markers were developed using 2b-RAD sequencing, and 4,463 of these markers were available for constructing the genetic linkage map. A 1,678.52-cM high-density map at an average interval of 0.40 cM with 4,217 markers, including 427 frameset simple sequence repeats (SSRs) and 3,800 novel SNPs, mapped into 15 linkage groups was successfully constructed. After QTL analysis, a total of 27 QTLs related to flavonoids or caffeine content (CAF) were mapped to 8 different linkage groups, LG01, LG03, LG06, LG08, LG10, LG11, LG12, and LG13, with an LOD from 3.14 to 39.54, constituting 7.5% to 42.8% of the phenotypic variation. CONCLUSIONS: To our knowledge, the highest density genetic map ever reported was constructed since the largest mapping population of tea plants was adopted in present study. Moreover, novel QTLs related to flavonoids and CAF were identified based on the new high-density genetic map. In addition, two markers were located in candidate genes that may be involved in flavonoid metabolism. The present study provides valuable information for gene discovery, marker-assisted selection breeding and map-based cloning for functional genes that are related to flavonoid content in tea plants.

Coagulation behavior of humic acid in aqueous solutions containing Cs+, Sr2+ and Eu3+: DLS, EEM and MD simulations.

The coagulation behaviors of humic acid (HA) with Cs+ (10-500 mM), Sr2+ (0.8-10.0 mM) and Eu3+ (0.01-1.0 mM) at different pH values (2.8, 7.1 and 10.0) were acquired through a dynamic light scattering (DLS) technique combined with spectroscopic analysis and molecular dynamic (MD) simulations. The coagulation rate and the average hydrodynamic diameter () increased significantly as the concentration of nuclides increased. could be scaled to time t as ∝ ta at higher Sr2+ concentrations, which shows that HA coagulation is consistent with the diffusion-limited colloid aggregation (DLCA) model. Trivalent Eu3+ induced HA coagulation at a much lower concentration than bivalent Sr2+ and monovalent Cs+. The coagulation value ratio of Sr2+ and Eu3+ to Cs+ is almost proportional to Z-6, indicating that the HA coagulation process is generally consistent with the Schulze-Hardy rule. Spectroscopic analysis indicated that the complexation between nuclides and carboxylic/phenolic groups of HA molecules played important roles in the coagulation of HA. MD modelling suggested that Sr2+ and Eu3+ ions increased the coagulation process through the formation of intra- or inter-molecular bridges between negatively charged HA molecules, whereas for Cs+, no inter-molecular bridges were formed. This work offers new insight into the interactions between HA and radionuclides and provides a prediction for the roles of HA in the transportation and elimination of radionuclides in severely polluted environments.

Dual and Opposing Roles of Xanthine Dehydrogenase in Defense-Associated Reactive Oxygen Species Metabolism in Arabidopsis.

While plants produce reactive oxygen species (ROS) for stress signaling and pathogen defense, they need to remove excessive ROS induced during stress responses in order to minimize oxidative damage. How can plants fine-tune this balance and meet such conflicting needs? Here, we show that XANTHINE DEHYDROGENASE1 (XDH1) in Arabidopsis thaliana appears to play spatially opposite roles to serve this purpose. Through a large-scale genetic screen, we identified three missense mutations in XDH1 that impair XDH1's enzymatic functions and consequently affect the powdery mildew resistance mediated by RESISTANCE TO POWDERY MILDEW8 (RPW8) in epidermal cells and formation of xanthine-enriched autofluorescent objects in mesophyll cells. Further analyses revealed that in leaf epidermal cells, XDH1 likely functions as an oxidase, along with the NADPH oxidases RbohD and RbohF, to generate superoxide, which is dismutated into H2O2 The resulting enrichment of H2O2 in the fungal haustorial complex within infected epidermal cells helps to constrain the haustorium, thereby contributing to RPW8-dependent and RPW8-independent powdery mildew resistance. By contrast, in leaf mesophyll cells, XDH1 carries out xanthine dehydrogenase activity to produce uric acid in local and systemic tissues to scavenge H2O2 from stressed chloroplasts, thereby protecting plants from stress-induced oxidative damage. Thus, XDH1 plays spatially specified dual and opposing roles in modulation of ROS metabolism during defense responses in Arabidopsis.