Leptin promotes methionine adenosyltransferase 2A expression in hepatic stellate cells by the downregulation of E2F-4 via the ß-catenin pathway.

Most obese patients develop hyperleptinaemia. Leptin, mainly produced by adipocytes, demonstrates a promotional role in liver fibrosis. Hepatic stellate cell (HSC) activation, a key step in liver fibrogenesis, requires global reprogramming of gene expression. The remodeling of DNA methylation is a mechanism of the epigenetic regulation of gene expression. The biosynthesis of S-adenosylmethionine, a principle biological methyl donor, is catalyzed by methionine adenosyltransferase (MAT) such as MATⅡ which has been shown to promote HSC activation in vitro. This study was mainly aimed to determine the effect of leptin on MAT2A expression (the catalytic subunit of MATⅡ) in HSCs. Results showed that MAT2A knockdown reduced leptin-induced HSC activation and liver fibrosis in the leptin-deficient mouse model. Leptin promoted MAT2A expression in HSCs and increased MAT2A promoter activity. The axis of the ß-catenin pathway/E2F-4 mediated the effect of leptin on MAT2A expression. Leptin-induced ß-catenin signaling reduced E2F-4 expression and thus abated E2F-4 binding to MAT2A promoter at a site around -2779 bp, leading to an increase in the MAT2A promoter activity. These data might shed more light on the mechanisms responsible for liver fibrogenesis in obese patients with hyperleptinaemia.

c-Jun acts downstream of PI3K/AKT signaling to mediate the effect of leptin on methionine adenosyltransferase 2B in hepatic stellate cells in vitro and in vivo.

Obese patients, often accompanied by hyperleptinemia, are prone to develop liver fibrosis. A large body of data including the results from human studies suggested the promotion role of leptin, an adipocyte-derived hormone, in liver fibrosis. Hepatic stellate cell (HSC) activation, a crucial step in liver fibrogenesis, requires global reprogramming of gene expression which is regulated by multiple mechanisms including epigenetic regulation such as methylation of DNA. S-Adenosylmethionine is a principal biological methyl donor and its biosynthesis is catalyzed by a methionine adenosyltransferase (MAT) such as MATII. MATII consists of the catalytic subunit MAT2A and regulatory subunit MAT2B which are essential for HSC activation. The present research investigated the effect of leptin on the expression of Mat2b in HSCs in vitro and in a leptin-deficient mouse model. Results demonstrated that leptin significantly increased Mat2b expression. Leptin-induced Mat2b expression required the PI3K/AKT signaling pathway. c-Jun, a component of activator protein (AP1), was phosphorylated by leptin-induced PI3K/AKT signaling and thus potentiated its binding to the element around -964 bp in the Mat2b promoter. MAT2B was involved in leptin-induced HSC activation and liver fibrosis in a leptin-deficient mouse model. These results might broaden understanding of the mechanisms underlying the liver fibrogenesis in obese patients with hyperleptinemia. © 2020 The Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Association mapping for yield traits in Paeonia rockii based on SSR markers within transcription factors of comparative transcriptome.

BACKGROUND: Allelic variation underlying the quantitative traits in plants is caused by the extremely complex regulation process. Tree peony originated in China is a peculiar ornamental, medicinal and oil woody plant. Paeonia rockii, one of tree peony species, is a precious emerging woody oil crop. However, in this valuable plant, the study of functional loci associated with yield traits has rarely been identified. Therefore, to explore the genetic architecture of 24 yield quantitative traits, the association mapping was first reported in 420 unrelated cultivated P. rockii individuals based on the next-generation sequencing (NGS) and single-molecule long-read sequencing (SMLRS). RESULTS: The developed 58 pairs of polymorphic expressed sequence tag-simple sequence repeat (EST-SSR) markers from 959 candidate transcription factors (TFs) associated with yield were used for genotyping the 420 P. rockii accessions. We observed a high level of genetic diversity (polymorphic information content, PIC = 0.514) and low linkage disequilibrium (LD) between EST-SSRs. Moreover, four subpopulations in the association population were revealed by STRUCTURE analyses. Further, single-marker association analysis identified 141 significant associations, involving 17 quantitative traits and 41 EST-SSRs. These loci were mainly from AP2, TCP, MYB, HSF, bHLH, GATA, and B3 gene families and showed a small proportion of the phenotypic variance (3.79 to 37.45%). CONCLUSIONS: Our results summarize a valuable collection of functional loci associated with yield traits in P. rockii, and provide a precious resource that reveals allelic variation underlying quantitative traits in Paeonia and other woody oil crops.

Comparative transcriptome and coexpression network analysis of carpel quantitative variation in Paeonia rockii.

BACKGROUND: Quantitative variation of floral organs in plants is caused by an extremely complex process of transcriptional regulation. Despite progress in model plants, the molecular mechanisms of quantitative variation remain unknown in woody flower plants. The Paeonia rockii originated in China is a precious woody plant with ornamental, medicinal and oil properties. There is a wide variation in the number of carpel in P. rockii, but the molecular mechanism of the variation has rarely been studied. Then a comparative transcriptome was performed among two cultivars of P. rockii with different development patterns of carpel in this study. RESULTS: Through the next-generation and single-molecule long-read sequencing (NGS and SMLRS), 66,563 unigenes and 28,155 differentially expressed genes (DEGs) were identified in P. rockii. Then clustering pattern and weighted gene coexpression network analysis (WGCNA) indicated that 15 candidate genes were likely involved in the carpel quantitative variation, including floral organ development, transcriptional regulatory and enzyme-like factors. Moreover, transcription factors (TFs) from the MYB, WD, RING1 and LRR gene families suggested the important roles in the management of the upstream genes. Among them, PsMYB114-like, PsMYB12 and PsMYB61-like from the MYB gene family were probably the main characters that regulated the carpel quantitative variation. Further, a hypothetical model for the regulation pattern of carpel quantitative variation was proposed in which the candidate genes function synergistically the quantitative variation process. CONCLUSIONS: We present the high-quality sequencing products in P. rockii. Our results summarize a valuable collective of gene expression profiles characterizing the carpel quantitative variation. The DEGs are candidate for functional analyses of genes regulating the carpel quantitative variation in tree peonies, which provide a precious resource that reveals the molecular mechanism of carpel quantitative variation in other woody flower crops.

Leptin up-regulates microRNA-27a/b-3p level in hepatic stellate cells.

Obese patients, often accompanied by hyperleptinemia, are prone to liver fibrogenesis. Leptin is an adipocyte-derived hormone and plays a promotion role in liver fibrosis. Sterol regulatory element binding protein-1c (SREBP1c) exerts a crucial role in inhibiting hepatic stellate cell (HSC) activation, a key step in liver fibrogenesis. Our previous studies indicated that leptin inhibited SREBP1c expression, contributing to leptin-induced HSC activation and liver fibrosis. microRNAs (miR) have emerged as important layers of regulatory control and regulate gene expression, and are implicated in numerous diseases. The present study revealed leptin up-regulation of miR-27a/b-3p levels in HSCs in vitro and in vivo. Three signaling pathways were required for leptin regulation of miR-27a/b-3p levels. miR-27a/b-3p could reduce SREBP1c and liver x receptor α (LXRα) levels, increased α-smooth muscle actin (α-SMA, a marker for HSC activation) and α1(I)collagen levels in cultured HSCs. miR-27a/b-3p regulation of SREBP1c and LXRα were independent of 3'-untranslated region of SREBP1c and LXRα mRNA. In vivo experiments further demonstrated the miR-27a/b-3p involved in leptin-associated decrease in SREBP1 level in HSCs, HSC activation, and liver fibrosis. These data might have potential implications for our understanding of molecular mechanisms underlying leptin roles in liver fibrogenesis of obese patients with hyperleptinaemia.

Leptin suppresses microRNA-122 promoter activity by phosphorylation of foxO1 in hepatic stellate cell contributing to leptin promotion of mouse liver fibrosis.

Adipocytokine leptin promotes hepatic stellate cell (HSC) activation (a key step in liver fibrogenesis) and liver fibrosis. microRNA-122 (miR-122) is the most abundant liver-specific miRNA and was demonstrated to inhibit liver fibrosis and reduced HSC proliferation. Our previous study revealed that leptin reduced miR-122 level in HSCs. This study was aimed to investigate whether leptin affected miR-122 promoter and the underlying mechanisms in HSCs. Results showed that leptin inhibited miR-122 promoter activity. Forkhead box protein O1(FoxO1) bound to miR-122 promoter at a site around - 56 and thus promoted miR-122 promoter activity, which could be suppressed by leptin-induced phosphorylation of FoxO1 at serine 256. The PI3K/Akt signaling pathway was involved in leptin-induced phosphorylation of FoxO1 and the effect of leptin on miR-122 expression. Furthermore, FoxO1 increased miR-122 and pri-miR-122 (primary miR-122) levels in HSCs in vivo, and reduced leptin-induced HSC activation and liver fibrosis in ob/ob mouse (leptin deficient) model. In conclusion, leptin suppressed microRNA-122 expression by PI3K/Akt/foxO1 axis in HSCs. These results have potential implications for clarifying the mechanisms for liver fibrogenesis in obese patients with hyperleptinaemia.

GATA binding protein 3 is correlated with leptin regulation of PPARγ1 in hepatic stellate cells.

Accumulating evidence reveals that hormone leptin, mainly produced by adipocyte, plays a unique role in promotion of liver fibrosis. Hepatic stellate cell (HSC) activation is a key step in liver fibrosis and peroxisome-proliferator activated receptor γ (PPARγ) exerts a crucial role in inhibition of HSC activation. Our previous researches demonstrated that leptin reduced PPARγ1 (a major subtype of PPARγ in HSCs) expression through GATA binding protein 2 (GATA2) binding to a site around -2323 in PPARγ1 promoter. The present researches aimed to examine the effect of GATA3 on leptin-induced inhibition of PPARγ1 and elucidate the relationship between GATA3 and GATA2. Gene expressions were analysed by real-time PCR, western blot, luciferase assay and immunostaining. C57BL/6J ob/ob mouse model of thioacetamide-induced liver injury was used in vivo. Results demonstrate that leptin significantly induces GATA3 expression in HSCs by multiple signalling pathways including NADPH oxidase pathway. There exist crosstalks between NADPH oxidase pathway and the other pathways. GATA3 can bind to GATA2-binding site in PPARγ1 promoter and interacts with GATA2, contributing to leptin inhibition of PPARγ1 expression in HSCs. These data demonstrated novel molecular events for leptin inhibition of PPARγ1 expression in HSCs and thus might have potential implications for clarifying the detailed mechanisms underlying liver fibrosis in diseases in which circulating leptin levels are elevated such as non-alcoholic steatohepatitis in obese patients.

Sex-determining region Y-box 9 acts downstream of NADPH oxidase to influence the effect of leptin on PPARγ1 expression in hepatic stellate cells.

Leptin, an adipocyte-derived hormone, promotes liver fibrogenesis and inhibits the expression of peroxisome-proliferator activated receptor γ (PPARγ), a key transcription factor in inhibition of hepatic stellate cell (HSC) activation, in HSCs. This research aimed to further investigate the mechanisms underlying leptin regulation of PPARγ1 in HSCs in vivo and in vitro. Results demonstrated that sex-determining region Y-box 9 (Sox9) could bind to a site around -2275 within leptin response region of PPARγ1 promoter and inhibited PPARγ1 expression. Sox9 upregulated the expressions of α1(I)collagen and alpha-smooth muscle actin in HSCs. Leptin stimulated Sox9 expression and Sox9 binding to PPARγ1 promoter. The signaling pathways of NADPH oxidase, ß-catenin, and delta-like homolog1 (DLK1) mediated leptin upregulation of Sox9 expression. Moreover, there existed crosstalk between NADPH oxidase pathway and ß-catenin or DLK1 signaling pathway. Human liver specimens of cirrhosis were shown to be of a large number of the positive HSCs for p47phox (playing a central role in NADPH oxidase activity), 4-hydroxynonenal (a lipid peroxidation product), Sox9, and α-smooth muscle actin whereas PPARγ-positive HSCs were rarely detected. These results might deepen understanding of the molecular mechanisms for leptin inhibition of PPARγ1 expression in HSCs and for the liver fibrosis associated with leptin.

Duplication and Whorl-Specific Down-Regulation of the Obligate AP3-PI Heterodimer Genes Explain the Origin of Paeonia lactiflora Plants with Spontaneous Corolla Mutation.

Herbaceous peony (Paeonia lactiflora) is a globally important ornamental plant. Spontaneous floral mutations occur frequently during cultivation, and are selected as a way to release new cultivars, but the underlying evolutionary developmental genetics remain largely elusive. Here, we investigated a collection of spontaneous corolla mutational plants (SCMPs) whose other floral organs were virtually unaffected. Unlike the corolla in normal plants (NPs) that withered soon after fertilization, the transformed corolla (petals) in SCMPs was greenish and persistent similar to the calyx (sepals). Epidermal cellular morphology of the SCMP corolla was also similar to that of calyx cells, further suggesting a sepaloid corolla in SCMPs. Ten floral MADS-box genes from these Paeonia plants were comparatively characterized with respect to sequence and expression. Codogenic sequence variation of these MADS-box genes was not linked to corolla changes in SCMPs. However, we found that both APETALA3 (AP3) and PISTILLATA (PI) lineages of B-class MADS-box genes were duplicated, and subsequent selective expression alterations of these genes were closely associated with the origin of SCMPs. AP3-PI obligate heterodimerization, essential for organ identity of corolla and stamens, was robustly detected. However, selective down-regulation of these duplicated genes might result in a reduction of this obligate heterodimer concentration in a corolla-specific manner, leading to the sepaloid corolla in SCMPs, thus representing a new sepaloid corolla model taking advantage of gene duplication. Our work suggests that modifying floral MADS-box genes could facilitate the breeding of novel cultivars with distinct floral morphology in ornamental plants, and also provides new insights into the functional evolution of the MADS-box genes in plants.

Association mapping for floral traits in cultivated Paeonia rockii based on SSR markers.

Tree peony (Paeonia Sect. Moutan) is an economically important ornamental plant, but little is known about the genetic architecture of important ornamental traits. To effectively improve ornamental value, we require a better understanding of genetic architecture in the complex traits of the tree peony. Association mapping is a powerful tool for detection of variation associated with traits. Thus, we examined the genetic diversity and the population structure of 462 unrelated cultivated P. rockii individuals, then performed association mapping to identify simple sequence repeat (SSR) markers associated with 12 floral traits. We observed a moderate level of genetic diversity (PIC = 0.459) and low linkage disequilibrium (LD) between markers, demonstrating that the potential value of an LD approach in elucidating the molecular basis of the quantitative variation in this species. An analysis of population structure revealed three subgroups in the association population. Subsequent single-marker association analysis identified 46 significant associations, involving the 11 traits with 37 SSRs. These loci explained a small proportion of the phenotypic variance, ranging from 2.68 to 23.97% (mean 5.50%). We also validated 15 of the 46 associations in a linkage mapping population of 159 individuals. Finally, five associations were further confirmed in the linkage mapping population, involving the four traits with four SSRs. These results can serve as a foundation for further analyses of the genetic architecture of floral traits, and the SSRs associated in this work have potential applications in marker-assisted breeding in tree peony.

Independent domestications of cultivated tree peonies from different wild peony species.

An understanding of plant domestication history provides insights into general mechanisms of plant adaptation and diversification and can guide breeding programmes that aim to improve cultivated species. Cultivated tree peonies (genus Paeonia L.) are among the most popular ornamental plants in the world; yet, the history of their domestication is still unresolved. Here, we explored whether the domestication in China of historically cultivated peonies, that is, the common and flare cultivated tree peonies, was a single event or whether independent domestications occurred. We used 14 nuclear microsatellite markers and a comprehensive set of 553 tree peonies collected across China, including common tree peonies, flare tree peonies and the wild species or subspecies that are potential contributors to the cultivated tree peonies, that is, Paeonia rockii ssp. rockii, P. rockii ssp. atava, P. jishanensis and P. decomposita. Assignment methods, a principal component analysis and approximate Bayesian computations provided clear evidence for independent domestications of these common tree and flare tree peonies from two distinct and allopatric wild species, P. jishanensis and P. rockii ssp. atava, respectively. This study provides the first example of independent domestications of cultivated trees from distinct species and locations. This work also yields crucial insight into the history of domestication of one of the most popular woody ornamental plants. The cultivated peonies represent an interesting case of parallel and convergent evolution. The information obtained in this study will be valuable both for improving current tree peony breeding strategies and for understanding the mechanisms of domestication, diversification and adaptation in plants.

Microsatellite markers for the Chinese herbaceous peony Paeonia lactiflora (Paeoniaceae).

PREMISE OF THE STUDY: Microsatellite (simple sequence repeat, SSR) primers were developed for the Chinese peony, P. lactiflora, to investigate the diversity within Chinese peony germplasm resources. METHODS AND RESULTS: Using an SSR-enriched genomic library, a set of 10 unique polymorphic genomic SSRs was developed and characterized. The primers amplified 61 alleles in all 10 loci, including di-, tri-, and tetranucleotide repeats. The primers were also effective for P. veitchii and P. obovata. CONCLUSIONS: The new primers will be useful for genetic research of the Chinese peony and extend the repertoire of SSR markers available to study the herbaceous taxa in Paeonia.

Dissection of Allelic Variation Underlying Floral and Fruit Traits in Flare Tree Peony (Paeonia rockii) Using Association Mapping.

Allelic variation in floral quantitative traits, including the elements of flowers and fruits, is caused by extremely complex regulatory processes. In the genetic improvement of flare tree peony (Paeonia rockii), a unique ornamental and edible oil woody species in the genus Paeonia, a better understanding of the genetic composition of these complex traits related to flowers and fruits is needed. Therefore, we investigated the genetic diversity and population structure of 160 P. rockii accessions and conducted single-marker association analysis for 19 quantitative flower and fruit traits using 81 EST-SSR markers. The results showed that the population had a high phenotypic diversity (coefficients of variation, 11.87-110.64%) and a high level of genetic diversity (mean number of alleles, N A = 6.09). These accessions were divided into three subgroups by STRUCTURE analysis and a neighbor-joining tree. Furthermore, we also found a low level of linkage disequilibrium between these EST-SSRs and, by single-marker association analysis, identified 134 significant associations, including four flower traits with 11 EST-SSRs and 10 fruit traits with 32 EST-SSRs. Finally, based on the sequence alignment of the associated markers, P280, PS2, PS12, PS27, PS118, PS131, and PS145 may be considered potential loci to increase the yield of flare tree peony. These results laid the foundation for further analysis of the genetic structure of some key traits in P. rockii and had an obvious potential application value in marker-assisted selection breeding.

Modelling environmentally suitable areas for the potential introduction and cultivation of the emerging oil crop Paeonia ostii in China.

Paeonia ostii is a traditional ornamental and medicinal species that has attracted considerable interest for its high oil value. To facilitate the effective and rational cultivation and application of P. ostii in China, it is necessary to determine its potential spatial habitat distribution and environmental requirements. Using high-resolution environmental data for current and future climate scenarios, the potential suitable area and climatic requirements of P. ostii were modelled. Among the 11 environmental variables investigated, growing degree days, precipitation of the wettest month, mean temperature of the coldest quarter, global UV-B radiation, annual precipitation, and soil pH played major roles in determining the suitability of a habitat for the cultivation of P. ostii. Under the current environmental conditions in China, a total area of 20.31 × 105 km2 is suitable for growing P. ostii, accounting for 21.16% of the country's total land area. Under the two future climate scenario/year combinations (i.e., representative concentration pathways [RCPs], RCP2.6 and RCP8.5 in 2050), this species would increase its suitable area at high latitudes while decrease at low latitudes. These results present valuable information and a theoretical reference point for identifying the suitable cultivation areas of P. ostii.

Late Pleistocene speciation of three closely related tree peonies endemic to the Qinling-Daba Mountains, a major glacial refugium in Central China.

Determining the factors promoting speciation is a major task in ecological and evolutionary research and can be aided by phylogeographic analysis. The Qinling-Daba Mountains (QDM) located in central China form an important geographic barrier between southern subtropical and northern temperate regions, and exhibit complex topography, climatic, and ecological diversity. Surprisingly, few phylogeographic analyses and studies of plant speciation in this region have been conducted. To address this issue, we investigated the genetic divergence and evolutionary histories of three closely related tree peony species (Paeonia qiui, P. jishanensis, and P. rockii) endemic to the QDM. Forty populations of the three tree peony species were genotyped using 22 nuclear simple sequence repeat markers (nSSRs) and three chloroplast DNA sequences to assess genetic structure and phylogenetic relationships, supplemented by morphological characterization and ecological niche modeling (ENM). Morphological and molecular genetic analyses showed the three species to be clearly differentiated from each other. In addition, coalescent analyses using DIYABC conducted on nSSR variation indicated that the species diverged from each other in the late Pleistocene, while ecological niche modeling (ENM) suggested they occupied a larger area during the Last Glacial Maximum (LGM) than at present. The combined genetic evidence from nuclear and chloroplast DNA and the results of ENM indicate that each species persisted through the late Pleistocene in multiple refugia in the Qinling, Daba, and Taihang Mountains with divergence favored by restricted gene flow caused by geographic isolation, ecological divergence, and limited pollen and seed dispersal. Our study contributes to a growing understanding of the origin and population structure of tree peonies and provides insights into the high level of plant endemism present in the Qinling-Daba Mountains of Central China.

Delta-like homolog1/GATA binding protein 2 axis mediates leptin inhibition of PPARγ2 expression in hepatic stellate cells in vitro.

AIMS: Peroxisome-proliferator activated receptor γ (PPARγ) plays a pivotal role in inhibition of hepatic stellate cell (HSC) activation, a key step for liver fibrogenesis. Adipocyte-derived hormone leptin has been shown to promote liver fibrosis in murine and human. PPARγ includes two subtypes, PPARγ1 and PPARγ2. Our previous study indicated that leptin down-regulated PPARγ1 expression in HSCs. The aim of this study was to investigate the effect of leptin on PPARγ2 expression and the underlying mechanisms in HSCs. MAIN METHODS: Real-time PCR and western blot analyses were used to examine gene expression. The promoter activities were detected by luciferase assay. KEY FINDINGS: Leptin reduced PPARγ2 expressions at promoter level, mRNA level, and protein level in HSCs, which required ß-catenin, p38 mitogen-activated protein kinase, and delta-like homolog1 (DLK1) signaling pathways. Leptin induced GATA binding protein 2 (GATA2) expression through DLK1 pathway and GATA2 reduced PPARγ2 expression. Ectopic expression of PPARγ2 reduced the protein levels of α-smooth muscle actin and α1(I)collagen in HSCs. SIGNIFICANCE: Since obese patients, often accompanied by hyperleptinemia, are more prone to liver fibrosis, the data from this study might have potential implications for clarifying the mechanisms for liver fibrogenesis in obese patients with hyperleptinemia.

Genetic analyses reveal independent domestication origins of the emerging oil crop Paeonia ostii, a tree peony with a long-term cultivation history.

Paeonia ostii, a member of tree peony, is an emerging oil crop with important medical and oil uses and widely cultivated in China. Dissolving the genetic diversity and domestication history of this species is important for further genetic improvements and deployments. We firstly selected 29 simple sequence repeats (SSRs) via transcriptome mining, segregation analyses and polymorphism characterizations; then, 901 individuals from the range-wide samples were genotyped using well-characterized SSR markers. We observed moderate genetic diversity among individuals, and Shaanxi Province was identified as the center of genetic diversity for our cultivated plants. Five well-separated gene pools were detected by STRUCTURE analyses, and the results suggested that multiple independent domestication origins occurred in Shaanxi Province and Tongling City (Anhui Province). Taken together, the genetic evidence and the historical records suggest multiple long-distance introductions after the plant was domesticated in Shandong, Henan and Hunan provinces. The present study provides the first genetic evaluation of the domestication history of P. ostii, and our results provide an important reference for further genetic improvements and deployments of this important crop.

Leptin reduces microRNA-122 level in hepatic stellate cells in vitro and in vivo.

Obese patients, often accompanied by hyperleptinemia, are more likely to develop liver fibrosis. Leptin, an adipocyte-derived hormone, augments inflammatory in liver and promotes hepatic stellate cell (HSC) activation (a key step for liver fibrogenesis) and liver fibrosis. microRNA-122 (miR-122) is the most abundant liver-specific miRNA and can attenuate liver fibrosis. This study examined the effect of leptin on miR-122 level in HSCs in vivo and in vitro. Results demonstrated that leptin reduced the levels of both miR-122 (mature miR-122) and primary miR-122 (pri-miR-122). The effects of leptin on the levels of miR-122 and pri-miR-122 were through at least hedgehog pathway. Leptin-induced decrease in sterol regulatory element-binding protein-1c (SREBP-1c) has been shown to contribute to leptin-induced HSC activation. We revealed a mutual promotional effect between SREBP-1c and miR-122. Further experiments indicated that miR-122 inhibited leptin-induced liver fibrosis in leptin-deficient mouse model. These data have potential implications for clarifying the mechanisms of hepatic fibrogenesis associated with elevated leptin level in human such as obese patients.

[Impact of canopy structural characteristics on inner air temperature and relative humidity of Koelreuteria paniculata community in summer].

To investigate the diurnal variation of the correlations between the cooling and humidifying effects and canopy structural characteristics of the Koelreuteria paniculata community, the measurements of air temperature, relative humidity, canopy density, leaf area index (LAI) and mean leaf angle (MLA) were performed on calm sunny summer days in the community in Beijing Olympic Forest Park, China. There were significant correlations between the canopy density, LAI and MLA, which affected the cooling and humidifying effects together. The cooling effect reached its maximum by 12:00, whereas the humidifying effect reached its peak at 10:00. Compared with the control open space site, the community appeared to lower the air temperature by 0.43 to 7.53 °C and to increase the relative humidity by 1%-22% during the daytime. However, the cooling and humidifying effects seem to be not effective during the night. The canopy density and LAI were better for determining the cooling and humidifying effects from 9:00 to 12:00. However, these effects were largely controlled only by the canopy density from 12:00 to 14:00 and were significantly correlated with the canopy density and LAI afterwards until 18:00.

The First High-Density Genetic Map Construction in Tree Peony (Paeonia Sect. Moutan) using Genotyping by Specific-Locus Amplified Fragment Sequencing.

Genetic linkage maps, permitting the elucidation of genome structure, are one of most powerful genomic tools to accelerate marker-assisted breeding. However, due to a lack of sufficient user-friendly molecular markers, no genetic linkage map has been developed for tree peonies (Paeonia Sect. Moutan), a group of important horticultural plants worldwide. Specific-locus amplified fragment sequencing (SLAF-seq) is a recent molecular marker development technology that enable the large-scale discovery and genotyping of sequence-based marker in genome-wide. In this study, we performed SLAF sequencing of an F1 population, derived from the cross P. ostti 'FenDanBai' × P. × suffruticosa 'HongQiao', to identify sufficient high-quality markers for the construction of high-density genetic linkage map in tree peonies. After SLAF sequencing, a total of 78 Gb sequencing data and 285,403,225 pair-end reads were generated. We detected 309,198 high-quality SLAFs from these data, of which 85,124 (27.5%) were polymorphic. Subsequently, 3518 of the polymorphic markers, which were successfully encoded in to Mendelian segregation types, and were in conformity with the criteria of high-quality markers, were defined as effective markers and used for genetic linkage mapping. Finally, we constructed an integrated genetic map, which comprised 1189 markers on the five linkage groups, and spanned 920.699 centiMorgans (cM) with an average inter-marker distance of 0.774 cM. There were 1115 'SNP-only' markers, 18 'InDel-only' markers, and 56 'SNP&InDel' markers on the map. Among these markers, 450 (37.85%) showed significant segregation distortion (P < 0.05). In conclusion, this investigation reported the first large-scale marker development and high-density linkage map construction for tree peony. The results of this study will serve as a solid foundation not only for marker-assisted breeding, but also for genome sequence assembly for tree peony.