Functional Characterization of AP2/ERF Transcription Factors during Flower Development and Anthocyanin Biosynthesis Related Candidate Genes in Lycoris.

The APETALA2/ethylene-responsive transcription factor (AP2/ERF) family has been extensively investigated because of its significant involvement in plant development, growth, fruit ripening, metabolism, and plant stress responses. To date, there has been little investigation into how the AP2/ERF genes influence flower formation and anthocyanin biosynthesis in Lycoris. Herein, 80 putative LrAP2/ERF transcription factors (TFs) with complete open reading frames (ORFs) were retrieved from the Lycoris transcriptome sequence data, which could be divided into five subfamilies dependent on their complete protein sequences. Furthermore, our findings demonstrated that genes belonging to the same subfamily had structural similarities and conserved motifs. LrAP2/ERF genes were analyzed for playing an important role in plant growth, water deprivation, and flower formation by means of gene ontology (GO) enrichment analysis. The expression pattern of the LrAP2/ERF genes differed across tissues and might be important for Lycoris growth and flower development. In response to methyl jasmonate (MeJA) exposure and drought stress, the expression of each LrAP2/ERF gene varied across tissues and time. Moreover, a total of 20 anthocyanin components were characterized using ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) analysis, and pelargonidin-3-O-glucoside-5-O-arabinoside was identified as the major anthocyanin aglycone responsible for the coloration of the red petals in Lycoris. In addition, we mapped the relationships between genes and metabolites and found that LrAP2/ERF16 is strongly linked to pelargonidin accumulation in Lycoris petals. These findings provide the basic conceptual groundwork for future research into the molecular underpinnings and regulation mechanisms of AP2/ERF TFs in anthocyanin accumulation and Lycoris floral development.

Characterization of the WRKY Gene Family Related to Anthocyanin Biosynthesis and the Regulation Mechanism under Drought Stress and Methyl Jasmonate Treatment in Lycoris radiata.

Lycoris radiata, belonging to the Amaryllidaceae family, is a well-known Chinese traditional medicinal plant and susceptible to many stresses. WRKY proteins are one of the largest families of transcription factors (TFs) in plants and play significant functions in regulating physiological metabolisms and abiotic stress responses. The WRKY TF family has been identified and investigated in many medicinal plants, but its members and functions are not identified in L. radiata. In this study, a total of 31 L. radiata WRKY (LrWRKY) genes were identified based on the transcriptome-sequencing data. Next, the LrWRKYs were divided into three major clades (Group I-III) based on the WRKY domains. A motif analysis showed the members within same group shared a similar motif component, indicating a conservational function. Furthermore, subcellular localization analysis exhibited that most LrWRKYs were localized in the nucleus. The expression pattern of the LrWRKY genes differed across tissues and might be important for Lycoris growth and flower development. There were large differences among the LrWRKYs based on the transcriptional levels under drought stress and MeJA treatments. Moreover, a total of 18 anthocyanin components were characterized using an ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) analysis and pelargonidin-3-O-glucoside-5-O-arabinoside as well as cyanidin-3-O-sambubioside were identified as the major anthocyanin aglycones responsible for the coloration of the red petals in L. radiata. We further established a gene-to-metabolite correlation network and identified LrWRKY3 and LrWRKY27 significant association with the accumulation of pelargonidin-3-O-glucoside-5-O-arabinoside in the Lycoris red petals. These results provide an important theoretical basis for further exploring the molecular basis and regulatory mechanism of WRKY TFs in anthocyanin biosynthesis and in response to drought stress and MeJA treatment.

The Classification, Molecular Structure and Biological Biosynthesis of Flavonoids, and Their Roles in Biotic and Abiotic Stresses.

With the climate constantly changing, plants suffer more frequently from various abiotic and biotic stresses. However, they have evolved biosynthetic machinery to survive in stressful environmental conditions. Flavonoids are involved in a variety of biological activities in plants, which can protect plants from different biotic (plant-parasitic nematodes, fungi and bacteria) and abiotic stresses (salt stress, drought stress, UV, higher and lower temperatures). Flavonoids contain several subgroups, including anthocyanidins, flavonols, flavones, flavanols, flavanones, chalcones, dihydrochalcones and dihydroflavonols, which are widely distributed in various plants. As the pathway of flavonoid biosynthesis has been well studied, many researchers have applied transgenic technologies in order to explore the molecular mechanism of genes associated with flavonoid biosynthesis; as such, many transgenic plants have shown a higher stress tolerance through the regulation of flavonoid content. In the present review, the classification, molecular structure and biological biosynthesis of flavonoids were summarized, and the roles of flavonoids under various forms of biotic and abiotic stress in plants were also included. In addition, the effect of applying genes associated with flavonoid biosynthesis on the enhancement of plant tolerance under various biotic and abiotic stresses was also discussed.

Genome-wide identification and characterization of PdbHLH transcription factors related to anthocyanin biosynthesis in colored-leaf poplar (Populus deltoids).

Basic helix-loop-helix (bHLH) proteins are transcription factors (TFs) that have been shown to regulate anthocyanin biosynthesis in many plant species. However, the bHLH gene family in Populus deltoids has not yet been reported. In this study, 185 PdbHLH genes were identified in the Populus deltoids genome and were classified into 15 groups based on their sequence similarity and phylogenetic relationships. Analysis of the gene structure, chromosome location and conserved motif of the PdbHLH genes were performed by bioinformatic methods. Gene duplication analyses revealed that 114 PdbHLH were expanded and retained after WGD/segmental and proximal duplication. Investigation of cis-regulatory elements of PdbHLH genes indicated that many PdbHLH genes are involved in the regulation of anthocyanin biosynthesis. The expression patterns of PdbHLHs were obtained from previous data in two colored-leaf poplar (QHP and JHP) and green leaf poplar (L2025). Further analysis revealed that 12 candidate genes, including 3 genes (PdbHLH57, PdbHLH143, and PdbHLH173) from the subgroup III(f) and 9 gene from other groups, were positively associated with anthocyanin biosynthesis. In addition, 4 genes (PdbHLH4, PdbHLH1, PdbHLH18, and PdbHLH164) may be involved in negatively regulating the anthocyanin biosynthesis. These results provide a basis for the functional characterization of bHLH genes and investigations on the molecular mechanisms of anthocyanin biosynthesis in colored-leaf poplar.

Identification of Differentially Expressed Genes Related to Floral Bud Differentiation and Flowering Time in Three Populations of Lycoris radiata.

The transition from vegetative to reproductive growth is important for controlling the flowering of Lycoris radiata. However, the genetic control of this complex developmental process remains unclear. In this study, 18 shoot apical meristem (SAM) samples were collected from early-, mid- and late-flowering populations during floral bud differentiation. The histological analysis of paraffin sections showed that the floral bud differentiation could be divided into six stages; the differentiation time of the early group was earlier than that of the middle and late groups, and the late group was the latest. In different populations, some important differential genes affecting the flowering time were identified by transcriptome profiles of floral bud differentiation samples. Weighted gene co-expression network analysis (WGCNA) was performed to enrich the gene co-expression modules of diverse flowering time populations (FT) and floral bud differentiation stages (ST). In the MEyellow module, five core hub genes were identified, including CO14, GI, SPL8, SPL9, and SPL15. The correlation network of hub genes showed that they interact with SPLs, AP2, hormone response factors (auxin, gibberellin, ethylene, and abscisic acid), and several transcription factors (MADS-box transcription factor, bHLH, MYB, and NAC3). It suggests the important role of these genes and the complex molecular mechanism of floral bud differentiation and flowering time in L. radiata. These results can preliminarily explain the molecular mechanism of floral bud differentiation and provide new candidate genes for the flowering regulation of Lycoris.

Genome-wide analysis and expression profiles of PdeMYB transcription factors in colored-leaf poplar (Populus deltoids).

BACKGROUND: MYB transcription factors, comprising one of the largest transcription factor families in plants, play many roles in secondary metabolism, especially in anthocyanin biosynthesis. However, the functions of the PdeMYB transcription factor in colored-leaf poplar remain elusive. RESULTS: In the present study, genome-wide characterization of the PdeMYB genes in colored-leaf poplar (Populus deltoids) was conducted. A total of 302 PdeMYB transcription factors were identified, including 183 R2R3-MYB, five R1R2R3-MYB, one 4R-MYB, and 113 1R-MYB transcription factor genes. Genomic localization and paralogs of PdeMYB genes mapped 289 genes on 19 chromosomes, with collinearity relationships among genes. The conserved domain, gene structure, and evolutionary relationships of the PdeMYB genes were also established and analyzed. The expression levels of PdeMYB genes were obtained from previous data in green leaf poplar (L2025) and colored leaf poplar (QHP) as well as our own qRT-PCR analysis data in green leaf poplar (L2025) and colored leaf poplar (CHP), which provide valuable clues for further functional characterization of PdeMYB genes. CONCLUSIONS: The above results provide not only comprehensive insights into the structure and functions of PdeMYB genes but also provide candidate genes for the future improvement of leaf colorization in Populus deltoids.

Physiological and Molecular Analysis Reveals the Differences of Photosynthesis between Colored and Green Leaf Poplars.

Leaf coloration changes evoke different photosynthetic responses among different poplar cultivars. The aim of this study is to investigate the photosynthetic difference between a red leaf cultivar (ZHP) and a green leaf (L2025) cultivar of Populus deltoides. In this study, 'ZHP' exhibited wide ranges and huge potential for absorption and utilization of light energy and CO2 concentration which were similar to those in 'L2025' and even showed a stronger absorption for weak light. However, with the increasing light intensity and CO2 concentration, the photosynthetic capacity in both 'L2025' and 'ZHP' was gradually restricted, and the net photosynthetic rate (Pn) in 'ZHP' was significantly lower than that in 'L2025'under high light or high CO2 conditions, which was mainly attributed to stomatal regulation and different photosynthetic efficiency (including the light energy utilization efficiency and photosynthetic CO2 assimilation efficiency) in these two poplars. Moreover, the higher anthocyanin content in 'ZHP' than that in 'L2025' was considered to be closely related to the decreased photosynthetic efficiency in 'ZHP'. According to the results from the JIP-test, the capture efficiency of the reaction center for light energy in 'L2025' was significantly higher than that in 'ZHP'. Interestingly, the higher levels of light quantum caused relatively higher accumulation of QA- in 'L2025', which blocked the electron transport and weakened the photosystem II (PSII) performance as compared with 'ZHP'; however, the decreased capture of light quantum also could not promote the utilization of light energy, which was the key to the low photosynthetic efficiency in 'ZHP'. The differential expressions of a series of photosynthesis-related genes further promoted these specific photosynthetic processes between 'L2025' and 'ZHP'.

Recent Research Progress in Taxol Biosynthetic Pathway and Acylation Reactions Mediated by Taxus Acyltransferases.

Taxol is one of the most effective anticancer drugs in the world that is widely used in the treatments of breast, lung and ovarian cancer. The elucidation of the taxol biosynthetic pathway is the key to solve the problem of taxol supply. So far, the taxol biosynthetic pathway has been reported to require an estimated 20 steps of enzymatic reactions, and sixteen enzymes involved in the taxol pathway have been well characterized, including a novel taxane-10ß-hydroxylase (T10ßOH) and a newly putative ß-phenylalanyl-CoA ligase (PCL). Moreover, the source and formation of the taxane core and the details of the downstream synthetic pathway have been basically depicted, while the modification of the core taxane skeleton has not been fully reported, mainly concerning the developments from diol intermediates to 2-debenzoyltaxane. The acylation reaction mediated by specialized Taxus BAHD family acyltransferases (ACTs) is recognized as one of the most important steps in the modification of core taxane skeleton that contribute to the increase of taxol yield. Recently, the influence of acylation on the functional and structural diversity of taxanes has also been continuously revealed. This review summarizes the latest research advances of the taxol biosynthetic pathway and systematically discusses the acylation reactions supported by Taxus ACTs. The underlying mechanism could improve the understanding of taxol biosynthesis, and provide a theoretical basis for the mass production of taxol.

Complete Chloroplast Genomes and Comparative Analyses of L. chinensis, L. anhuiensis, and L. aurea (Amaryllidaceae).

The genus Lycoris (about 20 species) includes important medicinal and ornamental plants. Due to the similar morphological features and insufficient genomic resources, germplasm identification and molecular phylogeny analysis are very limited. Here, we sequenced the complete chloroplast genomes of L. chinensis, L. anhuiensis, and L. aurea; they have very similar morphological traits that make it difficult to identify. The full length of their cp genomes was nearly 158k bp with the same guanine-cytosine content of 37.8%. A total of 137 genes were annotated, including 87 protein-coding genes, 42 tRNAs, and eight rRNAs. A comparative analysis revealed the conservation in sequence size, GC content, and gene content. Some variations were observed in repeat structures, gene expansion on the IR-SC (Inverted Repeat-Single-Copy) boundary regions. Together with the cpSSR (chloroplast simple sequence repeats), these genetic variations are useful to develop molecular markers for germplasm identification. Phylogenetic analysis showed that seven Lycoris species were clustered into a monophyletic group, and closed to Narcissus in Amaryllidaceae. L. chinensis, L. anhuiensis, and L. longituba were clustered together, suggesting that they were very likely to be derived from one species, and had the same ancestor with L. squamigera. Our results provided information on the study of genetic diversity, origins or relatedness of native species, and the identification of cultivars.

Metabolic Variations of Flavonoids in Leaves of T. media and T. mairei Obtained by UPLC-ESI-MS/MS.

The needles of Taxus species contain a large number of bioactive compounds, such as flavonoids. In the present study, the total flavonoid content in leaves of Taxus media and Taxus mairei was 19.953 and 14.464 mg/g, respectively. A total of 197 flavonoid metabolites (70 flavones, 42 flavonols, 26 flavone C-glycosides, 20 flavanones, 15 anthocyanins, 13 isoflavones, 6 flavonolignans, and 5 proanthocyanidins) were identified for the first time by a widely targeted Ultra Performance Liquid Chromatography-Electrospray Ionization-Tandem Mass Spectrometry (UPLC-ESI-MS/MS) method within the two Taxus species, containing 160 common metabolites, with 37 unique metabolites merely determined in T. mairei or T. media. Moreover, 42 differential flavonoid metabolites were screened in the two Taxus species, which showed specific metabolic patterns in isoflavonoid biosynthesis, anthocyanin biosynthesis, and flavone and flavonol biosynthesis pathways. Compared to T. mairei, a more activated phenylpropanoid pathway was found in T. media, which could be responsible for the higher content of total flavonoids in T. media. Our results provide new insights into the diversity of flavonoid metabolites between T. mairei and T. media, and provide a theoretical basis for the sufficient utilization of Taxus species and the development of novel drugs.

Therapeutic Effect of Sodium Glucose Co-Transporter 2 Inhibitor Dapagliflozin on Renal Cell Carcinoma.

BACKGROUND Patients with type 2 diabetes mellitus (T2DM) have a high incidence of renal cell carcinoma (RCC) and high sodium glucose co-transporters 2 (SGLT2) expressions. The purpose of this study was to evaluate the anticancer activity of dapagliflozin as an SGLT2 inhibitor on RCC cell lines in vitro and in vivo. MATERIAL AND METHODS qRT-PCR and Western blot were used to detect SGLT2 expression on different human renal cells. Then, flow cytometry and immunofluorescence were used to investigate the effects of dapagliflozin on cell cycle, apoptosis, and SGLT2 expression of CaKi-1 cells. Finally, a xenograft model and immunohistochemical staining were used to investigate the function of dapagliflozin in nude mice. RESULTS We proved that SGLT2 is highly expressed in RCC cell lines. We found that dapagliflozin exerts a higher cytotoxic effect on human RCC than on normal human renal cells, regulates the cell cycle and apoptosis, and reduces the glucose uptake and SGLT2 expression of CaKi-1 cells. Moreover, dapagliflozin inhibits tumor growth and reduces SGLT2 expression in vivo. CONCLUSIONS Our results indicate that dapagliflozin has high efficiency and low toxicity and could be a new therapeutic target for RCC.

Characterization of the Heat Shock Transcription Factor Family in Lycoris radiata and Its Potential Roles in Response to Abiotic Stresses.

Heat shock transcription factors (HSFs) are an essential plant-specific transcription factor family that regulates the developmental and growth stages of plants, their signal transduction, and their response to different abiotic and biotic stresses. The HSF gene family has been characterized and systematically observed in various species; however, research on its association with Lycoris radiata is limited. This study identified 22 HSF genes (LrHSFs) in the transcriptome-sequencing data of L. radiata and categorized them into three classes including HSFA, HSFB, and HSFC, comprising 10, 8, and 4 genes, respectively. This research comprises basic bioinformatics analyses, such as protein sequence length, molecular weight, and the identification of its conserved motifs. According to the subcellular localization assessment, most LrHSFs were present in the nucleus. Furthermore, the LrHSF gene expression in various tissues, flower developmental stages, two hormones stress, and under four different abiotic stresses were characterized. The data indicated that LrHSF genes, especially LrHSF5, were essentially involved in L. radiata development and its response to different abiotic and hormone stresses. The gene-gene interaction network analysis revealed the presence of synergistic effects between various LrHSF genes' responses against abiotic stresses. In conclusion, these results provided crucial data for further functional analyses of LrHSF genes, which could help successful molecular breeding in L. radiata.

Characterization of the complete chloroplast genome of 'Quanhong poplar' (Populus deltoides W. Bartram ex Humphry Marshall, 2011).

The color of the leaves is one of the most important factors for horticultural crops that are considered by breeders, and is also attracting more and more attention from economists and academics. 'Quanhong poplar' (QHP), a rare, bright reddish-purple color-leaf cultivar that has been widely cultivated in China as a landscape tree, is a very precious color-leaf cultivar. In the present study, a reference-based assembly was performed using whole-genome sequencing data to characterize the chloroplast genome of 'QHP'. The total chloroplast genome size of 'QHP' is 156,950 bp, which is divided into two inverted repeat structures of 27,649 bp each, a small single-copy region of 16,563 bp, and a large single-copy region (LSC) of 85,089 bp. From the chloroplast genome, 130 genes have been predicted, including 85 protein-coding genes, 37 tRNA genes, and eight rRNA genes. A chloroplast genome containing 36.68% GC content was detected in 'QHP'. Three SNP sites have been developed between 'QHP' and Populus deltoides Zhonglin 2025. Based on the phylogenetic analysis of chloroplast genomes reported for Populus, the chloroplast of 'QHP' is closest to several strains of Populus deltoides.

Functions and Regulatory Mechanisms of bHLH Transcription Factors during the Responses to Biotic and Abiotic Stresses in Woody Plants.

Environmental stresses, including abiotic and biotic stresses, have complex and diverse effects on the growth and development of woody plants, which have become a matter of contention due to concerns about the outcomes of climate change on plant resources, genetic diversity, and world food safety. Plant basic helix-loop-helix (bHLH) transcription factors (TFs) are involved in a variety of physiological processes and play an important role in biotic and abiotic stress responses of woody plants. In recent years, an increasing body of studies have been conducted on the bHLH TFs in woody plants, and the roles of bHLH TFs in response to various stresses are increasingly clear and precise. Therefore, it is necessary to conduct a systematic and comprehensive review of the progress of the research of woody plants. In this review, the structural characteristics, research history and roles in the plant growth process of bHLH TFs are summarized, the gene families of bHLH TFs in woody plants are summarized, and the roles of bHLH TFs in biotic and abiotic stresses in woody plants are highlighted. Numerous studies mentioned in this review have shown that bHLH transcription factors play a crucial role in the response of woody plants to biotic and abiotic stresses. This review serves as a reference for further studies about enhancing the stress resistance and breeding of woody plants. Also, the future possible research directions of bHLH TFs in response to various stresses in woody plants will be discussed.

Establishing a Virus-Induced Gene Silencing System in Lycoris chinensis.

Lycoris is an important plant with both medicinal and ornamental values. However, it does not have an efficient genetic transformation system, which makes it difficult to study gene function of the genus. Virus-induced gene silencing (VIGS) is an effective technique for studying gene functions in plants. In this study, we develop an efficient virus-induced gene-silencing (VIGS) system using the leaf tip needle injection method. The widely used TRV vector is constructed, and the Cloroplastos Alterados 1 (CLA1) and Phytoene Desaturase (PDS) genes are selected as visual indicators in the VIGS system. As a result, it is observed that leaves infected with TRV-LcCLA1 and TRV-LcPDS both show a yellowing phenotype (loss of green), and the chlorosis range of TRV-LcCLA1 was larger and deeper than that of TRV-LcPDS. qRT-PCR results show that the expression levels of LcCLA1 and LcPDS are significantly reduced, and the silencing efficiency of LcCLA1 is higher than that of LcPDS. These results indicate that the VIGS system of L. chinensis was preliminarily established, and LcCLA1 is more suitable as a gene-silencing indicator. For the monocotyledonous plant leaves with a waxy surface, the leaf tip injection method greatly improves the infiltration efficiency. The newly established VIGS system will contribute to gene functional research in Lycoris species.

Effects of Seasonal Changes on Chlorophyll Fluorescence and Physiological Characteristics in the Two Taxus Species.

Taxus is a rare and endangered woody plant worldwide with important economic and ecological values. However, the weak environmental adaptability of Taxus species, in particular the unstable photosynthetic activity in different seasons, always affects its normal growth and development and limits its conservation and exploitation. To improve the survival of Taxus trees in cultivated areas, the seasonal dynamics of chlorophyll fluorescence (CF) and key physiological parameters were comprehensively investigated in T. media and T. mairei. The results demonstrated that the photosynthetic activity of both Taxus species was sensitive to local summer and winter environmental conditions, with the heterogeneity of fluorescence signatures intuitively presented on the needle surface by CF-Imaging detection, while images of maximum quantum efficiency of PSII photochemistry (Fv/Fm) demonstrated values below 0.7 in the blue-green sectors in winter. The distribution of light energy was regulated by the photosynthetic apparatus in both Taxus species to maintain a stable actual quantum yield of PSII photochemistry (φPSII), which was around 0.4-0.5. Based on a redundancy discriminant analysis, the interpretation rate of light intensity and air temperature ranked as the top two in both Taxus species, which were considered the main environmental factors affecting the photosynthetic performance of Taxus by disturbing the electron transport chain. In the winter, T. mairei exhibited weaker electron transport activity than T. media, thus caused lower photochemistry and more severe photosynthetic damages. Interestingly, both Taxus species demonstrated consistent response patterns, including diverse energy dissipation strategies and enhancement of osmoregulatory substances and antioxidative activities, thus maintaining stable photosynthetic functions in response to environmental changes.

[Involvement of Wnt/ß-catenin signaling in the osteogenesis of bone marrow mesenchymal stem cells induced by drynaria total flavonoids].

OBJECTIVE: To explore the effects of the expression of Wnt/ß-catenin signaling factor mRNA during drynaria total flavonoids on the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). METHODS: The BMSCs were isolated from SD rats by whole bone marrow culture method and purified by passage. And the P3 BMSCs were intervened with 100 µg/ml drynaria total flavonoids. At Day 21, mineralized staining was performed. At Days 7, 14, 21 and 28 post-intervention, the activity of alkaline phosphatase (ALP) was detected and polymerase chain reaction (PCR) used to detect the expressions of Wnt/ß-catenin signaling pathway related factors ß-catenin, LEF-1 and cycline D mRNA. RESULTS: At each time point post-intervention, comparing the ALP activity in cell supernatant between two group, the drynaria total flavonoids group was higher than the blank control group (7 d: 11.10 ± 0.08 vs 1.61 ± 0.14; 14 d: 24.62 ± 0.34 vs 1.64 ± 0.04; 21 d: 18.41 ± 0.06 vs 1.53 ± 0.04; 28 d: 14.9 ± 0.14 vs 1.52 ± 0.04; all P < 0.01). At Day 21, upon staining with alizarin red, the drynaria total flavonoids group was positive while the blank control group negative. At Day 14, the expression of ß-catenin mRNA was higher in the drynaria total flavonoids group higher than that in the blank control group (0.357 ± 0.063 vs 0.174 ± 0.013, P < 0.05). At Day 7, the expressions of LEF-1 and cycline D mRNA were higher in the drynaria total flavonoids group than those in the blank control group (LEF-1 0.0611 ± 0.0002 vs 0.0345 ± 0.0131; cycline D 0.1510 ± 0.0255 vs 0.0718 ± 0.0294, all P < 0.05). CONCLUSION: Drynaria total flavonoids induce BMSCs to differentiate into osteoblasts. And it is accompanied with the altered expression of Wnt/ß-catenin signaling pathway related factor mRNA.

Transcriptome-wide characterization of bHLH transcription factor genes in Lycoris radiata and functional analysis of their response to MeJA.

As one of the biggest plant specific transcription factor (TF) families, basic helix-loop-helix (bHLH) protein, plays significant roles in plant growth, development, and abiotic stress responses. However, there has been minimal research about the effects of methyl jasmonate (MeJA) treatment on the bHLH gene family in Lycoris radiata (L'Her.) Herb. In this study, based on transcriptome sequencing data, 50 putative L. radiata bHLH (LrbHLH) genes with complete open reading frames (ORFs), which were divided into 20 bHLH subfamilies, were identified. The protein motif analyses showed that a total of 10 conserved motifs were found in LrbHLH proteins and motif 1 and motif 2 were the most highly conserved motifs. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of LrbHLH genes revealed their involvement in regulation of plant growth, jasmonic acid (JA) mediated signaling pathway, photoperiodism, and flowering. Furthermore, subcellular localization revealed that most LrbHLHs were located in the nucleus. Expression pattern analysis of LrbHLH genes in different tissues and at flower developmental stages suggested that their expression differed across lineages and might be important for plant growth and organ development in Lycoris. In addition, all LrbHLH genes exhibited specific spatial and temporal expression patterns under MeJA treatment. Moreover, protein-protein interaction (PPI) network analysis and yeast two-hybrid assay showed that numerous LrbHLHs could interact with jasmonate ZIM (zinc-finger inflorescence meristem) domain (JAZ) proteins. This research provides a theoretical basis for further investigation of LrbHLHs to find their functions and insights for their regulatory mechanisms involved in JA signaling pathway.

Transcriptome Analysis of Lycoris chinensis Bulbs Reveals Flowering in the Age-Mediated Pathway.

Lycoris is a summer bulbous flower that commonly needs to go through a long period of vegetative growth for 3 to 5 years before flowering. Plant flowering is regulated by a complex genetic network. Compared with most perennial flowers, knowledge on the molecular mechanism responsible for floral transition in bulbous flowers is lacking, and only a few genes that regulate flowering have been identified with few reports on the floral transition in Lycoris. In this study, we identified many differentially expressed genes (DEGs) and transcription factors (TFs) by RNA-Seq in L. chinensis bulbs of different ages, including one- to four-year-old nonflowering bulbs and four-year-old flowering bulbs. Some DEGs were enriched in Gene Ontology (GO) terms between the three- and four-year-old bulbs, and there most genes were enriched in terms of metabolic process and catalytic activity. In the four-year old bulbs, most of the DEGs that may be involved in flowering were classified under the GO term biological process, which was a totally different result from the vegetative bulbs. Some DEGs between flowering and nonflowering bulbs were enriched in plant hormone signal transduction, including the hormones auxin, cytokinin, abscisic acid, and ethylene, but no DEGs were enriched in the gibberellin pathway. Auxin is the main endogenous phytohormone involved in bulb growth and development, but cytokinin, abscisic acid, and ethylene were shown to increase in flowering bulbs. In addition, energy-metabolism-related genes maintain a high expression level in large bulbs, and some positive regulators (SPL, COL, and AP1) and early flowering genes were also shown to be highly expressed in the meristems of flowering bulbs. It suggested that sugar molecules may be the energy source that regulates the signal transduction of flowering by connecting with phytohormone signaling in Lycoris. A total of 1911 TFs were identified and classified into 89 categories, where the top six families with the largest gene numbers were C2H2, NAC, AP2/ERF-ERF, C3H, MYB-related, and WRKY. Most DEGs were in the AP2/ERF-ERF family, and most of them were downregulated in 4-year-old flowering bulbs. A number of families were reported to be involved in plant flowering, including NAC, AP2/ERF, MYB, WRKY, bZIP, MADS, and NF-Y. These results can act as a genetic resource to aid in the explanation of the genetic mechanism responsible for the flowering of Lycoris and other bulbous flowers.

[Relationship of glucose metabolic rate and plasma levels of adiponectin and leptin in patients with metabolic syndrome].

OBJECTIVE: To investigate the relationship of glucose metabolic rate (GMR) and plasma levels of adiponectin and leptin in patients with metabolic syndrome (MS). METHODS: A total of 30 MS subjects aged 36-60 years old were selected as MS group. And 20 normal adults were selected as control group. The GMR was evaluated by the technique of hyperinsulinemic euglycemia clamp. The plasma concentrations of adiponectin and leptin were detected by enzyme-linked immunosorbent assay (ELISA). Blood pressure, waist circumference (WC), body weight and body height were measured. RESULTS: (1) During the steady state (last 30 min), the GMR was significantly lower in MS group than that in control Group [(4.13 ± 1.34) mg×kg(-1)×min(-1) vs (8.33 ± 1.59) mg·kg(-1)×min(-1), P < 0.01]. (2) The plasma level of adiponectin was significantly lower in MS group than that in control group [(5.15 ± 2.54) µg/ml vs (10.28 ± 5.50) µg/ml, P < 0.01]. The plasma level of leptin were significantly higher in MS group than that in control group [(189.37 ± 90.48) ng/ml vs (126.55 ± 72.70) ng/ml, P < 0.01]. (3) In MS group, glucose metabolic rate was associated with WC, BMI, TG, HDL-C FINS, leptin, and adiponectin, (all P < 0.05). CONCLUSION: The technique of hyperinsulinemic euglycemic clamp shows that the BMR of MS patients significantly decreases. It may be associated with their lowered plasma levels of adiponectin and leptin.