Genome-wide analysis of the MADS-box gene family in Lonicera japonica and a proposed floral organ identity model.

BACKGROUND: Lonicera japonica Thunb. is widely used in traditional Chinese medicine. Medicinal L. japonica mainly consists of dried flower buds and partially opened flowers, thus flowers are an important quality indicator. MADS-box genes encode transcription factors that regulate flower development. However, little is known about these genes in L. japonica. RESULTS: In this study, 48 MADS-box genes were identified in L. japonica, including 20 Type-I genes (8 Mα, 2 Mß, and 10 Mγ) and 28 Type-II genes (26 MIKCc and 2 MIKC*). The Type-I and Type-II genes differed significantly in gene structure, conserved domains, protein structure, chromosomal distribution, phylogenesis, and expression pattern. Type-I genes had a simpler gene structure, lacked the K domain, had low protein structure conservation, were tandemly distributed on the chromosomes, had more frequent lineage-specific duplications, and were expressed at low levels. In contrast, Type-II genes had a more complex gene structure; contained conserved M, I, K, and C domains; had highly conserved protein structure; and were expressed at high levels throughout the flowering period. Eleven floral homeotic MADS-box genes that are orthologous to the proposed Arabidopsis ABCDE model of floral organ identity determination, were identified in L. japonica. By integrating expression pattern and protein interaction data for these genes, we developed a possible model for floral organ identity determination. CONCLUSION: This study genome-widely identified and characterized the MADS-box gene family in L. japonica. Eleven floral homeotic MADS-box genes were identified and a possible model for floral organ identity determination was also developed. This study contributes to our understanding of the MADS-box gene family and its possible involvement in floral organ development in L. japonica.

Systematic Discovery of a New Catalogue of Tyrosine-Type Integrases in Bacterial Genomic Islands.

Site-specific recombinases (integrases) can mediate the horizontal transfer of genomic islands. The ability to integrate large DNA sequences into target sites is very important for genetic engineering in prokaryotic and eukaryotic cells. Here, we characterized an unprecedented catalogue of 530 tyrosine-type integrases by examining genes potentially encoding tyrosine integrases in bacterial genomic islands. The phylogeny of putative tyrosine integrases revealed that these integrases form an evolutionary clade that is distinct from those already known and are affiliated with novel integrase groups. We systematically searched for candidate integrase genes, and their integration activities were validated in a bacterial model. We verified the integration functions of six representative novel integrases by using a two-plasmid integration system consisting of a donor plasmid carrying the integrase gene and attP site and a recipient plasmid harboring an attB site in recA-deficient Escherichia coli. Further quantitative reverse transcription-PCR (qRT-PCR) assays validated that the six selected integrases can be expressed with their native promoters in E. coli. The attP region reductions showed that the extent of attP sites of integrases is approximately 200 bp for integration capacity. In addition, mutational analysis showed that the conserved tyrosine at the C terminus is essential for catalysis, confirming that these candidate proteins belong to the tyrosine-type recombinase superfamily, i.e., tyrosine integrases. This study revealed that the novel integrases from bacterial genomic islands have site-specific recombination functions, which is of physiological significance for their genomic islands in bacterial chromosomes. More importantly, our discovery expands the toolbox for genetic engineering, especially for efficient integration activity. IMPORTANCE Site-specific recombinases or integrases have high specificity for DNA large fragment integration, which is urgently needed for gene editing. However, known integrases are not sufficient for meeting multiple integrations. In this work, we discovered an array of integrases through bioinformatics analysis in bacterial genomes. Phylogeny and functional assays revealed that these new integrases belong to tyrosine-type integrases and have the ability to conduct site-specific recombination. Moreover, attP region extent and catalysis site analysis were characterized. Our study provides the methodology for discovery of novel integrases and increases the capacity of weapon pool for genetic engineering in bacteria.

Luteolin Alleviates Oxidative Stress in Chronic Obstructive Pulmonary Disease Induced by Cigarette Smoke via Modulation of the TRPV1 and CYP2A13/NRF2 Signaling Pathways.

The current study aims to investigate the therapeutic potential of luteolin (Lut), a naturally occurring flavonoid found in various medicinal plants, for treating chronic obstructive pulmonary disease (COPD) through both in vitro and in vivo studies. The results demonstrated that Lut increased body weight, reduced lung tissue swelling and lung damage indices, mitigated systemic oxidative stress levels, and decreased alveolar fusion in cigarette smoke (CS)- and lipopolysaccharide (LPS)-induced COPD mice. Additionally, Lut was observed to downregulate the expression of the TRPV1 and CYP2A13 proteins while upregulating SIRT6 and NRF2 protein expression in CS + LPS-induced COPD mice and cigarette smoke extract (CSE)-treated A549 cells. The concentrations of total reactive oxygen species (ROS) and mitochondrial ROS in A549 cells induced by CSE significantly increased. Moreover, CSE caused a notable elevation of intracellular Ca2+ levels in A549 cells. Importantly, Lut exhibited inhibitory effects on the inward flow of Ca2+ and attenuated the overproduction of mitochondrial and intracellular ROS in A549 cells treated with CSE. In conclusion, Lut demonstrated a protective role in alleviating oxidative stress and inflammation in CS + LPS-induced COPD mice and CSE-treated A549 cells by regulating TRPV1/SIRT6 and CYP2A13/NRF2 signaling pathways.

Characterisation of the Mentha canadensis R2R3-MYB transcription factor gene McMIXTA and its involvement in peltate glandular trichome development.

BACKGROUND: Mentha canadensis L. has important economic value for the production of essential oils, which are synthesised, secreted and stored in peltate glandular trichomes. As a typical multicellular secretory trichome, glandular trichomes are important biological factories for the synthesis of some specialised metabolites. However, little is known about the molecular mechanism of glandular trichome development in M. canadensis. RESULTS: In this study, the R2R3-MYB transcription factor gene McMIXTA was isolated to investigate its function in glandular trichome development. Bioinformatics analysis indicated that McMIXTA belonged to the subgroup 9 R2R3-MYB, with a R2R3 DNA-binding domain and conserved subgroup 9 motifs. A subcellular localisation assay indicated that McMIXTA was localised in the nucleus. Transactivation analysis indicated that McMIXTA was a positive regulator, with transactivation regions located between positions N253 and N307. Yeast two-hybrid and bimolecular fluorescence complementation assays showed that McMIXTA formed a complex with McHD-Zip3, a trichome development-related HD-ZIP IV transcription factor. Overexpression of McMIXTA in Mentha × piperita L. caused an increase in peltate glandular trichomes density of approximately 25% on the leaf abaxial surface. CONCLUSIONS: Our results demonstrated that the subgroup 9 R2R3-MYB transcription factor McMIXTA has a positive effect on regulating peltate glandular trichome development and the MIXTA/HD-ZIP IV complexes might be conserved regulators for glandular trichome initiation. These results provide useful information for revealing the regulatory mechanism of multicellular glandular trichome development.

Systematic analysis of supervised machine learning as an effective approach to predicate ß-lactam resistance phenotype in Streptococcus pneumoniae.

Streptococcus pneumoniae is the most common human respiratory pathogen, and ß-lactam antibiotics have been employed to treat infections caused by S. pneumoniae for decades. ß-lactam resistance is steadily increasing in pneumococci and is mainly associated with the alteration in penicillin-binding proteins (PBPs) that reduce binding affinity of antibiotics to PBPs. However, the high variability of PBPs in clinical isolates and their mosaic gene structure hamper the predication of resistance level according to the PBP gene sequences. In this study, we developed a systematic strategy for applying supervised machine learning to predict S. pneumoniae antimicrobial susceptibility to ß-lactam antibiotics. We combined published PBP sequences with minimum inhibitory concentration (MIC) values as labelled data and the sequences from NCBI database without MIC values as unlabelled data to develop an approach, using only a fragment from pbp2x (750 bp) and a fragment from pbp2b (750 bp) to predicate the cefuroxime and amoxicillin resistance. We further validated the performance of the supervised learning model by constructing mutants containing the randomly selected pbps and testing more clinical strains isolated from Chinese hospital. In addition, we established the association between resistance phenotypes and serotypes and sequence type of S. pneumoniae using our approach, which facilitate the understanding of the worldwide epidemiology of S. pneumonia.

Comparative transcriptome analysis revealed candidate genes involved in fruiting body development and sporulation in Ganoderma lucidum.

Ganoderma lucidum is an edible mushroom highly regarded in the traditional Chinese medicine. To better understand the molecular mechanisms underlying fruiting body development in G. lucidum, transcriptome analysis based on RNA sequencing was carried out on different developmental stages: mycelium (G1); primordium (G2); young fruiting body (G3); mature fruiting body (G4); fruiting body in post-sporulation stage (G5). In total, 26,137 unigenes with an average length of 1078 bp were de novo assembled. Functional annotation of transcriptomes matched 72.49% of the unigenes to known proteins available in at least one database. Differentially expressed genes (DEGs) were identified between the evaluated stages: 3135 DEGs in G1 versus G2; 120 in G2 versus G3; 3919 in G3 versus G4; and 1012 in G4 versus G5. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of DEGs identified in G1 versus G2 revealed that, in addition to global and overview maps, enriched pathways were related to amino acid metabolism and carbohydrate metabolism. In contrast, DEGs identified in G2 versus G3 were mainly assigned to the category of metabolism of amino acids and their derivatives, comprising mostly upregulated unigenes. In addition, highly expressed unigenes associated with the transition between different developmental stages were identified, including those encoding hydrophobins, cytochrome P450s, extracellular proteases, and several transcription factors. Meanwhile, highly expressed unigenes related to meiosis such as DMC1, MSH4, HOP1, and Mek1 were also analyzed. Our study provides important insights into the molecular mechanisms underlying fruiting body development and sporulation in G. lucidum.

Isolation, Characterization of Bamboo Leaf Flavonoids by Size Exclusion Chromatography and Their Antioxidant Properties.

The utilization of bamboo industry exhibits varied but still needs to be improved. Bamboo leaf flavonoid (BLF) is an important resource of bamboo which has become a research focus. However, the isolation and purification techniques of four flavonoid carbon glycosides (orientin, isoorientin, vitexin, and isovitexin) from BLF were still confronted with difficulties due to their complex and similar structures, which obstructed the development of bamboo utilization. In this article, a purification technology of four flavonoid carbon glycosides from BLF by Sephadex LH-20 was improved. The results were evaluated by HPLC and pharmacological activity. Specifically, the eluent, flow rate, and loading amount were investigated, respectively. According to the results, the eluent would dominate the isolation effect among three factors. High concentration of isoorientin and four flavonoid carbon glycosides would be obtained under the optimized condition (The eluent was 70 % methanol, the loading amount was 1.5 g, and the flow rate was 0.5 mL/min). Meanwhile, the link between flavonoid carbon glycosides content and their antioxidant activity in vitro was also revealed. Overall, the results suggested that BLF may serve as potential functional food additives and medicine.

A GPAT1 Mutation in Arabidopsis Enhances Plant Height but Impairs Seed Oil Biosynthesis.

Glycerol-3-phosphate acyltransferases (GPATs) play an important role in glycerolipid biosynthesis, and are mainly involved in oil production, flower development, and stress response. However, their roles in regulating plant height remain unreported. Here, we report that Arabidopsis GPAT1 is involved in the regulation of plant height. GUS assay and qRT-PCR analysis in Arabidopsis showed that GPAT1 is highly expressed in flowers, siliques, and seeds. A loss of function mutation in GPAT1 was shown to decrease seed yield but increase plant height through enhanced cell length. Transcriptomic and qRT-PCR data revealed that the expression levels of genes related to gibberellin (GA) biosynthesis and signaling, as well as those of cell wall organization and biogenesis, were significantly upregulated. These led to cell length elongation, and thus, an increase in plant height. Together, our data suggest that knockout of GPAT1 impairs glycerolipid metabolism in Arabidopsis, leading to reduced seed yield, but promotes the biosynthesis of GA, which ultimately enhances plant height. This study provides new evidence on the interplay between lipid and hormone metabolism in the regulation of plant height.

Transcriptome-Wide Identification and Characterization of the JAZ Gene Family in Mentha canadensis L.

Jasmonate ZIM-domain (JAZ) proteins are the crucial transcriptional repressors in the jasmonic acid (JA) signaling process, and they play pervasive roles in plant development, defense, and plant specialized metabolism. Although numerous JAZ gene families have been discovered across several plants, our knowledge about the JAZ gene family remains limited in the economically and medicinally important Chinese herb Mentha canadensis L. Here, seven non-redundant JAZ genes named McJAZ1-McJAZ7 were identified from our reported M. canadensis transcriptome data. Structural, amino acid composition, and phylogenetic analysis showed that seven McJAZ proteins contained the typical zinc-finger inflorescence meristem (ZIM) domain and JA-associated (Jas) domain as conserved as those in other plants, and they were clustered into four groups (A-D) and distributed into five subgroups (A1, A2, B1, B2, and D). Quantitative real-time PCR (qRT-PCR) analysis showed that seven McJAZ genes displayed differential expression patterns in M. canadensis tissues, and preferentially expressed in flowers. Furthermore, the McJAZ genes expression was differentially induced after Methyl jasmonate (MeJA) treatment, and their transcripts were variable and up- or down-regulated under abscisic acid (ABA), drought, and salt treatments. Subcellular localization analysis revealed that McJAZ proteins are localized in the nucleus or cytoplasm. Yeast two-hybrid (Y2H) assays demonstrated that McJAZ1-5 interacted with McCOI1a, a homolog of Arabidopsis JA receptor AtCOI1, in a coronatine-dependent manner, and most of McJAZ proteins could also form homo- or heterodimers. This present study provides valuable basis for functional analysis and exploitation of the potential candidate McJAZ genes for developing efficient strategies for genetic improvement of M. canadensis.

De novo transcriptomic analysis of light-induced flavonoid pathway, transcription factors in the flower buds of Lonicera japonica.

KEY MESSAGE: Transcriptomic analysis of the relationship between gene expression patterns and flavonoid contents in the flower buds of Lonicera japonica under light-induced conditions, especially the flavonoid pathway genes and transcription factors. ABSTRACT: Flos Lonicerae Japonicae (FLJ), the flower buds of Lonicera japonica Thunb., has been used to treat some human diseases including severe respiratory syndromes and hand-foot-and-mouth diseases owing to its putative antibacterial, and antiviral effects. Luteoloside is a flavonoid that is used by the Chinese Pharmacopoeia to evaluate the quality of FLJ. Light is an important environmental factor that affects flavonoid biosynthesis in the flower buds of L. japonica. However, how light triggers increases in flavonoid production remains unclear. To enhance our understanding of the mechanism involved in light-regulated flavonoid biosynthesis, we sequenced the transcriptomes of L. japonica exposed to three different light conditions: 100% light intensity (CK), 50% light intensity (LI50), and 25% light intensity (LI25) using an Illumina HiSeq 4000 System. A total of 77,297 unigenes with an average length of 809 bp were obtained. Among them, 43,334 unigenes (56.06%) could be matched to at least one biomolecular database. Additionally, 4188, 1545 and 1023 differentially expressed genes (DEGs) were identified by comparative transcriptomics LI25-vs-CK, LI50-vs-CK, and LI25-vs-LI50, respectively. Of note, genes known to be involved in flavonoid biosynthesis, such as 4-coumarate coenzyme A ligase (4CL), and chalcone synthase (CHS) were up-regulated. In addition, a total of 1649 transcription factors (TFs) were identified and divided into 58 TF families; 98 TFs exhibited highly dynamic changes in response to light intensity. Quantitative real-time PCR (qRT-PCR) was used to test the expression profiles of the RNA sequencing (RNA-Seq) data. This study offers insight into how transcriptional expression pattern is influenced by light in the flower buds of L. japonica, and will enhance the understanding of molecular mechanisms of flavonoid biosynthesis in response to light in L. japonica.

Ectopic Expression of a R2R3-MYB Transcription Factor Gene LjaMYB12 from Lonicera japonica Increases Flavonoid Accumulation in Arabidopsis thaliana.

Lonicera japonica Thunb. is a widely used medicinal plant and is rich in a variety of active ingredients. Flavonoids are one of the important components in L. japonica and their content is an important indicator for evaluating the quality of this herb. To study the regulation of flavonoid biosynthesis in L. japonica, an R2R3-MYB transcription factor gene LjaMYB12 was isolated and characterized. Bioinformatics analysis indicated that LjaMYB12 belonged to the subgroup 7, with a typical R2R3 DNA-binding domain and conserved subgroup 7 motifs. The transcriptional level of LjaMYB12 was proportional to the total flavonoid content during the development of L. japonica flowers. Subcellular localization analysis revealed that LjaMYB12 localized to the nucleus. Transactivation activity assay indicated that LjaMYB12 was a transcriptional activator. Then, ectopic expression of LjaMYB12 in Arabidopsis could increase PAL activity and flavonoid content and promote transcription of a range of flavonoid biosynthetic genes. Interestingly, the fold changes of downstream genes in the flavonoid biosynthetic pathway were significantly higher than that of the upstream genes, which suggested that LjaMYB12 may have different regulatory patterns for the upstream and downstream pathways of flavonoid biosynthesis. The results provided here will effectively facilitate the study of subgroup 7 MYBs and transcriptional regulation of flavonoid biosynthesis in L. japonica.

Antibacterial and antifungal activities of different polar extracts from Anoectochilus roxburghii.

This study evaluates the antibacterial and antifungal activities of petroleum ether, acetic ether, n-butanol and aqueous extracts from Anoectochilus roxburghii. The in vitro antibacterial and antifungal effects against three bacterial strains (Escherichia coli, Bacillus subtilis, Bacillus thuringiensis) and three fungal species (Exserohilum turcicum (Pass.) Leonard et Suggs, Botrytis cinerea Pers., Fusahum graminearum Sehw.) were assayed by the dilution and disc-diffusion methods. All of the polar extracts expressed dose-dependent antimicrobial activity against all tested microorganisms. The most active extract was aqueous extract, with a minimum inhibitory concentration below 0.625mg/ml in both bacteria and fungi. The results suggest that new chemical classes of natural antimicrobial substances (such as A. roxiburghii extracts) can be selectively exploited for the chemotherapy and control of infectious diseases.

Transcriptome Analysis of JA Signal Transduction, Transcription Factors, and Monoterpene Biosynthesis Pathway in Response to Methyl Jasmonate Elicitation in Mentha canadensis L.

Mentha canadensis L. has important economic value for its abundance in essential oils. Menthol is the main component of M. canadensis essential oils, which is certainly the best-known monoterpene for its simple structure and wide applications. However, the regulation of menthol biosynthesis remains elusive in M. canadensis. In this study, transcriptome sequencing of M. canadensis with MeJA treatment was applied to illustrate the transcriptional regulation of plant secondary metabolites, especially menthol biosynthesis. Six sequencing libraries were constructed including three replicates for both control check (CK) and methyl jasmonate (MeJA) treatment and at least 8 Gb clean bases was produced for each library. After assembly, a total of 81,843 unigenes were obtained with an average length of 724 bp. Functional annotation indicated that 64.55% of unigenes could be annotated in at least one database. Additionally, 4430 differentially expressed genes (DEGs) with 2383 up-regulated and 2047 down-regulated transcripts were identified under MeJA treatment. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment indicated that "Monoterpenoid biosynthesis" was one of the most significantly enriched pathways in metabolism. Subsequently, DEGs involved in JA signal transduction, transcription factors, and monoterpene biosynthesis were analyzed. 9 orthologous genes involved in menthol biosynthesis were also identified. This is the first report of a transcriptome study of M. canadensis and will facilitate the studies of monoterpene biosynthesis in the genus Mentha.

Rapid detection of adulteration in Anoectochilus roxburghii by near-infrared spectroscopy coupled with chemometric methods.

To determine the authenticity of Anoectochilus roxburghii, this study presents an application of near-infrared spectroscopy and chemometric methods for evaluating adulteration of A. roxburghii with two cheaper adulterants, i.e. C. Goodyera schlechtendaliana and Ludisia discolor. Partial least squares discriminant analysis models were built for the accurate classification of authentic A. roxburghii and A. roxburghii adulterated at 5-100% (w/w) levels. Partial least squares regression models were used to predict the level of adulteration in the A. roxburghii. After by compared different spectral pretreatment methods, and using interval PLS and synergy interval PLS for variable selection, optimum models were developed. These results show that the NIR spectroscopy combined with chemometric methods offers a simple, fast, and reliable method for classifying and quantifying the adulteration of A. roxburghii.

The non-specific lipid transfer protein McLTPII.9 of Mentha canadensis is involved in peltate glandular trichome density and volatile compound metabolism.

Mentha canadensis L. is an important spice crop and medicinal herb with high economic value. The plant is covered with peltate glandular trichomes, which are responsible for the biosynthesis and secretion of volatile oils. Plant non-specific lipid transfer proteins (nsLTPs) belong to a complex multigenic family involved in various plant physiological processes. Here, we cloned and identified a non-specific lipid transfer protein gene (McLTPII.9) from M. canadensis, which may positively regulate peltate glandular trichome density and monoterpene metabolism. McLTPII.9 was expressed in most M. canadensis tissues. The GUS signal driven by the McLTPII.9 promoter in transgenic Nicotiana tabacum was observed in stems, leaves, and roots; it was also expressed in trichomes. McLTPII.9 was associated with the plasma membrane. Overexpression of McLTPII.9 in peppermint (Mentha piperita. L) significantly increased the peltate glandular trichome density and total volatile compound content compared with wild-type peppermint; it also altered the volatile oil composition. In McLTPII.9-overexpressing (OE) peppermint, the expression levels of several monoterpenoid synthase genes and glandular trichome development-related transcription factors-such as limonene synthase (LS), limonene-3-hydroxylase (L3OH), geranyl diphosphate synthase (GPPS), HD-ZIP3, and MIXTA-exhibited varying degrees of alteration. McLTPII.9 overexpression resulted in both a change in expression of genes for terpenoid biosynthetic pathways which corresponded with an altered terpenoid profile in OE plants. In addition, peltate glandular trichome density was altered in the OE plants as well as the expression of genes for transcription factors that were shown to be involved in trichome development in plants.

Effect of light quality on the growth and main chemical composition of Bletilla striata.

This study aimed to investigate the effects of light quality on the morphological traits, photosynthetic pigment content, protective enzyme (superoxide dismutase, peroxidase, and catalase) activity, and bioactive compound (BSP, total phenol, and militarine) content in Bletilla striata. Plants of B. striata were grown under light filtered through three differently colored films. The treatments were red film (RF), yellow film (YF), and blue film (BF), and an uncovered treatment was included as a control (CK). Compared with the B. striata plants in the RF, YF, and CK treatment groups, those receiving BF treatment showed significantly promoted growth of the aerial parts. Meanwhile, the total phenol and militarine contents in B. striata tubers were increased without affecting the accumulation of B. striata polysaccharides. These results show that growing B. striata plants under blue film could be a useful technique to improve quality and production. This technique is conducive to achieving large-scale sustainable production of high-quality plant materials.

Genetic control of RNA splicing and its distinct role in complex trait variation.

Most genetic variants identified from genome-wide association studies (GWAS) in humans are noncoding, indicating their role in gene regulation. Previous studies have shown considerable links of GWAS signals to expression quantitative trait loci (eQTLs) but the links to other genetic regulatory mechanisms, such as splicing QTLs (sQTLs), are underexplored. Here, we introduce an sQTL mapping method, testing for heterogeneity between isoform-eQTL effects (THISTLE), with improved power over competing methods. Applying THISTLE together with a complementary sQTL mapping strategy to brain transcriptomic (n = 2,865) and genotype data, we identified 12,794 genes with cis-sQTLs at P < 5 × 10-8, approximately 61% of which were distinct from eQTLs. Integrating the sQTL data into GWAS for 12 brain-related complex traits (including diseases), we identified 244 genes associated with the traits through cis-sQTLs, approximately 61% of which could not be discovered using the corresponding eQTL data. Our study demonstrates the distinct role of most sQTLs in the genetic regulation of transcription and complex trait variation.

A generalized linear mixed model association tool for biobank-scale data.

Compared with linear mixed model-based genome-wide association (GWA) methods, generalized linear mixed model (GLMM)-based methods have better statistical properties when applied to binary traits but are computationally much slower. In the present study, leveraging efficient sparse matrix-based algorithms, we developed a GLMM-based GWA tool, fastGWA-GLMM, that is severalfold to orders of magnitude faster than the state-of-the-art tools when applied to the UK Biobank (UKB) data and scalable to cohorts with millions of individuals. We show by simulation that the fastGWA-GLMM test statistics of both common and rare variants are well calibrated under the null, even for traits with extreme case-control ratios. We applied fastGWA-GLMM to the UKB data of 456,348 individuals, 11,842,647 variants and 2,989 binary traits (full summary statistics available at http://fastgwa.info/ukbimpbin ), and identified 259 rare variants associated with 75 traits, demonstrating the use of imputed genotype data in a large cohort to discover rare variants for binary complex traits.

Transcriptome Analysis of Light-Regulated Monoterpenes Biosynthesis in Leaves of Mentha canadensis L.

Light is a key environmental aspect that regulates secondary metabolic synthesis. The essential oil produced in mint (Mentha canadensis L.) leaves is used widely in the aromatics industry and in medicine. Under low-light treatment, significant reductions in peltate glandular trichome densities were observed. GC-MS analysis showed dramatically reduced essential oil and menthol contents. Light affected the peltate glandular trichomes' development and essential oil yield production. However, the underlying mechanisms of this regulation were elusive. To identify the critical genes during light-regulated changes in oil content, following a 24 h darkness treatment and a 24 h recovery light treatment, leaves were collected for transcriptome analysis. A total of 95,579 unigenes were obtained, with an average length of 754 bp. About 56.58% of the unigenes were annotated using four public protein databases: 10,977 differentially expressed genes (DEGs) were found to be involved in the light signaling pathway and monoterpene synthesis pathway. Most of the TPs showed a similar expression pattern: downregulation after darkness treatment and upregulation after the return of light. In addition, the genes involved in the light signal transduction pathway were analyzed. A series of responsive transcription factors (TFs) were identified and could be used in metabolic engineering as an effective strategy for increasing essential oil yields.