De novo assembly and analysis of Sonneratia ovata genome and population analysis.

Mangroves are an important part of coastal and estuarine ecosystems where they serve as nurseries for marine species and prevent coastal erosion. Here we report the genome of Sonneratia ovata, which is a true mangrove that grows in estuarine environments and can tolerate moderate salt exposure. We sequenced the S. ovata genome and assembled it into chromosome-level scaffolds through the use of Hi-C. The genome is 212.3 Mb and contains 12 chromosomes that range in size from 12.2 to 23.2 Mb. Annotation identified 29,829 genes with a BUSCO completeness of 95.9%. We identified salt genes and found copy number expansion of salt genes such as ADP-ribosylation factor 1, and elongation factor 1-alpha. Population analysis identified a low level of genetic variation and a lack of population structure within S. ovata.

Genes controlling hydrolysate toxin tolerance identified by QTL analysis of the natural Saccharomyces cerevisiae BCC39850.

Lignocellulosic material can be converted to valorized products such as fuels. Pretreatment is an essential step in conversion, which is needed to increase the digestibility of the raw material for microbial fermentation. However, pretreatment generates by-products (hydrolysate toxins) that are detrimental to microbial growth. In this study, natural Saccharomyces strains isolated from habitats in Thailand were screened for their tolerance to synthetic hydrolysate toxins (synHTs). The Saccharomyces cerevisiae natural strain BCC39850 (toxin-tolerant) was crossed with the laboratory strain CEN.PK2-1C (toxin-sensitive), and quantitative trait locus (QTL) analysis was performed on the segregants using phenotypic scores of growth (OD600) and glucose consumption. VMS1, DET1, KCS1, MRH1, YOS9, SYO1, and YDR042C were identified from QTLs as candidate genes associated with the tolerance trait. CEN.PK2-1C knockouts of the VMS1, YOS9, KCS1, and MRH1 genes exhibited significantly greater hydrolysate toxin sensitivity to growth, whereas CEN.PK2-1C knock-ins with replacement of VMS1 and MRH1 genes from the BCC39850 alleles showed significant increased ethanol production titers compared with the CEN.PK2-1C parental strain in the presence of synHTs. The discovery of VMS1, YOS9, MRH1, and KCS1 genes associated with hydrolysate toxin tolerance in S. cerevisiae indicates the roles of the endoplasmic-reticulum-associated protein degradation pathway, plasma membrane protein association, and the phosphatidylinositol signaling system in this trait. KEY POINTS: • QTL analysis was conducted using a hydrolysate toxin-tolerant S. cerevisiae natural strain • Deletion of VMS1, YOS9, MRH1, and KCS1 genes associated with hydrolysate toxin-sensitivity • Replacement of VMS1 and MRH1 with natural strain alleles increased ethanol production titers in the presence of hydrolysate toxins.

Rice height QTLs in KDML105 chromosome segment substitution lines.

Rice is an important crop that is consumed by approximately half of the world's population on a regular basis. Plant height is an important characteristic with shorter rice often having higher lodging resistance and better soil nutrient utilization allowing for lower fertilizer use. We used a Chromosome Segment Substitution Line (CSSL) population generated by introgressing segments of CT9993 and IR62266 into KDML 105. We identified height QTLs on chromosomes 1 and 4. We performed whole genome sequencing of the parental lines and found that IR62266 has the deletion in Gibberellin 20-oxidase 2 corresponding to the semi-dwarf 1 locus. However, short height on chromosome 1 came from CT9993 with no mutation in Gibberellin 20-oxidase 2, or any known height genes. The height QTL on chromosome 4 contains mutations in Peroxisome biogenesis protein 6, which has been linked to a reduced growth phenotype in A. thaliana, making this a good candidate height gene.

Assembly of a hybrid mangrove, Bruguiera hainesii, and its two ancestral contributors, Bruguiera cylindrica and Bruguiera gymnorhiza.

Mangroves are plants that live in tropical and subtropical coastal regions of the world, they are adapted to high salt environments and cyclic tidal flooding. Mangroves play important ecological roles, including acting as breeding grounds for many fish species and to prevent coastal erosion. The genomes of three mangrove species, Bruguiera gymnorhiza, Bruguiera cylindrica, and a hybrid of the two, Bruguiera hainesii were sequenced, assembled and annotated. The two progenitor species, B. gymnorhiza and B. cylindrica, were found to be highly similar to each other and sufficiently similar to B. parviflora to allow it to be used for reference based scaffolding to generate chromosome level scaffolds. The two subgenomes of B. hainesii were independently assembled and scaffolded. Analysis of B. hainesii confirms that it is a hybrid and the hybridisation event was estimated at 2.4 to 3.5 million years ago using a Bayesian Relaxed Molecular Clock approach.

A Large-Scale Candidate-Gene Association Mapping for Drought Tolerance and Agronomic Traits in Sugarcane.

Dissection of the genetic loci controlling drought tolerance traits with a complex genetic inheritance is important for drought-tolerant sugarcane improvement. In this study, we conducted a large-scale candidate gene association study of 649 candidate genes in a sugarcane diversity panel to identify genetic variants underlying agronomic traits and drought tolerance indices evaluated in plant cane and ratoon cane under water-stressed (WS) and non-stressed (NS) environments. We identified 197 significant marker-trait associations (MTAs) in 141 candidate genes associated with 18 evaluated traits with the Bonferroni correction threshold (α = 0.05). Out of the total, 95 MTAs in 78 candidate genes and 62 MTAs in 58 candidate genes were detected under NS and WS conditions, respectively. Most MTAs were found only in specific water regimes and crop seasons. These MTAs explained 7.93-30.52% of phenotypic variation. Association mapping results revealed that 34, 59, and 104 MTAs involved physiological and molecular adaptation, phytohormone metabolism, and drought-inducible genes. They identified 19 pleiotropic genes associated with more than one trait and many genes related to drought tolerance indices. The genetic and genomic resources identified in this study will enable the combining of yield-related traits and sugar-related traits with agronomic value to optimize the yield of sugarcane cultivars grown under drought-stressed and non-stressed environments.

Genetic diversity of the dengue virus population in dengue fever and dengue hemorrhagic fever patients.

BACKGROUND: The error-prone replication of dengue virus (DENV) in host results in the highly diverse viral population. Together with the host factor, intra-host diversity may influence the disease severity. Therefore, it is worth investigating whether there is a correlation between intra-host genetic diversity and disease severity. OBJECTIVE: To investigate the genetic diversity in DENV for four serotypes of the dengue population from patients with dengue fever (DF) and dengue hemorrhagic fever (DHF) using next-generation sequencing (NGS) technology. METHODS: Forty RNA samples categorized into eight groups by severity and serotypes were sequenced and analyzed for genetic variation. Analysis on the hot-cold genomic regions, selection pressure and correlation between genotype and disease severity were performed in this study. RESULTS: Comparison between the NGS data of the DF and DHF specimens showed conservation between their major populations with the consensus sequences for DF and DHF sharing 99% similarity. However, the minor populations in DF and DHF were more diverse. Many genes in DF had an #NS/#S ratio higher than in DHF. Only NS4B of DENV1 DF has #NS/#S ratio higher than one. Hot regions of the DF were detected in NS3 of DENV1, DENV2 and Envelope of DENV3, whereas the hot regions of the DHF samples were detected in the small region in 3'UTR of DENV2 and DENV3. CONCLUSIONS: Various explorations of the variations of DF and DHF were performed in this study. However, we have not yet found any specific characteristics of intra-host diversity associated with disease severity.

Candidate gene association of gene expression data in sugarcane contrasting for sucrose content.

Association mapping of gene expression data, generated from transcriptome and proteome studies, provides a means of understanding the functional significance and trait association potential of candidate genes. In this study, we applied candidate gene association mapping to validate sugarcane genes, using data from the starch and sucrose metabolism pathway, transcriptome, and proteome. We performed multiplex PCR targeted amplicon sequencing of 109 candidate genes, using NGS technology. A range of statistical models, both single-locus and multi-locus, were compared for minimization of false positives in association mapping of four sugar-related traits with different heritability. The Fixed and random model Circulating Probability Unification model effectively suppressed false positives for both low- and high-heritability traits. We identified favorable alleles of the candidate genes involved in signalling and transcriptional regulation. The results will support genetic improvement of sugarcane and may help clarify the genetic architecture of sugar-related traits.

De novo chromosome-level assembly of the Centella asiatica genome.

Centella asiatica is a herbaceous, perennial species indigenous to India and Southeast Asia. C. asiatica possesses several medicinal properties: anti-aging, anti-inflammatory, wound healing and memory enhancing. The lack of available genomics resources significantly impedes the improvement of C. asiatica varieties through molecular breeding. Here, we combined the 10× Genomics linked-read technology and the long-range HiC technique to obtain the genome assembly. The final assembly contained nine pseudomolecules, corresponding to the haploid chromosome number in C. asiatica. These nine chromosomes covered 402,536,584 bases or 93.6% of the 430-Mb assembly. Comparative genomics analyses based on single-copy orthologous genes showed that C. asiatica and the common ancestor of Coriandrum sativum (coriander) and Daucus carota (carrot) diverged about 48 million years ago. This assembly provides a valuable reference genome for future molecular studies, varietal development through marker-assisted breeding and comparative genomics studies in C. asiatica.

Taxonomic profiling of Symbiodiniaceae and bacterial communities associated with Indo-Pacific corals in the Gulf of Thailand using PacBio sequencing of full-length ITS and 16S rRNA genes.

Corals live with complex assemblages of microbes including bacteria, the dinoflagellate Symbiodiniaceae, fungi and viruses in a coral holobiont. These coral-associated microorganisms play an important role in their host fitness and survival. Here, we investigated the structure and diversity of algal and bacterial communities associated with five Indo-Pacific coral species, using full-length 16S rRNA and internal transcribed spacer sequences. While the dinoflagellate communities associated with Poriteslutea were dominated with Symbiodiniaceae genus Cladocopium, the other four coral hosts were associated mainly with members of the Durusdinium genus, suggesting that host species was one of the underlying factors influencing the structure and composition of dinoflagellate communities associated with corals in the Gulf of Thailand. Alphaproteobacteria dominated the microbiomes of Pocillopora spp. while Pavonafrondifera and P. lutea were associated primarily with Gammaproteobacteria. Finally, we demonstrated a superior performance of full-length 16S rRNA sequences in achieving species-resolution taxonomic classification of coral-associated microbiota.

Mass spectrometry and synchrotron-FTIR microspectroscopy reveal the anti-inflammatory activity of Bua Bok extracts.

INTRODUCTION: Bua Bok or Centella asiatica (CA) is an Asian vegetable with anti-inflammatory benefits. Asiaticoside, asiatic acid, madecassoside and madecassic have been characterised as major active ingredients with a wide range of pharmacological advantages. In manufacturing processes, high-performance liquid chromatography (HPLC) and liquid chromatography-mass spectrometry (LCMS) are used to routinely determine the active compounds in raw materials. OBJECTIVES: This research aims to explore anti-inflammatory properties, characterise metabolites and observe the biochemical changes of the inflammatory induced macrophages after pretreatment with the potential extracted fractions. METHODS: Bua Bok leaf extracts were prepared. Macrophages were pretreated with non-toxic fractions to determine the anti-inflammatory action. Tentative metabolites of effective fractions were identified by LC-MS. Synchrotron fourier-transform infrared (S-FTIR) microspectroscopy was utilised to observe the biochemical change of the lipopolysaccharide (LPS)-induced cells after pretreatment with potential fractions. RESULTS: Fractions of ethyl acetate, 30% and 100% ethanol highly increased the nitrile scavenging and suppressed the function of phospholipase A2 . Fractions of 70% and 100% ethanol strongly decreased nitric oxide production. The comparison of 39 chemical compounds was presented. The change of proteins was improved after pretreatment of macrophages with fraction 70% ethanol. Fraction of 100% ethanol revealed the lipid accumulation was lower than 70% ethanol and diclofenac. CONCLUSION: While the anti-inflammatory actions of 70% and 100% ethanol were similar. S-FTIR expressed they inhibited inflammatory response with the distinct features of biomolecules. The S-FTIR, LC-MS and biological assay confidently provided the efficient strategies to inform the advantage of herbal extract on cellular organisation instead of a single compound.

Quantitative analysis of methoxyflavones discriminates between the two types of Kaempferia parviflora.

INTRODUCTION: Kaempferia parviflora or black ginger is abundantly cultivated because its rhizomes contain methoxyflavones that have many pharmacological properties. K. parviflora can be divided into two types, based on morphological characteristics, but differences in their chemical compositions have never been explored. OBJECTIVES: This research aims to find chemical markers that can be used to differentiate between the two types of K. parviflora, the red-leaf and green-leaf types, by quantifying the amounts of methoxyflavones. MATERIAL AND METHODS: K. parviflora samples were collected from 39 locations in Thailand. Their genetic diversity was assessed by a genotyping-by-sequencing (GBS) technique to construct the population structure. Their chemical compositions were analyzed by high performance liquid chromatography-photodiode array detection to determine the methoxyflavone contents. RESULTS: The population structure based on >3,000 single nucleotide polymorphism (SNP) markers showed that the samples can be divided into two groups, which were consistent with the classification by leaf margin color (red-leaf and green-leaf types). HPLC analysis revealed 3,5,7,3',4'-pentamethoxyflavone (PMF), 5,7-dimethoxyflavone (DMF), 5,7,4'-trimethoxyflavone (TMF), 3,5,7-trimethoxyflavone and 3,5,7,4'-tetramethoxyflavone as major methoxyflavones that can be used as chemical markers. The red-leaf type showed higher amounts of PMF, TMF and 3,5,7,4'-tetramethoxyflavone than the green-leaf type, while the green-leaf type showed higher amounts of DMF and 3,5,7-trimethoxyflavone than the red-leaf type. CONCLUSION: These results provide another approach to discriminate the two types of K. parviflora using chemical profiles alongside genetic and morphological analyses. Therefore, a specific type of K. parviflora can be selected over the other based on preferences for a certain methoxyflavone.

Multi-scale comparative transcriptome analysis reveals key genes and metabolic reprogramming processes associated with oil palm fruit abscission.

BACKGROUND: Fruit abscission depends on cell separation that occurs within specialized cell layers that constitute an abscission zone (AZ). To determine the mechanisms of fleshy fruit abscission of the monocot oil palm (Elaeis guineensis Jacq.) compared with other abscission systems, we performed multi-scale comparative transcriptome analyses on fruit targeting the developing primary AZ and adjacent tissues. RESULTS: Combining between-tissue developmental comparisons with exogenous ethylene treatments, and naturally occurring abscission in the field, RNAseq analysis revealed a robust core set of 168 genes with differentially regulated expression, spatially associated with the ripe fruit AZ, and temporally restricted to the abscission timing. The expression of a set of candidate genes was validated by qRT-PCR in the fruit AZ of a natural oil palm variant with blocked fruit abscission, which provides evidence for their functions during abscission. Our results substantiate the conservation of gene function between dicot dry fruit dehiscence and monocot fleshy fruit abscission. The study also revealed major metabolic transitions occur in the AZ during abscission, including key senescence marker genes and transcriptional regulators, in addition to genes involved in nutrient recycling and reallocation, alternative routes for energy supply and adaptation to oxidative stress. CONCLUSIONS: The study provides the first reference transcriptome of a monocot fleshy fruit abscission zone and provides insight into the mechanisms underlying abscission by identifying key genes with functional roles and processes, including metabolic transitions, cell wall modifications, signalling, stress adaptations and transcriptional regulation, that occur during ripe fruit abscission of the monocot oil palm. The transcriptome data comprises an original reference and resource useful towards understanding the evolutionary basis of this fundamental plant process.

Metagenomics of antimicrobial and heavy metal resistance in the cecal microbiome of fattening pigs raised without antibiotics.

This study aimed to detect the cecal microbiome, antimicrobial resistance (AMR) and heavy metal resistance genes (MRGs) in fattening pigs raised under antibiotic-free (ABF) conditions compared with ordinary industrial pigs (control, C) using whole-genome shotgun sequencing. ABF pigs showed the enrichment of Prevotella (33%) and Lactobacillus (13%), whereas Escherichia coli (40%), Fusobacterium and Bacteroides (each at 4%) were notably observed in the C group. Distinct clusters of cecal microbiota of ABF and C pigs were revealed; however, microbiota of some C pigs (C1) appeared in the same cluster as ABF and were totally separated from the remaining C pigs (C2). For AMR genes, the highest abundance tet(Q) (35.7%) and mef(A) (12.7%) were markedly observed in the ABF group whereas tet(Q) (26.2%) and tet(W) (10.4%) were shown in the C group. tet(Q) was positively correlated to Prevotella in ABF and C1 samples. In the C2 group, the prominent tet(W) was positively correlated to Fusobacterium and Bacteroides Pigs have never received tetracycline but pregnant sows used chlortetracycline once 7 d before parturition. Chromosomal Cu and Zn resistance genes were also shown in both groups regardless the received Cu and Zn feed additives. A higher abundance of multi-metal resistance genes was observed in the C group (44%) compared with the ABF group (41%). In conclusion, the microbiome clusters in some C pigs were similar to that in ABF pigs. High abundant tetracycline resistance genes interrelated to major bacteria were observed in both ABF and C pigs. MRGs were also observed.IMPORTANCE: Owing to the increased problem of AMR in farm animals, raising farm animals without antibiotics is one method that could solve this problem. Our study showed that only some tetracycline and macrolide resistance genes, tet(Q), tet(W) and mef(A), were markedly abundant in ABF and C groups. The tet(Q) and tet(W) genes interrelated to different predominant bacteria in each group, showing the potential role of major bacteria as reservoirs of AMR genes. In addition, chromosomal Cu and Zn resistance genes were also observed in both pig groups, not depending on the use of Cu and Zn additives in both farms. The association of MRGs and AMR genotypes and phenotypes together with the method to re-sensitize bacteria to antibiotics should be studied further to unveil the cause of high resistance genes and solve the problems.

Establishment of Human-Induced Pluripotent Stem Cell-Derived Neurons-A Promising In Vitro Model for a Molecular Study of Rabies Virus and Host Interaction.

Rabies is a deadly viral disease caused by the rabies virus (RABV), transmitted through a bite of an infected host, resulting in irreversible neurological symptoms and a 100% fatality rate in humans. Despite many aspects describing rabies neuropathogenesis, numerous hypotheses remain unanswered and concealed. Observations obtained from infected primary neurons or mouse brain samples are more relevant to human clinical rabies than permissive cell lines; however, limitations regarding the ethical issue and sample accessibility become a hurdle for discovering new insights into virus-host interplays. To better understand RABV pathogenesis in humans, we generated human-induced pluripotent stem cell (hiPSC)-derived neurons to offer the opportunity for an inimitable study of RABV infection at a molecular level in a pathologically relevant cell type. This study describes the characteristics and detailed proteomic changes of hiPSC-derived neurons in response to RABV infection using LC-MS/MS quantitative analysis. Gene ontology (GO) enrichment of differentially expressed proteins (DEPs) reveals temporal changes of proteins related to metabolic process, immune response, neurotransmitter transport/synaptic vesicle cycle, cytoskeleton organization, and cell stress response, demonstrating fundamental underlying mechanisms of neuropathogenesis in a time-course dependence. Lastly, we highlighted plausible functions of heat shock cognate protein 70 (HSC70 or HSPA8) that might play a pivotal role in regulating RABV replication and pathogenesis. Our findings acquired from this hiPSC-derived neuron platform help to define novel cellular mechanisms during RABV infection, which could be applicable to further studies to widen views of RABV-host interaction.

Genome-wide association mapping of virulence gene in rice blast fungus Magnaporthe oryzae using a genotyping by sequencing approach.

Magnaporthe oryzae is a fungal pathogen causing blast disease in many plant species. In this study, seventy three isolates of M. oryzae collected from rice (Oryza sativa) in 1996-2014 were genotyped using a genotyping-by-sequencing approach to detect genetic variation. An association study was performed to identify single nucleotide polymorphisms (SNPs) associated with virulence genes using 831 selected SNP and infection phenotypes on local and improved rice varieties. Population structure analysis revealed eight subpopulations. The division into eight groups was not related to the degree of virulence. Association mapping showed five SNPs associated with fungal virulence on chromosome 1, 2, 3, 4 and 7. The SNP on chromosome 1 was associated with virulence against RD6-Pi7 and IRBL7-M which might be linked to the previously reported AvrPi7.

Shotgun metagenomic sequencing from Manao-Pee cave, Thailand, reveals insight into the microbial community structure and its metabolic potential.

BACKGROUND: Due to the cave oligotrophic environment, this habitat presents a challenge for microorganisms to colonize and thrive. However, it has been well documented that microorganisms play important roles in cave development. Survival of microbes in this unique habitat likely involves a broad range of adaptive capabilities. Recently, cave microbiomes all over the world are of great scientific interest. However, the majority of investigations focused mostly on small subunit ribosomal RNA (16S rRNA) gene, leaving the ecological role of the microbial community largely unknown. Here, we are particularly interested in exploring the taxonomic composition and metabolic potential of microorganisms in soil from Manao-Pee cave, a subterranean limestone cave in the western part of Thailand, by using high-throughput shotgun metagenomic sequencing. RESULTS: From taxonomic composition analysis using ribosomal RNA genes (rRNA), the results confirmed that Actinobacteria (51.2%) and Gammaproteobacteria (24.4%) were the dominant bacterial groups in the cave soil community. Metabolic potential analysis, based on six functional modules of the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, revealed that functional genes involved in microbial metabolisms are highly represented in this community (40.6%). To better understand how microbes thrive under unfavorable cave condition, we focused on microbial energy metabolism. The results showed that microbial genes involved in oxidative phosphorylation were the most dominant (28.8%) in Manao-Pee cave, and were followed by methane metabolism (20.5%), carbon fixation (16.0%), nitrogen metabolism (14.7%), and sulfur metabolism (6.3%). In addition, microbial genes involved in xenobiotic biodegradation (26 pathways) and in production of secondary metabolites (27 pathways) were also identified. CONCLUSION: In addition to providing information on microbial diversity, we also gained insights into microbial adaptations and survival strategies under cave conditions. Based on rRNA genes, the results revealed that bacteria belonging to the Actinobacteria and Gammaproteobacteria were the most abundant in this community. From metabolic potential analysis, energy and nutrient sources that sustain diverse microbial population in this community might be atmospheric gases (methane, carbon dioxide, nitrogen), inorganic sulfur, and xenobiotic compounds. In addition, the presence of biosynthetic pathways of secondary metabolites suggested that they might play important ecological roles in the cave microbiome.

Genome-wide association mapping of latex yield and girth in Amazonian accessions of Hevea brasiliensis grown in a suboptimal climate zone.

Latex yield and growth are the key complex traits in commercial rubber production. The present study is the first to report genome-wide association mapping of latex yield and girth, for 170 Amazonian accessions grown in a suboptimal area characterized by limited rainfall and a lengthy dry season. Targeted sequence enrichment to capture gene transcripts generated 14,155 high quality filtered single nucleotide polymorphisms (SNPs) of which 94.3% resided in coding regions. The rapid decay of linkage disequilibrium over physical and genetic distance found in the accessions was comparable to those previously reported for several outcrossing species. A mixed linear model detected three significant SNPs in three candidate genes involved in plant adaptation to drought stress, individually explaining 12.7-15.7% of the phenotypic variance. The SNPs identified in the study will help to extend understanding, and to support genetic improvement of rubber trees grown in drought-affected regions.

ACC oxidase and miRNA 159a, and their involvement in fresh fruit bunch yield (FFB) via sex ratio determination in oil palm.

Oil palm (Elaeis guineesis Jacq.) is the most productive oil-bearing crop, yielding more oil per area than any other oil-bearing crops. However, there are still efforts to improve oil palm yield, in order to serve consumer and manufacturer demand. Oil palm produces female and male inflorescences in an alternating cycle. So, high sex ratio (SR), the ratio of female inflorescences to the total inflorescences, is a favorable trait in term of increasing yields in oil palm. This study aims to understand the genetic control for SR related traits, such as fresh fruit bunch yield (FFB), by characterizing genes at FFB quantitative trait loci (QTLs) on linkage 10 (chromosome 6) and linkage 15 (chromosome 10). Published oil palm sequences at the FFB QTLs were used to develop gene-based and simple sequence repeat (SSR) markers. We used the multiple QTL analysis model (MQM) to characterize the relationship of new markers with the SR traits in the oil palm population. The RNA expression of the most linked QTL genes was also evaluated in various tissues of oil palm. We identified EgACCO1 (encoding aminocyclopropane carboxylate (ACC) oxidase) at chromosome 10 and EgmiR159a (microRNA 159a) at chromosome 6 to be the most linked QTL genes or determinants for FFB yield and/or female inflorescence number with a phenotype variance explained (PVE) from 10.4 to 15 % and suggest that these play the important roles in sex determination and differentiation in oil palm. The strongest expression of EgACCO1 and the predicted precursor of EgmiR159a was found in ovaries and, to a lesser extent, fruit development. In addition, highly normalized expression of EgmiR159a was found in female flowers. In summary, the QTL analysis and the RNA expression reveal that EgACCO1 and EgmiR159a are the potential genetic factors involved in female flower determination and hence would affect yield in oil palm. However, to clarify how these genetic factors regulate female flower determination, more investigation of their down regulation or target may be essential. Additionally, if more sex determination genes controlled by plant hormones are identified, it may possible to reveal a crosstalk of sex determination genes with hormones and environment factors.

Comparative Study of Bacterial Communities in Nepenthes Pitchers and Their Correlation to Species and Fluid Acidity.

Pitchers are specialized digestive organs of carnivorous plants which evolved for trapping prey and represent a unique environment harboring hidden diversity of unexplored microbes forming transient hydrolytic microcosms. In this study, the diversity of bacterial communities in the pitcher fluids of seven local Nepenthes found in Thailand was assessed by tagged 16S ribosomal RNA (rRNA) gene amplicon sequencing on an Ion PGM™ platform. A total of 1,101,000 filtered sequences were obtained which were taxonomically classified into 20 phyla, 48 classes, 72 orders, 153 families, and 442 genera while the remainder (1.43 %) could not be assigned to any existing taxa. Proteobacteria represented the predominant members in closed pitchers and more diversified bacterial taxa particularly Bacteriodetes and Actinobacteria, showed increasing abundance in open pitchers containing insect bodies. Principal coordinate analysis revealed that distribution of bacterial taxa was not significantly related to the Nepenthes species but strongly correlated to the pH of the pitcher fluids (pH 1.7-6.7). Acidicella was a highly dominant bacterial genus in acidic pitcher fluids while Dyella and Mycobacterium were also common genera in most pitchers. A unique microbial community structure was found in Nepenthes ampullaria which could reflect their adaptation to digest leaf litter, in addition to insect prey. The work revealed the highly unexplored nature of bacterial microcosms in Nepenthes pitcher fluids and provides insights into their community structure in this unique ecological system.

Genome-wide SNP discovery and identification of QTL associated with agronomic traits in oil palm using genotyping-by-sequencing (GBS).

Oil palm has become one of the most important oil crops in the world. Marker-assisted selections have played a pivotal role in oil palm breeding programs. Here, we report the use of genotyping-by-sequencing (GBS) approach for a large-scale SNP discovery and genotyping of a mapping population. Reduced representation libraries of 108 F2 progeny were sequenced and a total of 524 million reads were obtained. We detected 21,471 single nucleotide substitutions, most of which (62.6%) represented transition events. Of 3417 fully informative SNP markers, we were able to place 1085 on a linkage map, which spanned 1429.6 cM and had an average of one marker every 1.26 cM. Three QTL affecting trunk height were detected on LG 10, 14 and 15, whereas a single QTL associated with fruit bunch weight was identified on LG 3. The use of GBS approach proved to be rapid, cost-effective and highly reproducible in this species.