Biology subjects

Lu, Z.

Publications and source records attributed to Lu, Z..

At least 217 records · Page 12Linked to original sources

bioRxiv2021

Soil causes gut microbiota to flourish and total serum IgE levels to decrease in mice

Traditional farm environments induce protection from allergic diseases. In this study, farm environmental factors were classified into three categories, environmental microbes, soil, and organic matter. To explore the impact of soil and environmental microorganisms on gut microbiota and immune function, mice were fed sterilized soil, soil microbes (in lieu of environmental microbes), or non-sterilized soil. Metagenomic sequencing results showed the intake of sterile soil i.e. inhaling a small amount of soil microbes in the air increased gut microbial diversity and the abundance of type III secretion system (T3SS) genes, and decreased serum immune globulin E (IgE) levels induced by 2-4-dinitrofluorobenzene(DNFB). The intake of soil microbes increased the abundance of genes involved in the metabolism of short chain fatty acids and amino acid biosynthesis. Meanwhile, the intake of soil increased gut microbial diversity, the abundance of T3SS genes and related infectious elements, and genes associated with the metabolism of short chain fatty acids and amino acid biosynthesis, and decreased serum IgE levels. Therefore, soil may be useful as a potential "prebiotic" promoting the reproduction and growth of some intestinal microorganisms that harbor bacterial secretion system genes, especially those of T3SS, whose abundance was positively and significantly correlated with innate immune function of mice.

ecology↗

bioRxiv2021

De novo assembly, annotation, and comparative analysis of 26 diverse maize genomes

We report de novo genome assemblies, transcriptomes, annotations, and methylomes for the 26 inbreds that serve as the founders for the maize nested association mapping population. The data indicate that the number of pan-genes exceeds 103,000 and that the ancient tetraploid character of maize continues to degrade by fractionation to the present day. Excellent contiguity over repeat arrays and complete annotation of centromeres further reveal the locations and internal structures of major cytological landmarks. We show that combining structural variation with SNPs can improve the power of quantitative mapping studies. Finally, we document variation at the level of DNA methylation, and demonstrate that unmethylated regions are enriched for cis-regulatory elements that overlap QTL and contribute to changes in gene expression. One sentence summaryA multi-genome analysis of maize reveals previously unknown variation in gene content, genome structure, and methylation.

genomics↗

bioRxiv2020

Human gut Faecalibacterium prausnitzii deploy a highly efficient conserved system to cross-feed on β-mannan-derived oligosaccharides

{beta}-Mannans are hemicelluloses that are abundant in modern diets as components in seed endosperms and common additives in processed food. Currently, the collective understanding of {beta}-mannan saccharification in the human colon is limited to a few keystone species, which presumably liberate low-molecular-weight mannooligosaccharide fragments that become directly available to the surrounding microbial community. Here we show that a dominant butyrate-producer in the human gut, Faecalibacterium prausnitzii, is able to acquire and degrade various {beta}-mannooligosaccharides ({beta}-MOS), which are derived by the primary mannanolytic activity of neighboring gut microbiota. Detailed biochemical analyses of selected protein components from their two {beta}-mannooligosaccharides ({beta}-MOS) utilization loci (FpMULs) supported a concerted model whereby the imported {beta}-MOS are stepwise disassembled intracellularly by highly adapted enzymes. Coculturing experiments of F. prausnitzii with the primary degrader Bacteroides ovatus on polymeric {beta}-mannan resulted in syntrophic growth and production of butyrate, thus confirming the high efficiency of the FpMULs uptake system. Genomic comparison with human F. prausnitzii strains and analyses of 2441 public human metagenomes revealed that FpMULs are highly conserved and distributed worldwide. Together, our results provide a significant advance in the knowledge of {beta}-mannans metabolism and the degree to which its degradation is mediated by cross-feeding interactions between prominent beneficial microbes in the human gut. ImportanceCommensal butyrate-producing bacteria belonging to the Firmicutes phylum are abundant in the human gut and are crucial for maintaining health. Currently, insight is lacking into how they target otherwise indigestible dietary fibers and into the trophic interactions they establish with other glycan degraders in the competitive gut environment. By combining cultivation, genomic and detailed biochemical analyses this work reveals the mechanism enabling F. prausnitzii, as a model clostridial cluster IV Firmicute, to cross-feed and access {beta}-mannan-derived oligosaccharides released in the gut ecosystem by the action of primary degraders. A comprehensive survey of human gut metagenomes shows that FpMULs are ubiquitous in human populations globally, highlighting the importance of microbial metabolism of {beta}-mannans/{beta}-MOS as a common dietary component. Our findings provide a mechanistic understanding of the {beta}-MOS utilization capability by F. prausnitzii that may be exploited to select dietary formulations specifically boosting this beneficial symbiont, thus butyrate production, in the gut.

microbiology↗

bioRxiv2020

The jasmine (Jasminum sambac) genome and flower fragrances

Jasminum sambac, a world-renowned plant appreciated for its exceptional flower fragrance, is of cultural and economic importance. However, the genetic basis of its fragrance is largely unknown. Here, we present the first de novo genome of J. sambac with 550.12 Mb (scaffold N50 = 40.1 Mb) assembled into 13 pseudochromosomes. Terpene synthase genes associated with flower fragrance are significantly amplified in the form of gene clusters through tandem duplications in the genome. Eleven homolog genes within the SABATH super-family were identified as related to phenylpropanoid/benzenoid compounds. Several key genes regulating jasmonate biosynthesis were duplicated causing increased copy numbers. Furthermore, multi-omics analyses identified various aromatic compounds and the key genes involved in fragrance biosynthesis pathways. Our genome of J. sambac offers a basic genetic resource for studying floral scent biosynthesis and provides an essential foundation for functional genomic research and variety improvements in Jasminum.

plant biology↗

bioRxiv2020

Genome-wide DNA mutations in Arabidopsis plants after multigenerational exposure to high temperature

BackgroundElevated temperatures can cause physiological, biochemical, and molecular responses in plants that can greatly affect their growth and development. Mutations are the most fundamental force driving biological evolution. However, how long-term elevations in temperature influence the accumulation of mutations in plants remains unknown. ResultsHere we report that multigenerational exposure of Arabidopsis to extreme heat and moderate warming resulted in significantly increased mutation rates in single-nucleotide variants (SNVs) and small indels. We observed distinctive mutational spectra under extreme and moderately elevated temperatures, with significant increases in transition (C:G[->]T:A) and transversion (A:T[->]T:A) frequencies. Mutation occurred more frequently in intergenic regions, coding regions (especially nonsynonymous mutations), and transposable elements (TEs). At elevated temperatures, more mutations accumulated in genes associated with defense responses, DNA repair, and signaling, including the transcriptional response-related genes HSP70 and HSFA1A. Methylation was observed more frequently at mutation sites, indicating that it contributed significantly to the mutation process at elevated temperatures. Moreover, the mutations in lines and populations grown under elevated temperatures were significantly biased toward low gene density regions, special trinucleotides (GC context), tandem repeats, and adjacent simple repeats. Additionally, 24% (n = 64) of SNVs and 43% (n = 40) of indels found in all mutation accumulation lines overlapped significantly with genetic variations reported in 1001 Genomes, suggesting a non-uniform distribution of de novo mutations through the genome. ConclusionCollectively, our results suggest that elevated temperatures can accelerate the accumulation, and alter the molecular profiles, of DNA mutations in plants, thus providing significant insight into how environmental temperatures fuel plant evolution.

genetics↗

bioRxiv2020

Unusual predominance of maintenance DNA methylation in Spirodela polyrhiza

5-methylcytosine (5mC) is a modified base often described as necessary for the proper regulation of genes and transposons and for the maintenance of genome integrity in plants. However, the extent of this dogma is limited by the current phylogenetic sampling of land plant species diversity. Here, we report that a monocot plant, Spirodela polyrhiza, has lost CG gene body methylation, genome-wide CHH methylation, and the presence or expression of several genes in the highly conserved RNA-directed DNA methylation (RdDM) pathway. It has also lost the CHH methyltransferase CHROMOMETHYLASE 2. Consequently, the transcriptome is depleted of 24-nucleotide, heterochromatic, small interfering RNAs that act as guides for the deposition of 5mC to RdDM-targeted loci in all other currently sampled angiosperm genomes. Although the genome displays low levels of genome-wide 5mC primarily at LTR retrotransposons, CG maintenance methylation is still functional. In contrast, CHG methylation is weakly maintained even though H3K9me2 is present at loci dispersed throughout the euchromatin and highly enriched at regions likely demarcating pericentromeric regions. Collectively, these results illustrate that S. polyrhiza is maintaining CG and CHG methylation mostly at repeats in the absence of small RNAs. S. polyrhiza reproduces rapidly through clonal propagation in aquatic environments, which we hypothesize may enable low levels of maintenance methylation to persist in large populations. Significance StatementDNA methylation is a widespread chromatin modification that is regularly found in all plant species. By examining one aquatic duckweed species, Spirodela polyrhiza, we find that it has lost highly conserved genes involved in methylation of DNA at sites often associated with repetitive DNA, and within genes, however DNA methylation and heterochromatin is maintained during cell division at other sites. Consequently, small RNAs that normally guide methylation to silence repetitive DNA like retrotransposons are diminished. Despite the loss of a highly conserved methylation pathway, and the reduction of small RNAs that normally target repetitive DNA, transposons have not proliferated in the genome, perhaps due in part to the rapid, clonal growth lifestyle of duckweeds.

plant biology↗

bioRxiv2020

Intein-assisted bisection mapping systematically splits proteins for Boolean logic and inducibility engineering

Split inteins are powerful tools for seamless ligation of synthetic split proteins. Yet, their use remains limited because the already intricate split site identification problem is often complicated by the requirement of extein junction sequences. To address this, we augmented a mini-Mu transposon-based screening approach and devised the intein-assisted bisection mapping (IBM) method. IBM robustly revealed clusters of split sites on five proteins, converting them into AND or NAND logic gates. We further showed that the use of inteins expands functional sequence space for splitting a protein. We also demonstrated the utility of our approach over rational inference of split sites from secondary structure alignment of homologous proteins. Furthermore, the intein inserted at an identified site could be engineered by the transposon again to become partially chemically inducible, and to some extent enabled post-translational tuning on host protein function. Our work offers a generalizable and systematic route towards creating split protein-intein fusions and conditional inteins for protein activity control.

synthetic biology↗

bioRxiv2020

Computational optical sectioning by phase-space imaging with an incoherent multiscale scattering model

Optical sectioning is essential for fluorescence imaging in thick tissue to extract in-focus information from noisy background. Traditional methods achieve optical sectioning by rejecting the out-of-focus photons at a cost of photon efficiency, resulting in a tradeoff between sectioning capability and detection parallelization. Here, we show phase-space imaging with an incoherent multiscale scattering model can achieve computational optical sectioning with ~20 dB improvement for signal-to-background ratio in scattering medium, while maximizing the detection parallelization by imaging the entire volume simultaneously. We validated the superior performance by imaging various biological dynamics in Drosophila embryos, zebrafish larvae, and mice.

cell biology↗

bioRxiv2020

Isotropic 3D electron microscopy reference library of whole cells and tissues

Understanding cellular architecture is essential for understanding biology. Electron microscopy (EM) uniquely visualizes cellular structures with nanometer resolution. However, traditional methods, such as thin-section EM or EM tomography, have limitations inasmuch as they only visualize a single slice or a relatively small volume of the cell, respectively. Focused Ion Beam-Scanning Electron Microscopy (FIB-SEM) demonstrated the ability to image cellular samples at 4-nm isotropic voxels with rather limited imageable volume. Here, we present 3D EM images of whole cells and tissues with two orders of magnitude increases in imageable volume at 4-nm voxels. Such data with a combined fine resolution scale and large sample size do not currently exist, and are enabled by the advances in higher precision and stability of FIB milling, together with enhanced signal detection and faster SEM scanning. More importantly, we have generated a volume EM atlas encompassing ten diverse datasets of whole cells and tissues, from cancer cells to immune cells, and from mouse pancreatic islets to Drosophila neural tissues. These open-access data (via OpenOrganelle) represent a foundation to nucleate a new field of high-resolution whole-cell volume EM and subsequent analyses, and invite biologists to explore this new paradigm and pose fundamentally new questions.

cell biology↗

bioRxiv2020

SPDE: A Multi-functional Software for Sequence Processing and Data Extraction

Efficiently extracting information from biological big data can be a huge challenge for people (especially those who lack programming skills). We developed Sequence Processing and Data Extraction (SPDE) as an integrated tool for sequence processing and data extraction for gene family and omics analyses. Currently, SPDE has seven modules comprising 100 basic functions that range from single gene processing (e.g., translation, reverse complement, and primer design) to genome information extraction. All SPDE functions can be used without the need for programming or command lines. The SPDE interface has enough prompt information to help users run SPDE without barriers. In addition to its own functions, SPDE also incorporates the publicly available analyses tools (such as, NCBI-blast, HMMER, Primer3 and SAMtools), thereby making SPDE a comprehensive bioinformatics platform for big biological data analysis. AvailabilitySPDE was built using Python and can be run on 32-bit, 64-bit Windows and macOS systems. It is an open-source software that can be downloaded from https://github.com/simon19891216/SPDEv1.2.git. Contactxudongzhuanyong@163.com

bioinformatics↗

bioRxiv2020

A Mycobacterium tuberculosis effector protein attacks host innate immunity by acting as an unusual ubiquitinating enzyme

Protein kinase G (PknG), a eukaryotic type serine-threonine protein kinase (STPK) in Mycobacterium tuberculosis (Mtb), is secreted into the cytosol of infected macrophages to promote intracellular survival of mycobacteria and has been considered as a promising therapeutic target for tuberculosis (TB) treatment. However, the molecular details of Mtb PknG-host intracellular interactions remain obscure. Here, we demonstrate that PknG serves as both the ubiquitin-activating enzyme (E1) and the ubiquitin ligase (E3) to promote ubiquitination and degradation of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TGF-{beta}-activated kinase 1 (TAK1), and thus inhibits the NF-{kappa}B-mediated host innate immune responses. Surprisingly, PknG promotes the attachment of ubiquitin (Ub) to ubiquitin-conjugating enzyme (E2) UbcH7 via an isopeptide bond (UbcH7 K82-Ub), instead of a usual C86-Ub thiol-ester bond, and then promotes the discharge of Ub from UbcH7 by acting as an isopeptidase before attaching Ub to its substrates TRAF2 and TAK1. These results demonstrate that Mtb PknG promotes ubiquitination of the key components of the host innate immunity by acting as an unusual ubiquitinating enzyme to suppress innate immunity. Our findings provide a potential TB treatment via targeting unconventional ubiquitinating activities of PknG. SignificanceMycobacterium tuberculosis (Mtb) protein kinase G (PknG), which is critical for Mtb intracellular survival, is a promising target for tuberculosis (TB) treatment. However, the molecular mechanisms underlying PknG-host interactions remain largely unclear. Here we demonstrate that PknG serves as both the ubiquitin-activating enzyme and the ubiquitin ligase to promote the ubiquitination and degradation of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TGF-{beta}-activated kinase 1 (TAK1), thus inhibiting NF-{kappa}B signaling activation. PknG promotes the attachment of ubiquitin to ubiquitin-conjugating enzyme UbcH7 via an isopeptide bond, instead of a usual thiol-ester bond, and releases the ubiquitin from UbcH7 by acting as an isopeptidase. These findings provide important information for rational development of TB treatment via targeting unconventional ubiquitinating activity of PknG.

microbiology↗

bioRxiv2020

Tracking strains predicts personal microbiomes and reveals recent adaptive evolution

An individuals microbiome consists of a diverse set of bacterial strains that encode rich information on its colonization and evolutionary history. Here, we introduce a versatile and straightforward reference-based strain tracking approach (StrainTrack) that determines whether distinct metagenomes carry closely-related strains based on gene presence and absence profiles. We show that StrainTrack can predict whether two metagenomes originate from the same donor via counting the number of species sharing closely-related strains, achieving >96% specificity, and [~]100% sensitivity. When applied to the metagenomes of adult twins in the TwinsUK registry, we identify six cases of closely-related strains carried by both twins, potentially over decades of colonization.

bioinformatics↗

bioRxiv2020

Interaction network of SARS-CoV-2 with host receptome through spike protein

Host cellular receptors are key determinants of virus tropism and pathogenesis. Virus utilizes multiple receptors for attachment, entry, or specific host responses. However, other than ACE2, little is known about SARS-CoV-2 receptors. Furthermore, ACE2 cannot easily interpret the multi-organ tropisms of SARS-CoV-2 nor the clinical differences between SARS-CoV-2 and SARS-CoV. To identify host cell receptors involved in SARS-CoV-2 interactions, we performed genomic receptor profiling to screen almost all human membrane proteins, with SARS-CoV-2 capsid spike (S) protein as the target. Twelve receptors were identified, including ACE2. Most receptors bind at least two domains on S protein, the receptor-binding-domain (RBD) and the N-terminal-domain (NTD), suggesting both are critical for virus-host interaction. Ectopic expression of ASGR1 or KREMEN1 is sufficient to enable entry of SARS-CoV-2, but not SARS-CoV and MERS-CoV. Analyzing single-cell transcriptome profiles from COVID-19 patients revealed that virus susceptibility in airway epithelial ciliated and secretory cells and immune macrophages highly correlates with expression of ACE2, KREMEN1 and ASGR1 respectively, and ACE2/ASGR1/KREMEN1 (ASK) together displayed a much better correlation than any individual receptor. Based on modeling of systemic SARS-CoV-2 host interactions through S receptors, we revealed ASK correlation with SARS-CoV-2 multi-organ tropism and provided potential explanations for various COVID-19 symptoms. Our study identified a panel of SARS-CoV-2 receptors with diverse binding properties, biological functions, and clinical correlations or implications, including ASGR1 and KREMEN1 as the alternative entry receptors, providing insights into critical interactions of SARS-CoV-2 with host, as well as a useful resource and potential drug targets for COVID-19 investigation.

microbiology↗

bioRxiv2020

Deep learning and alignment of spatially-resolved whole transcriptomes of single cells in the mouse brain with Tangram

Charting a biological atlas of an organ, such as the brain, requires us to spatially-resolve whole transcriptomes of single cells, and to relate such cellular features to the histological and anatomical scales. Single-cell and single-nucleus RNA-Seq (sc/snRNA-seq) can map cells comprehensively5,6, but relating those to their histological and anatomical positions in the context of an organs common coordinate framework remains a major challenge and barrier to the construction of a cell atlas7-10. Conversely, Spatial Transcriptomics allows for in-situ measurements11-13 at the histological level, but at lower spatial resolution and with limited sensitivity. Targeted in situ technologies1-3 solve both issues, but are limited in gene throughput which impedes profiling of the entire transcriptome. Finally, as samples are collected for profiling, their registration to anatomical atlases often require human supervision, which is a major obstacle to build pipelines at scale. Here, we demonstrate spatial mapping of cells, histology, and anatomy in the somatomotor area and the visual area of the healthy adult mouse brain. We devise Tangram, a method that aligns snRNA-seq data to various forms of spatial data collected from the same brain region, including MERFISH1, STARmap2, smFISH3, and Spatial Transcriptomics4 (Visium), as well as histological images and public atlases. Tangram can map any type of sc/snRNA-seq data, including multi-modal data such as SHARE-seq data5, which we used to reveal spatial patterns of chromatin accessibility. We equipped Tangram with a deep learning computer vision pipeline, which allows for automatic identification of anatomical annotations on histological images of mouse brain. By doing so, Tangram reconstructs a genome-wide, anatomically-integrated, spatial map of the visual and somatomotor area with [~]30,000 genes at single-cell resolution, revealing spatial gene expression and chromatin accessibility patterning beyond current limitation of in-situ technologies.

genomics↗

bioRxiv2020

Prime editing primarily induces undesired outcomes in mice

Genome editing has transformed biomedical science, but is still unpredictable and often induces undesired outcomes. Prime editing (PE) is a promising new approach due to its proposed flexibility and ability to avoid unwanted indels. Here, we show highly efficient PE-mediated genome editing in mammalian zygotes. Utilizing chemically modified guideRNAs, PE efficiently introduced 10 targeted modifications including substitutions, deletions, and insertions across 6 genes in mouse embryos. However, we unexpectedly observed a high frequency of undesired outcomes such as large deletions and found that these occurred more often than pure intended edits across all of the edits/genes. We show that undesired outcomes result from the double-nicking PE3 strategy, but that omission of the second nick largely ablates PE function. However, sequential double-nicking with PE3b, which is only applicable to a fraction of edits, eliminated undesired outcomes. Overall, our findings demonstrate the promising potential of PE for predictable, flexible, and highly efficient in vivo genome editing, but highlight the need for improved variations of PE before it is ready for widespread use.

molecular biology↗

bioRxiv2020

Alveolitis in severe SARS-CoV-2 pneumonia is driven by self-sustaining circuits between infected alveolar macrophages and T cells

Some patients infected with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) develop severe pneumonia and the acute respiratory distress syndrome (ARDS) [1]. Distinct clinical features in these patients have led to speculation that the immune response to virus in the SARS-CoV-2-infected alveolus differs from other types of pneumonia [2]. We collected bronchoalveolar lavage fluid samples from 86 patients with SARS-CoV-2-induced respiratory failure and 252 patients with known or suspected pneumonia from other pathogens and subjected them to flow cytometry and bulk transcriptomic profiling. We performed single cell RNA-Seq in 5 bronchoalveolar lavage fluid samples collected from patients with severe COVID-19 within 48 hours of intubation. In the majority of patients with SARS-CoV-2 infection at the onset of mechanical ventilation, the alveolar space is persistently enriched in alveolar macrophages and T cells without neutrophilia. Bulk and single cell transcriptomic profiling suggest SARS-CoV-2 infects alveolar macrophages that respond by recruiting T cells. These T cells release interferon-gamma to induce inflammatory cytokine release from alveolar macrophages and further promote T cell recruitment. Our results suggest SARS-CoV-2 causes a slowly unfolding, spatially-limited alveolitis in which alveolar macrophages harboring SARS-CoV-2 transcripts and T cells form a positive feedback loop that drives progressive alveolar inflammation. This manuscript is accompanied by an online resource: https://www.nupulmonary.org/covid-19/ One sentence summarySARS-CoV-2-infected alveolar macrophages form positive feedback loops with T cells in patients with severe COVID-19.

immunology↗

bioRxiv2020

Development of non-transgenic glyphosate tolerant wheat by TILLING

Glyphosate (N-phosphonomethyl-glycine) is the worlds most widely used broad spectrum, post-emergence herbicide. It inhibits the chloroplast-targeted enzyme 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS; EC 2.5.1.19), a component of the plant and microorganism-specific shikimate pathway and a key catalyst in the production of aromatic amino acids. Variants of EPSPS that are not inhibited by glyphosate due to particular amino acid alterations in the active site of the enzyme are known. Some of these variants have been identified in weed species that have developed resistance to glyphosate because of the strong selective pressure of continuous, heavy glyphosate use. We have used TILLING (Targeting Induced Local Lesions in Genomes), a non-transgenic, target-selected, reverse genetics mutation breeding technique, and conventional genetic crosses, to identify and combine, through two rounds of mutagenesis, wheat lines having both T102I and P106S (so-called TIPS enzyme) mutations in both the A and the D sub-genome homoeologous copies of the wheat EPSPS gene. The combined effects of the T102I and P106S mutations are known from previous work in multiple species to minimize the binding of the herbicide while maintaining the affinity of the catalytic site for its native substrates. These novel wheat lines exhibit substantial tolerance to commercially relevant levels of glyphosate.

plant biology↗

bioRxiv2020

Stable unmethylated DNA demarcates expressed genes and their cis-regulatory space in plant genomes

The genomic sequences of crops continue to be produced at a frenetic pace. However, it remains challenging to develop complete annotations of functional genes and regulatory elements in these genomes. Here, we explore the potential to use DNA methylation profiles to develop more complete annotations. Using leaf tissue in maize, we define [~]100,000 unmethylated regions (UMRs) that account for 5.8% of the genome; 33,375 UMRs are found greater than 2 kilobase pairs from genes. UMRs are highly stable in multiple vegetative tissues and they capture the vast majority of accessible chromatin regions from leaf tissue. However, many UMRs are not accessible in leaf (leaf-iUMRs) and these represent a set of genomic regions with potential to become accessible in specific cell types or developmental stages. Leaf-iUMRs often occur near genes that are expressed in other tissues and are enriched for transcription factor (TF) binding sites of TFs that are also not expressed in leaf tissue. The leaf-iUMRs exhibit unique chromatin modification patterns and are enriched for chromatin interactions with nearby genes. The total UMRs space in four additional monocots ranges from 80-120 megabases, which is remarkably similar considering the range in genome size of 271 megabases to 4.8 gigabases. In summary, based on the profile from a single tissue, DNA methylation signatures pinpoint both accessible regions and regions poised to become accessible or expressed in other tissues. UMRs provide powerful filters to distill large genomes down to the small fraction of putative functional genes and regulatory elements. Significance StatementCrop genomes can be very large with many repetitive elements and pseudogenes. Distilling a genome down to the relatively small fraction of regions that are functionally valuable for trait variation can be like looking for needles in a haystack. The unmethylated regions in a genome are highly stable during vegetative development and can reveal the locations of potentially expressed genes or cis-regulatory elements. This approach provides a framework towards complete annotation of genes and discovery of cis-regulatory elements using methylation profiles from only a single tissue.

genomics↗