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At least 451 records · Page 25Linked to original sources

Super Pangenome of Grapevines Empowers Improvement of the Oldest Domesticated Fruit

Grapevine (Vitis) is the oldest domesticated fruit crop with great cultural and economic importance. Here, we assemble and annotate haplotype-resolved genomes of 72 Vitis accessions including 25 wild and 47 cultivated grapevines, and a haplotype-resolved complete genome of V. vinifera. Coalescent phylogenomics of 142 haplotype genomes disentangles the mysterious hybridization history of grapevines, revealing enormous genetic diversity among species. Pangenome analysis together with phenotyping data reveals that European cultivars, more susceptible to the most destructive disease downy mildew (DM), had a smaller repertoire of disease resistance genes of NLR family. Through extensive structural variation (SV) characterization, phenotyping, transcriptome profiling of 113 Vitis accessions, and SV-eQTL analysis, we have identified over 79 SVs and their relevant genes significantly associated with DM resistance, exemplified by a lysine histidine transporter, VvLHT8. This haplotype-resolved complete genome and pangenome of Vitis genus will accelerate grapevine breeding and enrich our understanding of the evolution and biology of grapevines.

plant biology↗

Differences in firing efficiency, chromatin and transcription underlie the developmental plasticity of Arabidopsis originome

Eukaryotic genome replication depends on thousands of DNA replication origins (ORIs) that constitute the originome. A major challenge is to learn ORI biology in multicellular organisms in the context of growing organs to understand their developmental plasticity. We have determined the originome and chromatin landscape of Arabidopsis thaliana at two stages of postembryonic development. ORIs associate with multiple chromatin signatures including TSS but also regulatory regions and heterochromatin, where ORIs colocalize with retrotransposons. In addition, quantitative analysis of ORI activity led us to conclude that strong ORIs have high GC content and clusters of GGN trinucleotides. Development primarily influences ORI firing strength rather than ORI location. ORIs that preferentially fire at early developmental stages colocalize with GC-rich heterochromatin whereas at later stages with transcribed genes, perhaps as a consequence of changes in chromatin features associated with developmental processes. Our study provides the originome of an organism at the postembryo stage that should allow us to study ORI biology in response to development, environment and mutations with a quantitative approach. In a wider scope, the computational strategies developed here can be transferred to other eukaryotic systems.

plant biology↗

The ribosomal protein RPS6A modulates auxin signalling and root development in Arabidopsis

Protein biosynthesis by the ribosome is a fundamental biological process in living systems. Recent studies suggest that ribosomal subunits also play essential roles in cell growth and differentiation beyond their roles in protein translation. The ribosomal subunit RPS6 has been studied for more than 50 years in various organisms, but little is known about its specific roles in a certain signalling pathway. In this study, we focused on the functions of Arabidopsis RPS6A in auxin-related root growth and development. The rps6a mutant exhibited a series of auxin-deficient phenotypes, such as shortened primary root length, reduced lateral root number, and defective vasculatures. Treatment of the rps6a mutant with various concentrations of auxin and its analogues did not restore the root defect phenotype, suggesting a defect in the auxin signalling pathway. Further cell biological and global transcriptome analyses revealed that auxin signalling was weakened in the rps6a mutant and that there was a reduced abundance of PIN-FORMED (PIN) auxin transporters. Our work provides insights into the role of the protein biosynthesis pathway involved in auxin signalling.

plant biology↗

A stop-gained mutation in a Peroxiredoxin gene may underlie the low-chill phenotype of the apricot spontaneous mutant 'Bulida Precoz'

1.Somatic mutations in clonally propagated fruit trees, known as "bud sports," are a primary source of new and agronomically valuable traits. This study addresses the study of Bulida Precoz, a spontaneous somatic variant of the Bulida apricot characterized by an early flowering (low-chill) phenotype. The main objective of this work was to design and implement a comprehensive bioinformatic workflow to identify the specific somatic mutation(s) responsible for this significant developmental change, using whole-genome sequencing (WGS) data. A comparative genomics approach was employed, analyzing the genomes of four biological replicates from the Bulida Precoz mutant and four from the original Bulida wild-type. The analysis was centered on a specialized somatic variant-calling workflow using GATK Mutect2, chosen for its high sensitivity in detecting low-frequency mutations. The results were cross-validated against an independent analysis using the germline caller GATK HaplotypeCaller. The final candidates were functionally annotated to predict their biological impact on gene function. This work establishes a solid foundation for future experimental validation and provides valuable molecular targets that could be used in marker-assisted breeding programs aimed at developing new apricot cultivars better adapted to climates with mild winters.

plant biology↗

A Decoy Library Uncovers U-box E3 Ubiquitin Ligases that Regulate Flowering Time in Arabidopsis

Targeted degradation of proteins is mediated by E3 ubiquitin ligases and is important for the execution of many biological processes. Previously, we created and employed a large library of E3 ubiquitin ligase decoys to identify regulators of the circadian clock (Feke et al., 2019). In tandem with the screen for circadian regulators, we performed a flowering time screen using our U-box-type E3 ubiquitin ligase decoy transgenic library. We identified five U-box decoy transgenic populations that have defects in flowering time or the floral development program. We used additional genetic and biochemical studies to validate PLANT U-BOX 14 (PUB14), MOS4-ASSOCIATED COMPLEX 3A (MAC3A), and MAC3B as bona fide regulators of flowering time. This work reinforces the utility of the decoy library in identifying regulators of important developmental transitions in plants and expands the scope of the technique beyond our previous studies.

plant biology↗

PLANT-Dx: A Molecular Diagnostic for Point of Use Detection of Plant Pathogens

Synthetic biology based diagnostic technologies have improved upon gold standard diagnostic methodologies by decreasing cost, increasing accuracy, and enhancing portability. However there has been little effort in adapting these technologies towards applications related to point-of-use monitoring of plant and crop health. Here, we take a step towards this vision by developing an approach that couples isothermal amplification of specific plant pathogen genomic sequences with customizable synthetic RNA regulators that are designed to trigger the production of a colorimetric output in cell-free gene expression reactions. We demonstrate our system can sense viral derived sequences with high-sensitivity and specificity, and can be utilized to directly detect viruses from infected plant material. Furthermore, we demonstrate that the entire system can operate using only body heat and naked-eye visual analysis of outputs. We anticipate these strategies to be important components of user-friendly and deployable diagnostic systems that can be configured to detect a range of important plant pathogens.

synthetic biology↗

Validation and characterisation of a wheat GENIE3 network using an independent RNA-Seq dataset

Gene regulatory networks are powerful tools which facilitate hypothesis generation and candidate gene discovery. However, the extent to which the network predictions are biologically relevant is often unclear. Recently, as part of an analysis of the RefSeqv1.0 wheat transcriptome, a GENIE3 network which predicted targets of wheat transcription factors was produced. Here we have used an independent and publicly-available RNA-Seq dataset to validate the predictions of the wheat GENIE3 network for the senescence-regulating transcription factor NAM-A1 (TraesCS6A02G108300). We re-analysed the RNA-Seq data against the RefSeqv1.0 genome and identified a de novo set of differentially expressed genes (DEGs) between the wild-type and nam-a1 mutant which recapitulated the known role of NAM-A1 in senescence and nutrient remobilisation. We found that the GENIE3-predicted target genes of NAM-A1 overlap significantly with the de novo DEGs, more than would be expected for a random transcription factor. Based on high levels of overlap between GENIE3-predicted target genes and the de novo DEGs, we also identified a set of candidate senescence regulators. We then explored genome-wide trends in the network related to polyploidy and homoeolog expression levels and found that only homoeologous transcription factors are likely to share predicted targets in common. However, homoeologs in dynamic triads, i.e. with higher variation in homoeolog expression levels across tissues, are less likely to share predicted targets than stable triads. This suggests that homoeologs in dynamic triads are more likely to act on distinct pathways. This work demonstrates that the wheat GENIE3 network can provide biologically-relevant predictions of transcription factor targets, which can be used for candidate gene prediction and for global analyses of transcription factor function. The GENIE3 network has now been integrated into the KnetMiner web application, facilitating its use in future studies.

plant biology↗

Comparative transcriptomic analysis of cassava genotypes under extended photoperiodism across flowering stages

Cassava (Manihot esculenta Crantz) is a major staple crop across tropical and subtropical regions. Despite advances in genomic selection, delayed, non-flowering, and asynchronous flowering remain key bottlenecks in breeding programs. To better understand the molecular basis of flowering-time variation, we performed RNA sequencing across three genotypes with contrasting flowering phenotypes (early, late, and non-flowering) sampled at three developmental stages under contrasting light regimes in field conditions (natural light and three-hour night-break with white light). Comparative transcriptomic analysis revealed distinct gene expression patterns associated with flowering responses. Genotype comparisons with no light supplementation revealed stage-specific enrichment of biological processes. Light supplementation was associated with changes in the expression of key components of photoperiodic and circadian regulation, as well as pathways involved in flowering-time integration and hormone and sugar-related signaling. These findings suggest that coordinated changes across multiple biological pathways regulate flowering behavior in cassava. The candidate genes and expression patterns reported provide a foundation for functional studies and advance our understanding of molecular mechanisms governing flowering-time regulation in cassava.

plant biology↗

A hierarchical transcriptional network activates specific CDK inhibitors that regulate G2 to control cell size and number in Arabidopsis

How cell size and number are determined during organ development remains a fundamental question in cell biology. Here, we identified a GRAS family transcription factor, called SCARECROW-LIKE28 (SCL28), with a critical role in determining cell size in Arabidopsis. SCL28 is part of a transcriptional regulatory network downstream of the central MYB3Rs that regulate G2 to M phase cell cycle transition. We show that SCL28 forms a dimer with the AP2-type transcription factor, AtSMOS1, which defines the specificity for promoter binding and directly activates transcription of a specific set of SIAMESE-RELATED (SMR) family genes, encoding plant-specific inhibitors of cyclin-dependent kinases and thus inhibiting cell cycle progression at G2 and promoting the onset of endoreplication. Through this dose-dependent regulation of SMR transcription, SCL28 quantitatively sets the balance between cell size and number without dramatically changing final organ size. We propose that this hierarchical transcriptional network constitutes a cell cycle regulatory mechanism that allows to adjust cell size and number to attain robust organ growth.

plant biology↗

Elucidating role of long non-coding RNAs of Tamarindus indica Linn. in post-transcriptional gene regulation.

Tamarindus indica, commonly known as tamarind, is a rich source of carbohydrates, proteins, lipids, fatty acids, vitamins, minerals and different bioactive compounds. It is well established that long non-coding RNAs (lncRNAs) play important role in transcriptional, post-transcriptional and epigenetic regulation. In spite of the tamarind genome information available, handful of studies have been done on its non-coding genome. In this study, 320 tamarind lncRNAs have been predicted by computational methods. Along with the experimental validation of seven randomly chosen lncRNAs, functional analysis of the predicted lncRNAs along with their targets elucidated their roles in various biological pathways. Sequence analysis of these predicted lncRNAs reveals the presence of different motifs and TRs. Our analysis provides information about the non-coding genome of tamarind and their involvement in gene regulation, which may be used to gain more knowledge about the medicinal properties of tamarind.

plant biology↗

Co-Expression Network-based Analysis associated with potato initial resistance

RNA sequencing (RNA-seq) providing genome-wide expression datasets has been successfully used to study gene expression patterns and regulation mechanism among multiple samples. Gene co-expression networks (GCNs) studies within or across species showed that coordinated genes in expression patterns are often functionally related. For potatoes, a large amount of publicly available transcriptome datasets have been generated but an optimal GCN detecting expression patterns in different genotypes, tissues and environmental conditions, is lacking. We constructed a potato GCN using 16 published RNA-Seq datasets covering 11 cultivars from native habitat worldwide. The correlations of gene expression were assessed pair-wisely and biologically meaningful gene modules which are highly connected in GCN were identified. One of the primitively native-farmer-selected cultivars in the Andes, ssp.Andigena, had relative far distance in gene expression patterns with other modern varieties. GCN in further enriched 134 highly and specifically co-expressed genes in ssp.Andigena associated with potato disease and stress resistance, which underlying the dramatic shift in evolutionary pressures during potato artificial domestication. In total, the network was consisted of into 14 gene models that involves in a variety of plant processes, which sheds light on how gene modules organized intra- and inter-varieties in the context of evolutionary divergence and provides a basis of information resource for potato gene functional studies.

plant biology↗

TimeTraits: extracting functional traits from biological time-series in R

SummaryTimeTraits provides a series of functions to enable the extraction of parameters from time series data using Functional Data Analysis methods. We demonstrate its utility in dissecting the changes in curve shape of a circadian clock bioluminescence marker, following a photoperiod shift in wildtype and phyB Arabidopsis. Availability and ImplementationTimeTraits is available in CRAN: https://cran.r-project.org/web/packages/TimeTraits/readme/README.html

plant biology↗

A Tyrosine Phospho-switch within the Longin Domain of VAMP721 modulates SNARE functionality

The final step in secretion is membrane fusion facilitated by SNARE proteins that reside in opposite membranes. The formation of a trans-SNARE complex between one R and three Q coiled-coiled SNARE domains drives the final approach of the membranes providing the mechanical energy for fusion. Biological control of this mechanism is exerted by additional domains within some SNAREs. For example, the N-terminal Longin domain (LD) of R-SNAREs (also called Vesicle-associated membrane proteins, VAMPs) can fold back onto the SNARE domain blocking interaction with other cognate SNAREs. The LD may also determine the subcellular localization via interaction with other trafficking related proteins. Here, we provide cell-biological and genetic evidence that phosphorylation of the Tyrosine57 residue regulates the functionality of VAMP721. We found that an aspartate mutation mimics phosphorylation, leading to protein instability and subsequent degradation in lytic vacuoles. The mutant SNARE also fails to rescue the defects of vamp721vamp722 loss-of-function lines in spite of its wildtype-like localization within the secretory pathway and the ability to interact with cognate SNARE partners. Most importantly, it imposes a dominant negative phenotype interfering with root growth, normal secretion and cytokinesis in wildtype plants generating large aggregates that mainly contain secretory vesicles. Non-phosphorylatable VAMP721Y57F needs higher gene dosage to rescue double mutants in comparison to native VAMP721 underpinning that phosphorylation modulates SNARE function. We propose a model where a short-lived phosphorylation of Y57 serves as a regulatory step to control VAMP721 activity, favouring its open state and interaction with cognate partners to ultimately drive membrane fusion.

plant biology↗

The ectomycorrhizal basidiomycete Laccaria bicolor releases a GH28 polygalacturonase that plays a key role in symbiosis establishment

O_LIIn ectomycorrhiza, root penetration and colonization of the intercellular space by symbiotic hyphae is thought to rely on the mechanical force that results from hyphal tip growth, enhanced by the activity of secreted cell-wall-degrading enzymes. C_LIO_LIHere, we characterize the biochemical properties of the symbiosis-induced polygalacturonase LbGH28A from the ectomycorrhizal fungus Laccaria bicolor. The transcriptional regulation of LbGH28A was measured by qPCR. The biological relevance of LbGH28A was confirmed by generating RNAi-silenced LbGH28A mutants. We localized the LbGH28A protein by immunofluorescence confocal and immunogold cytochemical microscopy in poplar ectomycorrhizal roots. C_LIO_LIqPCR confirmed the induced expression of LbGH28A during ectomycorrhiza formation. L. bicolor RNAi mutants have a lower ability to establish ectomycorrhiza confirming the key role of this enzyme in symbiosis. The purified recombinant LbGH28A has its highest activity towards pectin and polygalacturonic acid. In situ localization of LbGH28A indicates that this endopolygalacturonase is located in both fungal and plant cell walls at the symbiotic hyphal front. C_LIO_LIThe present findings suggest that the symbiosis-induced pectinase LbGH28A is involved in the Hartig net formation and is an important determinant for successful symbiotic colonization. C_LI

plant biology↗

Procrustean pseudo-landmark methods in Python to measure massive quantities of leaf shape data

PremiseWhen examining leaf shapes that are different from one another, it can be difficult to compare both the overall leaf shape and points along the leaf margin in biologically and statistically meaningful ways. MethodTo address this problem, we present a simple and user-friendly leaf shape analysis in Jupyter Notebook and Python that uses pseudo-landmarks and Generalized Procrustes Analysis to measure and compare the shape of any leaf. To demonstrate our analysis, we created a repository of real leaves gathered from eight experimental datasets. ResultsUsing our leaf repository, we explain how we can use pseudo-landmarks to compare all leaf shapes both within and between species using dimension reduction techniques like Principal Component Analysis and can predict leaf shapes using pseudo-landmarks through Linear Discriminant Analysis. Our leaf shape analysis also maps differences in shape as leaves grew around a rosette, showing the transition of shape across development (phyllotaxy). Finally, we showed how we can investigate the relationship between leaf shape variation and genetic diversity by combining shape with genetic data. DiscussionThrough the use of Generalized Procrustes Analysis and pseudo-landmarks, our leaf shape analysis presents a powerful tool for examining the shape of any leaf across multiple biological, ecological, evolutionary, and developmental scales.

plant biology↗

How to be dispensable: genomic and transcriptomic determinants in maize genes

BackgroundPlant genomes harbour a substantial proportion of dispensable genes - present only in a subset of individuals - that differ from ubiquitously shared core genes in multiple genomic and expression features. While these differences have been repeatedly documented, the factors shaping gene dispensability remain poorly understood. ResultsWe assembled a pan-gene set from eight maize inbred lines from American and European germplasms, together with their transcriptomic profile across 22 tissues/conditions, revealing the genomic and transcriptomic determinants of maize gene dispensability. Multivariate analysis demonstrates that gene expression level and purifying selection - rather than gene size - are the primary factors distinguishing core from dispensable genes. Dispensable genes overlap Helitrons at 4.6 times the rate of core genes, implicating Helitron-mediated gene capture as a major mechanism of dispensable gene formation. Classifying genes into stably expressed, variably expressed, and on-off categories shows that all three classes contain dispensable genes, though in different proportions than for core genes. Contrary to previous assumptions, we show that dispensable genes can participate in basal biological functions just as core genes, and that gene duplication likely provides only a partial mechanism for functional complementation of accessory genes absence. ConclusionsOur results provide novel insights into the molecular and evolutionary factors distinguishing core from dispensable genes and into the biological mechanisms shaping gene dispensability in maize, and demonstrate that classifying genes by transcriptional patterns provides a powerful framework for understanding the biological functions and evolutionary dynamics of both core and dispensable genes.

plant biology↗

Drastic differential CRISPR-Cas9 induced mutagenesis influenced by DNA methylation and chromatin features

CRISPR-Cas9 mediated genome editing has been widely adopted for basic and applied biological research in eukaryotic systems. While many studies considered DNA sequences of CRISPR target sites as the primary determinant for CRISPR mutagenesis efficiency and mutation profiles, increasing evidence revealed the significant role of chromatin context. Nonetheless, most of the prior studies were limited by the lack of sufficient epigenetic resources and/or by only transiently expressing CRISPR-Cas9 in a short time window. In this study, we leveraged the wealth of high-resolution epigenomic resources in Arabidopsis thaliana to address the impact of chromatin features on CRISPR-Cas9 mutagenesis using stable transgenic plants. Our results indicated that DNA methylation and chromatin features could lead to significant variations in mutagenesis efficiency by up to 250 folds. Low mutagenesis efficiencies were mostly associated with repressive heterochromatic features. This repressive effect appeared to persist through cell divisions but could be alleviated through substantial reduction of DNA methylation at CRISPR target sites. Moreover, specific chromatin features, such as H3K4me1, H3.3, and H3.1, appear to be associated with significant variations in CRISPR-Cas9 mutation profiles reflected by the 1 bp insertion rates. Our findings provided strong evidence that specific chromatin features could have significant and lasting impacts on both CRISPR-Cas9 mutagenesis efficiency and DNA double strand break repair outcomes.

plant biology↗

Mesoscale analyses of fungal networks as an approach for quantifying phenotypic traits

We investigate the application of mesoscopic response functions (MRFs) to characterize a large set of networks of fungi and slime moulds grown under a wide variety of different experimental treatments, including inter-species competition and attack by fungivores. We construct structural networks by estimating cord conductances (which yield edge weights) from the experimental data, and we construct functional networks by calculating edge weights based on how much nutrient traffic is predicted to occur along each edge. Both types of networks have the same topology, and we compute MRFs for both families of networks to illustrate two different ways of constructing taxonomies to group the networks into clusters of related fungi and slime moulds. Although both network taxonomies generate intuitively sensible groupings of networks across species, treatments, and laboratories, we find that clustering using the functional-network measure appears to give groups with lower intra-group variation in species or treatments. We argue that MRFs provide a useful quantitative analysis of network behaviour that can (1) help summarize an expanding set of increasingly complex biological networks and (2) help extract information that captures subtle changes in intra-specific and inter-specific phenotypic traits that are integral to a mechanistic understanding of fungal behaviour and ecology. As an accompaniment to our paper, we also make a large data set of fungal networks available in the public domain.

Plant Biology↗