ORCID Profile
0000-0002-9704-9788
Current Organisation
University of Adelaide
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Publisher: Cold Spring Harbor Laboratory
Date: 11-07-2021
DOI: 10.1101/2021.07.10.451923
Abstract: Factors such as host age, sex, diet, health status and genotype constitute the environmental envelope shaping microbial communities in the host’s gut. It has also been proposed that gut microbiota may be influenced by host epigenetics. Although the relationship between the host’s genotype/epigenotype and its associated microbiota has been the focus of a number of recent studies, the relative importance of these interactions and their biological relevance are still poorly understood. We used methylation-sensitive genotyping by sequencing to genotype and epigenotype invasive cane toads ( Rhinella marina ) from the species’ Australian range-core (three sites) and the invasion-front (three sites), and 16S rRNA gene sequencing to characterize their gut bacterial communities. We tested the effect of host genotype and epigenotype (i.e., methylome) on gut bacterial communities. Our results indicate that the genotypes, epigenotypes and gut communities of the range-core and invasion-front are significantly different from one another. We found a positive association between host pairwise genetic and epigenetic distances. More importantly, a positive relationship was found between the host’s epigenetic and gut bacterial pairwise distances. Interestingly, this association was stronger in in iduals with low genetic differentiation. Our findings suggest that in range-expanding populations, where in iduals are often genetically similar, the interaction between gut bacterial communities and host methylome may provide a mechanism through which invaders increase the plasticity of their response to novel environments, potentially increasing their invasion success.
Publisher: MDPI AG
Date: 25-04-2018
DOI: 10.20944/PREPRINTS201804.0328.V1
Abstract: The barley (Hordeum vulgare) genome comprises over 32,000 genes, with differentiated cells expressing only a subset of genes the remainder being silent. Mechanisms by which tissue-specific genes are regulated are not entirely understood, although DNA methylation is likely to be involved. DNA methylation patterns are not static during plant development, but it is still unclear whether different organs possess distinct methylation profiles. Methylation-sensitive GBS was used to generate DNA methylation profiles for roots, leaf-blades and leaf-sheaths from five barley varieties, using seedlings at the three-leaf stage. Differentially Methylated Markers (DMMs) were characterised by pairwise comparisons of roots, leaf-blades and leaf-sheaths of three different ages. While very many DMMs were found between roots and leaf parts, only a few existed between leaf-blades and leaf-sheaths, with differences decreasing with leaf rank. Organ-specific DMMs appeared to target mainly repeat regions, implying that organ differentiation partially relies on the spreading of DNA methylation from repeats to promoters of adjacent genes. Furthermore, the biological functions of differentially methylated genes in the different organs correlated with functional specialisation. Our results indicate that different organs do possess diagnostic methylation profiles and suggest that DNA methylation is important for both tissue development and differentiation and organ function.
Publisher: IntechOpen
Date: 07-2020
Publisher: Public Library of Science (PLoS)
Date: 12-07-2016
Publisher: Elsevier BV
Date: 04-2012
Publisher: MDPI AG
Date: 24-09-2021
Abstract: Different mating systems are expected to affect the extent and direction of hybridization. Due to the different levels of sexual conflict, the weak inbreeder/strong outbreeder (WISO) hypothesis predicts that gametes from self-incompatible (SI) species should outcompete gametes from self-compatible (SC) ones. However, other factors such as timing of selfing and unilateral incompatibilities may also play a role on the direction of hybridization. In addition, differential mating opportunities provided by different mating systems are also expected to affect the direction of introgression in hybrid zones involving outcrossers and selfers. Here, we explored these hypotheses with a unique case of recent hybridization between two mangrove killifish species with different mating systems, Kryptolebias ocellatus (obligately outcrossing) and K. hermaphroditus (predominantly self-fertilizing) in two hybrid zones in southeast Brazil. Hybridization rates were relatively high (~20%), representing the first ex le of natural hybridization between species with different mating systems in vertebrates. All F1 in iduals were sired by the selfing species. Backcrossing was small, but mostly asymmetrical with the SI parental species, suggesting pattern commonly observed in plant hybrid zones with different mating systems. Our findings shed light on how contrasting mating systems may affect the direction and extent of gene flow between sympatric species, ultimately affecting the evolution and maintenance of hybrid zones.
Publisher: Wiley
Date: 19-02-2020
Abstract: Noninvasive s ling methods for studying intestinal microbiomes are widely applied in studies of endangered species and in those conducting temporal monitoring during manipulative experiments. Although existing studies show that noninvasive s ling methods among different taxa vary in their accuracy, no studies have yet been published comparing nonlethal s ling methods in adult hibians. In this study, we compare microbiomes from two noninvasive s le types (faeces and cloacal swabs) to that of the large intestine in adult cane toads, Rhinella marina. We use 16S rRNA gene sequencing to investigate how microbial communities change along the digestive tract and which nonlethal s ling method better represents large intestinal microbiota. We found that cane toads' intestinal microbiota was dominated by Bacteroidetes, Proteobacteria and Firmicutes and, interestingly, we also saw a high proportion of Fusobacteria, which has previously been associated with marine species and changes in frog immunity. The large and small intestine of cane toads had a similar microbial composition, but the large intestine showed higher ersity. Our results indicate that cloacal swabs were more similar to large intestine s les than were faecal s les, and small intestine s les were significantly different from both nonlethal s le types. Our study provides valuable information for future investigations of the cane toad gut microbiome and validates the use of cloacal swabs as a nonlethal method to study changes in the large intestine microbiome. These data provide insights for future studies requiring nonlethal s ling of hibian gut microbiota.
Publisher: Cold Spring Harbor Laboratory
Date: 14-10-2023
Publisher: Agricultural and Food Science
Date: 04-12-2008
DOI: 10.2137/145960609789267579
Abstract: The inability to conserve cocoa (Theobroma cacao L.) germplasm via seed storage and the vulnerability of field collections make the establishment of cryopreserved genebanks for the crop a priority. An effective encapsulation-dehydration based cryopreservation system has been developed for cocoa but because the somatic embryos used for freezing arise after a protracted period of callus culture there is concern about maintenance of genetic fidelity during the process. Microsatellite markers for seven of the 10 cocoa linkage groups were used to screen a population of 189 primary somatic embryo-derived emblings and the 43 secondary somatic embryos they gave rise to. Of the primary somatic embryos, 38.1% exhibited polymorphic microsatellite profiles while for secondary somatic embryos the frequency was 23.3%. The same microsatellite markers used to screen another population of 44 secondary somatic embryos cryopreserved through encapsulation-dehydration revealed no polymorphisms. Scanning electron microscopy showed the secondary somatic embryos were derived from cotyledonary epidermal cells rather than callus. The influence of embryo ontogeny on somaclonal variation is discussed.
Publisher: Proceedings of the National Academy of Sciences
Date: 14-04-2021
Abstract: The placenta is the fetomaternal interface, which is essential for fetal growth and survival, playing a central role in the health of both the fetus and its mother. The dynamic gene expression during pregnancy dramatically contributes to the correct functionality of this temporary tissue. The epitheliochorial placenta of the horse is a valuable resource to understand parent-of-origin expression due to minimal bias associated with remnants of maternal tissue compared to other eutherian mammals. Here, we identified genes whose transcription is biased to either the paternal or maternal chromosome in the equine placenta. Overall, this study contributes to a better understanding of regulatory processes in placental function, evolution, and disease, using horses as a model for eutherian mammals’ placenta.
Publisher: Cold Spring Harbor Laboratory
Date: 11-04-2019
DOI: 10.1101/605600
Abstract: chromoMap is an R package for constructing interactive visualizations of chromosomes/chromosomal regions, and mapping of chromosomal elements (like genes) onto them, of any living organism. The package takes separate tab-delimited files (BED like) to specify the genomic co-ordinates of the chromosomes and the elements to annotate. Each rendered chromosome is composed of continuous loci of specific ranges where each locus, on hover, displays detailed information about the elements annotated within that locus range. By just tweaking parameters of a single function, users can generate a variety of plots that can either be saved as static image or shared as HTML documents. Users can utilize the various prominent features of chromoMap including, but not limited to, visualizing polyploidy, creating chromosome heatmaps, mapping groups of elements, adding hyperlinks to elements, multi-species chromosome visualization. The R package chromoMap is available under the GPL-3 Open Source license. It is included with a vignette for comprehensive understanding of its various features, and is freely available from: CRAN.Rackage=chromoMap . lakshayanand15@gmail.com Supplementary data are available online.
Publisher: MDPI AG
Date: 20-06-2018
Publisher: Bioscientifica
Date: 07-2016
DOI: 10.1530/REP-16-0014
Abstract: Epigenetic modifications, and particularly DNA methylation, have been studied in many tissues, both healthy and diseased, and across numerous developmental stages. The placenta is the only organ that has a transient life of 9 months and undergoes rapid growth and dynamic structural and functional changes across gestation. Additionally, the placenta is unique because although developing within the mother, its genome is identical to that of the foetus. Given these distinctive characteristics, it is not surprising that the epigenetic landscape affecting placental gene expression may be different to that in other healthy tissues. However, the role of epigenetic modifications, and particularly DNA methylation, in placental development remains largely unknown. Of particular interest is the fact that the placenta is the most hypomethylated human tissue and is characterized by the presence of large partially methylated domains (PMDs) containing silenced genes. Moreover, how and why the placenta is hypomethylated and what role DNA methylation plays in regulating placental gene expression across gestation are poorly understood. We review genome-wide DNA methylation studies in the human placenta and highlight that the different cell types that make up the placenta have very different DNA methylation profiles. Summarizing studies on DNA methylation in the placenta and its relationship with pregnancy complications are difficult due to the limited number of studies available for comparison. To understand the key steps in placental development and hence what may be perturbed in pregnancy complications requires large-scale genome-wide DNA methylation studies coupled with transcriptome analyses.
Publisher: Cold Spring Harbor Laboratory
Date: 12-08-2020
DOI: 10.1101/2020.08.12.246447
Abstract: Soil is an important factor that contributes to the uniqueness of a wine produced by vines grown in specific conditions. Recent data shows that the composition, ersity and function of soil microbial communities may play important roles in determining wine quality and indirectly affect its economic value. Here, we evaluated the impact of environmental variables on the soil microbiomes of 22 Barossa Valley vineyard sites based on the 16S rRNA gene hypervariable region 4. In this study, we report that environmental heterogeneity (soil plant-available P content, elevation, rainfall, temperature, spacing between row and spacing between vine) caused more microbial dissimilarity than geographic distance. Vineyards located in cooler and wetter regions showed lower beta ersity and a higher ratio of dominant taxa. Differences in microbial community composition were significantly associated with differences in fruit traits and in wine chemical and metabolomic profiles, highlighting the potential influence of microbial communities on the phenotype of grapevines. Our results suggest that environmental factors affect wine terroir, and this may be mediated by changes in microbial structure, thus providing a basic understanding of how growing conditions affect interactions between plants and their soil microbiomes.
Publisher: Cold Spring Harbor Laboratory
Date: 23-10-2023
Publisher: Springer Science and Business Media LLC
Date: 23-10-2004
DOI: 10.1007/S00122-004-1823-5
Abstract: Mutation rates are often elevated in plants regenerated from in vitro culture, giving rise to so-called 'somaclonal variation'. Detailed characterisation of mutation profiles that arise during culture should improve our understanding of processes influencing mutation and allow the selection of protocols yielding the fewest/least severe changes. Somatic mutations will usually produce genetic chimeras where unchanged alleles are retained by some cells. Such chimeras are difficult to detect but likely to form a significant proportion of any regenerant population. We present a simple protocol that enables the provisional diagnosis of both homogenous and chimeric mutants among large regenerant populations, together with a semi-quantitative means of estimating the proportion of mutant cells. The assay exploits consistent differential lification of alternate simple sequence repeat alleles at heterozygous loci. Calibration of the relative lification of alleles from two genotypes-and the synthetic chimeras created from them-revealed a strong linear relationship between 'peak heights' representing alternate alleles following capillary electrophoresis. The assay predicts chimeric composition to a reasonable level of confidence (+/-5%) so long as the infrequent allele exceeds 15% of the template. The system was applied to 233 regenerants of cocoa somatic embryogenesis and identified 72 (31%) putative chimeric mutants for slippage mutation or allele loss across two loci.
Publisher: Public Library of Science (PLoS)
Date: 26-04-2019
Publisher: Frontiers Media SA
Date: 13-08-2015
Publisher: Frontiers Media SA
Date: 15-05-2020
Publisher: American Chemical Society (ACS)
Date: 17-08-2012
DOI: 10.1021/AC301459X
Abstract: High resolution melting (HRM) can detect and quantify the presence of 5-methylcytosine (5mC) in DNA s les, but the ability of HRM to diagnose other DNA modifications remains unexplored. The DNA bases N6-methyladenine and 5-hydroxymethylcytosine occur across almost all phyla. While their function remains controversial, their presence perturbs DNA structure. Such modifications could affect gene regulation, chromatin condensation and DNA packaging. Here, we reveal that DNA containing N6-methyladenine or 5-hydroxymethylcytosine exhibits reduced thermal stability compared to cytosine-methylated DNA. These thermostability changes are sufficiently ergent to allow detection and quantification by HRM analysis. Thus, we report that HRM distinguishes between sequence-identical DNA differing only in the modification type of one base. This approach is also able to distinguish between two DNA fragments carrying both N6-methyladenine and 5-methylcytosine but differing only in the distance separating the modified bases. This finding provides scope for the development of new methods to characterize DNA chemically and to allow for low cost screening of mutant populations of genes involved in base modification. More fundamentally, contrast between the thermostabilizing effects of 5mC on dsDNA compared with the destabilizing effects of N6-methyladenine (m6A) and 5-hydroxymethylcytosine (5hmC) raises the intriguing possibility of an antagonistic relationship between modification types with functional significance.
Publisher: Hindawi Limited
Date: 19-10-2017
DOI: 10.1111/AJGW.12312
Publisher: Springer Science and Business Media LLC
Date: 03-11-2015
Publisher: Informa UK Limited
Date: 15-09-2022
Publisher: Springer Science and Business Media LLC
Date: 09-08-2011
DOI: 10.1038/NCOMMS1433
Publisher: Informa UK Limited
Date: 10-2013
DOI: 10.4161/PSB.25974
Publisher: Cold Spring Harbor Laboratory
Date: 11-2021
DOI: 10.1101/2021.10.30.466592
Abstract: Ziziphus are economically and nutritionally important fruiting plants that were domesticated in China around 7000 years ago. We identified genetic ersity in 141 accessions of four, different species collected in Pakistan and in China, including wild species of Ziziphus mauritiana, Z. nummularia and Z. oxyphllya , and both wild and domesticated Z. jujuba Mill. Population structure, phylogenetic analysis and principal coordinates analysis based on 10,889 high-quality SNPs derived from genotyping-by-sequencing indicated that the accessions clustered into two major groups. The wild Pakistani Z. jujuba and Z. nummularia exhibited higher genetic ersity and polymorphic information content (0.37 and 0.23 respectively) than other species. We further conducted a genome-wide association study and discovered six highly significant marker-trait associations for fruit weight and plant height in this population. Our study provides important information for future breeding of Ziziphus species.
Publisher: Cold Spring Harbor Laboratory
Date: 21-04-2020
DOI: 10.1101/2020.04.20.051326
Abstract: Environmental cues are known to alter the methylation profile of genomic DNA, and thereby change the expression of some genes. A proportion of such modifications may become adaptive by adjusting expression of stress response genes but others been shown to be highly stochastic, even under controlled conditions. The influence of environmental flux on plants adds an additional layer of complexity that has potential to confound attempts to interpret interactions between environment, methylome and plant form. We therefore adopt a positional and longitudinal approach to study progressive changes to barley DNA methylation patterns in response to salt exposure during development under greenhouse conditions. Methylation-Sensitive Amplified Polymorphism (MSAP) and phenotypic analyses of nine erse barley varieties were grown in a randomized plot design, under two salt treatments (0 mM and 75 mM NaCl). Combining environmental, phenotypic and epigenetic data analyses, we show that at least part of the epigenetic variability, previously described as stochastic, is linked to environmental micro-variations during plant growth. Additionally, we show that differences in methylation increase with time of exposure to micro-variations in environment. We propose that subsequent epigenetic studies take into account microclimate-induced epigenetic variability.
Publisher: Wiley
Date: 22-08-2016
Abstract: We hypothesize that under the predicted scenario of climate change epigenetically mediated environmental sex determination could become an epigenetic trap. Epigenetically regulated environmental sex determination is a mechanism by which species can modulate their breeding strategies to accommodate environmental change. Growing evidence suggests that epigenetic mechanisms may play a key role in phenotypic plasticity and in the rapid adaptation of species to environmental change, through the capacity of organisms to maintain a non-genetic plastic memory of the environmental and ecological conditions experienced by their parents. However, inherited epigenetic variation could also be maladaptive, becoming an epigenetic trap. This is because environmental sex determination can alter sex ratios by increasing the survival of one of the sexes at the expense of negative fitness consequences for the other, which could lead not only to the collapse of natural populations, but also have an impact in farmed animal and plant species.
Publisher: American Chemical Society (ACS)
Date: 14-10-2010
DOI: 10.1021/AC1024057
Abstract: High-resolution melting (HRM) analysis exploits the reduced thermal stability of DNA fragments that contain base mismatches to detect single nucleotide polymorphisms (SNPs). However, the capacity of HRM to reveal other features of DNA chemistry remains unexplored. DNA methylation plays a key role in regulating gene expression and is essential for normal development in many higher organisms. The presence of methylated bases perturbs the double-stranded DNA structure, although its effect on DNA thermal stability is largely unknown. Here, we reveal that methylated DNA has enhanced thermal stability and is sufficiently ergent from nonmethylated DNA to allow detection and quantification by HRM analysis. This approach reliably distinguishes between sequence-identical DNA differing only in the methylation of one base. The method also provides accurate discrimination between mixes of methylated and nonmethylated DNAs, allowing discrimination between DNA that is 1% and 0% methylated and also between 97.5% and 100% methylated. Thus, the method provides a new means of adjusting thermal optima for DNA hybridization and PCR-based techniques and to empirically measure the impact of DNA methylation marks on the thermostability of regulatory regions. In the longer term, it could enable the development of new techniques to quantify methylated DNA.
Publisher: Frontiers Media SA
Date: 05-06-2015
Publisher: Springer Science and Business Media LLC
Date: 12-2013
Abstract: The genus Limonium Miller comprises annual and perennial halophytes that can produce sexual and/or asexual seeds (apomixis). Genetic and epigenetic (DNA methylation) variation patterns were investigated in populations of three phenotypically similar putative sexual diploid species ( L. nydeggeri, L. ovalifolium , L. lanceolatum ), one sexual tetraploid species ( L. vulgare ) and two apomict tetraploid species thought to be related ( L. dodartii, L. multiflorum ). The extent of morphological differentiation between these species was assessed using ten diagnostic morphometric characters. A discriminant analysis using the morphometric variables reliably assigns in iduals into their respective species groups. We found that only modest genetic and epigenetic differentiation was revealed between species by Methylation Sensitive Amplification Polymorphism (MSAP). However, whilst there was little separation possible between ploidy levels on the basis of genetic profiles, there was clear and pronounced interploidy discrimination on the basis of epigenetic profiles. Here we investigate the relative contribution of genetic and epigenetic factors in explaining the complex phenotypic variability seen in problematic taxonomic groups such as Limonium that operate both apomixis and sexual modes of reproduction. Our results suggest that epigenetic variation might be one of the drivers of the phenotypic ergence between diploid and tetraploid taxa and discuss that intergenome silencing offers a plausible mechanistic explanation for the observed phenotypic ergence between these microspecies. These results also suggest that epigenetic profiling offer an additional tool to infer ploidy level in stored specimens and that stable epigenetic change may play an important role in apomict evolution and species recognition.
Publisher: Oxford University Press (OUP)
Date: 11-2020
DOI: 10.1038/S41438-020-00409-7
Abstract: Enset ( Ensete ventricosum (Welw.) Cheesman) is a drought tolerant, vegetatively propagated crop that was domesticated in Ethiopia. It is a staple food for more than 20 million people in Ethiopia. Despite its current importance and immense potential, enset is among the most genetically understudied and underexploited food crops. We collected 230 enset wild and cultivated accessions across the main enset producing regions in Ethiopia and applied lified fragment length polymorphism (AFLP) and genotype by sequencing (GBS) analyses to these accessions. Wild and cultivated accessions were clearly separated from each other, with 89 genes found to harbour SNPs that separated wild from cultivated accessions. Among these, 17 genes are thought to be involved in flower initiation and seed development. Among cultivated accessions, differentiation was mostly associated with geographical location and with proximity to wild populations. Our results indicate that vegetative propagation of elite clones has favoured capacity for vegetative growth at the expense of capacity for sexual reproduction. This is consistent with previous reports that cultivated enset tends to produce non-viable seeds and flowers less frequently than wild enset.
Publisher: MDPI AG
Date: 18-10-2021
DOI: 10.3390/EPIGENOMES5040024
Abstract: In contrast to animals, adult organs in plants are not formed during embryogenesis but generated from meristematic cells as plants advance through development. Plant development involves a succession of different phenotypic stages and the transition between these stages is termed phase transition. Phase transitions need to be tightly regulated and coordinated to ensure they occur under optimal seasonal, environmental conditions. Polycarpic perennials transition through vegetative stages and the mature, reproductive stage many times during their lifecycles and, in both perennial and annual species, environmental factors and culturing methods can reverse the otherwise unidirectional vector of plant development. Epigenetic factors regulating gene expression in response to internal cues and external (environmental) stimuli influencing the plant’s phenotype and development have been shown to control phase transitions. How developmental and environmental cues interact to epigenetically alter gene expression and influence these transitions is not well understood, and understanding this interaction is important considering the current climate change scenarios, since epigenetic maladaptation could have catastrophic consequences for perennial plants in natural and agricultural ecosystems. Here, we review studies focusing on the epigenetic regulators of the vegetative phase change and highlight how these mechanisms might act in exogenously induced plant rejuvenation and regrowth following stress.
Publisher: Elsevier BV
Date: 07-2008
Publisher: Wiley
Date: 14-04-2010
DOI: 10.1111/J.1469-8137.2010.03242.X
Abstract: *Relatively little is known about the timing of genetic and epigenetic forms of somaclonal variation arising from callus growth. We surveyed for both types of change in cocoa (Theobroma cacao) plants regenerated from calli of various ages, and also between tissues from the source trees. *For genetic change, we used 15 single sequence repeat (SSR) markers from four source trees and from 233 regenerated plants. For epigenetic change, we used 386 methylation-sensitive lified polymorphism (MSAP) markers on leaf and explant (staminode) DNA from two source trees and on leaf DNA from 114 regenerants. *Genetic variation within source trees was limited to one slippage mutation in one leaf. Regenerants were far more variable, with 35% exhibiting at least one mutation. Genetic variation initially accumulated with culture age but subsequently declined. MSAP (epigenetic) profiles erged between leaf and staminode s les from source trees. Multivariate analysis revealed that leaves from regenerants occupied intermediate eigenspace between leaves and staminodes of source plants but became progressively more similar to source tree leaves with culture age. *Statistical analysis confirmed this rather counterintuitive finding that leaves of 'late regenerants' exhibited significantly less genetic and epigenetic ergence from source leaves than those exposed to short periods of callus growth.
Publisher: Oxford University Press (OUP)
Date: 21-03-2012
DOI: 10.1093/JXB/ERS076
Publisher: Cold Spring Harbor Laboratory
Date: 26-10-2023
Publisher: Cold Spring Harbor Laboratory
Date: 17-11-2020
DOI: 10.1101/2020.11.16.385690
Abstract: Gut bacterial communities influence, and are influenced by, the behaviour and ecology of their hosts. Those interactions have been studied primarily in humans and model organisms, but we need field research to understand the relationship between an organism’s gut bacteria and its ecological challenges, such as those imposed by rapid range expansion (as in invasive species) and the presence of host-manipulating parasites. Cane toads ( Rhinella marina ) provide an excellent model system in this respect, because the species’ ongoing colonization of Australia has enforced major changes in phenotypic traits (including behaviour), and lungworm parasites ( Rhabdias pseudosphaerocephala ) modify host gut function in ways that enhance the viability of lungworm larvae. We collected female toads from across the species’ invasive range and studied their morphology, behaviour, parasite infection status and gut bacterial community. Range-core versus range-edge toads differed in morphology, behaviour, gut bacterial composition and predicted gut bacterial function but did not differ in the occurrence of parasite infection nor in the intensity of infection. Toads infected with lungworms differed from uninfected conspecifics in gut bacterial composition and ersity. Our study demonstrates strong associations between gut bacterial community and host ecology and behaviour.
Publisher: Frontiers Media SA
Date: 30-10-2017
Publisher: Cold Spring Harbor Laboratory
Date: 15-11-2018
DOI: 10.1101/471623
Abstract: Micronutrient deficiency is the cause of multiple diseases in developing countries. Staple crop biofortification is an efficient means to combat such deficiencies in the diets of local consumers. Biofortified lines of sweet potato ( Ipomoea batata L. Lam) with enhanced beta-carotene content have been developed in Ghana to alleviate Vitamin A Deficiency. These genotypes are propagated using meristem micropropagation to ensure the generation of virus-free propagules. In vitro culture exposes micropropagated plants to conditions that can lead to the accumulation of somaclonal variation with the potential to generate unwanted aberrant phenotypes. However, the effect of micropropagation induced somaclonal variation on the production of key nutrients by field-grown plants has not been previously studied. Here we assessed the extent of in vitro culture induced somaclonal variation, at a phenotypic, compositional and genetic/epigenetic level, by comparing field-maintained and micropropagated lines of three elite Ghanaian sweet potato genotypes grown in a common garden. Although micropropagated plants presented no observable morphological abnormalities compared to field maintained lines, they presented significantly lower levels of iron, total protein, zinc, and glucose. Methylation Sensitive Amplification Polymorphism analysis showed a high level of in vitro culture induced molecular variation in micropropagated plants. Epigenetic, rather than genetic variation, accounts for most of the observed molecular variability. Taken collectively, our results highlight the importance of ensuring the clonal fidelity of the micropropagated biofortified lines in order to reduce potential losses in the nutritional value prior to their commercial release.
Publisher: MDPI AG
Date: 26-03-2013
DOI: 10.3390/IJMS14046674
Publisher: Springer Science and Business Media LLC
Date: 12-11-2009
Publisher: Elsevier BV
Date: 12-2022
DOI: 10.1016/J.YMPEV.2022.107617
Abstract: Introgression is a widespread evolutionary process leading to phylogenetic inconsistencies among distinct parts of the genomes, particularly between mitochondrial and nuclear-based phylogenetic reconstructions (e.g., mito-nuclear discordances). Here, we used mtDNA and genome-wide nuclear sites to provide the first phylogenomic-based hypothesis on the evolutionary relationships within the killifish genus Kryptolebias. In addition, we tested for evidence of past introgression in the genus given the multiple reports of undergoing hybridization between its members. Our mtDNA phylogeny generally agreed with the relationships previously proposed for the genus. However, our reconstruction based on nuclear DNA revealed an unknown lineage - Kryptolebias sp. 'ESP' - as the sister group of the self-fertilizing mangrove killifishes, K. marmoratus and K. hermaphroditus. All in iduals sequenced of Kryptolebias sp. 'ESP' had the same mtDNA haplotype commonly observed in K. hermaphroditus, demonstrating a clear case of mito-nuclear discordance. Our analysis further confirmed extensive history of introgression between Kryptolebias sp. 'ESP' and K. hermaphroditus. Population genomics analyses indicate no current gene flow between the two lineages, despite their current sympatry and history of introgression. We also confirmed introgression between other species pairs in the genus that have been recently reported to form hybrid zones. Overall, our study provides a phylogenomic reconstruction covering most of the Kryptolebias species, reveals a new lineage hidden in a case of mito-nuclear discordance, and provides evidence of multiple events of ancestral introgression in the genus. These findings underscore the importance of investigating different genomic information in a phylogenetic framework, particularly in taxa where introgression is common as in the sexually erse mangrove killifishes.
Publisher: Cold Spring Harbor Laboratory
Date: 13-04-2020
DOI: 10.1101/2020.04.13.039131
Abstract: Transfer RNAs (tRNA) are crucial adaptor molecules between messenger RNA (mRNA) and amino acids. Recent evidence in plants suggests that dicistronic tRNA-like structures also act as mobile signals for mRNA transcripts to move between distant tissues. Co-transcription is not a common feature in the plant nuclear genome and, in the few cases where polycistronic transcripts have been found, they include non-coding RNA species such as small nucleolar RNAs and microRNAs. It is not known, however, the extent to which dicistronic transcripts of tRNA and mRNAs are expressed in field-grown plants, or the factors contributing to their expression. We analysed tRNA-mRNA dicistronic transcripts in the major horticultural crop grapevine ( Vitis vinifera ) using a novel pipeline developed to identify dicistronic transcripts from high-throughput RNA sequencing data. We identified dicistronic tRNA-mRNA in leaf and berry s les from 22 commercial vineyards. Of the 124 tRNA genes that were expressed in both tissues, 18 tRNA were expressed forming part of 19 dicistronic tRNA-mRNAs. The presence and abundance of dicistronic molecules was tissue and geographic sub-region specific. In leaves, the expression patterns of dicistronic tRNA-mRNAs significantly correlated with tRNA expression, suggesting that their transcriptional regulation might be linked. We also found evidence of syntenic genomic arrangements of tRNAs and protein coding genes between grapevine and Arabidopsis thaliana , and widespread prevalence of dicistronic tRNA-mRNA transcripts among vascular land plants but no evidence of these transcripts in nonvascular lineages. This suggests that the appearance of plant vasculature and tRNA-mRNA occurred concurrently during the evolution of land plants.
Publisher: Elsevier BV
Date: 09-2015
Publisher: MDPI AG
Date: 25-04-2018
DOI: 10.20944/PREPRINTS201804.0323.V1
Abstract: Salinity can negatively impact crop growth and yield. Changes in DNA methylation are known to occur when plants are challenged by stress and have been associated to the regulation of stress-response genes. However, the role of DNA-methylation in moderating gene expression in response to salt stress has been relatively poorly studied among crops such as barley. Here we assess the extent of salt-induced alterations of DNA methylation in barley, and their putative role in perturbed gene expression. Using Next Generation Sequencing, we screened the leaf and root methylomes of five ergent barley varieties grown under control and three salt concentrations, to seek genotype independent salt-induced changes in DNA methylation. Salt stress caused increased methylation in leaves but diminished methylation in roots with a higher number of changes in leaves than in roots, indicating that salt induced changes to global methylation are tissue specific. DMMs were mostly located in close proximity to repeat elements but also 1094 genes, of which many possessed GO terms associated with plant responses to stress. Identified markers identified have potential value as sentinels of salt stress and provide a start point to understand the functional role of DNA methylation in facilitating barley& rsquo s response to this stressor.
Publisher: The Royal Society
Date: 22-11-2015
Abstract: Self-fertilization (selfing) favours reproductive success when mate availability is low, but renders populations more vulnerable to environmental change by reducing genetic variability. A mixed-breeding strategy (alternating selfing and outcrossing) may allow species to balance these needs, but requires a system for regulating sexual identity. We explored the role of DNA methylation as a regulatory system for sex-ratio modulation in the mixed-mating fish Kryptolebias marmoratus. We found a significant interaction between sexual identity (male or hermaphrodite), temperature and methylation patterns when two selfing lines were exposed to different temperatures during development. We also identified several genes differentially methylated in males and hermaphrodites that represent candidates for the temperature-mediated sex regulation in K. marmoratus . We conclude that an epigenetic mechanism regulated by temperature modulates sexual identity in this selfing species, providing a potentially widespread mechanism by which environmental change may influence selfing rates. We also suggest that K. marmoratus , with naturally inbred populations, represents a good vertebrate model for epigenetic studies.
Publisher: Wiley
Date: 06-03-2020
Publisher: Springer Science and Business Media LLC
Date: 20-10-2012
Abstract: Epigenetic marks superimposed on the DNA sequence of eukaryote chromosomes provide agility and plasticity in terms of modulating gene expression, ontology, and response to the environment. Modulating the methylation status of cytosine can generate epialleles, which have been detected and characterised at specific loci in several plant systems, and have the potential to generate novel and relatively stable phenotypes. There have been no systematic attempts to explore and utilise epiallelic variation, and so extend the range of phenotypes available for selection in crop improvement. We developed an approach for generating novel epialleles by perturbation of the DNA methylation status. 5- Azacytidine (5-AzaC) provides selective targeting of 5m CG, which in plants is associated with exonic DNA. Targeted chemical intervention using 5-AzaC has advantages over transgenic or mutant modulation of methyltransferases, allowing stochastic generation of epialleles across the genome. We demonstrate the potential of stochastic chemically-induced hypomethylation to generate novel and valuable variation for crop improvement. Systematic analysis of dose–response to 5-AzaC in B. rapa guided generation of a selfed stochastically hypomethylated population, used for forward screening of several agronomic traits. Dose–response was sigmoidal for several traits, similar to that observed for chemical mutagens such as EMS. We demonstrated transgenerational inheritance of some phenotypes. BraRoAZ is a unique hypomethylated population of 1000 E2 sib lines. When compared to untreated controls, 5-Aza C-treated lines exhibited reduced immuno-staining of 5m C on pachytene chromosomes, and Methylation Sensitive Amplified Polymorphism (MSAP) profiles that were both ergent and more variable. There was coincident phenotypic variation among these lines for a range of seed yield and composition traits, including increased seed protein content and decreased oil content, as well as decreased erucic acid and corresponding increases in linoleic and/or palmitic acid. Each 5-AzaC-treated line represents a unique combination of hypomethylated epialleles. The approach and populations developed are available for forward and reverse screening of epiallelic variation and subsequent functional and inheritance studies. The generation of stochastically hypomethylated populations has utility in epiallele discovery for a wide range of crop plants, and has considerable potential as an intervention strategy for crop improvement.
Publisher: Springer Science and Business Media LLC
Date: 02-2018
DOI: 10.1038/S41598-018-19655-W
Abstract: Genotyping-by-sequencing (GBS) or restriction-site associated DNA marker sequencing (RAD-seq) is a practical and cost-effective method for analysing large genomes from high ersity species. This method of sequencing, coupled with methylation-sensitive enzymes (often referred to as methylation-sensitive restriction enzyme sequencing or MRE-seq), is an effective tool to study DNA methylation in parts of the genome that are inaccessible in other sequencing techniques or are not annotated in microarray technologies. Current software tools do not fulfil all methylation-sensitive restriction sequencing assays for determining differences in DNA methylation between s les. To fill this computational need, we present msgbsR , an R package that contains tools for the analysis of methylation-sensitive restriction enzyme sequencing experiments. msgbsR can be used to identify and quantify read counts at methylated sites directly from alignment files (BAM files) and enables verification of restriction enzyme cut sites with the correct recognition sequence of the in idual enzyme. In addition, msgbsR assesses DNA methylation based on read coverage, similar to RNA sequencing experiments, rather than methylation proportion and is a useful tool in analysing differential methylation on large populations. The package is fully documented and available freely online as a Bioconductor package ( ackages/release/bioc/html/msgbsR.html ).
Publisher: IntechOpen
Date: 07-2020
Publisher: Elsevier BV
Date: 08-2020
Publisher: Cold Spring Harbor Laboratory
Date: 17-06-2016
DOI: 10.1101/059477
Abstract: Pathogenic fungi can lose virulence after protracted periods of culture but little is known of the underlying mechanisms. Here we present the first single-base resolution methylome for the plant pathogen B. cinerea and identify differentially methylated genes/genomic regions associated with virulence erosion. Cultures were maintained for eight months with subcultures and virulence testing every month. Methylation-sensitive lified polymorphisms were performed at monthly intervals to characterise global changes to the pathogen's genome during culture and also on DNA from mycelium inoculated onto Arabidopsis thaliana after eight months in culture. Characterisation of culture-induced epialleles was assessed by whole-genome re-sequencing and whole-genome bisulfite sequencing. Virulence declined with time in culture and recovered after inoculation on A. thaliana. Variation detected by methylation-sensitive lified polymorphisms followed virulence changes during culture. Whole-genome (bisulfite) sequencing showed marked changes on global and local methylation during culture but no significant genetic changes. We imply that virulence is a non-essential plastic character that is at least partly modified by changing levels of DNA methylation during culture. We hypothesise that changing DNA methylation during culture may be responsible for the high virulence/low virulence transition in B. cinerea and speculate that this may offer fresh opportunities to control pathogen virulence.
Start Date: 2014
End Date: 2015
Funder: Grape and Wine Research and Development Corporation
View Funded ActivityStart Date: 2017
End Date: 2021
Funder: Australian Research Council
View Funded Activity