Diploid Nuclei Occur throughout the Life Cycles of Pucciniales Fungi.

Within Eukaryotes, fungi are the typical representatives of haplontic life cycles. Basidiomycota fungi are dikaryotic in extensive parts of their life cycle, but diploid nuclei are known to form only in basidia. Among Basidiomycota, the Pucciniales are notorious for presenting the most complex life cycles, with high host specialization, and for their expanded genomes.

Genome-wide identification, phylogeny, and gene duplication of the epigenetic regulators in Fagaceae.

Epigenetic regulators are proteins involved in controlling gene expression. Information about the epigenetic regulators within the Fagaceae, a relevant family of trees and shrubs of the northern hemisphere ecosystems, is scarce. With the intent to characterize these proteins in Fagaceae, we searched for orthologs of DNA methyltransferases (DNMTs) and demethylases (DDMEs) and Histone modifiers involved in acetylation (HATs), deacetylation (HDACs), methylation (HMTs), and demethylation (HDMTs) in Fagus, Quercus, and Castanea genera.

Epigenetics at the crossroads of secondary growth regulation.

The development of plant tissues and organs during post-embryonic growth occurs through the activity of both primary and secondary meristems. While primary meristems (root and shoot apical meristems) promote axial plant growth, secondary meristems (vascular and cork cambium or phellogen) promote radial thickening and plant axes strengthening. The vascular cambium forms the secondary xylem and phloem, whereas the cork cambium gives rise to the periderm that envelops stems and roots.

The Dynamics of Flower Development in Mill.

The sweet chestnut tree ( Mill.) is one of the most significant Mediterranean tree species, being an important natural resource for the wood and fruit industries. It is a monoecious species, presenting unisexual male catkins and bisexual catkins, with the latter having distinct male and female flowers.

Cork cells in cork oak periderms undergo programmed cell death and proanthocyanidin deposition.

Vascular plants with secondary growth develop a periderm mostly composed of dead suberized cork cells to face environmental hostile conditions. Cork oak has a highly active and long-living phellogen forming a remarkably thick periderm that is periodically debarked for industrial purposes. This wounding originates the quick formation of a new traumatic periderm, making cork oak an exceptional model to study the first periderm differentiation during normal development in young sprigs and traumatic (wound) periderm formation after debarking.

Genome-Wide Identification of Epigenetic Regulators in L.

Modifications of DNA and histones, including methylation and acetylation, are critical for the epigenetic regulation of gene expression during plant development, particularly during environmental adaptation processes. However, information on the enzymes catalyzing all these modifications in trees, such as L., is still not available.

ChIP-Seq reveals that QsMYB1 directly targets genes involved in lignin and suberin biosynthesis pathways in cork oak (Quercus suber).

Background: Gene activity is largely controlled by transcriptional regulation through the action of transcription factors and other regulators. QsMYB1 is a member of the R2R3-MYB transcription factor family related to secondary growth, and in particular, with the cork development process. In order to identify the putative gene targets of QsMYB1 across the cork oak genome we developed a ChIP-Seq strategy.

Cork Oak Young and Traumatic Periderms Show PCD Typical Chromatin Patterns but Different Chromatin-Modifying Genes Expression.

Plants are subjected to adverse conditions being outer protective tissues fundamental to their survival. Tree stems are enveloped by a periderm made of cork cells, resulting from the activity of the meristem phellogen. DNA methylation and histone modifications have important roles in the regulation of plant cell differentiation.

Differential DNA Methylation Patterns Are Related to Phellogen Origin and Quality of Quercus suber Cork.

DNA methylation is thought to influence Quercus suber cork quality, which is the main constraint for its economic valorisation. However, a deep knowledge of the cytosine methylation patterns disclosing the epigenetic variability of trees with different cork quality types is totally missing. This study investigates the hypothesis that variations in DNA methylation contribute to differences in cork cellular characteristics directly related to original or traumatic phellogen activity.

Advancing Eucalyptus Genomics: Cytogenomics Reveals Conservation of Eucalyptus Genomes.

The genus Eucalyptus encloses several species with high ecological and economic value, being the subgenus Symphyomyrtus one of the most important. Species such as E. grandis and E.

The Quest for Molecular Regulation Underlying Unisexual Flower Development.

The understanding of the molecular mechanisms responsible for the making of a unisexual flower has been a long-standing quest in plant biology. Plants with male and female flowers can be divided mainly into two categories: dioecious and monoecious, and both sexual systems co-exist in nature in ca of 10% of the angiosperms. The establishment of male and female traits has been extensively described in a hermaphroditic flower and requires the interplay of networks, directly and indirectly related to the floral organ identity genes including hormonal regulators, transcription factors, microRNAs, and chromatin-modifying proteins.

Comparative transcriptomic analysis of male and female flowers of monoecious Quercus suber.

Monoecious species provide a comprehensive system to study the developmental programs underlying the establishment of female and male organs in unisexual flowers. However, molecular resources for most monoecious non-model species are limited, hampering our ability to study the molecular mechanisms involved in flower development of these species. The objective of this study was to identify differentially expressed genes during the development of male and female flowers of the monoecious species Quercus suber, an economically important Mediterranean tree.

Molecular organization of the 25S-18S rDNA IGS of Fagus sylvatica and Quercus suber: a comparative analysis.

The 35S ribosomal DNA (rDNA) units, repeated in tandem at one or more chromosomal loci, are separated by an intergenic spacer (IGS) containing functional elements involved in the regulation of transcription of downstream rRNA genes. In the present work, we have compared the IGS molecular organizations in two divergent species of Fagaceae, Fagus sylvatica and Quercus suber, aiming to comprehend the evolution of the IGS sequences within the family. Self- and cross-hybridization FISH was done on representative species of the Fagaceae.

A comprehensive assessment of the transcriptome of cork oak (Quercus suber) through EST sequencing.

Background: Cork oak (Quercus suber) is one of the rare trees with the ability to produce cork, a material widely used to make wine bottle stoppers, flooring and insulation materials, among many other uses. The molecular mechanisms of cork formation are still poorly understood, in great part due to the difficulty in studying a species with a long life-cycle and for which there is scarce molecular/genomic information. Cork oak forests are of great ecological importance and represent a major economic and social resource in Southern Europe and Northern Africa.

Corky, a gypsy-like retrotransposon is differentially transcribed in Quercus suber tissues.

Background: Transposable elements (TEs) make up a large part of eukaryotic genomes. Due to their repetitive nature and to the fact that they harbour regulatory signals, TEs can be responsible for chromosomal rearrangements, movement of gene sequences and evolution of gene regulation and function. Retrotransposon ubiquity raises the question about their function in genomes and most are transcriptionally inactive due to rearrangements that compromise their activity.

Genomic organization and dynamics of repetitive DNA sequences in representatives of three Fagaceae genera.

Oaks, chestnuts, and beeches are economically important species of the Fagaceae. To understand the relationship between these members of this family, a deep knowledge of their genome composition and organization is needed. In this work, we have isolated and characterized several AFLP fragments obtained from Quercus rotundifolia Lam.

Epigenetic marks in the mature pollen of Quercus suber L. (Fagaceae).

We have analysed the distribution of epigenetic marks for histone modifications at lysine residues H3 and H4, and DNA methylation, in the nuclei of mature pollen cells of the Angiosperm tree Quercus suber; a monoecious wind pollinated species with a protandrous system, and a long post-pollination period. The ultrasonic treatment developed for the isolation of pollen nuclei proved to be a fast and reliable method, preventing the interference of cell wall autofluorescence in the in situ immunolabelling assays. In contrast with previous studies on herbaceous species with short progamic phases, our results are consistent with a high level of silent (5-mC and H3K9me2) epigenetic marks on chromatin of the generative nucleus, and the prevalence of active marks (H3K9me3 and H4Kac) in the vegetative nucleus.

Transcriptionally active heterochromatin in rye B chromosomes.

B chromosomes (Bs) are dispensable components of the genomes of numerous species. Thus far, there is a lack of evidence for any transcripts of Bs in plants, with the exception of some rDNA sequences. Here, we show that the Giemsa banding-positive heterochromatic subterminal domain of rye (Secale cereale) Bs undergoes decondensation during interphase.

Molecular and cytological characterization of genomic variability in hexaploid wheat 'Lindström'.

'Lindström' wheat (AABBDD+rye B chromosomes) was used to study the effects of alien chromatin introgressed into a wheat genetic background, subjecting the wheat genome to a new and transient allopolyploidisation episode. Using this experimental material, we have previously demonstrated that no large-scale chromosomal translocations occurred as a result of the genomic constitution of the addition line. However, we have shown that the presence of a number of rye B chromosomes is associated with changes in the interphase organization and expression patterns of wheat rDNA loci.

Genomic analysis of Grapevine Retrotransposon 1 (Gret 1) in Vitis vinifera.

The complete sequence of the first retrotransposon isolated in Vitis vinifera, Gret 1, was used to design primers that permitted its analysis in the genome of grapevine cultivars. This retroelement was found to be dispersed throughout the genome with sites of repeated insertions. Fluorescent in situ hybridization indicated multiple Gret 1 loci distributed throughout euchromatic portions of chromosomes.

Evidence for 'cross-talk' between A and B chromosomes of rye.

Spontaneous DNA insertions from supernumerary B chromosomes (Bs) into the standard A chromosome complement were detected in rye (Secale cereale L.), using fluorescent in situ hybridization (FISH) analysis with the D1100 B-specific sequence probe. The insertions were seen in individuals derived from plants possessing deleted Bs, characterized in this study by not having the B-specific sequences that are normally found at the distal part of the long arm of the standard rye B.

Genomic characterization and physical mapping of two fucosyltransferase genes in Medicago truncatula.

Fucosyltransferases catalyse fucose transfer onto oligosaccharides. Two fucosylated structures have been identified in plants: the alpha1,4-fucosylated Lewis-a epitope and the alpha1,3-fucosylated core. Here we report the cloning, genomic characterization, and physical mapping of two genes encoding proteins similar to alpha1,4-fucosyltransferase (EC 2.

Genome restructuring in rye affects the expression, organization and disposition of homologous rDNA loci.

The standard rye cultivar 'Imperial' and a structural variant carrying an intact 1R chromosome and two telocentric 1R chromosomes (short and long arms) were used to investigate expression patterns of homologous rDNA loci, and the influence of chromosome structural change on their interphase organisation and relative disposition. Sequential silver staining and in situ hybridization with the rDNA probe pTa71, established a correspondence between the expression and organization patterns of rDNA domains in metaphase and interphase cells. In most cells of the cultivar Imperial, nucleolar organizer region (NOR) silver staining on metaphase chromosomes with equivalent numbers of rDNA genes revealed a size heteromorphism between homologous rDNA loci, resulting from their differential expression.