Discovery of a -regulatory element involved in dynamic regulation of synergid-specific .

is a key regulator of the genetic network behind pollen tube attraction toward the female gametophyte. is specifically expressed in the synergid cells (SCs), a female gametophyte component cells specialized for pollen tube attraction. However, it had not been clear how exactly achieves this specific expression pattern.

RNA-seq analysis of synchronized developing pollen isolated from a single anther.

Pollen development, from unicellular microspores to anthesis, is a complex process involving the coordinated specification, differentiation and functions of different cell types. Key to understanding this development is identifying the genes expressed at precise stages of development. However, transcriptomic studies on pollen prior to anthesis are complicated by the inaccessible nature of pollen developing in the anther and the resistant pollen wall.

Identification of the genes at and reveals the molecular basis and evolution of grass self-incompatibility.

Self-incompatibility (SI) is a feature of many flowering plants, whereby self-pollen is recognized and rejected by the stigma. In grasses (Poaceae), the genes controlling this phenomenon have not been fully elucidated. Grasses have a unique two-locus system, in which two independent genetic loci (S and Z) control self-recognition.

Meiocyte size is a determining factor for unreduced gamete formation in Arabidopsis thaliana.

Polyploidy, the presence of more than two sets of chromosomes within a cell, is a widespread phenomenon in plants. The main route to polyploidy is considered through the production of unreduced gametes that are formed as a consequence of meiotic defects. Nevertheless, for reasons poorly understood, the frequency of unreduced gamete formation differs substantially among different plant species.

Plant breeding: Revealing the secrets of cytoplasmic male sterility in wheat.

While cytoplasmic male sterility is used for breeding in many crops, it has proved difficult to implement in wheat. A new study identifying the key molecules and their mode of action in cytoplasmic male sterility provides new opportunities for wheat breeding.

Identification and Characterization of Perennial Ryegrass () Vernalization Genes.

Perennial ryegrass () is a temperate grass species commonly used as pasture for livestock. Flowering (heading) of ryegrass impacts metabolizable energy content and seed yield, therefore this trait is important for both farmers and seed producers. In related grass species, the genes (-) have been largely implicated in the determination of vernalization response and are responsible for much of the intra-species variation in this trait.

A simple and rapid method for imaging male meiotic cells in anthers of model and non-model plant species.

We describe a simple method to view meiotic cells in whole anthers from a range of plants. The method retains spatial organisation and enables simultaneous analysis of many meiotic cells. Understanding the process of male meiosis in flowering plants, and the role of genes involved in this process, offers potential for plant breeding, such as through increasing the level of genetic variation or the manipulation of ploidy levels in the gametes.

Identification of Cis-Regulatory Modules that Function in the Male Germline of Flowering Plants.

The male germline of flowering plants develops within the vegetative cell of the male gametophyte and displays a distinct transcriptional profile. Key to understanding the development of this unique cell lineage is determining how gene expression is regulated within germline cells. This knowledge impacts upon our understanding of cell specification, differentiation, and plant fertility.

Analysis of Fluorescent Reporter Activity in the Male Germline During Pollen Development by Confocal Microscopy.

The male germline of flowering plants develops within the vegetative cell of the male gametophyte (pollen). The germline is established by asymmetric division of the microspore to form the generative cell. Mitotic division of the generative cell then produces the two sperm cells required for double fertilization.

The meiotic regulator JASON utilizes alternative translation initiation sites to produce differentially localized forms.

The JASON (JAS) protein plays an important role in maintaining an organelle band across the equator of male meiotic cells during the second division, with its loss leading to unreduced pollen in Arabidopsis. In roots cells, JAS localizes to the Golgi, tonoplast and plasma membrane. Here we explore the mechanism underlying the localization of JAS.

A Conserved cis-Regulatory Module Determines Germline Fate through Activation of the Transcription Factor DUO1 Promoter.

The development of the male germline within pollen relies upon the activation of numerous target genes by the transcription factor DUO POLLEN1 (DUO1). The expression of DUO1 is restricted to the male germline and is first detected shortly after the asymmetric division that segregates the germ cell lineage. Transcriptional regulation is critical in controlling DUO1 expression, since transcriptional and translational fusions show similar expression patterns.

Convergent occurrence of the developmental hourglass in plant and animal embryogenesis?

Background: The remarkable similarity of animal embryos at particular stages of development led to the proposal of a developmental hourglass. In this model, early events in development are less conserved across species but lead to a highly conserved 'phylotypic period'. Beyond this stage, the model suggests that development once again becomes less conserved, leading to the diversity of forms.

Organelles maintain spindle position in plant meiosis.

Accurate positioning of spindles is a critical aspect of cell division as it ensures that each daughter cell contains a single nucleus. In many flowering plants, two meiotic chromosome separations occur without intervening cytokinesis, resulting in two spindles in one cell during the second division. Here we report a detailed examination of two mutants, jason (jas) and parallel spindle1 (ps1), in which disturbed spindle position during male meiosis II results in the incorporation of previously separated chromosome groups into a single cell.

The R2R3 MYB transcription factor DUO1 activates a male germline-specific regulon essential for sperm cell differentiation in Arabidopsis.

The male germline in flowering plants arises through asymmetric division of a haploid microspore. The resulting germ cell undergoes mitotic division and specialization to produce the two sperm cells required for double fertilization. The male germline-specific R2R3 MYB transcription factor DUO1 POLLEN1 (DUO1) plays an essential role in sperm cell specification by activating a germline-specific differentiation program.

Unreduced gamete formation in plants: mechanisms and prospects.

Polyploids, organisms with more than two sets of chromosomes, are widespread in flowering plants, including many important crop species. Increases in ploidy level are believed to arise commonly through the production of gametes that have not had their ploidy level reduced during meiosis. Although there have been cytological descriptions of unreduced gamete formation in a number of plants, until recently none of the underlying genes or molecular mechanisms involved in unreduced gamete production have been described.

A dynamic DUO of regulatory proteins coordinates gamete specification and germ cell mitosis in the angiosperm male germline.

The production of two functional sperm cells within each male gametophyte is essential for double fertilization in flowering plants and involves a single mitotic division of the male germ cell and cell specification to produce functional gametes. Several proteins that are important regulators of male germ cell division have been identified as well as the R2R3 MYB protein DUO1 that has a dual role in cell division and cell specification. We recently identified a novel regulatory protein DUO3, that has overlapping roles with DUO1 in cell division and specification and shows similarity to GON4 related cell lineage regulators in animals.

Induction of RNA-directed DNA methylation upon decondensation of constitutive heterochromatin.

Centromeric constitutive heterochromatin is marked by DNA methylation and dimethylated histone H3 Lys 9 (H3K9me2) in Arabidopsis. RNA-directed DNA methylation (RdDM) is a process that uses 24-nucleotide (nt) small interfering RNAs (siRNAs) to induce de novo methylation to its homologous DNA sequences. Despite the presence of centromeric 24-nt siRNAs, mutations in genes required for RdDM do not appreciably influence the methylation of centromeric repeats.

Arabidopsis DUO POLLEN3 is a key regulator of male germline development and embryogenesis.

Male germline development in angiosperms produces the pair of sperm cells required for double fertilization. A key regulator of this process in Arabidopsis thaliana is the male germline-specific transcription factor DUO POLLEN1 (DUO1) that coordinates germ cell division and gamete specification. Here, we uncover the role of DUO3, a nuclear protein that has a distinct, but overlapping role with DUO1 in male germline development.

A plant germline-specific integrator of sperm specification and cell cycle progression.

The unique double fertilisation mechanism in flowering plants depends upon a pair of functional sperm cells. During male gametogenesis, each haploid microspore undergoes an asymmetric division to produce a large, non-germline vegetative cell and a single germ cell that divides once to produce the sperm cell pair. Despite the importance of sperm cells in plant reproduction, relatively little is known about the molecular mechanisms controlling germ cell proliferation and specification.

Male gametophyte development: a molecular perspective.

Pollen grains represent the highly reduced haploid male gametophyte generation in flowering plants, consisting of just two or three cells when released from the anthers. Their role is to deliver twin sperm cells to the embryo sac to undergo fusion with the egg and central cell. This double fertilization event along with the functional specialization of the male gametophyte, are considered to be key innovations in the evolutionary success of flowering plants.

Control of plant germline proliferation by SCF(FBL17) degradation of cell cycle inhibitors.

Flowering plants possess a unique reproductive strategy, involving double fertilization by twin sperm cells. Unlike animal germ lines, the male germ cell lineage in plants only forms after meiosis and involves asymmetric division of haploid microspores, to produce a large, non-germline vegetative cell and a germ cell that undergoes one further division to produce the twin sperm cells. Although this switch in cell cycle control is critical for sperm cell production and delivery, the underlying molecular mechanisms are unknown.