The kinase ATR controls meiotic crossover distribution at the genome scale in Arabidopsis.

Meiotic crossover, i.e. the reciprocal exchange of chromosome fragments during meiosis, is a key driver of genetic diversity.

Mutations of PDS5 genes enhance TAD-like domain formation Arabidopsis thaliana.

In eukaryotes, topologically associating domains (TADs) organize the genome into functional compartments. While TAD-like structures are common in mammals and many plants, they are challenging to detect in Arabidopsis thaliana. Here, we demonstrate that Arabidopsis PDS5 proteins play a negative role in TAD-like domain formation.

Synthetically induced Arabidopsis thaliana autotetraploids provide insights into the analysis of meiotic mutants with altered crossover frequency.

Mutations affecting crossover (CO) frequency and distribution lead to the presence of univalents during meiosis, giving rise to aneuploid gametes and sterility. These mutations may have a different effect after chromosome doubling. The combination of altered ploidy and mutations could be potentially useful to gain new insights into the mechanisms and regulation of meiotic recombination; however, studies using autopolyploid meiotic mutants are scarce.

The Hop1 homolog ASY1 mediates cross-over assurance and interference.

The chromosome axis plays a crucial role in meiotic recombination. Here, we study the function of ASY1, the Arabidopsis homolog of the yeast chromosome axis-associated component Hop1. Specifically, we characterized cross-over (CO) distribution in female and male meiosis by deep sequencing of the progeny of an allelic series of mutants.

Exploitation of epigenetic variation of crop wild relatives for crop improvement and agrobiodiversity preservation.

Crop wild relatives (CWRs) are recognized as the best potential source of traits for crop improvement. However, successful crop improvement using CWR relies on identifying variation in genes controlling desired traits in plant germplasms and subsequently incorporating them into cultivars. Epigenetic diversity may provide an additional layer of variation within CWR and can contribute novel epialleles for key traits for crop improvement.

The INDEPTH (Impact of Nuclear Domains on Gene Expression and Plant Traits) Academy: a community resource for plant science.

This Community Resource paper introduces the range of materials developed by the INDEPTH (Impact of Nuclear Domains on Gene Expression and Plant Traits) COST Action made available through the INDEPTH Academy. Recent rapid growth in understanding of the significance of epigenetic controls in plant and crop science has led to a need for shared, high-quality resources, standardization of protocols, and repositories for open access data. The INDEPTH Academy provides a range of masterclass tutorials, standardized protocols, and teaching webinars, together with a rapidly developing repository to support imaging and spatial analysis of the nucleus and deep learning for automated analysis.

Genomic and Meiotic Changes Accompanying Polyploidization.

Hybridization and polyploidy have been considered as significant evolutionary forces in adaptation and speciation, especially among plants. Interspecific gene flow generates novel genetic variants adaptable to different environments, but it is also a gene introgression mechanism in crops to increase their agronomical yield. An estimate of 9% of interspecific hybridization has been reported although the frequency varies among taxa.

Structural Maintenance of Chromosomes 5/6 Complex Is Necessary for Tetraploid Genome Stability in .

Polyploidization is a common phenomenon in the evolution of flowering plants. However, only a few genes controlling polyploid genome stability, fitness, and reproductive success are known. Here, we studied the effects of loss-of-function mutations in NSE2 and NSE4A subunits of the Structural Maintenance of Chromosomes 5/6 (SMC5/6) complex in autotetraploid plants.

Defects in meiotic chromosome segregation lead to unreduced male gametes in Arabidopsis SMC5/6 complex mutants.

Structural maintenance of chromosome 5/6 (SMC5/6) complex is a crucial factor for preserving genome stability. Here, we show that mutants for several Arabidopsis (Arabidopsis thaliana) SMC5/6 complex subunits produce triploid offspring. This phenotype is caused by a meiotic defect leading to the production of unreduced male gametes.

The role of the nuclear envelope in the regulation of chromatin dynamics during cell division.

The nuclear envelope delineates the eukaryotic cell nucleus. The membrane system of the nuclear envelope consists of an outer nuclear membrane and an inner nuclear membrane separated by a perinuclear space. It serves as more than just a static barrier, since it regulates the communication between the nucleoplasm and the cytoplasm and provides the anchoring points where chromatin is attached.

Duplication and divergence: New insights into AXR1 and AXL functions in DNA repair and meiosis.

Rubylation is a conserved regulatory pathway similar to ubiquitination and essential in the response to the plant hormone auxin. In Arabidopsis thaliana, AUXIN RESISTANT1 (AXR1) functions as the E1-ligase in the rubylation pathway. The gene AXR1-LIKE (AXL), generated by a relatively recent duplication event, can partially replace AXR1 in this pathway.

Chromatin dynamics during interphase and cell division: similarities and differences between model and crop plants.

Genetic information in the cell nucleus controls organismal development and responses to the environment, and finally ensures its own transmission to the next generations. To achieve so many different tasks, the genetic information is associated with structural and regulatory proteins, which orchestrate nuclear functions in time and space. Furthermore, plant life strategies require chromatin plasticity to allow a rapid adaptation to abiotic and biotic stresses.

How to Perform an Accurate Analysis of Metaphase I Chromosome Configurations in Autopolyploids of Arabidopsis thaliana.

During meiosis, accurate segregation of chromosomes requires the formation of bivalents at metaphase I. In autopolyploids, there are more than two copies of each chromosome with the same chance to form chiasmata at meiosis. This leads to the formation of multivalent configurations in which chiasma quantification is rather complicated.

The Cdk1/Cdk2 homolog CDKA;1 controls the recombination landscape in .

Little is known how patterns of cross-over (CO) numbers and distribution during meiosis are established. Here, we reveal that cyclin-dependent kinase A;1 (CDKA;1), the homolog of human Cdk1 and Cdk2, is a major regulator of meiotic recombination in plants with reduced CDKA;1 activity experienced a decrease of class I COs, especially lowering recombination rates in centromere-proximal regions. Interestingly, this reduction of type I CO did not affect CO assurance, a mechanism by which each chromosome receives at least one CO, resulting in all chromosomes exhibiting similar genetic lengths in weak loss-of-function mutants.

Insights Into the Role of Ubiquitination in Meiosis: Fertility, Adaptation and Plant Breeding.

Ubiquitination is a post-translational modification process that plays a central role in protein degradation in eukaryotic cell cell division, including meiosis. This modification affects different cellular processes on a global scale by its pleiotropic ability to modify numerous proteins. Meiosis is essential for sexual reproduction and involves two rounds of nuclear division following a single round of DNA replication to produce haploid gametes.

The nuclear envelope in higher plant mitosis and meiosis.

Mitosis and meiosis in higher plants involve significant reconfiguration of the nuclear envelope and the proteins that interact with it. The dynamic series of events involves a range of interactions, movement, breakdown, and reformation of this complex system. Recently, progress has been made in identifying and characterizing the protein and membrane interactome that performs these complex tasks, including constituents of the nuclear envelope, the cytoskeleton, nucleoskeleton, and chromatin.

Competition for Chiasma Formation Between Identical and Homologous (But Not Identical) Chromosomes in Synthetic Autotetraploids of .

Polyploid organisms provide additional opportunities to study meiosis in a more complex context since more than two potential homologous chromosomes are available. When the chromosome complement of a diploid individual is duplicated, each chromosome is accompanied by one identical and two homologous chromosomes within the same nucleus. In this situation, a competition in pairing/synapsis/chiasma formation between identical and homologous (but not necessarily identical) chromosomes can occur.

Genes involved in miRNA biogenesis affect meiosis and fertility.

MicroRNAs (miRNAs) are a class of small (containing about 22 nucleotides) single-stranded non-coding RNAs that regulate gene expression at the post-transcriptional level in plants and animals, being absent from unicellular organisms. They act on diverse key physiological and cellular processes, such as development and tissue differentiation, cell identity, cell cycle progression, and programmed cell death. They are also likely to be involved in a broad spectrum of human diseases.

Immunolabeling Protocols for Studying Meiosis in Plant Mutants Defective for Nuclear Envelope Components.

The nuclear envelope (NE) is a dynamic boundary that allows the communication between nuclear and cytoplasmic components. It has essential roles in a variety of physiological processes including cell division. The linker of nucleoskeleton and cytoskeleton (LINC) complexes span the NE and are important during meiosis, the specialized cell division needed for sexual reproduction.