Highly reactive chemicals meet haploidization.

Mutation of the sperm-specific phospholipase A and treatment of pollen with reactive oxygen species (ROS) reagents lead to the induction of maize haploids. ZmPOD65, a gene associated with sperm-specific ROS metabolism, also exhibits a haploidization effect.

B-A Chromosome Translocations Possessing an A Centromere Partly Overcome the Root-Restricted Process of Chromosome Elimination in .

Some eukaryotes exhibit dramatic genome size differences between cells of different organs, resulting from the programmed elimination of chromosomes. is an annual diploid species from the Poaceae family, with a maximum number of eight B chromosomes (Bs) in addition to its inherent seven pairs of standard A chromosomes (As). The Bs of this species undergo precise elimination in roots early in embryo development.

Tissue-Specific Transcriptome Analysis Reveals Candidate Transcripts Associated with the Process of Programmed B Chromosome Elimination in .

Some eukaryotes exhibit dramatic genome size differences between cells of different organs, resulting from programmed elimination of chromosomes. Here, we present the first transcriptome analysis of programmed chromosome elimination using laser capture microdissection (LCM)-based isolation of the central meristematic region of embryos where B chromosome (B) elimination occurs. The comparative RNA-seq analysis of meristematic cells of embryos with (Bplus) and without Bs (B0) allowed the identification of 14,578 transcript isoforms (35% out of 41,615 analyzed transcript isoforms) that are differentially expressed during the elimination of Bs.

European maize genomes highlight intraspecies variation in repeat and gene content.

The diversity of maize (Zea mays) is the backbone of modern heterotic patterns and hybrid breeding. Historically, US farmers exploited this variability to establish today's highly productive Corn Belt inbred lines from blends of dent and flint germplasm pools. Here, we report de novo genome sequences of four European flint lines assembled to pseudomolecules with scaffold N50 ranging from 6.

Supernumerary B chromosomes of Aegilops speltoides undergo precise elimination in roots early in embryo development.

Not necessarily all cells of an organism contain the same genome. Some eukaryotes exhibit dramatic differences between cells of different organs, resulting from programmed elimination of chromosomes or their fragments. Here, we present a detailed analysis of programmed B chromosome elimination in plants.

Analysis of Pollen Grains by Immunostaining and FISH in Triticeae Species.

In this chapter we describe protocols for immunolabeling and FISH of pollen grains undergoing postmeiotic mitosis using Aegilops speltoides, Secale cereale, and Hordeum vulgare as models. Tissue sectioning of pollen overcomes the problem of the pollen grain wall impermeability that interferes with immunolocalization and in situ hybridization. The crucial element of the protocol is the generation and immobilization of tissue sections.

Nondisjunction and unequal spindle organization accompany the drive of Aegilops speltoides B chromosomes.

B chromosomes (Bs) are supernumerary chromosomes, which are often preferentially inherited. When transmission rates of chromosomes are higher than 0.5, not obeying the Mendelian law of equal segregation, the resulting transmission advantage is collectively referred to as 'chromosome drive'.

Evolution of the S-Genomes in Alliance: Evidences From Chromosome Analysis.

Five diploid species of the section: , and , two tetraploid species (= ) and ( section) and hexaploid ( section) carry the S-genomes. The B- and G-genomes of polyploid wheat are also the derivatives of the S-genome. Evolution of the S-genome species was studied using Giemsa C-banding and fluorescence hybridization (FISH) with DNA probes representing 5S (pTa794) and 18S-5.

Discovery of multi-megabase polymorphic inversions by chromosome conformation capture sequencing in large-genome plant species.

Chromosomal inversions occur in natural populations of many species, and may underlie reproductive isolation and local adaptation. Traditional methods of inversion discovery are labor-intensive and lack sensitivity. Here, we report the use of three-dimensional contact probabilities between genomic loci as assayed by chromosome-conformation capture sequencing (Hi-C) to detect multi-megabase polymorphic inversions in four barley genotypes.

How Next-Generation Sequencing Has Aided Our Understanding of the Sequence Composition and Origin of B Chromosomes.

Accessory, supernumerary, or-most simply-B chromosomes, are found in many eukaryotic karyotypes. These small chromosomes do not follow the usual pattern of segregation, but rather are transmitted in a higher than expected frequency. As increasingly being demonstrated by next-generation sequencing (NGS), their structure comprises fragments of standard (A) chromosomes, although in some plant species, their sequence also includes contributions from organellar genomes.

Chromatin Ring Formation at Plant Centromeres.

We observed the formation of chromatin ring structures at centromeres of somatic rye and Arabidopsis chromosomes. To test whether this behavior is present also in other plant species and tissues we analyzed Arabidopsis, rye, wheat, Aegilops and barley centromeres during cell divisions and in interphase nuclei by immunostaining and FISH. Furthermore, structured illumination microscopy (super-resolution) was applied to investigate the ultrastructure of centromere chromatin beyond the classical refraction limit of light.

A Set of Cytogenetic Markers Allows the Precise Identification of All A-Genome Chromosomes in Diploid and Polyploid Wheat.

Karyotypes of 3 diploid wheat species containing different variants of the A-genome, Triticum boeoticum (A(b)), T. monococcum (A(b)), and T. urartu (A(u)), were examined using C-banding and FISH with DNA probes representing 5S and 45S rDNA families, the microsatellite sequences GAAn and GTTn, the already known satellite sequences pSc119.

B chromosomes of Aegilops speltoides are enriched in organelle genome-derived sequences.

B chromosomes (Bs) are dispensable components of the genome exhibiting non-Mendelian inheritance. Chromosome counts and flow cytometric analysis of the grass species Aegilops speltoides revealed a tissue-type specific distribution of the roughly 570 Mbp large B chromosomes. To address the question whether organelle-to-nucleus DNA transfer is a mechanism that drives the evolution of Bs, in situ hybridization was performed with labelled organellar DNA.