The genomes of many plants, animals, and fungi frequently comprise dispensable B chromosomes that rely upon various chromosomal drive mechanisms to counteract the tendency of non-essential genetic elements to be purged over time. The B chromosome of rye - a model system for nearly a century - undergoes targeted nondisjunction during first pollen mitosis, favouring segregation into the generative nucleus, thus increasing their numbers over generations. However, the genetic mechanisms underlying this process are poorly understood. Here, using a newly-assembled, ~430 Mb-long rye B chromosome pseudomolecule, we identify five candidate genes whose role as trans-acting moderators of the chromosomal drive is supported by karyotyping, chromosome drive analysis and comparative RNA-seq. Among them, we identify DCR28, coding a microtubule-associated protein related to cell division, and detect this gene also in the B chromosome of Aegilops speltoides. The DCR28 gene family is neo-functionalised and serially-duplicated with 15 B chromosome-located copies that are uniquely highly expressed in the first pollen mitosis of rye.
- MeSH
- Aegilops genetika metabolismus MeSH
- chromozomy rostlin * genetika MeSH
- karyotypizace MeSH
- mitóza * genetika MeSH
- nondisjunkce genetická MeSH
- pyl genetika MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika metabolismus MeSH
- žito * genetika MeSH
- Publikační typ
- časopisecké články MeSH
The detection of meiotic crossovers in crop plants currently relies on scoring DNA markers in a segregating population or cytological visualization. We investigated the feasibility of using flow-sorted haploid nuclei, Phi29 DNA polymerase-based whole-genome-amplification (WGA) and multi-locus KASP-genotyping to measure meiotic crossovers in individual barley pollen grains. To demonstrate the proof of concept, we used 24 gene-based physically mapped single nucleotide polymorphisms to genotype the WGA products of 50 single pollen nuclei. The number of crossovers per chromosome, recombination frequencies along chromosome 3H and segregation distortion were analysed and compared to a doubled haploid (DH) population of the same genotype. The number of crossovers and chromosome wide recombination frequencies show that this approach is able to produce results that resemble those obtained from other methods in a biologically meaningful way. Only the segregation distortion was found to be lower in the pollen population than in DH plants.
- MeSH
- chromozomy rostlin MeSH
- crossing over (genetika) * MeSH
- DNA rostlinná MeSH
- genom rostlinný MeSH
- haploidie MeSH
- ječmen (rod) genetika MeSH
- lokus kvantitativního znaku MeSH
- meióza genetika MeSH
- multilokusová sekvenční typizace * MeSH
- pyl genetika MeSH
- rekombinace genetická MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
