Abstract
In various eukaryotes, supernumerary B chromosomes (Bs) are an optional genomic component that affect their integrity and functioning. In the present study, the impact of Bs on the current changes in the genome of goatgrass, Aegilops speltoides, was addressed. Individual plants from contrasting populations with and without Bs were explored using fluorescence in situ hybridization. In parallel, abundances of the Ty1-copia, Ty3-gypsy, and LINE retrotransposons (TEs), and the species-specific Spelt1 tandem repeat (TR) in vegetative and generative spike tissues were estimated by real-time quantitative PCR. The results revealed: (i) ectopic associations between Bs and the regular A chromosomes, and (ii) cell-specific rearrangements of Bs in both mitosis and microgametogenesis. Further, the copy numbers of TEs and TR varied significantly between (iii) genotypes and (iv) different spike tissues in the same plant(s). Finally, (v) in plants with and without Bs from different populations, genomic abundances and/or copy number dynamics of TEs and TR were similar. These findings indicate that fluctuations in TE and TR copy numbers are associated with DNA damage and repair processes during cell proliferation and differentiation, and ectopic recombination is one of the mechanisms by which Bs play a role in genome changes.
Highlights
Numerous species of animals, plants, and fungi have supernumerary B chromosomes (Bs), which are known as a facultative genomic component
Repetitive sequences are the main targets for recombination; the evolutionarily conserved 5S rDNA, Spelt1, CCS1, and (TTTAGGG)n telomere repeats were utilized as markers for B chromosome rearrangements
Among 10 to 15 well-spread chromosome plates analyzed on the single cytological slide, in 2 to 5 cases, ectopic associations between B and standard A chromosomes and/ or B chromosome rearrangements were detected in a cell-specific manner
Summary
Plants, and fungi have supernumerary B chromosomes (Bs), which are known as a facultative genomic component. The presence of Bs, especially in high numbers, is associated with destabilization of the genome that, implies selection against “selfish” chromosomes. Aucheri (recessive) morphotypes co-exist at varying ratios in wild populations [13,14]. Ae. speltoides is a dimorphic species, and the ssp. This is a predominantly cross-pollinated but self-compatible species, which under stressful conditions transits to self-pollination [13,14]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
