1
|
Rajpal VR, Sharma S, Sehgal D, Sharma P, Wadhwa N, Dhakate P, Chandra A, Thakur RK, Deb S, Rama Rao S, Mir BA, Raina SN. Comprehending the dynamism of B chromosomes in their journey towards becoming unselfish. Front Cell Dev Biol 2023; 10:1072716. [PMID: 36684438 PMCID: PMC9846793 DOI: 10.3389/fcell.2022.1072716] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 12/13/2022] [Indexed: 01/06/2023] Open
Abstract
Investigated for more than a century now, B chromosomes (Bs) research has come a long way from Bs being considered parasitic or neutral to becoming unselfish and bringing benefits to their hosts. B chromosomes exist as accessory chromosomes along with the standard A chromosomes (As) across eukaryotic taxa. Represented singly or in multiple copies, B chromosomes are largely heterochromatic but also contain euchromatic and organellar segments. Although B chromosomes are derived entities, they follow their species-specific evolutionary pattern. B chromosomes fail to pair with the standard chromosomes during meiosis and vary in their number, size, composition and structure across taxa and ensure their successful transmission through non-mendelian mechanisms like mitotic, pre-meiotic, meiotic or post-meiotic drives, unique non-disjunction, self-pairing or even imparting benefits to the host when they lack drive. B chromosomes have been associated with cellular processes like sex determination, pathogenicity, resistance to pathogens, phenotypic effects, and differential gene expression. With the advancements in B-omics research, novel insights have been gleaned on their functions, some of which have been associated with the regulation of gene expression of A chromosomes through increased expression of miRNAs or differential expression of transposable elements located on them. The next-generation sequencing and emerging technologies will further likely unravel the cellular, molecular and functional behaviour of these enigmatic entities. Amidst the extensive fluidity shown by B chromosomes in their structural and functional attributes, we perceive that the existence and survival of B chromosomes in the populations most likely seem to be a trade-off between the drive efficiency and adaptive significance versus their adverse effects on reproduction.
Collapse
Affiliation(s)
- Vijay Rani Rajpal
- Department of Botany, Hansraj College, University of Delhi, Delhi, India,*Correspondence: Vijay Rani Rajpal, , ; Soom Nath Raina,
| | - Suman Sharma
- Department of Botany, Ramjas College, University of Delhi, Delhi, India
| | - Deepmala Sehgal
- Syngenta, International Maize and Wheat Improvement Center (CIMMYT), Texcoco, Mexico
| | - Prashansa Sharma
- Department of Botany, Hansraj College, University of Delhi, Delhi, India
| | - Nikita Wadhwa
- University School of Biotechnology, Guru Gobind Singh Indraprastha University, New Delhi, India
| | | | - Atika Chandra
- Department of Botany, Maitreyi College, University of Delhi, New Delhi, India
| | - Rakesh Kr. Thakur
- Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India
| | - Sohini Deb
- Department of Biotechnology and Bioinformatics, North Eastern Hill University, Shillong, Meghalaya, India
| | - Satyawada Rama Rao
- Department of Biotechnology and Bioinformatics, North Eastern Hill University, Shillong, Meghalaya, India
| | - Bilal Ahmad Mir
- Department of Botany, University of Kashmir, Srinagar, India
| | - Soom Nath Raina
- Amity Institute of Biotechnology, Amity University, Noida, Uttar Pradesh, India,*Correspondence: Vijay Rani Rajpal, , ; Soom Nath Raina,
| |
Collapse
|
2
|
Divashuk MG, Nikitina EA, Sokolova VM, Yurkina AI, Kocheshkova AA, Razumova OV, Karlov GI, Kroupin PY. qPCR as a Selective Tool for Cytogenetics. PLANTS (BASEL, SWITZERLAND) 2022; 12:80. [PMID: 36616209 PMCID: PMC9824742 DOI: 10.3390/plants12010080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 12/18/2022] [Accepted: 12/20/2022] [Indexed: 06/17/2023]
Abstract
qPCR is widely used in quantitative studies of plant genomes and transcriptomes. In this article, this method is considered as an auxiliary step in the preparation and selection of markers for FISH analysis. Several cases from the authors' research on populations of the same species were reviewed, and a comparison of the closely related species, as well as the adaptation of the markers, based on satellite tandem repeats (TRs) using quantitative qPCR data was conducted. In the selected cases, TRs with contrast abundance were identified in the cases of the Dasypyrum, Thinopyrum and Aegilops species, and the transfer of TRs between the wheat and related species was demonstrated. TRs with intraspecific copy number variation were revealed in Thinopyrum ponticum and wheat-wheatgrass partial amphidiploids, and the TR showing predominant hybridization to the sea buckthorn Y chromosome was identified. Additionally, problems such as the absence of a reference gene for qPCR, and low-efficiency and self-complementary primers, were illustrated. In the cases considered here, the qPCR results clearly show high correlation with the subsequent results of the FISH analysis, which confirms the value of this method for cytogenetic studies.
Collapse
|
3
|
Li D, Ruban A, Fuchs J, Kang H, Houben A. B-A Chromosome Translocations Possessing an A Centromere Partly Overcome the Root-Restricted Process of Chromosome Elimination in Aegilops speltoides. Front Cell Dev Biol 2022; 10:875523. [PMID: 35419361 PMCID: PMC8995527 DOI: 10.3389/fcell.2022.875523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2022] [Accepted: 03/11/2022] [Indexed: 12/02/2022] Open
Abstract
Some eukaryotes exhibit dramatic genome size differences between cells of different organs, resulting from the programmed elimination of chromosomes. Aegilops speltoides 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. In areal parts of the plant, the number of Bs is stable. To affect the root restricted process of B chromosome elimination, we employed X-ray mutagenesis, and different types of restructured Bs were identified. Standard Bs were observed in all analyzed shoots of mutagenized plants, while B-A translocations were only observed in 35.7% of F1 plants. In total 40 different B variants inconsistently escaped the elimination process in roots. As a result, mosaicism of B chromosome variants was found in roots. Only a small B chromosome fragment fused to an A chromosome was stably maintained in roots and shoots across F1 to F3 generations. The absence of B-A translocation chromosomes possessing a derived B centromere in root cells implies that the centromere of the B is a key component of the chromosome elimination process.
Collapse
Affiliation(s)
- Daiyan Li
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.,State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Sichuan Agricultural University, Chengdu, China.,Triticeae Research Institute, Sichuan Agricultural University, Chengdu, China
| | - Alevtina Ruban
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany.,KWS SAAT SE & Co. KGaA, Einbeck, Germany
| | - Jörg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| | - Houyang Kang
- State Key Laboratory of Crop Gene Exploration and Utilization in Southwest China, Sichuan Agricultural University, Chengdu, China.,Triticeae Research Institute, Sichuan Agricultural University, Chengdu, China
| | - Andreas Houben
- Leibniz Institute of Plant Genetics and Crop Plant Research (IPK), Gatersleben, Germany
| |
Collapse
|
4
|
Maravilla AJ, Rosato M, Rosselló JA. Interstitial Telomeric-like Repeats (ITR) in Seed Plants as Assessed by Molecular Cytogenetic Techniques: A Review. PLANTS (BASEL, SWITZERLAND) 2021; 10:2541. [PMID: 34834904 PMCID: PMC8621592 DOI: 10.3390/plants10112541] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Revised: 11/11/2021] [Accepted: 11/16/2021] [Indexed: 05/12/2023]
Abstract
The discovery of telomeric repeats in interstitial regions of plant chromosomes (ITRs) through molecular cytogenetic techniques was achieved several decades ago. However, the information is scattered and has not been critically evaluated from an evolutionary perspective. Based on the analysis of currently available data, it is shown that ITRs are widespread in major evolutionary lineages sampled. However, their presence has been detected in only 45.6% of the analysed families, 26.7% of the sampled genera, and in 23.8% of the studied species. The number of ITR sites greatly varies among congeneric species and higher taxonomic units, and range from one to 72 signals. ITR signals mostly occurs as homozygous loci in most species, however, odd numbers of ITR sites reflecting a hemizygous state have been reported in both gymnosperm and angiosperm groups. Overall, the presence of ITRs appears to be poor predictors of phylogenetic and taxonomic relatedness at most hierarchical levels. The presence of ITRs and the number of sites are not significantly associated to the number of chromosomes. The longitudinal distribution of ITR sites along the chromosome arms indicates that more than half of the ITR presences are between proximal and terminal locations (49.5%), followed by proximal (29.0%) and centromeric (21.5%) arm regions. Intraspecific variation concerning ITR site number, chromosomal locations, and the differential presence on homologous chromosome pairs has been reported in unrelated groups, even at the population level. This hypervariability and dynamism may have likely been overlooked in many lineages due to the very low sample sizes often used in cytogenetic studies.
Collapse
Affiliation(s)
| | | | - Josep A. Rosselló
- Jardín Botánico, ICBiBE, Universitat de València, c/Quart 80, E-46008 València, Spain; (A.J.M.); (M.R.)
| |
Collapse
|