Comprehending the dynamism of B chromosomes in their journey towards becoming unselfish

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.

Bibliographic Details

Main Authors:	Vijay Rani Rajpal, Sharma, S., Sehgal, D., Sharma, P., Wadhwa, N., Dhakate, P., Chandra, A., Thakur, R.K., Deb, S., Rama Rao, S., Mir, B.A., Raina, S.N.
Format:	Article biblioteca
Language:	English
Published:	Frontiers Media 2023
Subjects:	AGRICULTURAL SCIENCES AND BIOTECHNOLOGY, B Chromosomes, Non-Mendelian Transmission, Genetic Drive, Preferential Fertilization, Adaptive Significance, CHROMOSOMES, GENETICS, FERTILIZATION, MENDELISM, Wheat,
Online Access:	https://hdl.handle.net/10883/22485
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