Abstract
Satellite DNA sequences consist of tandemly arranged repetitive units up to thousands nucleotides long in head-to-tail orientation. The evolutionary processes by which satellites arise and evolve include unequal crossing over, gene conversion, transposition and extra chromosomal circular DNA formation. Large blocks of satellite DNA are often observed in heterochromatic regions of chromosomes and are a typical component of centromeric and telomeric regions. Satellite-rich loci may show specific banding patterns and facilitate chromosome identification and analysis of structural chromosome changes. Unlike many other genomes, nuclear genomes of banana (Musa spp.) are poor in satellite DNA and the information on this class of DNA remains limited. The banana cultivars are seed sterile clones originating mostly from natural intra-specific crosses within M. acuminata (A genome) and inter-specific crosses between M. acuminata and M. balbisiana (B genome). Previous studies revealed the closely related nature of the A and B genomes, including similarities in repetitive DNA. In this study we focused on two main banana DNA satellites, which were previously identified in silico. Their genomic organization and molecular diversity was analyzed in a set of nineteen Musa accessions, including representatives of A, B and S (M. schizocarpa) genomes and their inter-specific hybrids. The two DNA satellites showed a high level of sequence conservation within, and a high homology between Musa species. FISH with probes for the satellite DNA sequences, rRNA genes and a single-copy BAC clone 2G17 resulted in characteristic chromosome banding patterns in M. acuminata and M. balbisiana which may aid in determining genomic constitution in interspecific hybrids. In addition to improving the knowledge on Musa satellite DNA, our study increases the number of cytogenetic markers and the number of individual chromosomes, which can be identified in Musa.
Highlights
A significant part of nuclear genomes in plants, including those with small genomes such as rice, Brachypodium and Arabidopsis is occupied by various types of repetitive DNA sequences [1,2,3]
Satellite repeats may undergo rapid changes in copy number and nucleotide sequence, which may result in the evolution of genus and species-specific repeats [18,19,20,44,45]
About 45% of the Musa genome consists of various repetitive DNA sequences [35], satellite DNA repeats represent only,0.3% of the genome [13]
Summary
A significant part of nuclear genomes in plants, including those with small genomes such as rice, Brachypodium and Arabidopsis is occupied by various types of repetitive DNA sequences [1,2,3]. Repetitive DNA sequences are classified based on genomic organization of repetitive units as dispersed and tandem. Dispersed repeats, represented by various classes of transposable elements encode for proteins which facilitate their replication and integration into nuclear genome [4]. Tandem repeats usually contain non-coding sequences organized in tandem arrays [5,6,7,8,9]. The arrays may be large and consist of thousands or even millions of repetitive units arranged in head-to-tail orientation [10,11]. The processes by which satellites arise and evolve are not well understood, and unequal crossing over, gene conversion, transposition and formation of extra chromosome circular DNA (eccDNA) were implicated [12]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
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 call
