AUTHOR=Nguyen Thi Hong , Kang Byung Yong , Kim Hyun Hee 

TITLE=Chromosomal dynamics in Senna: comparative PLOP–FISH analysis of tandem repeats and flow cytometric nuclear genome size estimations

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1288220

DOI=10.3389/fpls.2023.1288220

ISSN=1664-462X

ABSTRACT=<sec><title>Introduction</title><p>Tandem repeats (TRs) occur abundantly in plant genomes. They play essential roles that affect genome organization and evolution by inducing or generating chromosomal rearrangements such as duplications, deletions, inversions, and translocations. These impact gene expression and chromosome structure and even contribute to the emergence of new species.</p></sec><sec><title>Method</title><p>We investigated the effects of TRs on speciation in <italic>Senna</italic> genus by performing a comparative analysis using fluorescence <italic>in situ</italic> hybridization (FISH) with <italic>S. tora</italic>-specific TR probes. We examined the chromosomal distribution of these TRs and compared the genome sizes of seven <italic>Senna</italic> species (estimated using flow cytometry) to better understand their evolutionary relationships.</p></sec><sec><title>Results</title><p>Two (StoTR03_159 and StoTR04_55) of the nine studied TRs were not detected in any of the seven <italic>Senna</italic> species, whereas the remaining seven were found in all or some species with patterns that were similar to or contrasted with those of <italic>S. tora</italic>. Of these studies species, only <italic>S. angulata</italic> showed significant genome rearrangements and dysploid karyotypes resembling those of <italic>S. tora</italic>. The genome sizes varied among these species and did not positively correlate with chromosome number. Notably, <italic>S. angulata</italic> had the fewest chromosomes (2<italic>n</italic> = 22) but a relatively large genome size.</p></sec><sec><title>Discussion</title><p>These findings reveal the dynamics of TRs and provide a cytogenetic depiction of chromosomal rearrangements during speciation in <italic>Senna</italic>. To further elucidate the dynamics of repeat sequences in <italic>Senna</italic>, future studies must include related species and extensive repeatomic studies, including those on transposable elements.</p></sec>