Reduced rates of sequence evolution of Y-linked satellite DNA in Rumex (Polygonaceae).
One characteristic of sex chromosomes is the accumulation of a set of different types of repetitive DNA sequences in the Y chromosomes. However, little is known about how this occurs or about how the absence of recombination affects the subsequent evolutionary fate of the repetitive sequences in the Y chromosome. Here we compare the evolutionary pathways leading to the appearance of three different families of satellite-DNA sequences within the genomes of Rumex acetosa and R. papillaris, two dioecious plant species with a complex XX/XY(1)Y(2) sex-chromosome system. We have found that two of these families, one autosomic (the RAE730 family) and one Y-linked (the RAYSI family), arose independently from the ancestral duplication of the same 120-bp repeat unit. Conversely, a comparative analysis of the three satellite-DNA families reveals no evolutionary relationships between these two and the third, RAE180, also located in the Y chromosomes. However, we have demonstrated that, regardless of the mechanisms that gave rise to these families, satellite-DNA sequences have different evolutionary fates according to their location in different types of chromosomes. Specifically, those in the Y chromosomes have evolved at half the rate of those in the autosomes, our results supporting the hypothesis that satellite DNAs in nonrecombining Y chromosomes undergo lower rates of sequence evolution and homogenization than do satellite DNAs in autosomes.
Navajas-Pérez
Rafael
R
Departamento de Genética, Facultad de Ciencias, Universidad de Granada, Spain.
la Herrán
Roberto de
Rd
Jamilena
Manuel
M
Lozano
Rafael
R
Rejón
Carmelo Ruiz
CR
Rejón
Manuel Ruiz
MR
Garrido-Ramos
Manuel A
MA
D001483:Base Sequence; D015139:Blotting, Southern; D032461:Chromosomes, Plant / Q000235:genetics*; D003001:Cloning, Molecular; D016000:Cluster Analysis; D017931:DNA Primers; D004276:DNA, Satellite / Q000235:genetics*; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D031804:Rumex / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013030:Spain; D014998:Y Chromosome / Q000235:genetics*
D017931:DNA Primers; D004276:DNA, Satellite