TY-3 gypsy Copy Number is Correlated with Genome Size in Subtribe Hieraciinae (Lactuceae, Asteraceae)
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| Year of publication | 2012 |
| Type | Conference abstract |
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| Description | The subtribe Hieraciinae is composed of the genera Hieracium, Pilosella, Andryala, and Hispidella. Phylogenetic studies have revealed the existence of three major phylogenetic groups: (1) Pilosella/Hispidella, (2) Hieracium s.l., and (3) Andryala. These lineages differ from each other in reproductive mode, ploidy level, and number of polyploid taxa included. The aims of the present study were (1) to fill the gap in the pattern of genome size variation within the Hieraciinae by providing these data for genus Andryala, and (2) to investigate the relation between genome size variation and abundance of gypsy-like retrotransposons in the subtribe. Genome sizes of 14 species and subspecies of Andryala were estimated using flow cytometry. An estimate of gypsy-like retrotransposon density was performed in 23 diploid taxa with known genome size, representing the major phylogenetic lineages of the Hieraciinae using (1) quantitative PCR with degenerate primers and (2) Southern dot blot analysis. Substantial variation in genome size was found among the three major phylogenetic groups of the Hieraciinae. The 1Cx values varied 1.22-fold (3.51-4.34 pg) in subgen. Hieracium, 1.26-fold (1.72-2.16 pg) in Pilosella and 1.66-fold (1.54-2.56 pg) in Andryala. A positive correlation between monoploid genome size and density of gypsy-like retrotransposons was found in the complete dataset. The total proportion of repetitive DNA represented by gypsy-like retrotransposons in the whole genome varied from 11.4% in Andryala to 51.0% in Hieracium s.str. in particular species. While the genome size ranges in Pilosella and Andryala more or less overlapped, species of both genera consistently showed only about 50% of the DNA content compared to Hieracium s.str. despite the same base chromosome number (x = 9). The evolution of genome size in the tribe Hieraciinae is to a considerable degree associated with gypsy-like retrotransposon proliferation/removal. |
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