Transposable Elements in the Organization and Diversification of the Genome of Aegilops speltoides Tausch (Poaceae, Triticeae)

Figure 2

Fluorescent in situ hybridization (FISH) with individual cloned transposable element (TE) sequences on meiotic and somatic chromosomes of Aegilops speltoides. (a–b) Chromosomal distribution of the clone Aesp2 (WIS, Ty1-copia) on meiotic and somatic chromosomes of two different genotypes. (a) Meiotic chromosomes of the hybrid genotype F₁_K5/A2 obtained in the cross ♀Katzir-5 × ♂Ankara-2 (K5/A2). In the small box, supernumerary B chromosome and chromosome 6 forming bivalents are enlarged. In the B chromosome, large intercalary TE and small TE clusters adjacent to the 5S rDNA blocks are revealed in both arms. Large TE clusters in both arms in both instances of homologous chromosome 6 are detected. Nonhomologous synapses between chromosome 6 and another bivalent is indicated by an arrow. (b) Somatic chromosomes of the genotype S1GK achieved by self-pollination of the TS43 (Giv’at Koach (GK)) plant. In the small box, instances of homologous chromosome 6 are enlarged; TE clusters are detected in the long arms. (c) Chromosomal distribution of clone Aesp29 (Barbara, Ty1-copia) in the hybrid genotype F₂_C1/K17 obtained by self-pollination of the F₁_C1/K17 genotype; cross-combination ♀Cankiri-1 × ♂Katzir-17 (C1/K17). Homologous chromosomes 1 are enlarged in the small box. Significant depletion in TE abundance is observed in the pericentromeric and distal/terminal chromosomal regions, including DAPI-positive AT-enriched heterochromatic and Spelt1 clusters. (d) Distribution of the clone Aesp15 (Fatima, Ty3-gypsy) on meiotic chromosomes in the genotype GK (line TS43). Panchromosomal TE clustering is observed; homologous chromosomes are similar in their TE patterns. In the small box, the bivalent of chromosome 1 is enlarged. The nonhomologous synapsis between chromosomes 1 and 5 is shown with an arrow in the small upper box; the ectopic chromatin fiber between bivalents is shown with a dashed line. (e) Chromosomal pattern of clone Aesp18 (Carmilla, Ty3-gypsy) in the somatic chromosomes of genotype C1 (Cankiri-1). Intensive clustering throughout the whole chromosome lengths is observed. In the small box, instances of homologous chromosome 5 are enlarged. (f) Patterning of clone Aesp19 (Nusif, Ty3-gypsy) in the somatic chromosomes of genotype C1. The homologous chromosomes show similarity in TE patterning. In the small box, instances of chromosome 5 are enlarged. Differences in the chromosome 5s morphology give evidence for heterozygosity in terms of rearrangement in the C1 genotype. (g) Distribution of clone Aesp18 (Carmilla, Ty3-gypsy) in genotype F₂_GK/A1 obtained by self-pollination of the F1_GK/A1 (cross-combination ♀GK × ♂Ankara-1 (GK/A1)). The TE pattern is comparable to the pattern observed in genotype C1 (e). (h) Dispersal distribution of clone Aesp23 (Ty3-gypsy + mitochondrial DNA) throughout the somatic chromosomes in genotype F₂_C1/K17. (i) Chromosomal patterning of clone Aesp24 (long interspersed nucleotide element (LINE)) in the F₂_GK/A1 genotype. Large clusters are observed in the intercalary regions. Chromosomes 1 and 6 are enlarged in the small box. (j) Distribution of clone Aesp25 (LINE) in the somatic chromosomes of the F₂_GK/A1 genotype. Rear large TE clusters are revealed in some chromosomes. In the small box, individual chromosomes 5, 6, and 7 are enlarged. Scale bar = 10 μm.

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