Figure 7: Model for meiotic events in R. pubera and R. tenuis.
From: Chiasmatic and achiasmatic inverted meiosis of plants with holocentric chromosomes
During meiosis I chromosomes of R. pubera recombine, pair and bivalents with chiasmata become visible in diakinesis. In contrast, chromosomes of R. tenuis do not form chiasmata and univalents become visible. In metaphase I (only one, rod-shaped bivalent of R. pubera is shown; all four chromosomes of R. tenuis are shown), chromosomes align at the metaphase plate and sister chromatid show amphitelic attachment to the spindle. In anaphase I (only one, rod-shaped bivalent of R. pubera is shown; all four chromosomes of R. tenuis are shown), sister chromatids are separated from each other and pulled to different poles. For prophase II, each half of the dyad is shown. While chromatids of R. pubera appear mostly in pairs, with some chromatids being connected with thin chromatin threads, all four chromatids of R. tenuis appear interconnected by thin chromatin threads. In metaphase II, chromatids align and subsequently undergo regular disjunction during anaphase II. Note, the model idealizes regular disjunction in meiosis II but actually 19.5 and 30% of all meiotic products of R. pubera and R. tenuis, respectively, show irregularities. Refer to text for further details. Parental chromosomes/chromatids are in red and blue, the spindle in green and chromatin threads in grey.
