Rapid Birth or Death of Centromeres on Fragmented Chromosomes in Maize. Issue 10 (18th August 2020)

• Record Type: Journal Article
• Authors: Liu, Yalin; Su, Handong; Zhang, Jing; Shi, Lindan; Liu, Yang; Zhang, Bing; Bai, Han; Liang, Shuang; Gao, Zhi; Birchler, James A.; Han, Fangpu
• Is Part Of: The Plant Cell. Volume 32:Issue 10(2020)
• Page Start: 3113
• Page End: 3123
• Publication Date: 2020-08-18
• DOI: 10.1105/tpc.20.00389
• Languages: English
• ISSNs: 1040-4651

Abstract

Abstract : Centromere death and birth can occur at experimentally recognizable frequencies and in a narrow developmental window, providing insight into centromere activity and karyotype evolution. Abstract: Comparative genomics has revealed common occurrences in karyotype evolution such as chromosomal end-to-end fusions and insertions of one chromosome into another near the centromere, as well as many cases of de novo centromeres that generate positional polymorphisms. However, how rearrangements such as dicentrics and acentrics persist without being destroyed or lost remains unclear. Here, we sought experimental evidence for the frequency and timeframe for inactivation and de novo formation of centromeres in maize ( Zea mays ). The pollen from plants with supernumerary B chromosomes was gamma-irradiated and then applied to normal maize silks of a line without B chromosomes. In ∼8, 000 first-generation seedlings, we found many B–A translocations, centromere expansions, and ring chromosomes. We also found many dicentric chromosomes, but a fraction of these show only a single primary constriction, which suggests inactivation of one centromere. Chromosomal fragments were found without canonical centromere sequences, revealing de novo centromere formation over unique sequences; these were validated by immunolocalization with Thr133-phosphorylated histone H2A, a marker of active centromeres, and chromatin immunoprecipitation-sequencing with the CENH3 antibody. These results illustrate the regular occurrence of centromere birth and death after chromosomal rearrangement during a narrow window of one to potentially only a few cell cycles for the rearranged chromosomes to be recognized in this experimental regime.