Next Generation Cytogenetics of Fabeae Centromeres

Centromeric regions of plant chromosomes are usually made of complex populations of repetitive elements which are difficult to investigate using conventional cloning and sequencing approaches. In addition, requirements for large-scale sequencing and the lack of suitable bioinformatics tools have long hampered centromere investigation in non-model species. In this lecture, we will present an experimental workflow that takes advantage of recently introduced next generation sequencing technologies and newly developed computational tools to overcome these limitations and allow investigation of centromere composition in a wide range of plant species. Combining whole genome and CenH3-ChIP sequencing with data analysis using RepeatExplorer pipeline led to the identification of all major centromeric repeats in cultivated pea (Pisum sativum) and its wild relative P. fulvum. Both species have extended centromeres which are composed of multiple CenH3 domains associated with more than ten different satellite repeats. However, the number of CenH3 domains and some of the satellite repeats are not conserved between homeologous chromosomes, suggesting a dynamic nature of pea centromeres. Investigating other representatives of the legume tribe Fabeae, including genera of Lathyrus, Vicia nad Lens revealed that only Lathyrus has centromere organization similar to Pisum, whereas Vicia nad Lens chromosomes have morphologically simple centromeres composed of a single CenH3 domain.