Centromeres Off the Hook: Massive Changes in Centromere Size and Structure Following Duplication ofCenH3Gene inFabeaeSpecies

Abstract

In most eukaryotes, centromere is determined by the presence of the centromere-specific histone variant CenH3. Two types of chromosome morphology are generally recognized with respect to centromere organization. Monocentric chromosomes possess a single CenH3-containing domain in primary constriction, whereas holocentric chromosomes lack the primary constriction and display dispersed distribution of CenH3. Recently, metapolycentric chromosomes have been reported in Pisum sativum, representing an intermediate type of centromere organization characterized by multiple CenH3-containing domains distributed across large parts of chromosomes that still form a single constriction. In this work, we show that this type of centromere is also found in other Pisum and closely related Lathyrus species, whereas Vicia and Lens genera, which belong to the same legume tribe Fabeae, possess only monocentric chromosomes. We observed extensive variability in the size of primary constriction and the arrangement of CenH3 domains both between and within individual Pisum and Lathyrus species, with no obvious correlation to genome or chromosome size. Search for CenH3 gene sequences revealed two paralogous variants, CenH3-1 and CenH3-2, which originated from a duplication event in the common ancestor of Fabeae species. The CenH3-1 gene was subsequently lost or silenced in the lineage leading to Vicia and Lens, whereas both genes are retained in Pisum and Lathyrus. Both of these genes appear to have evolved under purifying selection and produce functional CenH3 proteins which are fully colocalized. The findings described here provide the first evidence for a highly dynamic centromere structure within a group of closely related species, challenging previous concepts of centromere evolution.

Brassica juncea Lines with Substituted Chimeric GFP-CENH3 Give Haploid and Aneuploid Progenies on Crossing with Other Lines

“…CENH3 and centromereic repeats often show parallel evolution (Henikoff et al, 2001). Even diplod species such as A. halleri and A. lyrata (Kawabe et al, 2006), Pisum, Lathyrus (Neumann et al, 2015), and barley (Sanei et al, 2011), which possess complex centromeres and different kinds of centromeric satellite repeats show two copies of CENH3 . B. juncea is an allotetraploid and has five different kinds of centromeric satellite repeats (CentBr1, CentBr2, TR238, TR805, pBNBH35) (Lim et al, 2007; Koo et al, 2011).…”

“…B. juncea is an allotetraploid and has five different kinds of centromeric satellite repeats (CentBr1, CentBr2, TR238, TR805, pBNBH35) (Lim et al, 2007; Koo et al, 2011). Diversity of centromeric repeats is a feature of B. rapa (Lim et al, 2007) and pea (Neumann et al, 2015) and in both these species, isoforms of CENH3 are found. In B. juncea, B. rapa -like CENH3 transcripts were more abundant than B. nigra -like transcripts.…”

Genomic characterisation of Arachis porphyrocalyx (Valls & C.E. Simpson, 2005) (Leguminosae): multiple origin of Arachis species with x = 9

“…& W.C. Gregory, 1994) and Arachis correntina ((Burkart) Krapov. & W.C. Gregory, 1994) all belonging to the section Arachis (Fernández and Krapovickas 1994), and of other genera such as Antirrhinum majus (Linneaus, 1753), Allium sphaerocephalum (Crome ex Schltdl, 1824) (Lima De Faria 1956), Libocedrus chilensis (Endlicher, 1847) (Hunziker 1961), Pisum (Linneaus, 1753) and Lathyrus (Linnaeus, 1753) (Neumann et al 2015). Just recently, Neumann et al (2015) have classified this type of centromere as ‘intermediate’ between the two types of centromeres, monocentric and holocentric, and having an organization characterized by multiple Cen-H3 domains.…”

Centromeric histone H3 protein: from basic study to plant breeding applications

“…Diploid cereals like rice and maize have single copy of CENH3, while barley has two copies of CENH3 gene (Sanei et al 2011). Similarly, in the Leguminaceae family, Vicia faba and Lens culinaris have single copy of CENH3 while Pisum sativum and Lathyrus sativus have two copies of CENH3 (Neumann et al 2015).…”