Presentation Title

Characterizing centromere and telomere sequences in the genomes of aquatic ferns, Azolla foliculoides and Salvinia cucullata

Start Date

November 2016

End Date

November 2016

Location

HUB 302-#41

Type of Presentation

Poster

Abstract

Centromeres and telomeres are universal components of eukaryotic genomes and are essential for cell division and preventing the deterioration of chromosomes during DNA replication, respectively. Ferns represent an important lineage in the evolution of land plants, but have lagged behind other plants in genome sequencing. As part of an effort to sequence the nuclear genomes of ferns, we present a characterization of centromere and telomere repeat sequences in two aquatic ferns, Azolla filiculoides and Salvinia cucullata. Using bioinformatic approaches, we searched the genome assembly for tandemly-arrayed satellite repeats and examined the distribution repeat motif length and copy number to identify candidate centromere and telomere sequences. The most abundant tandem satellite sequence correspondes to the canonical 7 bp telomere sequence (TTTAGGG) conserved across most land plant species. Centromere motifs ranged from 185 to 194 bp long in Azolla, and 179 to 194 bp long in Salvinia. The candidate motif sequences were clustered and aligned to construct a consensus sequence for each genome. The motif sequences in Azolla and Salvinia were different. These results represent the first reported telomere and centromere sequences for ferns and demonstrate that telomere sequences are deeply conserved among ancient plant lineages, while centromere sequences are highly variable and divergent between even closely related fern genera.

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Characterizing centromere and telomere sequences in the genomes of aquatic ferns, Azolla foliculoides and Salvinia cucullata

HUB 302-#41

Centromeres and telomeres are universal components of eukaryotic genomes and are essential for cell division and preventing the deterioration of chromosomes during DNA replication, respectively. Ferns represent an important lineage in the evolution of land plants, but have lagged behind other plants in genome sequencing. As part of an effort to sequence the nuclear genomes of ferns, we present a characterization of centromere and telomere repeat sequences in two aquatic ferns, Azolla filiculoides and Salvinia cucullata. Using bioinformatic approaches, we searched the genome assembly for tandemly-arrayed satellite repeats and examined the distribution repeat motif length and copy number to identify candidate centromere and telomere sequences. The most abundant tandem satellite sequence correspondes to the canonical 7 bp telomere sequence (TTTAGGG) conserved across most land plant species. Centromere motifs ranged from 185 to 194 bp long in Azolla, and 179 to 194 bp long in Salvinia. The candidate motif sequences were clustered and aligned to construct a consensus sequence for each genome. The motif sequences in Azolla and Salvinia were different. These results represent the first reported telomere and centromere sequences for ferns and demonstrate that telomere sequences are deeply conserved among ancient plant lineages, while centromere sequences are highly variable and divergent between even closely related fern genera.