Telomere Length in Plants Estimated with Long Read Sequencing

Abstract

Telomeres play an important role in chromosome stability and their length is thought to be related to an organism's lifestyle and lifespan. Telomere length is variable across plant species and between cultivars of the same species, possibly conferring adaptive advantage. However, it is not known whether telomere length is related to lifestyle or life span across a diverse array of plant species due to the lack of information on telomere length in plants. Here we leverage genomes assembled with long read sequencing data to estimate telomere length by chromosome. We find that long read assemblies based on Oxford Nanopore Technologies (ONT) accurately predict telomere length in the two model plant species Arabidopsis thaliana and Oryza sativa matching lab-based length estimates. We then estimate telomere length across an array of plant species with different lifestyles and lifespans and find that in general gymnosperms have shorter telomeres compared to eudicots and monocots. Crop species frequently have longer telomeres than their wild relatives, and species that have been maintained clonally such as hemp have long telomeres possibly reflecting that this lifestyle requires long term chromosomal stability.

Chromosome-level baobab (Adansonia digitata) genome illuminates its evolutionary insights

“…In Arabidopsis thaliana , loss of the RPA1B ortholog is sensitive to Ultraviolet B (UV-B) light with reduced chlorophyll A and B and inhibited root growth, which is due to elevated DNA damage 33 . It is thought that long lived organisms actively protect their telomere length 35,36 , and repair their DNA 37,38 .…”

“…In addition, telomere sequences were assembled on the ends of most chromosomes, and these telomeres were long compared to other plants with maximum sequences spanning 30 kb as compared to the model plants Arabidopsis thaliana and Zea mays that have 3-5 kb telomeres (Fig. 3b; Supplementary Table 3) 35 . In the Ad77271a genome, we assembled a total of 300 Kb of the ribosomal DNA (rDNA) with only one 26S array that included 35 copies on Chr38, and one 5S array that included 442 copies on Ad77271a Chr01 (Supplementary Table 4).…”

“…s 3a; d; e). In general, the centromere arrays assembled well into 1-2 Mb regions that were both metacentric as well as acrocentric (Chr12, 24,26,28,35,38,39 are acrocentric; Supplementary Fig. 9).…”

“…In Arabidopsis thaliana, loss of the RPA1B ortholog is sensitive to Ultraviolet B (UV-B) light with reduced chlorophyll A and B and inhibited root growth, which is due to elevated DNA damage 33 . It is thought that long lived organisms actively protect their telomere length 35,36 , and repair their DNA 37,38 . Since the K-mer frequency analysis yielded a haploid genome size of approximately 750 Mb (Table 1) and a graph structure indicative of high heterozygosity ( Fig.…”

Chromosome-level baobab (Adansonia digitata) genome illuminates its evolutionary insights

“…The HiC connection map suggested the centromere sequence was highly conserved across the chromosomes, and consistent with this, we found a putative centromere repeat with a base unit of 158 bp, and a higher order repeats (HORs) of 314 and 468 bp (Fig.s 3a; d; e). In general, the centromere arrays assembled well into 1-2 Mb regions that were both metacentric as well as acrocentric (Chr12, 24,26,28,35,38,39 are acrocentric; Supplementary Fig. 9).…”