Introduction

Louis, Edward J.

doi:10.1007/978-3-642-41566-1_1

Cited by 7 publications

(5 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Numerous copies of the telomeric repeat and its derivatives were detected in the subtelomeres of human, Arabidopsis and wheat chromosomes (Ambrosini, Paul, Hu, & Riethman, 2007;Uchida, Matsunaga, Sugiyama, & Kawano, 2002). In organisms previously studied, the subtelomeric region is defined as the extension between the telomere and the most distal chromosome-specific sequence (Kuo et al, 2006;Louis, 2014;Mefford et al, 2002;Pryde, Gorham, & Louis, 1997). A common feature supposed to be shared by plants is a stretch of tens of kilobases of highly rearranged and repetitive DNA before the first active gene at the distal part of subtelomeres (Alkhimova et al, 2004;Ohmido, Kijima, Ashikawa, de Jong, & Fukui, 2001;Pearce, Pich, Harrison, Flavell, & Heslop-Harrison, 1996;Röder et al, 1993;Vershinin, Schwarzacher, & Heslop-Harrison, 1995;Wu & Tanksley, 1993).…”

Section: Discussionmentioning

confidence: 99%

Sequence analysis of wheat subtelomeres reveals a high polymorphism among homoeologous chromosomes

Aguilar

Prieto

2020

The Plant Genome

View full text Add to dashboard Cite

Bread wheat, Triticum aestivum L., is one of the most important crops in the world. Understanding its genome organization (allohexaploid; AABBDD; 2n = 6x = 42) is essential for geneticists and plant breeders. Particularly, the knowledge of how homologous chromosomes (equivalent chromosomes from the same genome) specifically recognize each other to pair at the beginning of meiosis, the cellular process to generate gametes in sexually reproducing organisms, is fundamental for plant breeding and has a big influence on the fertility of wheat plants. Initial homologous chromosome interactions contribute to specific recognition and pairing between homologues at the onset of meiosis. Understanding the molecular basis of these critical processes can help to develop genetic tools in a breeding context to promote interspecific chromosome associations in hybrids or interspecific genetic crosses to facilitate the transfer of desirable agronomic traits from related species into a crop like wheat. The terminal regions of chromosomes, which include telomeres and subtelomeres, participate in chromosome recognition and pairing. We present a detailed molecular analysis of subtelomeres of wheat chromosome arms 1AS, 4AS, 7AS, 7BS and 7DS. Results showed a high polymorphism in the subtelomeric region among homoeologues (equivalent chromosomes from related genomes) for all the features analyzed, including genes, transposable elements, repeats, GC content, predicted CpG islands, recombination hotspots and targeted sequence motifs for relevant DNA-binding proteins. These polymorphisms might be the molecular basis for the specificity of homologous recognition and pairing in initial chromosome interactions at the beginning of meiosis in wheat. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made.

show abstract

Section: Discussionmentioning

confidence: 99%

Sequence analysis of wheat subtelomeres reveals a high polymorphism among homoeologous chromosomes

Aguilar

Prieto

2020

The Plant Genome

View full text Add to dashboard Cite

show abstract

“…The difference in the distribution of genes in the different genomic regions was evaluated using Chi-squared tests (p < 0.05), by comparing those within and outside subtelomeric regions, with the null hypothesis that they are characterized by similar frequencies. Here, we regarded the first and last 500 kb from chromosome ends as subtelomeres [71,[122][123][124]. Furthermore, the synteny and conservation of the location of the different host-rangeassociated genes were studied with SynChro which revealed the synteny breakpoints between the reference and query genomes [54].…”

Section: Genomic Distribution Of the Host-range-associated Genesmentioning

confidence: 99%

Characterization of Host-Specific Genes from Pine- and Grass-Associated Species of the Fusarium fujikuroi Species Complex

et al. 2022

View full text Add to dashboard Cite

The Fusarium fujikuroi species complex (FFSC) includes socioeconomically important pathogens that cause disease for numerous crops and synthesize a variety of secondary metabolites that can contaminate feedstocks and food. Here, we used comparative genomics to elucidate processes underlying the ability of pine-associated and grass-associated FFSC species to colonize tissues of their respective plant hosts. We characterized the identity, possible functions, evolutionary origins, and chromosomal positions of the host-range-associated genes encoded by the two groups of fungi. The 72 and 47 genes identified as unique to the respective genome groups were potentially involved in diverse processes, ranging from transcription, regulation, and substrate transport through to virulence/pathogenicity. Most genes arose early during the evolution of Fusarium/FFSC and were only subsequently retained in some lineages, while some had origins outside Fusarium. Although differences in the densities of these genes were especially noticeable on the conditionally dispensable chromosome of F. temperatum (representing the grass-associates) and F. circinatum (representing the pine-associates), the host-range-associated genes tended to be located towards the subtelomeric regions of chromosomes. Taken together, these results demonstrate that multiple mechanisms drive the emergence of genes in the grass- and pine-associated FFSC taxa examined. It also highlighted the diversity of the molecular processes potentially underlying niche-specificity in these and other Fusarium species.

show abstract

“…The sequences found adjacent to the telomeres are often called “subtelomeres.” Strictly speaking, however, for a sequence to be classified as “subtelomeric,” it should contain motifs that only occur near to chromosome termini, and should be duplicated at multiple ends ( Louis, 2014 ; Figure 1A ). True subtelomeres in many organisms have a domain structure, with distal segments containing short, subtelomere-specific, tandem repeat motifs, and proximal segments harboring a number of genes that are duplicated at multiple chromosome ends ( Pryde et al, 1997 ).…”

Section: Introductionmentioning

confidence: 99%

Telomere Roles in Fungal Genome Evolution and Adaptation

et al. 2021

View full text Add to dashboard Cite

Telomeres form the ends of linear chromosomes and usually comprise protein complexes that bind to simple repeated sequence motifs that are added to the 3′ ends of DNA by the telomerase reverse transcriptase (TERT). One of the primary functions attributed to telomeres is to solve the “end-replication problem” which, if left unaddressed, would cause gradual, inexorable attrition of sequences from the chromosome ends and, eventually, loss of viability. Telomere-binding proteins also protect the chromosome from 5′ to 3′ exonuclease action, and disguise the chromosome ends from the double-strand break repair machinery whose illegitimate action potentially generates catastrophic chromosome aberrations. Telomeres are of special interest in the blast fungus, Pyricularia, because the adjacent regions are enriched in genes controlling interactions with host plants, and the chromosome ends show enhanced polymorphism and genetic instability. Previously, we showed that telomere instability in some P. oryzae strains is caused by novel retrotransposons (MoTeRs) that insert in telomere repeats, generating interstitial telomere sequences that drive frequent, break-induced rearrangements. Here, we sought to gain further insight on telomeric involvement in shaping Pyricularia genome architecture by characterizing sequence polymorphisms at chromosome ends, and surrounding internalized MoTeR loci (relics) and interstitial telomere repeats. This provided evidence that telomere dynamics have played historical, and likely ongoing, roles in shaping the Pyricularia genome. We further demonstrate that even telomeres lacking MoTeR insertions are poorly preserved, such that the telomere-adjacent sequences exhibit frequent presence/absence polymorphism, as well as exchanges with the genome interior. Using TERT knockout experiments, we characterized chromosomal responses to failed telomere maintenance which suggested that much of the MoTeR relic-/interstitial telomere-associated polymorphism could be driven by compromised telomere function. Finally, we describe three possible examples of a phenomenon known as “Adaptive Telomere Failure,” where spontaneous losses of telomere maintenance drive rapid accumulation of sequence polymorphism with possible adaptive advantages. Together, our data suggest that telomere maintenance is frequently compromised in Pyricularia but the chromosome alterations resulting from telomere failure are not as catastrophic as prior research would predict, and may, in fact, be potent drivers of adaptive polymorphism.

show abstract

Introduction

Cited by 7 publications

References 85 publications

Sequence analysis of wheat subtelomeres reveals a high polymorphism among homoeologous chromosomes

Sequence analysis of wheat subtelomeres reveals a high polymorphism among homoeologous chromosomes

Characterization of Host-Specific Genes from Pine- and Grass-Associated Species of the Fusarium fujikuroi Species Complex

Telomere Roles in Fungal Genome Evolution and Adaptation

Contact Info

Product

Resources

About