4/23/2024 0 Comments Nn model sets budding![]() ![]() ![]() Alternatively, telomere length differences could have fitness effects that are subject to natural selection, possibly due to their association with cellular senescence, which has been implicated in controlling lifespan in yeast and animals ( Aubert and Lansdorp, 2008 Kupiec, 2014). In Arabidopsis, a recent QTL analysis using MAGIC lines suggested that genes involved in ribosome biogenesis and cell proliferation, such as NOP2A, RPL5A, and RPL5B, may be involved in setting telomere length set points ( Abdulkina et al., 2019).Ī more puzzling question is this: What is the significance of natural variation in telomere length for organisms? Telomere length variation could be neutral and result from random genetic drift or random stochasticity in the activity of the telomerase. Quantitative trait locus (QTL) studies in Arabidopsis thaliana and maize ( Zea mays) have indicated that natural variation in telomere length is a heritable complex trait ( Burr et al., 1992 Brown et al., 2011 Fulcher et al., 2015). In plants, variation in telomere length has also been observed between individuals ( Burr et al., 1992 Shakirov and Shippen, 2004 Maillet et al., 2006 Fulcher et al., 2015), between organs ( Kilian et al., 1995), and between cell types ( González-García et al., 2015). Several examples of telomere length polymorphisms and the underlying genes responsible for this variation have been identified in humans ( Homo sapiens), yeast, and the roundworm Caenorhabditis elegans ( Liti et al., 2009 Levy et al., 2010 Jones et al., 2012 Codd et al., 2013 Cook et al., 2016). Within species, telomere sequences also display substantial heritable length variation. The most noticeable difference in telomeres between organisms is differences in telomere length, which can be as short as 300 bps in yeast ( Saccharomyces cerevisiae Gatbonton et al., 2006) and up to 150 kb in tobacco ( Nicotiana tabacum Fajkus et al., 1995). For instance, vertebrates have the telomeric repeat TTAGGG ( Meyne et al., 1989), while in most plants, the sequence is TTTAGGG ( Fajkus et al., 2005). The core telomeric repeat sequence is conserved among species. Other specialized telomere binding proteins are also recruited to prevent the telomere from being detected as damaged DNA ( Fulcher et al., 2014).Įukaryotic telomeres consist of a tandem repeat of TG-rich microsatellite sequences ( Podlevsky and Chen, 2016). To prevent this loss of chromosomal DNA at the termini, the ribonucleoprotein enzyme complex telomerase, whose core components consist of a telomerase reverse transcriptase (TERT) and RNA template ( TR Osterhage and Friedman, 2009 Song et al., 2019), binds to single-stranded telomeric DNA at the 3′-end and processively extends the telomere sequence ( Wu et al., 2017). During DNA replication, failure to fill in terminal base pairs at the lagging strand leads to the end-replication problem ( Olovnikov, 1971, 1973 Watson, 1972), resulting in the shortening of chromosome ends during each cell division and the eventual loss of replicative capacity ( Hayflick and Moorhead, 1961 van Deursen, 2014). Telomeres are regions of repetitive sequences that cap the ends of eukaryotic chromosomes to protect them from deterioration and from eliciting a DNA damage response ( Shay and Wright, 2019). Open in new tab Download slide Introduction Our work suggests that chromosomal structure itself might be an adaptive trait associated with plant life-history strategies. Our results point to several possible reasons for this correlation, including the possibility that longer telomeres may be more adaptive in plants that have faster developmental rates (and therefore flower earlier). thaliana, but also in maize and rice, indicating a link between life-history traits and chromosome integrity. We found that telomere length is negatively correlated with flowering time variation not only in A. Population genomic analysis provided evidence for a selective sweep at the TERT region associated with longer telomeres. thaliana identified 13 regions with GWAS-significant associations underlying telomere length variation, including a region that harbors the telomerase reverse transcriptase ( TERT) gene. Genome-wide association study (GWAS) mapping in A. Here, using whole-genome re-sequencing and terminal restriction fragment assays, we found substantial natural intraspecific variation in telomere length in Arabidopsis thaliana, rice ( Oryza sativa), and maize ( Zea mays). Telomeres are highly repetitive DNA sequences found at the ends of chromosomes that protect the chromosomes from deterioration duringcell division. ![]()
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