Abstract
In striking contrast to animals, plants are able to develop and reproduce in the presence of significant levels of genome damage. This is seen clearly in both the viability of plants carrying knockouts for key recombination and DNA repair genes, which are lethal in vertebrates, and in the impact of telomere dysfunction. Telomerase knockout mice show accelerated ageing and severe developmental phenotypes, with effects on both highly proliferative and on more quiescent tissues, while cell death in Arabidopsis tert mutants is mostly restricted to actively dividing meristematic cells. Through phenotypic and whole-transcriptome RNAseq studies, we present here an analysis of the response of Arabidopsis plants to the continued presence of telomere damage. Comparison of second-generation and seventh-generation tert mutant plants has permitted separation of the effects of the absence of the telomerase enzyme and the ensuing chromosome damage. In addition to identifying a large number of genes affected by telomere damage, many of which are of unknown function, the striking conclusion of this study is the clear difference observed at both cellular and transcriptome levels between the ways in which mammals and plants respond to chronic telomeric damage.
Highlights
Telomere structure and DNA damage response (DDR) and repair networks are very highly conserved among eukaryotes
Absence of the telomerase reverse transcriptase (TERT) in Arabidopsis leads to the progressive erosion of telomeric DNA sequences, which, in turn, results in telomere uncapping and increasingly severe genetic instability accompanied by visible developmental defects and reduced fertility in the fourth or fifth mutant generations
Taking advantage of the progressive appearance of the phenotypic effects in succeeding generations of Arabidopsis tert mutants, we present here phenotypic and whole-transcriptome RNAseq analyses separating the effects of the absence of telomerase and the resulting genome damage
Summary
Telomere structure and DNA damage response (DDR) and repair networks are very highly conserved among eukaryotes. Absence of the telomerase reverse transcriptase (TERT) in Arabidopsis leads to the progressive erosion of telomeric DNA sequences, which, in turn, results in telomere uncapping and increasingly severe genetic instability accompanied by visible developmental defects and reduced fertility in the fourth or fifth mutant generations. These become progressively more severe in succeeding generations, resulting in problems in growth and development and in complete sterility by the tenth or eleventh generation [22]. Our data provide a strikingly different picture from that reported in the study of telomerase mutant mice [27]
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