Here we report the consequences of telomere erosion in Arabidopsis thaliana, studied by examining seed and pollen production and the course of male meiosis through the last five generations (G5-G9) of telomerase-deficient Arabidopsis mutants. We used a previously described mutant line in which telomerase activity was abolished by T-DNA insertion into the TERT gene encoding telomerase reverse transcriptase. Reduced fertility accompanied by morphological abnormalities occurred in G6, which produced on average 35 seeds per silique (vs. 43 in wild type) and worsened in G7 (30 seeds) and G8 (14 seeds), as did the morphological abnormalities. The last generation of tert mutants (G9) did not form reproductive organs. Analysis of meiosis indicated that the main cause of reduced fertility in the late generation tert mutants of Arabidopsis was the numerous chromosomal end-to-end fusions which led to massive genome rearrangements in meiocytes. Fusion of meiotic chromosomes began in G5 and increased in each of the next generations. Unpaired chromosomes (univalents) were observed in G7 and G8. The study highlights some differences in the meiotic consequences of telomere shortening between plant and animal systems.
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