Changes in telomere length in Arabidopsis thaliana plants infected with the phytopathogenic bacteria Pseudomonas syringae DC3000.

Telomeres are specialized nucleoprotein complexes at the physical ends of linear chromosomes of most eukaryotes that represent a key structural element in genome stability regulation. One of the most important characteristics determining the protective capacity of telomeres is telomere length (TL). In Arabidopsis thaliana, telomere length varies among ecotypes, which may be considered as an adaptive mechanism to various environmental and stress conditions, including phytopathogenic infections. However, the mechanisms of TL regulation under biotic stress remain unclear. Here, we show the results of our study of the TL changes in A. thaliana plants under the Pseudomonas syringae pv. tomato DC3000 infection. In the study, we used natural ecotypes Col-0 (medium telomere length) and Sf-2 (long telomeres), as well as mutant plant lines with disordered and wild-type telomere length phenotypes, oli5- 2-/- and nop2c-2-/-, respectively. It was found that susceptibility to the phytopathogen varies in plants: the line with short telomeres, oli5-2-/-, showed the highest sensitivity compared to the WT and nop2c-2-/-. Sf-2 plants possessed the highest resistance to the infection. Significant shortening of TL on the third day after infection was found on the short arm of chromosome 4 of infected nop2c-2-/- plants, whereas TL of infected oli5-2-/- plants slightly decreased on the third day and increased on the seventh day after infection. The most resistant line Sf-2 retained TL on the third and seventh days after infection but significantly lost it on the 18th day. So, it was shown for the first time that phytopathogenic infection affects telomere length in plants, which opens a new direction in the study of plant telomere regulation under biotic stress.