DNA glycosylase MBD4L modulates chromatin structure in Arabidopsis infected tissues

TORRES JR; ARIAS S; NOTA F; LESCANO CI ; CECCHINI NM ; ALVAREZ ME

Glasgow

Congreso; XVIII International Congress on Molecular Plant-Microbe Interactions; 2019

International Society for Molecular Plant-Microbe Interactions

Chromatin structure controls gene expression, transposon silencing and DNA repair, among many other nuclear processes. Under certain stress conditions, plants exhibit chromatin remodeling apparently due to changes in the epigenetic marks of the genome. We previously described that Arabidopsis tissues infected with Pseudomonas syringae pv tomato (Pst) trigger decondensation of chromocenters, demethylation of DNA, and transient activation of pericentromeric transposons. In addition, other authors showed that the host genome is damaged under such condition, and that plant defense mechanisms help to maintain DNA integrity. We wondered if DNA glycosylases help repair DNA and/or remodel chromatin in Pst-infected tissues. To evaluate this we used comet assays to monitor DNA strand brakes in wild type and mutant plants. Mutants impaired in the DNA glycosylase MBD4L (Methyl Binding Domain 4-Like) had lower DNA damage than wild type plants. By confocal microscopy we performed a time course analysis of Pst-induced heterochromatin relaxation and found that this response is reduced in mbd4l plants. Consistently, MBD4L maintained a nuclear localization in both basal and infection conditions, and its two splicing variants reached different subnuclear domains under different stress conditions. Thus, our results suggest that MBD4L mediates genome repair and chromatin remodeling under biotic stress conditions.