The Arabidopsis heterochromatin remodeling protein MOM1 regulates defenses against pathogens

CAMBIAGNO D; ALVAREZ ME

Rosario

Congreso; L Reunión Anual SAIB; 2014

SAIB

In Arabidopsis, transposable elements (TEs) are concentrated at centromeric heterochromatin but also present at the proximity of genes. Different mechanisms repress TE expression by recruiting epigenetic marks. Among them, MOM1 negatively affects a subset of pericentromeric TEs from the Athila superfamily allowing methylation of Lysine 9 from histone H3. Consequently, mom1 mutant shows activation of these elements. To study how this protein affects defenses against hemibiotrophic pathogens, we used the mom1 mutant in infection studies. mom1 was more resistant to Pseudomonas syringae pv tomato, but did not up-regulate defense genes at basal conditions. RT-PCR analysis and available mom1 transcriptomes suggested that this plant was prone to induce pathogen defense genes. In fact, infection assays confirmed that the mutant exhibited priming. Some TEs modulate the expression of neighboring genes by affecting local chromatin structure. After evaluating this possibility, we propose a model for MOM1 mediated defense activation.