Pathogen infection and MORC1 affect chromatin accessibility of transposable elements and expression of their proximal genes in Arabidopsis
H. KANG (1), Y. Bordiya (1), Y. Zheng (2), J. Nam (1), H. Choi (2), B. Lee (3), J. Kim (3), D. Klessig (2), Z. Fei (2) (1) Texas State University, U.S.A.; (2) Boyce Thompson Institute, U.S.A.; (3) University of Texas, Austin, U.S.A.

To investigate how MORC1’s role in epigenetic gene silencing impacts its function in plant immunity, genome-wide chromatin accessibility was compared between mock- or Pseudomonas syringae pv. tomato (Pst)-inoculated wild type (WT) Arabidopsis and/or the morc1/2 double mutant. Most changes in chromatin accessibility, reflected by the appearance of DNase I hypersensitive sites (DHSs), were located in the promoters of genes and transposable elements (TEs). Comparisons between morc1/2 and WT receiving the same treatment identified differential DHSs (dDHSs) predominantly associated with heterochromatic TEs. By contrast, comparisons between mock- and Pst-inoculated plants from the same genotype identified dDHSs associated with biotic/abiotic stress-related genes; a smaller but significant population was in TEs. Defense genes, including PR-1, PR-2 and PR-5, were proximal to Pst-induced TE-associated dDHSs. Notably, a random subset of these defense genes showed delayed/reduced expression in Pst-infected morc1/2 as compared with WT. Analysis of chromatin regions precipitated by antibodies against MORC1 revealed that MORC1 bound chromatin in a Pst infection-responsive manner at sites dispersed throughout the genome, although a preference for heterochromatin was observed. These results provide evidence that MORC1 is associated with TEs and raise the possibility that a subset of these TEs have regulatory roles for their proximal defense genes.

Abstract Number: P17-542
Session Type: Poster