The 30th International Conference on Arabidopsis Research (ICAR 2019)

657 / 2019-04-30 08:28:12

HOS15 and HDA9 negatively regulate immunity through histone deacetylation on intracellular immune receptor NLR genes in Arabidopsis

HOS15, HDA9, Acetylation, Immunity, Arabidopsis

Plenary track > Epigenetics

Growth-defense balance is crucial for plant survival and fitness. Plant intracellular immune receptor Nod-Like Receptor (NLR) genes are precisely modulated to ensure timely and effective immune responses. Epigenetic modification has emerged to be an important player in plant immunity. However, the mechanism underlying this regulation for growth-defense balance is poorly understood. Here, we uncovered HIGH EXPRESSION OF OSMOTICALLY RESPONSIVE GENES 15 (HOS15) and HISTONE DEACETYLASE 9 (HDA9) as two negative regulators of plant immunity. We found that loss-of-function HOS15 and HDA9 confer enhanced resistance to pathogen infection. Further analysis showed that HOS15 and HDA9 directly bind to many NLR genes and repress their expression. The repression is likely through reducing H3K9ac level, as seen in one of the NLR genes, SUPPRESSOR OF npr1-1, CONSTITUTIVE 1 (SNC1). In addition, HOS15 represses the basal expression of NLRs, and HDA9 specifically functions during the infection stage to prevent overstimulation of NLR genes. Together, this study uncovers a previously uncharacterized histone deacetylase complex in plant immunity and highlights the importance of histone modifying enzymes acting together with their cofactors to fine-tune the defense responses.