Epigenetic variation in Arabidopsis disease resistance

Abstract

Plant pathogen resistance is mediated by a large repertoire of resistance (R) genes, which are often clustered in the genome and show a high degree of genetic variation. Here, we show that anArabidopsis thaliana R-gene cluster is also subject to epigenetic variation. We describe a heritable but metastable epigenetic variant bal that overexpresses the R-like geneAt4g16890 from a gene cluster on Chromosome 4. The balvariant and Arabidopsis transgenics overexpressing theAt4g16890 gene are dwarfed and constitutively activate the salicylic acid (SA)-dependent defense response pathway. Overexpression of a related R-like gene also occurs in the ssi1(suppressor of SA insensitivity1) background, suggesting that ssi1 is mechanistically related to bal.