Growth deficiency and enhanced basal Immunity inArabidopsis thalianamutants ofEDM2,EDM3andIBM2are genetically interlinked

Mutants of the Arabidopsis thaliana genes, EDM2 , EDM3 and IBM2 are known to show defects in a diverse set of defense and developmental processes. For example, they jointly exhibit enhanced levels of basal defense and stunted growth. Here we show that these two phenotypes are functionally connected by their dependency on the salicylic acid biosynthesis gene SID2 and the basal defense regulatory gene PAD4 . Stunted growth of edm2 , edm3 and ibm2 plants is a consequence of up-regulated basal defense. Constitutively enhanced activity of reactive oxygen species-generating peroxidases, we observed in these mutants, appears also to contribute to both, their enhanced basal defense and their growth retardation phenotypes. Furthermore, we found the histone H3 demethylase gene IBM1 , a direct regulatory target of EDM2, EDM3 and IBM2, to be at least partially required for the basal defense and growth-related effects observed in these mutants. We recently reported that EDM2 , EDM3 and IBM2 coordinate the extent of basal immunity with the timing of the floral transition. Together with these observations, data presented here show that at least some of the diverse phenotypic effects in edm2 , edm3 and ibm2 mutants are genetically interlinked and functionally connected.