Pathogen induces MEDEA gene in a parent-of-origin nonspecific manner and causes embryo lethality in MEDEA overexpressing plants

MEDEA (MEA) is an imprinted gene, and only the maternal copy is expressed in female gametophytes and developing endosperms. Upon pathogen inoculation, MEA ectopically expresses in vegetative tissues. MEA overexpressing plants are susceptible to pathogens. Unlike mea mutant plants, MEA overexpressing plants bear healthy seeds with fertile embryos. It was not known whether there is any parent-of-origin specificity in pathogen-induced MEA expression. Using F1 of inter-ecotype accessions of Arabidopsis lines, we show that ectopic expression is nonspecific to the parent-of-origin copy of the genome. We also report here that MEA overexpressing plants (p35S:MEA-HA), though constitutively accumulates MEA mRNA, protein accumulates only upon pathogen inoculation. Repeated foliar application of pathogens results in embryo abortion in p35S:MEA-HA plants but not in WT plants. Results suggest that pathogen-mediated immunity activation stabilizes MEA protein, which is lethal to embryonic development.