Sulforaphane Modifies Histone H3, Unpacks Chromatin, and Primes Defense.

Modern crop production calls for agrochemicals that prime plants for enhanced defense. Reliable test systems for spotting priming-inducing chemistry, however, are rare. We developed an assay for the high-throughput search for compounds that prime microbial pattern-induced secretion of antimicrobial furanocoumarins (phytoalexins) in cultured parsley cells. The screen produced 1-isothiocyanato-4-methylsulfinylbutane (sulforaphane; SFN), a secondary metabolite in many crucifers, as a novel defense priming compound. While elucidating SFN's mode of action in defense priming, we found that in Arabidopsis () the isothiocyanate provokes covalent modification (K4me3, K9ac) of histone H3 in the promoter and promoter-proximal region of defense genes and , but not SFN-triggered H3K4me3 and H3K9ac coincide with chromatin unpacking in the and regulatory regions, primed expression, unprimed activation, and reduced susceptibility to downy mildew disease (). Because SFN also directly inhibits and other plant pathogens, the isothiocyanate is promising for the development of a plant protectant with a dual mode of action.