Endogenous suppressor(s) in Arabidopsis thaliana

An ethyl acetate extract of Arabidopsis thaliana plants was tested for the presence of endogenous suppressor(s) (ES), and the active fraction, which partitioned into water phase contained a molecule(s) < 3000 Da based on a rough estimate using sized membrane filters. Foliar application of the ES enabled typically nonpathogenic fungi (non-adapted pathogens) to cause disease symptoms on A. thaliana . Consistently, the ES fraction severely suppressed the oxidative burst and the expression of defense-related genes such as FRK1 , NHO1 , WRKY22 , WRKY29 , PEN2 , and PEN3 in plants challenged with non-adapted fungus Colletotrichum gloeosporioides or the fungal elicitor chitin.