Ethylene and salicylic acid synergistically accelerate leaf senescence in Arabidopsis

The phytohormones ethylene and salicylic acid (SA) have long been known to promote senescence, but their interplay during this process remains elusive. Here we report the synergistic effects of ethylene and SA on promoting leaf senescence in Arabidopsis. EIN3, a key transcription factor of ethylene signaling, physically interacted with the core SA signaling regulator NPR1 in senescing leaves. EIN3 and NPR1 synergistically promoted the expression of the senescence-associated genes ORE1 and SAG29. The senescence phenotype was more delayed for the ein3eil1npr1 triple mutant than ein3eil1 or npr1 with ethylene or/and SA treatment. NPR1-promoted leaf senescence may depend on functional EIN3/EIL1.