Ethylene response pathway is essential for ARABIDOPSIS A-FIFTEENfunction in floral induction and leaf senescence

ARABIDOPSIS A-FIFTEEN(AAF) encodes a plastid protein and was originally identified as a SENESCENCE-ASSOCIATED GENE. Previously, we found that overexpression of AAF(AAF-OX) in Arabidopsis led to accumulated reactive oxygen species and promoted leaf senescence induced by oxidative stress, which was suppressed by a null mutant, ein2-5, in ethylene response pathway. Whether AAFfunction is involved in ethylene biosynthesis and/or the response pathway remained unknown. Here we show that neither overexpression (AAF-OX) nor a null mutant (aaf-KO) of AAFgenerates a higher level of ethylene than the wild type and display a typical triple-response phenotype in etiolated seedlings treated with 1-aminocyclopropane-1-carboxylic acid (ACC). Nevertheless, ein2-5suppresses the phenotypes of early flowering and age-dependent leaf senescence in AAF-OXplants. We reveal that a functional ethylene response is essential for AAF function in leaf senescence and floral induction, but AAF is unlikely a regulatory component integral to the ethylene pathway.