Unraveling the ACC Signaling Pathway in Plants

 The volatile plant hormone ethylene regulates a diversity of growth and developmental processes as well as biotic and abiotic stress responses in plants. During the last few years, increasing evidence has been gathered suggesting that the ethylene biosynthesis precursor, 1-aminocyclopropane-1-carboxylic acid (ACC), functions as a signaling molecule by itself, independently from ethylene. It remains unknown if and how ACC is perceived by specific receptors, how the signaling pathways is composed, and which downstream responses are achieved. Therefore, it has become particularly timely and intriguing to dissect the components involved in the ACC sensing and signaling pathway. In this proposal, we use the non-vascular liverwort Marchantia polymorpha as an elegant model plant to unravel the ACC signaling pathway. Marchantia has a dedicated ACC response and does not produce ethylene using ACC as in higher land plants, allowing us to better untangle ACC from ethylene signaling. Subsequently we will validate our findings in the model plant Arabidopsis to better understand the functions of ACC signaling and its evolutionary conservation across the plant Kingdom.