Auxin transport during leaf abscission in poplar

• Applicant: Dr. Urs Fischer
• Subject Area: Plant Cell and Developmental Biology
• Term: from 2009 to 2015
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 157680243

Timing of leaf abscission is an important trait for biomass production and seasonal acclimation in deciduous tress of the temperate region. The signaling leading to organ separation, from the external cue (decreasing photoperiod) perceived in the leaves to hydrolysis of cell walls and middle lamellae in the abscission zone, is only poorly understood. Data from annual species indicate that auxin transport from the leaf blade to its axil and the formation of an auxin gradient spanning the abscission zone are required for the inhibition of abscission. In order to study auxin transport during abscission, we established an experimental system in poplar, which allows us to induce abscission synchronously under controlled conditions. We will identify and localize the auxin carriers in the abscission zone as well as perform functional analysis with the help of specific inhibitors. Furthermore, we will monitor gradients of auxin response and their changes at cellular resolution in the abscission zone. Finally we will turn the auxin responsive cells of the abscission zone into cells insensitive to ethylene or overproduce ethylene therein in order to determine if ethylene signaling acts downstream of auxin. These experiments will contribute to a holistic understanding of auxin function during leaf abscission.

• DFG Programme: Research Grants
• International Connection: Sweden