Temporal analysis of poplar woody root response to bending stress.

Temperate perennial woody plants use different environmental signals to coordinate their growth and development in relation to seasonal changes. Preliminary evidences suggest that, even during dormancy, plants maintain effective metabolic activities and molecular mechanisms ensuring them an eventual recording of mechanical loads during winter times. Despite their great importance for productivity and survival, plant biology investigations have poorly characterized the root growth cycle and its response to environmental stresses. In this study, we describe the proteomic changes occurring over the time in poplar root either in the absence or in response to a bending stress; corresponding expression of cell cycle regulator and auxin transporter genes was also evaluated by reverse transcription polymerase chain reaction analysis (RT-PCR). Our results confirm previous evidences on the effect of the bending stress on the anticipation of root growth resumption, providing additional insights on a temporal modulation of various plant metabolic processes involved in dormancy break, growth resumption and stress response in the bent root; these events seem related to the differential compression and tension force distribution occurring over the plant taproot.