PARENT SESSION
Organized Oral Session 1: Understanding the impacts of oxidative stress in plants: From molecules to ecosystems
Organizer(s): HS Neufeld and N Grulke
Monday, August 8, 8:00 AM - 11:30 AM, Meeting Room 510a, Level 5, Palais des congrès de Montréal
Understanding the impacts of oxidative stress: Stomatal responses.
Grulke, Nancy*,1, Neufeld, Howard2, 1 Pacific Southwest Research Station, Riverside, CA, USA2 Department of Biology, Boone, NC, USA
ABSTRACT- Atmospheric oxidants make their first entry into the plant via the stomata, thus understanding their effect on this gateway is critical to developing an accurate view of plant water balance in a chemically changing atmosphere. We have developed our understanding of stomatal conductance primarily from photosynthesis (A), assuming that oxidant-induced depression of photosynthesis is accompanied by a concurrent reduction in stomatal conductance (gs). However, with moderately high ozone exposure, there may not be a direct relationship between A and gs due to changes in membrane permeability to cation fluxes. For example, ozone-stressed Jeffrey pine exhibit temporal delays in stomatal closure with increasing vapor pressure deficit (VPD). California black oak shows similar responses to abrupt changes in light availability. Ozone-sensitive plants of cutleaf coneflower have lower overall gs than insensitive plants, as well as temporal delays in gs in response to VPD, but no gs response to rapidly changing light. The lack of direct relationship between A and gs will affect projections of whole plant water balance, as well as higher order landscape water balance. Here we present examples of stomatal aberration in elevated ozone environments from a number of plant physiognomic classes.
Key words: stomatal conductance, ozone exposure, light response, VPD response