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Title:Investigating hydrogen peroxide dynamics and the role of plasma membrane aquaporin PIP1:4 in plant sensitivity to ozone.
Author(s):Demler, Hannah Jane
Advisor(s):Ainsworth, Lisa
Contributor(s):Ort, Don; Marshall-Colon, Amy
Department / Program:Plant Biology
Discipline:Plant Biology
Degree Granting Institution:University of Illinois at Urbana-Champaign
Degree:M.S.
Genre:Thesis
Subject(s):Ozone
Arabidopsis
Hydrogen peroxide
ROS
Aquaporins
Abstract:Tropospheric ozone is both a greenhouse gas and a damaging oxidative agent. Increasing anthropogenic emissions of precursor pollutants since the Industrial Revolution has led to significant increases in ground-level ozone concentrations. Phytotoxic concentrations of ozone occur throughout many regions of the world, posing a risk to agricultural production and ecosystem health through reducing photosynthetic carbon assimilation, inducing premature senescence, and at high enough concentrations causing a hypersensitive response and wide-spread tissue necrosis. Reactive oxygen species (ROS) including hydrogen peroxide (H2O2), form upon ozone entry into the leaf and their production is propagated endogenously. In the present study visible ozone-induced damage and the dynamics of the ozone H2O2 response of Arabidopsis thaliana lines with differential expression of plasma membrane intrinsic protein PIP1:4, along with wildtype Columbia ecotype (Col), were investigated to probe the relationship between the ROS burst and ozone-sensitivity and the potential role of H2O2 transport across the plasma membrane. Ozone-sensitive Cape Verde Island ecotype (Cvi) was included in several experiments for an ozone-sensitive control. Rosette growth in Col and aquaporin lines was impaired by growth at chronic elevated ozone of 150ppb 8 h/day, though significant increases in leaf H2O2 content were only found in wildtype Col and overexpressing line OE4.2. In response to acute ozone exposure, 350 ppb for 6 h only caused H2O2 accumulation in Cvi plants, associated with the development of widespread necrotic lesions. No visible damage or ROS burst was observed in wildtype Col or the aquaporin lines during or after exposure to 350 ppb ozone, regardless of day length conditions (8 h or 24 h day length). A hypersensitive ozone response and an ROS burst was observed in Col and all aquaporin lines after a 6 h fumigation of 500 ppb ozone, but not after fumigation at 410 ppb ozone for the same duration, indicating a relatively specific threshold ozone concentration for H2O2 accumulation and initiation of cell death. No correlation was found between expression of PIP1:4 and ozone-sensitivity or H2O2 dynamics. The findings from this research demonstrate 1) that chronic ozone exposure of 150 ppb 8 h/day inhibits growth in Col and the aquaporin lines largely without significant changes in leaf H2O2 levels, 2) that an ROS burst is associated with a hypersensitive response to ozone and is both ozone concentration-dependent and genotype-specific, and 3) that differential expression of AtPIP1:4 and H2O2 transport across the plasma membrane through this aquaporin does not effect Arabidopsis sensitivity to chronic or acute ozone exposure.
Issue Date:2021-07-21
Type:Thesis
URI:http://hdl.handle.net/2142/113220
Rights Information:Copyright 2021 Hannah Demler
Date Available in IDEALS:2022-01-12
Date Deposited:2021-08


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