SAES-422
Multistate Research Activity
Accomplishments Report
Project/Activity Number: NE-176
Project
Title: Characterization and
Mechanisms of Plant Responses to Ozone
(O3) in the
Period
Covered:
Date
of This Report:
Annual
Meeting Dates:
Participants:
Chris Andersen (EPA, OR), Fitzgerald Booker (USDA, NC), Steve Britz (BARC,
USDA), Kent Burkey (USDA, NC), Art Chappelka (AL), Boris Chevone (VA), David
Grantz (CA), Allen Heagle (USDA, NC), Robert Kohut (NY), Sagar Krupa (MN), Ed
Lee (BARC, USDA), William Manning (MA, Margaret McGrath (NY), Joseph Miller
(USDA, NC), Charles Mulchi (MD), Howard Neufeld (NC), Eva Pell (PA), Mike
Robinson (BARC, MD), John Skelly (PA), Barbara Zilinskas (NJ)
Art Chappelka
Boris Chevone Virginia
Polytechnic Institute and
David Grantz University
of California –
Robert Kohut Boyce Thompson Institute
Sagar Krupa University of Minnesota
William Manning
Margaret McGrath
Charles Mulchi
Howard Neufeld Appalachian
Eva Pell The
John Skelly The Pennsylvania State University
Barbara Zilinskas
Chris Andersen U.S.
EPA,
Fitzgerald Booker USDA-ARS
Air Quality Research Unit,
Kent Burkey
Allen Heagle
Joseph Miller
Steve Britz USDA-ARS
Climate Stress Unit,
Ed Lee
Mike Robinson
Jack Barnes CSREES
Representative,
Robin Huettel
Daniel Jones
Pat Logan
Robert Seem
Summary of minutes of annual meetings: 1995 1996-2002
Accomplishments
and Impacts:
Over
200 peer-reviewed publications, book chapters, and theses (21) were produced
during this project. These publications
include 18 papers co-authored by project participants from different locations. One paper was entirely co-authored by members
of the project and highlighted the objectives and accomplishments of NE-176 (Krupa,
S, MT McGrath, C Andersen, FL Booker, KO Burkey, AH Chappelka, BI Chevone, EJ
Pell, BA Zilinskas. 2001. Ambient ozone
and plant health. Plant Disease 85:4-12).
Significant
accomplishments were made regarding ozone-elicited molecular and physiological
responses. Research indicated that ozone
inhibits carbon fixation and translocation by plants and induces numerous plant
defense responses against oxidative stress.
Landmark research findings by Eva Pell’s laboratory showed that ozone
inhibits a primary enzyme (Rubisco) involved in photosynthesis and stimulates
genes involved in plant senescence, which reduces growth and yield of sensitive
plants. Ozone may also lower the rate of
sugar export from leaves, which further limits growth and yield. Several laboratories in our group made important
discoveries regarding the biochemical basis for differences in ozone
sensitivity among plant species and cultivars based on the level of ascorbic
acid found in plant leaves. This
research has paved the way for a better understanding of the molecular and
biochemical pathways involved in ozone toxicity and provided the underpinnings
for genetic modifications aimed at increasing plant resistance to ambient ozone
and other oxidative stressors in the environment.
Research
on interactions between tropospheric ozone and other environmental factors
showed that elevated atmospheric carbon dioxide can suppress ozone damage in
crops such as soybean, bean, cotton, and wheat.
A major finding was that crop growth and yield stimulation by elevated
carbon dioxide could be attributed in part to decreased damage from ambient
ozone due to reductions in ozone uptake at elevated carbon dioxide
concentrations. Significant variability
in physiological, growth, and yield responses was found among crops and
cultivars due to differing sensitivities to ozone injury. At present it is unclear how future changes
in atmospheric trace gas concentrations will affect crop production and forest
health, although increasing ambient ozone concentrations will likely detract
from the potentially beneficial effects of elevated atmospheric carbon dioxide
on plant growth.
Advances were made in identifying and documenting ambient
ozone injury to crop and native plants.
A multi-site project conducted by members of this project showed that
ambient ozone caused visible injury and reduced growth of bioindicator plants
(Heagle et al. 1996. Responses of a white clover indicator system to
tropospheric ozone at eight locations in the United States. Water, Air and Soil
Pollution 85: 1373-1378). Computer
models were developed to capture cause (ozone) and effect (crop response)
relationships under ambient conditions.
These models are also capable of segregating the individual
contributions of various climatic factors to crop growth and productivity. Surveys and models indicate that injury to
plants from ambient ozone is pervasive in most regions of the U.S. and other
industrialized countries worldwide.
Overall, project accomplishments made significant strides toward achieving the project goals. The large number of publications that emanated from research conducted by members of this project was a major accomplishment. Advances were made at all levels of research interest, from the molecular to the ecosystem level in both agricultural and forest systems. Findings at basic biological levels contributed to our understanding of ambient ozone effects on whole-plants, communities, and ecosystems. The converse was also true. Thus, progress was made toward the goal of integrating and understanding ozone effects at multiple levels of biological organization. Effects of biotic and abiotic factors that determine plant responses to ozone were also investigated. The research was conducted at various laboratories affiliated with the project in both coordinated multi-site experiments and as informal associations among researchers interested in similar questions. The project served to facilitate research by fostering communication and collaboration among participants. The outreach objective was met by publication of general-interest and review papers, the open forum of annual meetings at which interested guests were invited to attend and participate, and by participation in peer-review panels for US EPA Ozone Criteria Document preparation. We consider the project to be an outstanding success and plan to promote its continuation.