REPORT OF THE SECRETARY
NE -1013 Annual
Technical Committee Meeting
June 2006
Champaign,
IL
The NE-1013
Annual Technical Committee Meeting was called to order at 8:15 AM EST on June 19, 2006 by S. Long
(IL) as presiding chair-elect D. Decoteau (PA) was delayed by inclement
weather. Committee chair Howard Neufeld
was unable to attend the meeting due to weather. Welcoming comments were made by S. Long the
local host who mentioned the continuous crop plots started in the 1870’s at the
University of Illinois
and the current SoyFACE project where a 20% yield loss of soybean has been
observed under ambient ozone concentrations.
Introductions by the attending members then followed. S. Krupa (MN) briefly discussed the draft
renewal of NE1013 and reminded members that NIMMS has limited proposals to 20K
words in the past year. Discussion then proceeded to improve the renewal draft.
R. Knighton, the National Program Leader for Air Quality and the NE-1013
CSREES/USDA advisor, remarked that a major concern in Washington
was the contribution of agriculture to air quality, not the effects of air
quality on crop production. He further
commented that the emission of ammonia, particulates and animal-produced
reactive VOCs in relation to ozone production was an important consideration.
Ammonium in rainwater is increasing and the contribution from crop production
is not known. Several committee members then raised a concern that the research
focus of NE1013 has been the effects of air quality (ozone) on crop production and
the health of native vegetation. Most
members expressed concern about continuing in the program if research emphasis
shifted to a monitoring/modeling effort from an effects/mitigation effort.
Station
reports then began and A. Chappelka (AL) discussed the use of EDU to assess
effects of ozone on two coneflower species. Experiments were conducted in
open-top chambers for two years. EDU at 300 ppm resulted in a decrease in
biomass in the first year, but protected against changes in cell wall digestibility.
In year two, EDU alleviated the effect of ozone on food quality and reduced
foliar injury, but decreased root and total biomass in cut-leaf
coneflower. B. Manning (MA) presented
results of EDU effects on seedling and sapling European Ash which are ozone
sensitive. Seedlings were protected from ozone injury by 450 ppm EDU. In larger trees (17 cm dbh,
16 m high) an equivalent sapling dose on a leaf area basis also reduced leaf
injury. L. Ainsworth (USDA/ARS Univ. IL) discussed ozone effects on photosynthesis,
seed fill and leaf development in Spencer soybean. Ozone restricted net
photosynthesis late in the season and exposure during seed filling led to
reduced leaf growth. In 2004, a low
ozone year, exposure reduced photosynthesis in upper leaf canopy and leaf
carbohydrate, but did not affect yield. Ozone affected spatial and temporal
leaf growth, measured as displacement vector field,
by increasing patchy growth rate heterogeneity.
K. Burkey (USDA/ARS NCSU, NC) presented information on ozone tolerance
in ancestral soybean germplasm. Thirty-five ancestors provide 95% of the
current genes in commercial soybean lines.
Thirty ancestors were screened in controlled chambers at 80 ppb ozone
for 7 d at 6 h per day. Injury rankings
ranged from 25 to 247 (low to high). Six
soybean lines in maturity groups 00 and 0 (northern varieties) were exposed in
open-top chambers. Injury and yield loss were similar to that in the controlled
environment study. Fiskeby was the most tolerant
ancestral variety. S. Krupa (MN)
discussed progress on the collaborative project of ambient ozone effects on
snapbean yield. Two varieties, R331 and S156, are typically grown in the field
and temperature, R.H., wind speed, solar radiation and ozone data are
collected. The variables are then incorporated in a yield response model that
accounts for the contribution of ozone to yield loss. Participating stations
include OR, USDA, NSCU, PA, CA-Kerney, MN, NY-Long
Island, MA, and NJ. The tolerant cultivar performed better than the sensitive one;
however, data from only a few stations are available at present.
Inconsistencies in atmospheric data need to be corrected. Also, the timing of
harvests needs to be resolved due to differential growth rates of the two
cultivars. The application of data from this project to crop production must be
addressed.
P. Morgan
(NC) presented results of studies on ozone signaling in Arabidopsis using
several mutants defective in signaling pathways. Some of the mutants used included G-proteins,
RCD1, EIN, ethylene over-producer (high peroxidase), jasmonate
(ozone sensitive, low peroxidase) and MLO (powdery mildew receptor). Ozone
increased peroxidase activity in most transgenic lines. G-protein
double mutants were not highly ozone sensitive. Peroxidase mutants had varying
responses to ozone but all lines with low enzyme activity were more sensitive.
The MLO receptor protein may be involved in sensing ozone oxidative stress
through modification of SH groups. H.
Sandermann (Freiburg, Ger.)
discussed the toxic agent responsible for ozone foliar injury which is not
ozone itself. The toxic effect appears
to be associated with ethylene signaling.
Ozone exposure results in an initial oxidative burst in both Bel W3 and Bel B tobacco, but a
second burst occurs only in Bel W3. The initial
propagation of phytotoxicity is caused by a local increase in ROS,
probably H2O2 or superoxide. ROS
production is then contained limiting injury to necrotic lesions. B. Chevone
(VA) presented results of altering leaf ascorbate content on ozone sensitivity
in Arabidopsis mutants. A putative F-box protein, VCF1, is developmentally
regulated and causes reduced ascorbate levels as leaf tissue ages making the
foliage more sensitive to ozone. VCF1 reduces expression of several genes in
the mannose/galactose pathway of ascorbate synthesis.
A purple acid phosphatase, PAP15 in
Arabidopsis, is a phytase and over-expression of this
gene results in a 2X to 3X increase in foliar ascorbate. These mutants are more
tolerant to ozone exposure than wild type plants. Phytase
presumably increases foliar myo-inositol and enhances ascorbate synthesis though the myo-inositol
pathway.
C.
Bernacchi (IL State Water Survey) discussed leaf-level processes involved in
canopy scaling in soybean/corn ecosystems exposed to ozone. Ozone caused a small loss in net radiation
resulting in a warmer canopy. Soil heat flux was somewhat higher and diurnal
evapotranspiration somewhat lower under ozone exposure since control plants had
higher transpiration rates. Water use efficiency decreased 17% in ozone-treated
plants in 2002 and 2003 which were high ozone years. No effect was observed in
2004 because of low ozone. D. Decoteau (PA) presented information on the Air
Quality Demonstration
Center at Penn.
State University.
This is the major outreach program of NE1013 and contains open-top chambers, an
air quality monitoring station, a bio-indicator garden, lecture pavilion, and
several display boards showing foliar ozone injury on cultivated and native
plant species. V. Wittig (IL) presented
a meta-analytical review of the effects of tropospheric ozone on trees. Forests
cover 30% of the global land mass and over 1000 articles on ozone impacts exist
in the primary literature. Environmental
conditions, such as drought and ozone concentrations, influence effects. Principal results of the analysis indicated
that ozone negatively impacts root/shoot ratio and foliage biomass. There is
little effect on tree height. The principal mechanism behind these effects is a
29% decrease in stomatal conductance. Of the tree species studied, 44% of
gymnosperms and only 14% of angiosperms showed adverse effects from ozone
exposure. A conclusion of the study was that ozone is reducing the ability of
forests to mitigate increases in atmospheric CO2. B. Zilinskas (NJ) discussed changes in yield,
antioxidant levels and stomatal conductance in wheat under ozone and high CO2
and moisture stress. Two wheat varieties, Gore (S) and Susquehanna (T) were
used and exposed to ambient ozone + 30 ppb and CO2 +150 ppm for 7 h
and 18 h per day, respectively. Stomatal
conductance and net photosynthesis were not different between the two
cultivars. Both lines had similar levels
of oxidized to reduced ascorbate and glutathione. However, Gore had high
ascorbate peroxidase (APX) activity and a low ascorbate pool, while Susquehanna
had low APX activity and a higher ascorbate pool. No change in the ascorbate pool size was
noted after ozone exposure; however, APX activity increased in Susquehanna, but
not in Gore. The yield loss in Gore from ozone exposure was greater than in the
tolerant cultivar. The increase in APX activity and the high ascorbate pool may
contribute to the ozone tolerance of Susquehanna. A. Leakey (IL) presented
results on differences in gene expression in soybean exposed to ambient ozone vs 1.25X ambient. The Affymetrix G. max chip with 38,000 soybean genes was used in this study. The MLO protein, WRYK, and F-box genes were
up-regulated whereas protein synthesis genes were down-regulated.
After the
station reports, a long discussion ensued concerning the collaborative effort
of the snapbean project. One purpose of the project was to determine the
contribution of ambient ozone levels to yield loss of the sensitive cultivar
compared to the tolerant one. This information was deemed important to US EPA
to consider when setting the ozone standard. The question was raised if the project
would really affect the standard setting process since snapbeans are a small
component of U.S.
agriculture. Additionally, since the resistant and sensitive cultivars do not
mature at the same time, the question arose as to the appropriate sampling
time. This decision was left to the participating collaborators on the
project. A discussion then began on the
renewal of NE1013. Several areas were mentioned for inclusion in the renewal
and the topics/coordinators were natural vegetation/A. Chappelka; water
quality/air quality/B. Momen (MD); mechanisms and adaptation/S. Long and K.
Burkey; education and outreach/D. Decoteau; and biomonitoring/W. Manning. S.
Long was denoted coordinator of the renewal with a draft made available by October 1, 2006. R. Knighton
suggested in the future that station reports, either oral or written, should be
directed toward specific objectives of the existing proposal.
A.
Chappelka was voted as the new chair-elect. Potential new members included N.
Grulke (USFS, CA)
and D. Karnosky (Michigan Tech, MI). The
meeting site for next year was selected as Rhinelander, WI. D. Decoteau adjourned
the meeting at 12N on June
20, 2006.
Respectfully submitted,
B. Chevone
Secretary NE1013
Virginia Tech
Blacksburg, VA