MECHANISMS OF PLANT RESPONSES TO GLOBAL ATMOSPHERIC CHANGE

Authors: LONG, S - UNIVERSITY OF ILLINOIS; Ainsworth, Elizabeth - Lisa; BERNACCHI, C - IL STATE WATER SURVEY; LEAKEY, A D - UNIVERSITY OF ILLINOIS; Morgan, Patrick; NAIDU, S - UNIVERSITY OF ILLINOIS; ROGERS, A - BROOKHAVEN NATIONAL LAB; BOHNERT, H - UNIVERSITY OF ILLINIOS; Ort, Donald; Nelson, Randall

Submitted to: International Botanical Congress
Publication Type: Abstract Only
Publication Acceptance Date: 7/17/2005
Publication Date: 7/17/2005
Citation: Long, S.P., Ainsworth, E.A., Bernacchi, C.J., Leakey, A.B., Morgan, P.B., Naidu, S.L., Rogers, A., Bohnert, H.J., Ort, D.R., Nelson, R.L. 2005. Mechanisms of plant responses to global atmospheric change [abstract]. XVII International Botanical Congress. Paper No. GL2.5.

Interpretive Summary: Carbon dioxide and ozone concentrations in the atmosphere are rising. Both of these global environmental changes directly affect crop performance. Ozone damage currently costs crop production over 5 billions Euros per year and similar damage is caused to natural ecosystems. New experiments that expose crops to elevated carbon dioxide and ozone under totally open-air conditions have revealed some surprising results that were not anticipated from studies in enclosures. Season-long exposure to elevated ozone causes a decrease in plant productivity and accelerated senescence. While carbon dioxide increases photosynthesis and plant productivity, ozone damage will significantly decrease plant produtivity in the future.

Technical Abstract: The CO2 and ozone (O3) concentrations of the troposphere are rising with direct impacts on plants. O3 currently costs crop production >5bn Euro a year with parallel damage to natural ecosystems. In the short-term, elevated CO2 stimulates and elevated O3 depresses photosynthesis in highly predictable ways. Longer-term effects are less predictable, but new patterns are now emerging via meta-analysis of realistic field treatment in Free-Air Concentration Enrichment (FACE) facilities. The chain of effects from gene expression to acclimated phenotype that result from long-term growth in elevated CO2 or O3 will be reviewed. Significant season-long increases in photosynthesis and production with CO2 are found, with some surprising changes in plant development that were not apparent or suspected in studies with field enclosures. Season-long exposures to the moderate increases in O3 observed in the field caused more transcripts to be down-regulated than up-regulated, cause a chronic decrease in photosynthetic capacity, largely attributed to decreased Rubisco activity, and cause slightly accelerated senescence.