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Title: DIFFERENTIAL RESPONSES OF G-PROTEIN ARABIDOPSIS THALIANA MUTANTS TO OZONE

Author
item Booker, Fitzgerald
item Burkey, Kent
item OVERMYER, KIRK - UNIV. OF NORTH CAROLINA
item JONES, ALAN - UNIV. OF NORTH CAROLINA

Submitted to: New Phytologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/15/2004
Publication Date: 3/1/2004
Citation: Booker, F.L., Burkey, K.O., Overmyer, K., and Jones, A.M. 2004. Differential responses of G-protein Arabidopsis thaliana mutants to ozone. New Phytologist 162:633-641.

Interpretive Summary: Current concentrations of ground-level ozone curtail production of susceptible crops by 5 to 15% in many agricultural regions worldwide. However, the exact basis for ozone toxicity remains unclear. It appears to consist of a combination of cellular damage from a powerful oxidant (ozone) combined with plant defense responses that compound plant injury. Because some plant defense responses involve membrane-bound GTPases (G proteins), we chose to evaluate the ozone sensitivity of Arabidopsis mutants with altered G-proteins. After exposure to ozone, the leaf curling response that is typically observed for wild type leaves does not occur in mutant plants lacking the alpha subunit of the G protein complex. Ozone-induced decreases in leaf chlorophyll levels and leaf mass are less for these mutants, which is further support for a reduced ozone effect in the mutants. These results indicate that a G-protein is critically involved in conveying ozone effects at the cellular level that lead to lost productivity and suggest possible targets for improving plant resistance to ozone.

Technical Abstract: Current concentrations of ground-level ozone curtail production of susceptible crops by 5 to 15% in many agricultural regions worldwide. However, the etiology of ozone toxicity remains unclear. It appears to consist of a combination of biochemical lesions inflicted by activated oxygen species and elicited plant defense responses that compound plant injury. Because some plant defense responses involve membrane-delimited GTPases (G proteins), we chose to evaluate the ozone sensitivity of Arabidopsis mutants altered in the heterotrimeric G-protein pathway. After treatment with ozone for six days, the hyponastic growth that is typically observed for wild type leaves does not occur in mutant plants lacking the alpha subunit of the heterotrimeric G protein complex (gpa1). Ozone-induced suppression of leaf chlorophyll levels and leaf mass per unit leaf are less for gpa1 mutant and are not due to differences in ozone flux. These results indicate that a heterotrimeric G protein is critically involved in transducing ozone effects in plants.