Submitted to: Molecular Plant-Microbe Interactions
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/10/2008
Publication Date: 10/1/2008
Citation: Bilgin, D.D., Aldea, M., O'Neill, B.F., Benitez, M., Li, M., Clough, S.J., Delucia, E.H. 2008. Elevated Ozone Alters Soybean-Virus Interaction. Molecular Plant-Microbe Interactions. 21(10):1297-1308. Interpretive Summary: In the Midwest U.S., ozone commonly occurs at levels damaging to soybean and the general ozone concentration is expected to continue to increase. This research studied the effect of elevated ozone (elevated to levels predicted to be common in the Midwest in the year 2050) on soybean defense to the virus Soybean Mosaic Virus (SMV). Increased levels of ozone stress plants and therefore generate a more inhospitable environment for pathogens like SMV. Although plants exposed to higher ozone levels were slightly more resistant to SMV, they were still infected and the disease advanced sufficiently to cause yield losses. This information will be of use to plant pathologists, geneticists and breeders, and climate change scientists.
Technical Abstract: We examine the effects of elevated O3 and elevated CO2, two major components of global change, on the interaction between soybean and Soybean Mosaic Virus (SMV) by measuring molecular, cellular, and physiological processes, in natural field conditions and in controlled environment. In natural field conditions, both elevated O3 and elevated CO2 treatments slowed systemic infection and disease development by SMV and prevented the negative effect of virus infection on light-saturated carbon assimilation rate. To understand how the oxidative stress produced by elevated O3 altered soybean immunity, the soybean gene expression profile was analyzed. In controlled environment, the soybean transcriptional response to elevated O3, with or without SMV infection, was measured, and specific and common genes that were regulated by both stresses were identified. Fungal, bacterial and viral defense-related genes, including PR-1, PR-5, PR-10, EDS1 and isoflavonoid biosynthesis pathway genes were up regulated by exposure to elevated O3 inducing a non-specific defense response in soybean. Elevated CO2 increased the formation of Reactive Oxygen Species in soybean foliar tissue and induction of PR-5 gene transcription. Both elevated O3 and CO2 conferred non-specific resistance to SMV, suggesting that these elements of global change will alter the co-evolutionary relationship and ecological consequences of plant-pathogen interactions in the future.