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Elevated Ozone Alters Soybean-Virus Interaction

¹Institute for Genomic Biology, University of Illinois at Urbana-Champaign (UIUC), 1206 W. Gregory Drive; ²Department of Plant Biology, UIUC, 265 Morrill Hall, 505 South Goodwin Avenue; ³Department of Entomology, UIUC, 320 Morrill Hall, 505 South Goodwin; ⁴Department of Crop Sciences, UIUC, 1101 W. Peabody Drive; and ⁵United States Department of Agriculture--Agricultural Research Service, 1101 W. Peabody Drive, Urbana, IL 61801, U.S.A.

Increasing concentrations of ozone (O₃) in the troposphere affect many organisms and their interactions with each other. To analyze the changes in a plant--pathogen interaction, soybean plants were infected with Soybean mosaic virus (SMV) while they were fumigated with O₃. In otherwise natural field conditions, elevated O₃ treatment slowed systemic infection and disease development by inducing a nonspecific resistance against SMV for a period of 3 weeks. During this period, the negative effect of virus infection on light-saturated carbon assimilation rate was prevented by elevated O₃ exposure. To identify the molecular basis of a soybean nonspecific defense response, high-throughput gene expression analysis was performed in a controlled environment. Transcripts of fungal, bacterial, and viral defense-related genes, including PR-1, PR-5, PR-10, and EDS1, as well as genes of the flavonoid biosynthesis pathways (and concentrations of their end products, quercetin and kaempherol derivatives) increased in response to elevated O₃. The drastic changes in soybean basal defense response under altered atmospheric conditions suggest that one of the elements of global change may alter the ecological consequences and, eventually, coevolutionary relationship of plant--pathogen interactions in the future.

Additional keywords:microarray, photosynthesis, ROS, SoyFACE.