Quantitative Trait Loci Mapping of Soybean Response to Elevated Ozone

With approximately 80 million metrics tons produced annually, the United States is the largest producer of soybean [Glycine max (L.) Merr.] in the world. Soybean is known to be one of the more sensitive major agricultural food crops to tropospheric ozone (O₃). Ozone is a secondary air pollutant currently estimated to reduce soybean seed yield by 8.5 to 14% in the United States. With O₃ concentrations having already doubled over the past century and projected to increase by an additional 10% by 2030, the losses in soybean production due to O₃ are expected to continue. To investigate the genetic basis of O₃ sensitivity, a soybean population consisting of 192 recombinant inbred lines (RILs) was grown under ambient (~40 ppb) and elevated (~100ppb) O₃ concentrations for three years at the Soybean Free Air Concentration Enrichment (SoyFACE) site in Champaign, IL. Seed yield, seed weight, plant height, and leaf spectral traits were monitored in all plants during the three years of study. Leaf N content, chlorophyll content, photochemical reflective index, specific leaf area and photosynthetic capacity were estimated from leaf spectrum. Overall, O₃ treated plots reduced yield, 100 seed weight, plant height, stem diameter, and shortened the number of days to maturity when compared to control plots. Future work will involve the mapping of O₃ response QTL for each of the measured traits in order aid in gene discovery and future plant breeding applications.