|BURTON, AMY - Bayer Cropscience|
|ORF, JAMES - University Of Minnesota|
Submitted to: Theoretical and Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/30/2016
Publication Date: 2/26/2016
Citation: Burton, A., Burkey, K.O., Carter Jr, T.E., Orf, J., Cregan, P.B. 2016. Phenotypic variation and identification of quantitative trait loci for ozone injury in a Fiskeby III x Mandarin (Ottawa) soybean population. Theoretical and Applied Genetics. 129:1113-1125.
Interpretive Summary: Ground level ozone is formed by the action of sunlight on volatile hydrocarbons and nitrogen oxides produced during combustion of carbon based fuels. Although frequently considered an urban problem, ozone pollution is much broader in scope because weather systems transport the pollutants into agricultural areas. Ozone is toxic to plants, causing visible injury to foliage and a reduction in the growth and yield of sensitive crops such as soybean. Estimates suggest that current ambient ozone levels are sufficient to reduce soybean yield by 10% or more with greater yield losses anticipated if tropospheric ozone concentrations continue to rise. In the absence of successful efforts to control air pollution, future crop productivity may depend on the development of ozone-tolerant soybean varieties. In this study, USDA-ARS researchers and colleagues from the University of Minnesota developed a mapping population from ozone-sensitive and tolerant soybean genotypes and used DNA techniques to identify molecular markers for ozone response genes in soybean. The results are a first step toward using genetic approaches to develop cultivars capable of maintaining yields under elevated ozone conditions.
Technical Abstract: Ground-level ozone reduces yield in crops such as soybean (Glycine max (L.) Merr.). Phenotypic variation has been observed for this trait in multiple species; however, breeding for ozone tolerance has been limited. A recombinant inbred population was developed from soybean genotypes differing in tolerance to ozone: tolerant Fiskeby III and sensitive Mandarin (Ottawa). Plants were exposed to ozone treatment for five days in greenhouse chambers followed by visual scoring for foliar injury. Mean injury score in the mid-canopy was 16% for Fiskeby III, and 81% for Mandarin (Ottawa). Injury scores were lower in younger leaves for both parents and their progeny, compared to scores in the older leaves. Segregation was consistent with multigenic inheritance. Correlations of injury among leaf positions were generally strong (0.40-0.87), with neighboring leaves showing the strongest correlations. Narrow sense heritability within an ozone treatment chamber was 0.59, 0.40, 0.29, 0.30, 0.19, and 0.35 for the 2nd, 3rd, 4th, 5th, 6th, and combined 3rd-5th main stem leaf positions (numbered acropetally), respectively, based on genotypic means over three independent experiments. Quantitative trait loci (QTL) analysis showed that loci were associated with distinct leaf developmental stages. QTL were identified on linkage group (LG) 17 for the 2nd and 3rd leaf positions, and on LG 4 for the 5th and 6th leaf positions. Additional loci were identified on LGs 6, 18, 19, and 20. Interacting loci were identified on LG 5 and 15 for injury on trifoliate 4. The ozone sensitive parent contributed one favorable allele for ozone response.