2012 Annual Report
1a.Objectives (from AD-416):
Map abiotic resistance genes in soybean for iron deficiency chlorosis, drought, salt stress, aluminum tolerance, and ozone tolerance.
1b.Approach (from AD-416):
Approximately 200 random inbred lines at the F5 stage are ready for seed increase during the summer of 2010 to generate the seed stocks that will be used as material for subsequent evaluations of environmental stress resistance. DNA extraction will be performed and SNP markers will be generated for each random inbred line of the population. A linkage map for the population will be constructed from the DNA data. The population will be evaluated for drought, iron deficiency chlorosis, toxic soil aluminum, salt, and atmospheric ozone pollution, the association of each trait with DNA markers (QTL analysis) will be performed.
Independent preliminary research conducted by USDA-ARS in Raleigh, NC, and by the University of Minnesota identified a family of soybean genotypes from Fiskeby, Sweden, that are resistant or partially resistant to drought, iron deficiency chlorosis, toxic soil aluminum, salt, and atmospheric ozone pollution. A population developed from hybridization of Fiskeby III (representing the stress resistance of the Fiskeby soybean family) with Mandarin (Ottawa) (susceptible to drought, ozone, salt, and iron deficiency chlorosis, but resistant to aluminum) will be used to map resistance genes. The original hybridization was made in 2006 and seed of the resulting population were advanced by single seed descent.
This research is related to Objective 3 of the parent project to identify soybean germplasm that will contribute to development of stress tolerant cultivars.
A mapping population of random inbred lines has been developed from a cross between tolerant (Fiskeby III) and sensitive (Mandarin Ottawa) genotypes. Each random inbred line will be assessed for response to each abiotic stress factor and these phenotypic data combined with DNA marker data to construct linkage maps for each factor.
Initial phenotyping of the population for iron deficiency chlorosis was conducted during the summer of 2011 in Minnesota field trials by our University of Minnesota cooperator. Injury evaluations revealed good separation of the parents with Fiskeby III having a lower score than Mandarin (Ottawa). Variation for iron deficiency chlorosis injury is extensive within the population with scores for individual lines distributed throughout the complete range of injury scores from 1 to 5. The experiment is being repeated during the summer of 2012.
Excessive rain throughout the 2011 growing season prevented collection of wilting score data from the drought plots in Minnesota by our University of Minnesota cooperator. Seeds were harvested, processed and stored to ensure an adequate seed supply for remaining phenotyping studies. Drought tolerance evaluation of the population is being conducted in 2012, but success will depend on rainfall patterns providing drought conditions in Minnesota later in the season when canopy wilting can be accurately assessed.