Nutrient solution screening of Fe chlorosis resistance in soybean evaluated by molecular characterization

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Abstract
Nutrient solution systems have been considered an alternative method to field evaluations for studies of iron deficiency chlorosis (IDC) and for breeding soybeans with improved iron efficiency. To map genes controlling IDC in nutrient solution, 120 F24 lines in a Pride B216 × A15 population, and 92 F24 lines in an Anoka × A7 population were grown in nutrient solution in greenhouse plantings and evaluated for IDC by visual scores and determinations of chlorophyll concentrations. Eighty‐nine restriction fragment length polymorphism (RFLP) and 10 simple sequence repeat (SSR) markers in the Pride B216 x A15 population, and 82 RFLP, 14 SSR and one morphological (hilum color) markers in the Anoka x A7 population were used to construct linkage maps and to locate quantitative trait loci (QTL) controlling IDC. In the Anoka × A7 population, one major gene on linkage group N, and modifying QTL on linkage groups A1 and I previously mapped during field tests also were identified in the nutrient solution test. Different genetic linkage groups in soybean have been identified by letters, and as such will be used throughout the paper. One newly identified QTL was mapped on linkage group B2. In the Pride B216 × A15 population, one QTL previously mapped on linkage group I during field tests was not identified in the nutrient solution test, and two newly identified QTL were mapped on linkage groups A2 and B1. QTL on linkage groups B2, G, H, L, and N were identified in both field and nutrient solution tests. Due to significant interaction between genotype and environment in both field and nutrient solution tests, QTL identifications from multiple environments were used to compare the similarity between field and nutrient solution tests. We concluded that similar QTL are identified in nutrient solution and field tests and therefore, both systems identify similar genetic mechanisms of iron uptake and/or utilization.