POSSIBLE IDENTIFICATION OF QUANTITATIVE TRAIT LOCI AFFECTING IRON EFFICIENCY IN SOYBEAN

Iron (Fe)-deficiency in soybean [Glycine max (L.) merr.] may cause yield reductions when certain genotypes are planted on 4 calcareous soil. This research was conducted to map quantitative trait loci (QTL) for Fe-efficiency in a set of lines (set 1), and to test these associations in another set of lines of the same population (tester set). The population was formed by crossing a Glycine max experimental line (Fe-inefficient) and a C. soja plant introduction (Fe-efficient). Set 1 was used to construct a restriction fragment length polymorphism (RFLP) linkage map using 272 markers for the analysis. The tester set was developed to check the results obtained from set 1. Iron-efficiency was measured using 13 F2-derived lines of both sets in field plantings on calcareous soils. Set 1 and and the tester set were evaluated over two and one years, respectively. The lines were grown each year at two locations per year, with three replications per location in Iowa. Three markers were significantly (P<0.01) associated with Fe-efficiency in set 1. Two of these markers were linked and explained 31 and 25% of the variation for Fe-efficiency in the population. The other marker explained 17% of the variation. The associations were inconsistent between sets. Several important associations in set 1 were not significant in the tester set. These results indicated that of the 272 molecular markers used, none was associated with the observed variation in Fe-efficiency.