Nutrient Determination In a Soybean Breeding Population Developed for Iron Deficiency Chlorosis Resistance.

Iron deficiency chlorosis (IDC) is a nutritional disease of soybean (Glycine max (L.) Merr.) which when left unchecked can result in a severe yield penalty or even death in the most extreme cases. In order to curb these effects, resistance to the disease is needed. Breeding for resistance has been somewhat successful but no cultivar has complete resistance. Mineral content of the soybean could be an indicator of the ability of the plant to withstand the effects of IDC. We evaluated iron and zinc content in soybean seed and leaves to be used as an estimator of mineral deficiency resistance in early growing stages of soybean, when symptoms are commonly observed. Specifically, leaf and seed tissue of two near-isogenic lines (NILs), Fe-efficient Clark (PI548533) and Fe-inefficient Iso-Clark (PI 547430), and Fe-inefficient Pride B216 and Fe-efficient A15, as well as progeny (F2:4) of the cross Anoka x A7 were analyzed to quantify Fe and Zn content. Preliminary evaluation of the genotypes suggested that Fe and Zn concentration in seeds is higher in the Fe-efficient lines than in the Fe-inefficient lines. Significant differences in Fe and Zn content were also observed in the progeny population. For seed Fe, the range for the top 10% was 83.97 – 92.71 µg/g and the bottom 10% was 64.14 – 69.77 µg/g. The top 10% in seed Zn was 3.79 – 3.97 µg/g, and the bottom 10% 3.54 – 3.64 µg/g. Leaf Zn and Fe was not influenced by Fe efficiency or inefficiency, although there were significant differences in the population. We next plan to map variation in these mineral traits as quantitative trait loci (QTL). Our hypothesis is that QTL for Fe and Zn content will correlate to known QTL for IDC resistance.