QTL Associated with Maize Kernel Oil, Protein, and Starch Concentrations; Kernel Mass; and Grain Yield in Illinois High Oil × B73 Backcross‐Derived Lines

Abstract

Illinois long‐term selection strains of maize ( Zea mays L.) have been useful for identifying genomic regions controlling kernel oil, protein, and starch concentrations. To identify kernel trait quantitative trait loci (QTL) in a genetic background more relevant to practical breeding, 150 BC 1 ‐derived S 1 lines (BC 1 S 1 s) were produced from Illinois High Oil and recurrent parent B73. Oil, protein, and starch were measured in BC 1 S 1 s and in Mo17‐topcross hybrids (TCs). Kernel mass of BC 1 S 1 s and grain yield of TCs were also determined. Starch was positively correlated with mass in BC 1 S 1 s (r p = 0.67**, α ≤ 0.01) and with yield in TCs (r p = 0.59**). Oil was negatively correlated with mass in BC 1 S 1 s (r p = −0.29**) and with yield in TCs (r p = −0.30**). Oil was negatively correlated with starch in BC 1 S 1 s (r p = −0.75**) and TCs (r p = −0.66**). A genetic map with length = 1486 cM was created with 110 markers. Multiple regression models with QTL detected by composite interval mapping (CIM) explained 46.9, 45.2, 44.3, and 17.7% of phenotypic variance for oil, protein, starch, and mass, respectively, in BC 1 S 1 s and 17.5, 22.9, 40.1, and 28.7% for oil, protein, starch, and yield, respectively, in TCs. A 22 cM‐interval on chromosome 6 in BC 1 S 1 s included oil, protein, and starch QTL, including a QTL explaining 36.7% of the BC 1 S 1 phenotypic variation for oil. No yield QTL were detected in this region. Introgression of this QTL into breeding lines might increase oil while maintaining yield.