Abstract
Grain oil content is negatively correlated with starch content in maize in general. In this study, 282 and 263 recombinant inbred lines (RIL) developed from two crosses between one high-oil maize inbred and two normal dent maize inbreds were evaluated for grain starch content and its correlation with oil content under four environments. Single-trait QTL for starch content in single-population and joint-population analysis, and multiple-trait QTL for both starch and oil content were detected, and compared with the result obtained in the two related F2∶3 populations. Totally, 20 single-population QTL for grain starch content were detected. No QTL was simultaneously detected across all ten cases. QTL at bins 5.03 and 9.03 were all detected in both populations and in 4 and 5 cases, respectively. Only 2 of the 16 joint-population QTL had significant effects in both populations. Three single-population QTL and 8 joint-population QTL at bins 1.03, 1.04–1.05, 3.05, 8.04–8.05, 9.03, and 9.05 could be considered as fine-mapped. Common QTL across F2∶3 and RIL generations were observed at bins 5.04, 8.04 and 8.05 in population 1 (Pop.1), and at bin 5.03 in population 2 (Pop.2). QTL at bins 3.02–3.03, 3.05, 8.04–8.05 and 9.03 should be focused in high-starch maize breeding. In multiple-trait QTL analysis, 17 starch-oil QTL were detected, 10 in Pop.1 and 7 in Pop.2. And 22 single-trait QTL failed to show significance in multiple-trait analysis, 13 QTL for starch content and 9 QTL for oil content. However, QTL at bins 1.03, 6.03–6.04 and 8.03–8.04 might increase grain starch content and/or grain oil content without reduction in another trait. Further research should be conducted to validate the effect of these QTL in the simultaneous improvement of grain starch and oil content in maize.
Highlights
Maize is widely used as an important renewable resource for industrial materials, biodiesel production, and dietary consumption by humans and animals all over the world [1,2,3,4]
Wassom et al [9] found that starch content was positively correlated with kernel mass in BC1S1s and with yield in TCs, while oil content was negatively correlated with kernel mass and starch content in BC1S1s and with yield in TCs by analyzing kernel traits in a backcross and testcross populations derived from Illinois High Oil (IHO) and the recurrent parent B73
Further negative correlations between starch and oil content at different levels were reflected in populations for QTL mapping using different genetic backgrounds, such as Illinois High Protein (IHP) and Illinois Low Protein (ILP) [5,14], Illinois High Oil (IHO) and Illinois Low Oil (ILO) [9,15,16,17], Beijing high-oil (BHO) [18,19], tropical [8], Alexho Single-Kernel (ASK) high-oil [20,21], and popcorn [13]
Summary
Maize is widely used as an important renewable resource for industrial materials, biodiesel production, and dietary consumption by humans and animals all over the world [1,2,3,4]. After Hopkins (1899) initiated the selection of high and low grain oil content in maize [6], several research went along with the improvement of grain chemical composition using different genetic backgrounds [5,7,8,9,10]. Several early research demonstrated that the negative correlation between grain starch and oil content was resulted in the reduction of starch content and grain yield along with the increase of oil content [4,11,12,13]. The molecular basis of QTL for oil and starch content and their relationship should be extensively revealed in further research
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