QTL mapping for six ear leaf architecture traits under water-stressed and well-watered conditions in maize (Zea mays L.)

Morphological traits for ear leaf are determinant traits influencing plant architecture and drought tolerance in maize. However, the genetic controls of ear leaf architecture traits remain poorly understood under drought stress. Here, we identified 100 quantitative trait loci (QTLs) for leaf angle, leaf orientation value, leaf length, leaf width, leaf size and leaf shape value of ear leaf across four populations under drought-stressed and unstressed conditions, which explained 0.71%-20.62% of phenotypic variation in single watering condition. Forty-five of the 100 QTLs were identified under water-stressed conditions, and 29 stable QTLs (sQTLs) were identified under water-stressed conditions, which could be useful for the genetic improvement of maize drought tolerance via QTL pyramiding. We further integrated 27 independent QTL studies in a meta-analysis to identify 21 meta-QTLs (mQTLs). Then, 24 candidate genes controlling leaf architecture traits coincided with 20 corresponding mQTLs. Thus, new/valuable information on quantitative traits has shed some light on the molecular mechanisms responsible for leaf architecture traits affected by watering conditions. Furthermore, alleles for leaf architecture traits provide useful targets for marker-assisted selection to generate high-yielding maize varieties.