QTL mapping of leaf angle on eight nodes in maize enable the optimize canopy by differential operating of leaf angle at different levels of plant

Leaf angle (LA) is one of the most important canopy architecture traits of maize (Zea mays L.). To date, there is an urgent need to characterize the genetic control of LA at multiple nodes to bridge the information gap remain in optimizing canopy architecture for maximum yield at different canopy levels. In this study, through the cross between B73 (compact plant architecture) and SICAU1212 (expanded plant architecture), 199 derived RIL families were used to perform QTL mapping for LA from eight leaves at different nodes in three environments, utilizing single-environment analysis and joint mapping. Combining the results of two mapping strategies, we identified 15 common QTL associated with LA at eight nodes. The phenotypic variation explained by the individual QTL ranged from 0.39% to 20.14% and the number of leaves controlled by a single QTL varied from 1 to 8. Among them, QTL qLA2.1 and qLA5.1 simultaneously controlled LA of all the eight nodes; however, qLA2.2 only affected that of 1stLA. The total phenotypic variation explained by all QTL identified for LA at eight nodes ranged from 15.69% (8thLA) to 51.73% (1stLA). The number of QTL detected for LA at each nodes ranged from 4 (7thLA) to 11 (1stLA). These results provide comprehensive insights into the molecular bases of regulatory networks in LA morphogenesis, and will benefit the molecular design breeding of ideotype and further cloning of LA QTL at different plant levels in maize.