QTL Meta-Analysis for Flowering Time and Yield in Maize

Yield is the most important and complex trait in maize and flowering time has a direct impact on it. Many studies have been carried out with the objective to map yield and flowering time quantitative trait loci (QTLs). These studies produced hundreds of scientific publications and a large amount of information which has been deposited in different databases. Therefore, an important synthesis effort is required in order to more effectively harness this information. QTL meta-analysis allows us to identify consensus QTLs across studies while refining QTL mapping. In this study, an exhaustive literature search was carried out in order to extract information on the number, position and genetic effect of yield and flowering time QTLs in maize. A total of 1,048 yield and yield-related QTLs from 47 studies and 174 flowering time QTLs from 21 studies were projected on the IBM Genetic maize reference map. MetaQTLs (MQTLs) were computed using Biomercator 3.0. In total, 75 and 53 MQTLs for yield and flowering time were identified, respectively. Forty-nine percent of the MQTLs for flowering time overlap with MQTLs for yield, while 34.6% of yield MQTL overlap with MQTL for flowering time. Positions and distribution of QTLs and MQTLs on the maize genome map will also be compared with genomic features such as genetic diversity and gene density. These results provide a comprehensive view of the genomic landscape underpinning flowering time and yield in maize while contributing opportunities toward a more effective exploitation of allelic variants in marker-assisted breeding.