Meta-QTL analysis and identification of candidate genes related to root traits in maize

Maize root system architecture determines key functions of uptake of water and nutrients in plants. A large number of quantitative trait loci (QTLs) of root-related traits have been found in different populations of maize. Identification of consistent QTLs across diverse genetic backgrounds could be instrumental on marker-assisted selection of traits and identification of candidate functional genes. In this study, 20 published papers were investigated regarding on reported results of QTLs related to root traits of maize, and in total 428 individual QTLs for 23 root-related traits were used for meta-analysis, resulting in 53 Meta-QTLs (MQTLs) retrieved over ten maize chromosomes. Among these MQTLs regions, in total 45 maize homologs were considered as candidate genes affecting maize root traits by comparing with 7 genes from rice and 36 genes from Arabidopsis. Three maize genes (GRMZM5G813206, GRMZM2G167220 and GRMZM2G467069) identified from MQTL_8-5 could play important roles on lateral root and crown root development of maize. Two of the MQTLs, i.e. MQTL_7-2 and MQTL_9-1, involved in nitrogen (N) and phosphorus (P) stress responses and both of them with small physical distance (less than 3 Mb), could be used for abiotic stress improvement of maize root traits. These MQTLs and candidate genes will be helpful for future gene cloning and marker-assisted selection in maize.