Location and mapping of the NCLB resistance genes in maize by bulked segregant analysis (BSA) using whole genome re-sequencing

Northern corn leaf blight (NCLB) is one of the main diseases of maize, which greatly reduces production and causes millions of dollars in losses worldwide annually. Identification of NCLB resistance genes in maize plays an important role in the crop disease resistance breeding. In this study, a BC1F1 population with 1290 individuals was constructed using high resistance line CML493 and high susceptible line PH4CV. In total, 50 resistant individuals and 50 susceptible individuals from the BC1F1 population were selected to construct 4 DNA pools (also with the two parents) which were used for high-throughput sequencing. The key candidate genes associated with NCLB resistance genes were identified using BSA-seq and KASP platforms. The results showed that 3 genes including CDPK21, HEX9, and MKKK18 were identified and this prediction was further verified by RT-qPCR. The annotation functions were sugar signaling, calcium signaling, and MAPK signaling pathways. This research provided key NCLB resistance candidate genes and also provided important markers for disease resistance breeding in maize.