Association mapping of haploid male fertility in sweet corn

Association mapping of a subset of the SweetCAP diversity panel revealed ten single-nucleotide polymorphisms (SNPs) associated with haploid male fertility (HMF), which provided four candidate genes. Doubled haploid (DH) technology using in vivo haploid induction has dramatically improved the efficiency of maize breeding programs worldwide. However, limitations from genome doubling create a bottleneck for DH line production. To overcome such limitations, spontaneous haploid genome doubling (SHGD) has gained prominence over the last decade, specifically in field corn materials. On the contrary, SHGD in sweet corn has been largely overlooked. A subset of 286 sweet corn genotypes from the SweetCAP diversity panel was evaluated for their ability to restore male fertility in the haploid state, otherwise known as haploid male fertility (HMF). Association mapping identified ten single-nucleotide polymorphisms (SNPs) associated with HMF, which provided four candidate genes. Our results highlight significant variation for HMF, with 11 genotypes having > 54% HMF. These genotypes demonstrate HMF naturally exists in sweet corn germplasm and can be used for population improvement.