Long-read sequencing reveals genomic structural variations that underlie creation of quality protein maize

Mutation of o2 doubles maize endosperm lysine content, but causes inferior kernel phenotype. Quality protein maize (QPM) is developed by introgressing o2 modifiers (Mo2s) into the o2 mutant. Here the authors report the genome sequence and annotation of South African QPM line K0326Y assembled from single-molecule, real-time reads collinear with an optical map. The assembly achieves an N50 contig length of 7.7 Mb from long-read assembly (vs 1.04 Mb for B73 and 1.48 Mb for Mo17). To characterize Mo2s, QTLs are mapped to chromosomes 1, 6, 7, and 9 using an F2 population from K0326Y × W64Ao2. RNA-seq of QPM and o2 endosperms reveals differentially expressed genes that coincide with Mo2 QTLs, suggesting roles in vitreous endosperm formation.

Changsheng Li, Xiaoli Xiang, Yongcai Huang, Yong Zhou, Dong An, Jiaqiang Dong, Chenxi Zhao, Hongjun Liu, Yubin Li, Qiong Wang, Chunguang Du, Joachim Messing, Brian A. Larkins, Yongrui Wu, Wenqin Wang