Analysis of candidate genes identified via genome-wide association analysis of sugar-related traits in maize kernels

Maize (Zea mays L.) is a globally significant crop, with its kernel sugar content playing a crucial role in determining nutritional quality and industrial applications. This study aimed to elucidate the genetic mechanisms underlying sugar-related traits in maize kernels through genome-wide association studies. We evaluated 495 maize inbred lines for reducing sugar content, soluble sugar content, and the reducing/soluble sugar ratio. Phenotypic analysis revealed substantial variation, with coefficients of variation ranging from 28.84% to 53.86%, and high broad-sense heritability (87.90%-93.98%). Using 12,617,573 high-quality single-nucleotide polymorphisms, we identified 93 significant quantitative trait nucleotides associated with these traits. Transcriptomic data from the maize inbred line B73 highlighted six candidate genes (Zm00001d040189, Zm00001d032517, Zm00001d052399, Zm00001d028974, Zm00001d036971, and Zm00001d022316) with high expression during kernel development. Protein-protein interaction and coexpression network analyses suggested that these genes are involved in metabolic processes, cell communication, and carbohydrate metabolism. Haplotype analysis further revealed that the optimal haplotypes of the six candidate genes could increase the kernel sugar content without affecting the yield traits of maize. These findings advance our understanding of the genetic basis of sugar-related traits in maize and offer valuable molecular markers for future breeding programs.