Genetic diversity and population structure of sweet corn in China as revealed by mSNP

Corn is a widely grown cereal crop that serves as a model plant for genetic and evolutionary studies. However, the heterosis pattern of sweet corn remains unclear. Here, we analysed the genetic diversity and population structure of 514 sweet corn inbred lines and 181 field corn inbred lines. The population structure study enabled the classification of sweet corn into four groups: temperate sweet corns 1 and 2, tropical sweet corn, and subtropical sweet corn, in addition to the temperate and tropical field corn groups. Temperate sweet corn groups 1 and 2 were merged into the temperate sweet corn cluster in the phylogenetic trees. Principal component analysis divided sweet corn into four groups: temperate groups 1 and 2, tropical, and subtropical. Sweet corn exhibited lower levels of genetic diversity, polymorphism information content, and minor allele frequency than field corn. The average genetic distances and differentiation coefficients between inbreds within each sweet corn group were lower than those within field corn groups, indicating a relatively narrow genetic base in sweet corn. Taken together, the 514 sweet corn inbred lines can be divided into four groups: temperate 1, temperate 2, tropical, and subtropical. The classification of sweet corn groups in this study provides a reference for the breeding of sweet corn.