Genetic dissection of seedling traits in a BC 4 F 3 population under the stress of cadmium in sweet corn

Cadmium pollution has become a serious global threat to agricultural sustainability. Uncovering genetic loci and candidate genes associated with cadmium tolerance is of great importance. In this study, a BC₄F₃ population was used to identify quantitative trait loci (QTL) controlling cadmium tolerance in sweet corn seedlings by applying composite interval mapping. The results revealed significant transgressive segregation in the population phenotypes, with broad-sense heritability values of 0.60, 0.63, and 0.66 for seedling height (SH), root length (RL), and seeding fresh weight (SFW), respectively. A total of eight QTLs were detected over two years, distributed on chromosomes 1, 2, 3, 4, and 6, with phenotypic variation explained (PVE) ranging from 6.2% to 8.0%. Among these, five QTLs were associated with SH, with qSH2.1 showing the highest PVE. Gene annotation and GO enrichment analysis of the genes within the eight QTL intervals revealed significant enrichment in three pathways: GO:0016667 (oxidoreductase activity, acting on a sulfur group of donors), GO:0030983 (mismatched DNA binding), and GO:0030151 (molybdenum ion binding). Within these significantly enriched pathways, 15 candidate genes related to cadmium stress response were identified. These findings will facilitate the identification of functional genes and molecular marker-assisted breeding, thereby improving heavy metal tolerance in sweet corn.