Identification of genomic regions associated with the important micronutrients in maize (Zea mays L.) for multi-trait stacking

Abstract

Maize (Zea mays L.), a global staple, is often deficient in essential micronutrients and amino acids, contributing significantly to malnutrition. To solve this problem, genetic biofortification has emerged as a practical, cost-effective, convenient, and sustainable approach. Despite numerous QTL mapping studies for micronutrients (such as iron and zinc), only a few of these have been effectively utilized in a breeding program. To bridge this gap, a meta-QTL (MQTL) analysis was conducted using 532 QTLs from 14 published studies. These QTLs were associated with key vitamins (A and E) and minerals (iron, zinc, calcium, copper, manganese, magnesium, phosphorus, potassium, and sulphur). The analysis identified 28 MQTLs distributed across all ten chromosomes of maize. Additionally, 139 candidate genes associated with different minerals and vitamins were also detected. Several known genes encoding for some enzymes involved in biosynthetic pathways were also found to be co-localized with several MQTL, including MQTL 2.1, 2.3, 5.2, 6.1, 6.2, 7.1, 7.2, 8.2, 9.1, 10.1, and 10.2. Furthermore, 161 significant SNPs or marker-trait associations (MTAs) from previous genome-wide association studies (GWAS) also co-localized with as many as 14 MQTLs. By integrating MQTL analysis, GWAS, and gene expression data, this study precisely refines key genomic regions and identifies promising candidate genes, providing the necessary molecular markers to accelerate maize nutritional enhancement via marker-assisted breeding.