Discovery of candidate genes enhancing kernel protein content in tropical maize introgression lines

Abstract

Background

In this study, tropical maize germplasms were used to construct a multiparent population (MPP) to identify novel genes associated with kernel protein content. The kernel protein content was quantified using near-infrared spectroscopy (NIRS) in the MPP, which was evaluated in three different environments.

Results

QTL mapping revealed 23 significant QTLs tightly linked to kernel protein content, with phenotypic variation ranging from 8.88 to 28.86%. Genome-wide association analysis (GWAS) identified 21 SNPs that were significantly associated with kernel protein content, with phenotypic variation explained (PVE) ranging from 4.09 to 16.15%. Through combined QTL mapping and GWAS, co-localized loci were identified, as well as two novel genes (Zm00001d034933 and Zm00001d029999) that had not been previously reported.

Conclusions

These genes encode pentatricopeptide repeat-containing proteins (PPR proteins), which regulate kernel endosperm development. The significant SNPs associated with these genes accounted for 23.59% of the PVE, whereas the QTLs accounted for 46.02% of the phenotypic variation. Since kernel protein synthesis and storage occur in the endosperm, this study suggests that Zm00001d034933 and Zm00001d029999 may potentially regulate kernel protein content in maize.