In summary, among the seven leading candidate genes for starch QTL in this study, three genes, ZmGAL, ZmTPS and ZmKCS, encoding the key enzymes in non-starch metabolism, might have an indirect effect on starch content by regulating the oil content in maize kernels or have a direct effect on starch content by influencing the amount of the important intermediate product, glucose, in starch metabolism; ZmWRKY78 and ZmMYB132, encoding WRKY and MYB transcription factor family domains, may regulate the expression of key enzymes in starch or the entire metabolism; ZmSnRK1, encoding a serine or threonine protein kinase, and its interactor ZmSnRK1I, may serve as counterparts that affect the starch content by regulating certain enzyme activities in starch biosynthesis.
Naringenin is the key intermediate of the flavone/anthocyanin pathway, serving as the common precursor for a large number of downstream flavonoids, as described previously46. The occurrence of various flavones and O- or C-glycosyl flavones found here demonstrates the existence of the pathway including glycosyltransferase genes, implicating the genetic and biochemical basis for the formation of diverse flavonoids in the maize kernel. Metabolite GWAS thus facilitated characterization of the flavonoid metabolic pathway and identification of genes involved in its biosynthesis. 153554b96e