Fig. 1

Expression profiles of starch biosynthetic genes. a The expression of 40 known starch biosynthetic genes and the pathways in which they could be involved in the endosperm of maize inbred lines Mo17 and Ji419 at 15 and 25 DAP. The heat map represents the expression of each gene in a specific line. Red boxes represent up-regulated genes in Ji419 compared with Mo17 at both 15 and 25 DAP; orange boxes represent genes up-regulated in Ji419 at only one stage; yellow boxes represent genes up-regulated in Ji419 at one stage, but down-regulated at the other stage; green boxes represent genes down-regulated in Ji419 at only one stage; blue boxes represent genes with no differential expression between Mo17 and Ji419 at both 15 and 25 DAP. b Venn diagram of starch biosynthetic genes that are differentially expressed in the endosperm of Mo17 and Ji419 at 15 and 25 DAP. Red represents genes down-regulated in Ji419 compared with Mo17 at 15 DAP; blue represents genes up-regulated in Ji419 at 15 DAP; yellow represents genes down-regulated in Ji419 at 25 DAP; green represents genes up-regulated in Ji419 at 25 DAP. c-d Expression levels of eight key starch biosynthetic genes in the endosperm of Mo17 and Ji419 at 15 DAP (c) and 25 DAP (d). Black bars represent the expression of genes in Ji419; grey bars represent the expression of genes in Mo17. The data in c and d are means ± SD (n = 3). ** significant at p ≤ 0.01 by the Student’s t test