Fig. 3

Heatmap of changes in content of free amino acids (a) and expression levels of representative genes involving in metabolism of amino acids (b) in wheat endosperm as affected by nitrogen topdressing timing. Note: A. TL5, TL3 and TL1 indicate topdressing timing of nitrogen at the growth stage of fifth, third and first leaf (flag leaf) from the top, respectively. Content of each amino acid was the mean of three biological replicates. The content was normalized after logarithm of each free amino acid is shown in reference to the continuous scale color bar. The complete data of content of free amino acids are shown in Additional file 1: Table S1–2. FAA, free amino acid. GSA indicates c-glutamyl semialdehyde, and P-homoserine indicates phosphohomoserine. Pcr, pyrroline-5-carboxylate reductase; pa, phosphoserine aminotransferase; ad, arogenate dehydrogenase; imd, isopropyl malate dehydrogenase; aa, alanine aminotransferase; aga, alanine glyoxylate aminotransferase. B. The line charts represent genes expression during grain filling stage in TL3. The bar charts represent the relative variation of TL5 (red) and TL1 (blue) in relation to TL3. All data were subjected to one-way analysis of variance (ANOVA) to determine the significant differences between treatments. Bars indicate standard errors. n, not significant (P > 0.05). The amino acids metabolic process that each gene involved in are shown as abbreviations in blue in Fig. 3a