Fig. 6

Highly efficient C4 photosynthesis pathway and cellulose synthesis contribute to the high biomass of Pennisetum giganteum. a Morphological characteristics of the whole plant and stem of P. giganteum at seven different periods, including three developing stages (tillering stage at 2, 4, 6 weeks, jointing stage at 8, 10 weeks, and maturing stage at 12, 14 weeks). Scale bars in the upper and lower panels correspond to 50 and 1 cm, respectively. b Heatmap of the expression of cellulose synthase-related genes that were expressed at, at least, one time point in leaves. c Simplified representation of the C4 photosynthesis pathway showing gene expression patterns of C4 pathway-related genes in leaf. PEPC, phosphoenolpyruvate carboxylase; NADP-ME, NADP-dependent malic enzyme; NAD-MDH, NAD-dependent malate dehydrogenase; AlaAT, alanine aminotransferase; NAD-ME, NAD-dependent malic enzyme; NADP-MDH, NADP-dependent malate dehydrogenase; PEPCK, phosphoenolpyruvate carboxykinase; PPDK, pyruvate/orthophosphate dikinase; AspAT, aspartate aminotransferase. The expression levels of C4 pathway-related genes in leaf are colored according to the log2(FPKM + 0.01) values across seven periods. Red indicates candidate C4 pathway-related genes that were highly expressed in seven periods; asterisks indicate genes that were differentially expressed at different developmental stages. The number of genes in each gene family is shown for four closely related species, P. giganteum, P. purpureum, C. americanus, and S. italica. d Similarity analysis of homologous genes in the A and B subgenomes of P. giganteum. e Gene structures of a pair of homologous NAD-MDH genes (Pgi0G0022029 and Pgi0G0048817) spanning the gene body and 2-kb regions upstream and downstream in the A and B subgenomes. Both genes shared high similarity and all the exons had one-to-one relationships, except for Pgi0G0022029