Analysis of gene expression and histone modification between C4 and non-C4 homologous genes of PPDK and PCK in maize

More efficient photosynthesis has allowed C 4 plants to adapt to more diverse ecosystems (such as hot and arid conditions) than C 3 plants. To better understand C 4 photosynthesis, we investigated the expression patterns of C 4 genes ( C4PPDK and PCK1 ) and their non-C 4 homologous genes ( CyPPDK1 , CyPPDK2 , and PCK2 ) in the different organs of maize ( Zea mays ). Both C 4 genes and non-C 4 genes showed organ-dependent expression patterns. The mRNA levels of C 4 genes were more abundant in leaf organ than in seeds at 25 days after pollination (DAP), while non-C 4 genes were mainly expressed in developing seeds. Further, acetylation of histone H3 lysine 9 (H3K9ac) positively correlates with mRNA levels of C 4 genes ( C4PPDK and PCK1 ) in roots, stems, leaves, and seeds at 25 DAP, acetylation of histone H4 lysine 5 (H4K5ac) in the promoter regions of both C 4 ( C4PPDK and PCK1 ) and non-C 4 genes ( CyPPDK1 , CyPPDK2 , and PCK2 ) correlated well with their transcripts abundance in stems. In photosynthetic organs (stems and leaves), dimethylation of histone H3 lysine 9 (H3K9me2) negatively correlated with mRNA levels of both C 4 and non-C 4 genes. Taken together, our data suggest that histone modification was involved in the transcription regulation of both C 4 genes and non-C 4 genes, which might provide a clue of the functional evolution of C 4 genes.