AUTHOR=Li Yuan , Dong Xiu-Mei , Jin Feng , Shen Zhuo , Chao Qing , Wang Bai-Chen 

TITLE=Histone Acetylation Modifications Affect Tissue-Dependent Expression of Poplar Homologs of C4 Photosynthetic Enzyme Genes

JOURNAL=Frontiers in Plant Science

VOLUME=8

YEAR=2017

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2017.00950

DOI=10.3389/fpls.2017.00950

ISSN=1664-462X

ABSTRACT=<p>Histone modifications play important roles in regulating the expression of C<sub>4</sub> photosynthetic genes. Given that all enzymes required for the C<sub>4</sub> photosynthesis pathway are present in C<sub>3</sub> plants, it has been hypothesized that this expression regulatory mechanism has been conserved. However, the relationship between histone modification and the expression of homologs of C<sub>4</sub> photosynthetic enzyme genes has not been well determined in C<sub>3</sub> plants. In the present study, we cloned nine hybrid poplar (<italic>Populus simonii</italic> × <italic>Populus nigra</italic>) homologs of maize (<italic>Zea mays</italic>) C<sub>4</sub> photosynthetic enzyme genes, <italic>carbonic anhydrase</italic> (<italic>CA</italic>), <italic>pyruvate orthophosphate dikinase</italic> (<italic>PPDK</italic>), <italic>phosphoenolpyruvate carboxykinase</italic> (<italic>PCK</italic>), and <italic>phosphoenolpyruvate carboxylase</italic> (<italic>PEPC</italic>), and investigated the correlation between the expression levels of these genes and the levels of promoter histone acetylation modifications in four vegetative tissues. We found that poplar homologs of C<sub>4</sub> homologous genes had tissue-dependent expression patterns that were mostly well-correlated with the level of histone acetylation modification (H3K9ac and H4K5ac) determined by chromatin immunoprecipitation assays. Treatment with the histone deacetylase inhibitor trichostatin A further confirmed the role of histone acetylation in the regulation of the nine target genes. Collectively, these results suggest that both H3K9ac and H4K5ac positively regulate the tissue-dependent expression pattern of the <italic>PsnCAs</italic>, <italic>PsnPPDKs</italic>, <italic>PsnPCKs</italic>, and <italic>PsnPEPCs</italic> genes and that this regulatory mechanism seems to be conserved among the C<sub>3</sub> and C<sub>4</sub> species. Our findings provide new insight that will aid efforts to modify the expression pattern of these homologs of C<sub>4</sub> genes to engineer C<sub>4</sub> plants from C<sub>3</sub> plants.</p>