Histone deacetylase 19 interacts with GLK2 to inhibit chlorophyll synthesis and photosynthetic activity in Populus davidiana.

Maintaining the homeostasis of chlorophyll biosynthesis is essential for ensuring efficient photosynthesis and preventing photooxidative damage in plants. Histone deacetylases (HDACs) regulate plant development and stress responses, but their role in chlorophyll metabolism and photosynthesis remains unclear. Here, we identified and characterized PdHDA19, an RPD3-type HDAC from Populus davidiana Dode. PdHDA19 is highly expressed in leaves and apical buds, and its expression is induced by light. Overexpression of PdHDA19 leads to light green leaves, reduced chlorophyll content and decreased photosynthetic activity. RT-qPCR results show that PdHDA19 represses genes involved in chlorophyll synthesis and photosystem. Further analysis reveals that PdHDA19 physically interacts with the transcription factor PdGLK2 and suppresses PdGLK2-mediated activation of target genes. Together, these results reveal that PdHDA19 negatively regulates chlorophyll accumulation and photosynthetic activity in poplar via interaction with PdGLK2, providing new insights into epigenetic regulation of photosynthesis in woody plants.