PvMYB106 Increases Switchgrass Biomass Via Activating Photosystem II Subunit Protein PvPsbP and Carbonic Anhydrase PvCA Expression

Switchgrass (Panicum virgatum) is a model herbaceous bioenergy crop performing C4 photosynthesis as an alternative to fossil-based feedstocks for industrial applications. Improving photosynthetic capacity is one of the potential strategies to increase switchgrass yield. Through genome-wide bioinformatic analyses of MYB genes in switchgrass, we identified several MYBs that might play regulatory roles in plant photosynthesis, including PvMYB106. Here, we show that PvMYB106 is localized in the nucleus and cytoplasm, has transcriptional activation activity, and its expression pattern is in agreement with photosynthetic rhythm. Overexpressing PvMYB106 in switchgrass promotes the biomass accumulation to a maximum of 82% as compared to the control plants, we further show that the increased biomass in switchgrass is due to enhanced photosynthetic capacity as manifested by higher Pn (net photosynthetic rate). Comparative transcriptomic analyses and dual-luciferase experiment confirm that PvMYB106 mediates photosynthetic process through up-regulating expression levels of photosynthetic genes including genes encoding subunit of photosystem II protein (PvPsbP) and carbonic anhydrase (PvCA). Taken together, our study demonstrates that PvMYB106 is a new elicitor for switchgrass photosynthesis enhancement, and provides a subset of potential downstream candidate genes for genetic improvements of biofuel crops.