Physcomitrium patens response to elevated CO2 is flexible and determined by an interaction between sugar and nitrogen availability

Mosses hold a unique position in plant evolution and are crucial for protecting natural, long-term carbon storage systems such as permafrost and bogs. Due to small stature, mosses grow close to the soil surface and are exposed to high levels of CO2, produced by soil respiration. However, the impact of elevated CO2 (eCO(2)) levels on mosses remains underexplored. We determined the growth responses of the moss Physcomitrium patens to eCO(2) in combination with different nitrogen levels and characterized the underlying physiological and metabolic changes.Three distinct growth characteristics, an early transition to caulonema, the development of longer, highly pigmented rhizoids, and increased biomass, define the phenotypic responses of P. patens to eCO(2). Elevated CO2 impacts growth by enhancing the level of a sugar signaling metabolite, T6P. The quantity and form of nitrogen source influences these metabolic and phenotypic changes. Under eCO(2), P. patens exhibits a diffused growth pattern in the presence of nitrate, but ammonium supplementation results in dense growth with tall gametophores, demonstrating high phenotypic plasticity under different environments.These results provide a framework for comparing the eCO(2) responses of P. patens with other plant groups and provide crucial insights into moss growth that may benefit climate change models.

Automated summary

Mosses play a crucial role in protecting natural carbon storage systems and the impacts of elevated CO2 levels on mosses have been underexplored. This study analyzed the growth responses of the moss Physcomitrium patens to elevated CO2 levels and different nitrogen levels, and identified the underlying physiological and metabolic changes. The results provide insights into the phenotypic responses and metabolic mechanisms involved in moss growth under elevated CO2, which can be valuable for climate change models.