Magnesium-nitrogen co-doped carbon dots enhance plant growth through multifunctional regulation in photosynthesis

Herein, we designed and prepared a magnesium and nitrogen co-doped carbon dots (Mg,N-CDs) for plant photosynthesis, in which Mg and N were in carbonate-like and graphite N forms with 5.38% and 3.83% contents, respectively. During a 1-h incubation with chloroplast suspension, Mg,N-CDs entered chloroplasts and transferred energy to them under a xenon lamp, which increased their photosynthetic activity to reduce DCPIP and ferricyanide by up to 52.48% and 41.86%, respectively. After 16 days of foliar spraying, Mg,N-CDs at 300 mu gmL- 1 up-regulated the gene expressions of enzymes (15.26-115.02%) related to chlorophyll synthesis and metabolism in rice plants, increasing chlorophyll a and chlorophyll b contents by 14.39% and 26.54%, respectively. The rice seedlings treated with Mg,N-CDs at 300 mu gmL- 1 exhibited 109.54%, 104.48%, and 127.16% higher photosynthetic activity, electron transport rate, and photosynthetic efficiency relative to the control, respectively. Moreover, Mg,N-CDs also increased the RuBisCO activity of rice plants by 46.62%. With the energy transformation and physiological regulation, Mg,N-CDs (300 mu gmL- 1) increased the height and fresh biomass of rice plants by 22.34% and 70.60%, respectively, through the overall improvement of photosynthesis. This study suggests the great potential of Mg,N-CDs in increasing global agricultural production in the future.

Automated summary

The study demonstrated that magnesium and nitrogen co-doped carbon dots can enhance plant photosynthesis and increase growth and yield, particularly in rice plants. By enhancing the gene expressions of enzymes related to chlorophyll synthesis and metabolism, as well as improving photosynthetic activity and efficiency, the magnesium and nitrogen co-doped carbon dots showed great potential in promoting plant growth.