Enhanced photosynthetic efficiency by nitrogen-doped carbon dots via plastoquinone-involved electron transfer in apple

Abstract

Artificially enhancing photosynthesis is critical for improving crop yields and fruit qualities. Nanomaterials have demonstrated great potential to enhance photosynthetic efficiency; however, the mechanisms underlying their effects are poorly understood. This study revealed that the electron transfer pathway participated in nitrogen-doped carbon dots (N-CDs)-induced photosynthetic efficiency enhancement (24.29%), resulting in the improvements of apple fruit qualities (soluble sugar content: 11.43%) in the orchard. We also found that N-CDs alleviated mterf5 mutant-modulated photosystem II (PSII) defects, but not psa3 mutant-modulated photosystem I (PSI) defects, suggesting that the N-CDs-targeting sites were located between PSII and PSI. Measurements of chlorophyll fluorescence parameters suggested that plastoquinone (PQ), the mobile electron carrier in the photosynthesis electron transfer chain (PETC), was the photosynthesis component that N-CDs targeted. In vitro experiments demonstrated that plastoquinone-9 (PQ-9) could accept electrons from light-excited N-CDs to produce the reduced plastoquinone 9 (PQH₂-9). These findings suggested that N-CDs, as electron donors, offer a PQ-9-involved complement of PETC to improve photosynthesis and thereby fruit quality. Our study uncovered a mechanism by which nanomaterials enhanced plant photosynthesis and provided some insights that will be useful in the design of efficient nanomaterials for agricultural/horticultural applications.

Acknowledgements

We thank Congming Lu (Shandong Agricultural University) for providing A. thaliana mterf5 and psa3 mutants and technical assistance. This work was financially supported by major basic research projects of Shandong Province (ZR2020ZD43), National Natural Science Foundation of China (22207067, 31972378), Natural Science Foundation of Shandong Province (ZR2021MC073), China Agriculture Research System of MOF and MARA (CARS-27).

Author contributions

X.J., Y.L., X.L., G.W., F.Y., and Y.Z. performed the research; Y.Z., C.-X.Y., S.Z., and X.-F.W. designed the research; Y.Z., X.-F.W., Z.-L.Z., and S.Z. analysed the data. D.C., C.-X.Y., and S.Z. supervised the project and provided funding; and S.Z. and X.-F.W. wrote the paper.

Data availability

All the data supporting the findings of this study are available in the paper and supplementary data.

Conflict of interest statement.

The authors declare no competing interests.

Supplementary data

Supplementary data is available at Horticulture Research online.

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