Carbon dots promote tomato growth and yield via photosynthesis enhancement and leaf senescence delay

Food security is increasingly threatened by population growth, regional conflicts, and climate disasters, making it imperative to further increase crop production. One safe approach to achieving this goal is to expand the utilization of agricultural inputs. Recent research has revealed that carbon dots (CDs), a class of carbon-based nanomaterials, have potential in interacting with plants to enhance growth. However, the underlying molecular mechanisms remain poorly understood. In this study, we synthesized CDs that emit red light at a wavelength of 670 nm when excited by green light at 560 nm. When tomato seedlings were treated with these CDs via foliar spraying, their plant height increased by 10.26 % and fresh weight by 19.81 %. Measurements of photosynthesis and the Hill reaction showed significant improvements in both photosynthetic efficiency and chloroplast electron transport. Transcriptome analysis of tomato leaves revealed downregulation of genes associated with leaf senescence, including those involved in ethylene response, protein ubiquitination, chlorophyll degradation, ATP hydrolysis, and lignin synthesis. Transient expression assays of phyB1::GFP and phyB2::GFP demonstrated that CDs accelerate the translocation of red light-responsive phytochrome B (PhyB) from the cytoplasm to the nucleus, a process that may contribute to delayed leaf senescence. Additionally, during the harvesting period, CD-treated tomato plants showed evident enhancements in both fruit quantity and quality. These results collectively indicate that CDs promote tomato growth and fruit production by enhancing photosynthesis and delaying leaf senescence. This study not only provides insights for promoting tomato growth and yield but also offers valuable guidance for investigating interactions between nanomaterials and plants.