Chloroplast-targeting gold nanoclusters promoting leafy and fruit vegetables yields through improving photosynthesis

Low solar energy utilization and reactive oxygen species (ROS) accumulation limit the growth of photosynthetic plants, including leafy and fruit vegetables. Herein, we developed chloroplast-targeted peptide-modified bovine serum albumin-gold nanoclusters (TBSA-Au NCs) for improving vegetable yields. The incorporation of chloroplast-targeted peptide could effectively improve the binding ability of Au NCs whether by foliar spraying or root fertilization. After being accumulated in chloroplast, on the one hand, TBSA-Au NCs can absorb sunlight and emit red light to activate photosystem I and photosystem II through fluorescence resonance energy transfer, improving photosynthetic efficacy; on the other hand, they could effectively scarify ROS due to their radical scavenging capacities, further promoting plant growth. Taken Romaine lettuce and tomato as model plants, in foliar spraying Romaine lettuce, TBSA-Au NCs could promote the dry weight of leaves by 1.29 and 1.58 times compared to BSA-Au NCs and the control group, and 1.30 and 1.63 times in root fertilization Romaine lettuce, respectively. The net photosynthesis efficiency (Pn) in tomato leaves, which was 1.18 and 2.61 times of the BSA-Au NCs and the control group. Furthermore, lettuce leaves and tomato fruit juice from TBSA-Au treated vegetables show well biocompatibility against mice. This study develops a multifunctional photosynthetic synergist for effectively boosting crop yield.