Exogenous nano-silicon treatment enhanced the low temperature tolerance of tomato seedlings

Low-temperature (LT) stress limits the growth, yield, and quality of warm-season crops like tomatoes. We compared Sodium silicate (Ion-Si) and silicon nanoparticles (SiNPs) sprayed on tomato ‘Zhongza-9’ seedlings under LT. SiNPs surpassed Ion-Si by reducing malondialdehyde (MDA) and reactive oxygen species (ROS) levels, while increasing chlorophyll content, net photosynthetic rate and biomass, stabilizing membranes, enhancing macro- and micronutrient uptake. Additionally, SiNPs upregulated sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities, downregulated starch synthase (AI) and neutral invertase (NI) activities, increasing sucrose. Transcriptome showed SiNPs activated genes for chlorophyll metabolism, photosynthesis, antioxidants, sugar metabolism, and hormone signaling, elevating superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) to strengthen LT tolerance. Our findings provide a basis for using SiNPs to improve the cold tolerance of tomatoes.