Transcriptomic and physiological approaches to decipher cold stress mitigation exerted by brown-seaweed extract (BSE) application in tomato

Cold stress represents a challenge for plants that are native to warm regions. In this situation, biostimulants serve as an eco-friendly resource to assist crops in overcoming this stress. Tomato (Solanum lycopersicum L.) is a valuable crop very sensitive to cold stress, which it encounters in both open field and greenhouse settings. In this study, the effect of a brown-seaweed extract (BSE)-based biostimulant has been evaluated under control and cold conditions in tomato. To assess whether the product improves tomato tolerance to cold stress, physiological parameters, yield, and transcriptomic responses have been evaluated. Under cold stress conditions, stomatal conductance, net photosynthesis, and yield were significantly (p = 0.05) higher in BSE-treated plants than in the untreated plants. Gene Ontology (GO) analysis of transcriptomic data highlighted how the BSE treatment affects the pathways of proline, flavonoids, chlorophyll, and phenylpropanoid (FDR = 0.05). Indeed, antioxidants have been measured in BSE-treated and untreated plants, under both control and cold conditions, showing how the treatment significantly affects the quantity of these molecules. This study highlighted the mode of action of a BSE-based biostimulant in the protection against cold stress in tomato.