Exploiting Laminaria digitata L. Aqueous Extract for Tomato Biostimulation: A Physiological and Metabolomic Approach

Area of Science:

• Agricultural Science
• Plant Physiology
• Marine Biotechnology

Background:

• Water deficit significantly reduces crop yield and quality.
• Biostimulants, like brown seaweed extracts, present sustainable strategies to mitigate drought stress.
• Laminaria digitata extract (LE) is a potential biostimulant for enhancing plant resilience.

Purpose of the Study:

• To evaluate the impact of Laminaria digitata-aqueous extract (LE) on tomato plants under well-watered and water-limited conditions.
• To investigate LE's potential to alleviate drought stress by examining morphological, physiological, and metabolic responses.
• To understand the mechanisms underlying LE-mediated drought tolerance in tomatoes.

Main Methods:

• Tomato plants were foliar-sprayed with different concentrations of LE (0.0, 0.1, 1.0 g L⁻¹).
• Plants were subjected to well-watered (WW) or water-limited (WL) conditions, with a recovery phase (REC) for some WL plants.
• Evaluated morphological, physiological (photosynthesis, gas exchange, water use efficiency), and metabolomic parameters.

Main Results:

• Under WW, LE improved photochemical efficiency and gas exchange by regulating photosystem antenna size and stomatal conductance.
• Under WL, LE (0.1 g L⁻¹) enhanced water use efficiency via stomatal closure without compromising CO₂ assimilation.
• LE treatment induced ROS detoxification and phytohormone modulation, contributing to improved antioxidant capacity and drought tolerance.

Conclusions:

• Laminaria digitata extract (LE) application enhances drought tolerance in tomato plants.
• LE improves physiological regulation, including photosystem efficiency and water use efficiency, under water-limited conditions.
• LE acts as a biostimulant by modulating phytohormone levels and boosting antioxidant capacity, supporting sustainable agriculture.