Tomato Cold Stress Alleviation with ALA

WT tomato (cultivar Ailsa Craig) was used as the background. The cultivation of tomato seedlings and the culture conditions were conducted following our previous research [72 (link), 73 (link)]. Tomato seedlings with fully expanded fifth leaves were divided into four treatment groups. One group of tomato was sprayed with 6 mL distilled water containing 0.02% Silwet L-77 (Sigma Aldrich, St. Louis, MO, USA) 12 hours before normal temperature treatment (25°C day/18°C night). The second group of tomato was sprayed with 6 mL 25 mg/L ALA (Sigma Aldrich, St. Louis, MO, USA) solution containing 0.02% Silwet L-77 12 hours before normal temperature treatment (25°C day/18°C night). The third group of tomato was sprayed with 6 mL distilled water containing 0.02% Silwet L-77 12 hours before cold treatment (4°C day/4°C night). The fourth group of tomato was sprayed with 6 mL 25 mg/L ALA solution containing 0.02% Silwet L-77 12 hours before cold treatment (4°C day/4°C night). The other environmental conditions were the same as those of the previous planting environment.