Malondialdehyde Content Measurement

We adapted a method from Wang et al. (2019) for measuring the malondialdehyde (MDA) content. Leaves of ice plants were harvested before and after salt treatment, and then ground to a fine powder in liquid nitrogen. A total of 3 mL 10% trichloroacetic acid (TCA) was added to 0.2 g leaf tissue powder and kept in 4°C overnight. After centrifugation at 10,000 × g, 4°C for 20 min, the supernatant (2 mL) was transferred to a new tube. Then, 2 mL 0.6% thiobarbituric acid was added to the supernatant, and vortexed thoroughly. The mixture was heated in boiling water for 15 min, cooled to 4°C immediately and centrifuged at 10,000 × g, 4°C for 10 min. Absorbance of the supernatant was recorded at wavelengths of 532 and 450 nm. The MDA content (μmol L^–1) was calculated by 6.45 ^∗ OD₅₃₂ – 0.56 ^∗ OD₄₅₀. Four biological replicates were conducted at each time point.