Quantifying Leaf Ion Leakage and Lipid Peroxidation

The upper leaves (3rd to 8th from the top) were collected from the WT P. × canescens and two PeGRP2-overexpressing lines, L-7 and L-8, after 15 days of NaCl treatment (0 or 100 mM). The REL was calculated from the initial relative conductivity (EC1) before boiling and the final conductivity (EC2) after boiling: REL (%) = (EC1/EC2) × 100% [7 (link)]. The MDA content was determined using the micro MDA assay kit (BC0025) (Beijing Solarbio Science & Technology, Beijing, China). Fresh leaves (0.1 g) were ground into a homogenate by adding 1 mL of extraction buffer and then centrifuged at 8000× g for 10 min at 4 °C, and the supernatant was collected. The absorbance values (ΔA) were measured at 532 nm and 600 nm using a microplate reader. The MDA concentration (nmol g⁻¹) was calculated as 32.258 × (ΔA₅₃₂ − ΔA₆₀₀)/0.1.