Detection of jasmonic acid and SA

0.5 g of leaves from WT and sscd1 seedlings that were grown under LD for 3 weeks and then transferred to SD for 0, 2 and 3 days was harvested for jasmonic acid and SA extraction. The harvested tissues were immediately ground to a fine powder in liquid N₂, and then exposed to extraction buffer (1.0 mL of 80% methanol) at 4 °C overnight. The samples were centrifuged at 10,000g for 5 min, and the residues were re-extracted with 0.6 mL of 80% methanol (HPLC grade methanol, Merck, Germany). The supernatants were vacuum freeze dried to dryness at − 60 °C, then dissolved in 200 μL of 0.1 M sodium phosphate buffer (pH 7.8), and extracted with 200 μL of petroleum ether. The aqueous phase was purified using a Waters Sep-Pak C18 cartridge (Waters, USA). The cartridge was washed with 200 μL of ddH₂O and then eluted with 1.5 mL of 80% methanol. The eluate with 80% methanol was vacuum freeze dried. The dried extract was dissolved in 40 μL of 50% methanol and used for LC/MS assay in a WATERS ACQUITY SQD (LC/MS) system according to Liu et al.⁶⁰.