The extraction of SA from the soybean hypocotyls was conducted according to the method described by Marek et al. [34], with slight modification. Briefly, 0.5 g of hypocotyls were ground with a mortar and pestle, mixed with 3 mL of 90% methanol, and then centrifuged at 14,000g at 4°C for 10 min, after which the supernatant was collected. The pellets were re-extracted with 1.5 mL of 100% methanol, after which the supernatant was combined with the previously collected supernatant. The combined supernatant samples were then concentrated to a final volume of around 250 μL using a speed vacuum (miVac DUO concentrator, New York, USA), then resuspended in 1 mL of hydrolysis buffer (0.1 M sodium acetate buffer, pH 5.5).