Pigment extraction at −30°C in pure acetone and at 4°C in DMF. Mature Arabidopsis leaves (7th to the 9th leaves counting from the bottom of the plant) that were treated with or without MeJA (see the Method section for the detail) were harvested and their pigments were extracted by three different methods. In the first two methods, leaves were immersed in pure acetone at 4°C for 12 hours (“acetone 4°C”) and at −30°C for 96 hours (“acetone −30°C”) respectively. In the third method, leaves were immersed in DMF at 4°C for 12 hours (“DMF 4°C”). A. Levels of chlorophyll a and chlorophyllide a per gram fresh weight of leaves. B. Chlorophyllide a levels in sample extracts expressed as the ratio of chlorophyllide a to the sum of chlorophyll a and chlorophyllide a. Chl a, chlorophyll a. Chlide a, chlorophyllide a. Error bars indicate standard deviations. Sample size, n = 3.