*4.5. Measurement of Chlorophyll Biosynthetic Enzyme Activities*

Fresh leaves were collected at 0 h, 0.5 h, 12 h, and 48 h after exposure to light, and immediately grounded with extracting buffers at 4 ◦C. Glutamate 1-semialdehyde aminotransferase (GSA-AT) activity was analyzed according to Shalygo et al. [62]. ALA dehydratase (ALAD) activity was evaluated as described by Kumar et al. [43]. Mg-chelatase activity was determined based on Yaronskaya et al. [69]. POR activity was measured according to Rebeiz et al. [67].
