Storage N form

Combining the morphological N and functional N, storage N is divided into three forms (Fig. 3). The carboxylation system (Rubisco) and respiration proteins are mainly contained within the chloroplast matrix and mitochondrial matrix, classified as water-soluble protein (N_w). Therefore, the remaining N_w with N_cb and N_resp removed is regarded as the water-soluble protein form of storage N (N_ow) and is given by:

The light capture system proteins and electron transport components are located in the thylakoid membrane of the chloroplast, classified as SDS-soluble protein (N_s). The remaining N_s without N_lc and N_et is regarded as the SDS-soluble protein form of storage N (N_os) and is given by:

The non-protein N is the remaining fraction of total N, without the three previously specified fractions of N, and is regarded as the non-protein form of storage N (N_np).