FIGURE 3.

Metabolic reconstruction and the proposed exchange of phytohormone, nitrogen, sulfur, phosphorus, and vitamin B₁₂ between P. haitanensis symbionts and the host. Blue, phytohormone metabolism; orange, Vitamin B₁₂ biosynthesis; purple, sulfur metabolism; pink, phosphorus metabolism; and deep red, nitrogen metabolism. TAM pathway, Tryptamine pathway; IAM pathway, Indole-3-acetamide pathway; DMB, 5,6-dimethylbenzimidazole; DOP, dissolved organic phosphorus; ACC, 1-aminocyclopropane-1-carboxylate. Lineages within the taurine metabolism box contain genes encoding for the taurine transporter (tauACB) and taurine dioxygenase (tauD). The morphology of Pyropia haitanensis is presented in Supplementary Figure 8C.