2021 Awards in the Journal of Plant Research.

In Sato's paper ([2]), a large-scale phylogenetic analysis was conducted and four types of phylogenetic relationships between chloroplast enzymes (encoded by the chloroplast and nuclear genomes) and cyanobacterial counterparts were found: Type 1, chloroplast enzymes diverged from inside of cyanobacterial clade; Type 2, chloroplast and cyanobacterial enzymes are sister groups; Type 3, chloroplast enzymes originated from homologs of bacteria other than cyanobacteria; Type 4, chloroplast enzymes diverged from eukaryotic homologs. There are many chloroplast membrane lipid synthases and photosynthesis-related enzymes that originated outside of cyanobacteria. Sato ([2]) proposes that the host-directed chloroplast formation hypothesis, in which host eukaryotes prepared the membrane lipid synthesis system in advance, should be important for re-examining the origin of chloroplasts. [Extracted from the article]