a. Alignment of ß-finger sequences from clade I AGOs from diverse plants, algae, and animals. The insertion can be found in clade I AGOs in all plant phyla but is not apparent in animals or algae, indicating β-finger arose around the emergence of land plants and has been broadly maintained in the clade I AGOs over the last ~500 million years. b. All-against-all correspondence analysis34 of known eukaryotic AGO and PIWI guide-bound structures (target-bound structures not included). c. Cα alignment of AtAgo10 with known human AGO (PDB: 4KRF, 4KXT, 4OLA, 4W5N, 5JS1, 5VM9, 6OON), PIWI (PDB: 5GUH, 6KR6, 7KX7), and yeast AGO (PDB: 4F1N) guide-bound structures.