Biological activity of CLE peptides in Medicago truncatula. Confirmation of the biological activity of synthetic CLE peptides corresponding to 14 amino acids of the conserved domain of predicted CLE signaling peptides in a plate assay using M. truncatula. Peptides were added at a concentration of 10 μM as growth media additives. The top row (A-C) shows plant growth in the absence of peptide, the middle row (D-F) in the presence of peptide 1 (SKRKVPSCPDPLHN), and the bottom row (G-I) in the presence of peptide 2 (SKRRVPNGPDPIHN). Plant growth is shown on day 6 after treatment (left column; A, D, G), on day 20 after treatment (middle column; B, E, H) and on day 20 of recovery, whereby seedlings were treated for 6 days and then transferred to plates without peptide for the remaining 14 days (right column; C, F, I). Bar on the bottom of each column indicates 2 cm.