To determine gene expression in juvenile vs. adult, respectively Gd vs. Re adult apices, RNA was extracted as described above. cDNA synthesis was performed using the Superscript III (SSIII) kit (ThermoFisher Scientific) according to the manufacturers` protocol but using ½ of the SSIII amount. Primers were designed manually with an annealing temperature +/− 60°C and a product length of ca. 300 bp. Single genomic locus binding properties were tested by using BLAST against the V3.3 genome of P. patens. Real-time PCR was performed using 5 ng of cDNA as input for PCR reaction with OneTaq from New England Biolabs). PCR products were visualized via gel electrophoresis using peqGREEN from (VWR, Germany). As size standard, the 100 bp ladder (NEB) was used. Real-time qPCR was carried out with two (for juvenile vs. adult comparison) or three (expression determination of ccdc39) biological replicates as published in Hiss et al., 2017 (link). As reference gene, act5 (Pp3c10_17070V3.1, (Le Bail et al., 2013 (link)) was chosen, due to homogenous expression in juvenile and adult apices in Gd and Re (Fig. S2). For primer sequences see Table S1.