Genotype characterization of flva KO and flvb KO lines. Effective homologous recombination with the insertion of the resistance cassette in FLVA or FLVB loci was first verified by PCR to prove the integration of resistance cassette in the expected position of the genome (SI Appendix, Fig. S2). (A) FLVA and FLVB gene expression was assessed by RT-PCR in WT and selected flva KO and flvb KO lines grown in control light. Amplification of Actin transcript is also reported as control. (B) Western blotting against P. patens FLVA and FLVB proteins. In each lane, 100 µg total proteins from CL-grown samples were loaded. In the case of WT, 0.5X and 2X indicates lanes loaded with 50 or 200 µg, respectively. WT and two independent lines for each flva KO and flvb KO mutants are reported, but additional independent lines were analyzed with indistinguishable results (SI Appendix, Fig. S3).