Mutant analysis
T-DNA lines for candidate genes were obtained from NASC and are listed in Table S4. Genomic DNA was extracted using the Sucrose Prep method (Berendzen et al., 2005), following genotyping by PCR for the respective T-DNA insertion using the primer pairs listed in Table S8. Homozygous mutant lines were tested on the same conditions used for the N screening experiments at which the genome-wide association was identified, using Col-0 wild type as a reference. Two and three independent experiments with 10 replicate plants/line for each condition were performed to confirm the associations to FT and ERD plasticities, respectively.