Growth conditions
Plants were grown in a growth chamber in a long day (16 h light) photoperiod at 22 °C/18 °C at day/night. The seeds were surface-sterilized by treatment with an aqueous solution of 5% calcium hypochlorite for 8 min, subsequently rinsed four times with sterile water and planted on plates. Before location in the growth chamber, plates with seeds were kept for 4 days at 4 °C in darkness for stratification. The Arabidopsis accessions, the AI-RIL mapping population and the T-DNA insertion mutant lines were grown on Petri dishes on solid ½ Murashige-Skoog medium with vitamins (1L of medium contained 0.5 µg nicotinic acid, 0.5 µg pyridoxine, 0.1 µg thiamine, 2 µg glycine) and 0.8% agar. For each genotype analyzed (accessions, mapping population, T-DNA mutants), plants were cultivated in at least three biological replicates, full set of plates with accessions or RIL lines was grown at the same time.