with minor modifications. Seeds of the WT, atv, Aft and SB lines were surface-sterilized with 2.5% NaClO and germinated in Petri dishes on sterile bench paper disks soaked with 4 mL of sterile dH2O, at 23 1 C under either constant darkness, constant light (200 mmolm 2 s 1 from Sylvania F36 W/GRO fluorescent lamps) or a photoperiod of 16/8 h (day/night).