qRT-PCR analysis of the split-root experiment. A, FER1 expression in shoots. Leaf samples were taken from plants at 6 and 24 h after placement on the split-root plates. In this context, +Fe indicates plants that had been grown on normal iron-containing medium prior to being moved to the split plate. –Fe indicates plants that had been grown on –Fe medium for 3 d prior to being moved to the split plate. B, IRT1 root expression after 6 and 24 h on a split plate. C, FRO2 root expression after 6 and 24 h on a split plate. D, FER1 shoot expression. E, IRT1 root expression after 6 and 24 h on a split plate. F, FRO2 root expression after 6 and 24 h on a split plate. For A and D, 6 and 24 h denote the time points at which the shoot was harvested after transfer to the split plate. +Fe indicates that plants experienced iron-replete conditions prior to transfer. –Fe indicates that plants were started on iron-deficient conditions prior to transfer. For B, C, E, and F, +/+ denotes a plant that was started on iron-replete medium and placement of roots on the replete side of the split plate. +/− denotes a plant that was started on iron-replete medium and placement of roots on the iron-deficient side of the split plate. −/+ denotes a plant that was started on iron-deficient medium and placement of roots on the iron-replete side of the split plate. −/− denotes a plant that was started on iron-deficient medium and placement of roots on the iron-deficient side of the split plate. The results reflect three biological replicates. In cases where multiple significantly different levels of expression were observed, these are indicated using lower case letters.