Reciprocal grafting between wild-type and miR399-overexpressing transgenic tobacco plants. Pi concentration in the scions (A and B) and the relative level of PHO2 mRNA (C and D), pri-miR399 (E and F), and mature miR399 (G and H) in scions (black bars) and rootstocks (gray bars) of grafted plants were measured. A, C, E, and G represent data from grafts between wild-type and miR399f-overexpressing plants. Results from B, D, F, and H are from grafts between wild-type and miR399b-overexpressing plants. The error bars represent the sd (n = 4–5 independent grafted plants). ND, Nondetectable.