Figure 6.

Rootward long-distance transport of iP-type CKs is mediated by AtABCG14.

(A) Morphological phenotypes of 25-DAG cypDM and atabcg14 cypDM. Scale bars, 1.5 cm. A solution of 5 ppm ²H_6^-iP was dripped onto the third and fourth leaves of plants (7 μl/cm² leaf area) and incubated for 6 h. The roots (B), younger (fifth to tenth) leaves (C), and third and fourth leaves (D) were then harvested for CK quantification.

(E and F) Quantification of iP and iPR content in phloem sap of cypDM, atabcg14 cypDM(E), WT, and atabcg14(F). Phloem sap from 25-DAG plants was collected for CK quantification.

(G) A solution of 5 ppm ²H₆^-iP was dripped onto the third and fourth leaves of 25-DAG plants and incubated for 6 h. The roots were harvested for CK quantification.

(H) WT plants were incubated under split-root conditions with or without ²H₆-labeled iP.

(I) Quantification of ²H₆-labeled iP and iPR contents in the shoot and untreated root (which did not receive ²H₆-labeled iP) after feeding with ²H₆-iP for 4 h in (H).

Data are means ± SD. n = 3 in (B)–(E), n = 4 in (F), (G), and (I). ∗P < 0.5, ∗∗P < 0.01 (Student’s t-test). Groups marked with different letters are significantly different (P < 0.05, ANOVA).