ABCG14

ABCG14 is an ATP-binding cassette (ABC) transporter in Arabidopsis thaliana, belonging to the subfamily G (ABCG). It encodes a half-size transporter that localizes to the plasma membrane, primarily in root vascular tissues, where it is thought to form functional transporters through dimerization.

Functionally, ABCG14 mediates the long-distance movement of cytokinins from roots to shoots. It is implicated in exporting cytokinin ribosides, especially trans-zeatin riboside (tZR), from root cells into the xylem for translocation to the aerial parts of the plant. This root-to-shoot transport supports cytokinin signaling and affects shoot development and productivity.

Genetic evidence supports its role in cytokinin transport. Loss-of-function abcg14 mutants exhibit reduced cytokinin content in shoots and altered shoot growth, consistent with impaired root-to-shoot cytokinin delivery. Conversely, overexpression can elevate shoot cytokinin levels and influence shoot architecture. Studies using grafting and hormone feeding have shown that root-derived cytokinins depend on ABCG14 for efficient long-distance trafficking to shoots.

ABCG14 operates within the broader network of plant hormone transporters that control cytokinin homeostasis. It contributes to the regulation of shoot growth, leaf senescence, and nutrient signaling by influencing the systemic distribution of cytokinins rather than local synthesis alone.

In summary, ABCG14 is a plasma membrane–localized plant transporter essential for the root-to-shoot translocation of cytokinins, shaping hormonal signaling and developmental outcomes in Arabidopsis thaliana.