FIGURE 3.

A molecular mechanism determining xylem axis domain. Schematic illustration showing a machanism underlying the formation of xylem axis domain in the root stele. (1) Mutual inhibition of high auxin and cytokinin domain defines protoxylem vessel domain, in which auxin inhibits cytokinin signaling via AHP6 and cytokinin restricts the auxin accumulation via PIN3 and PIN7. (2) AHLs movement plays a role in the determination of not only protoxylem vessel but also metaxylem vessel domain, thereby establishing the boundary between xylem axis and procambium domain in root stele. (3) The combination of these regulations leads to the formation of spatially regulated xylem axis domain. The details are described in the main text.