Figure 7.

Sequential action of PIN3 and LAX3 determines the specific expression pattern of LAX3 during lateral root emergence. (A) Regulatory network controlling LAX3 induction by auxin during lateral root emergence. (B) Auxin moves from the central xylem-pole pericycle file (XPP, red) towards the outer tissue and activates PIN3 in the cortex, resulting in a net flux of auxin towards the epidermis (red arrowheads). (C) The two files expressing PIN3 that make the most (indirect) contact with the cortex then accumulate enough auxin to induce LAX3 at a later stage (blue arrowheads). Accumulation of LAX3 then leads to further increases in auxin levels, which subsequently trigger cell separation and promote the passage of the LRP.