Auxin transport and signaling pathways. (A) Survey and localization of main transporters involved in inter- and intracellular auxin transport processes. (B) Number and relationship of PIN gene family members (Supplementary Table 8) are illustrated for the 13 selected plant species (abbreviations s–e Fig. 1) by red diamonds (Pin5), green ellipses (Pin8), and blue rectangles (Pin1–4, 6, 7). (C) Principle mechanisms and factors involved in auxin signaling in plants. For further details and explanations, see text. The bar-headed dashed line in red indicates indirect suppression mechanisms.
Abbreviations: Proteins: AUX, auxin resistant; LAX, like auxin resistant; ABCB, ATP-binding cassette B; ABCG, ATP-binding cassette G; NRT, nitrate transporter; PIN, PIN-formed; IAA, indole-3-acetic acid inducible; AUX, auxin inducible; TPL, TOPLESS; TPR, TOPLESS related; ARF, auxin-responsive factor; TIR, transport inhibitor response; AFB, auxin signaling F-box protein; ASK, Arabidopsis SKP1 homolog; CUL, Cullin; RBX, RING-box.