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. 2021 Apr 20;128(2):137–148. doi: 10.1093/aob/mcab052

Fig. 3.

Fig. 3.

Trichome initial patterning and its intersection with the core stomatal developmental programme. (A) Trichome initial fate specification. The Myb–bHLH–WD40 complex containing GL1/MYB23, GL3/EGL3 (and MYC2) and TTG autoactivates itself and induces the expression of the HD-ZIP IV protein GL2, which specifies the trichome fate. The Myb–bHLH–WD40 complex in addition induces the expression of small Myb proteins, TRY/CPC/ETC2/ETC3, which can move from cell to cell via plasmodesmata and repress the activity of the Myb–bHLH–WD40 in the adjacent cell through competitive inhibition. (B) Role of the core stomatal development programme in trichome fate specification. Left: protoderm and MMCs may induce the trichome initiation programme, whereas later in the developmental progression both stomata and trichome precursors may mutually exclude each other’s fate. Right: in the protoderm/MMC, SPCH directly upregulates MYC1. In addition, SPCH directly upregulates TMM, whose overexpression reduces trichome numbers via an unknown mechanism. (C) Regulation of trichome (hair) development in maize. A trichome precursor cell (pink) is generated via an asymmetric cell division of a protodermal cell (white). ZmSPL10/14/26 upregulate the expression of ZmWOX3A, and promote trichome fate of the precursor, probably through auxin. In the absence of these ZmSPL genes, a stomatal complex transdifferentiates from the precursor instead of the trichome. The figure is modified and re-drawn from Kong et al. (2021).