Epidermal patterning genes are active during embryogenesis in Arabidopsis

Abstract

Epidermal cells in the root of Arabidopsis seedling differentiate either as hair or non-hair cells, while in the hypocotyl they become either stomatal or elongated cells. WEREWOLF (WER) and GLABRA2 (GL2) are positive regulators of non-hair and elongated cell development. CAPRICE (CPC) is a positive regulator of hair cell development in the root. We show that WER, GL2and CPC are expressed and active during the stages of embryogenesis when the pattern of cells in the epidermis of the root-hypocotyl axis forms. GL2 is first expressed in the future epidermis in the heart stage embryo and its expression is progressively restricted to those cells that will acquire a non-hair identity in the transition between torpedo and mature stage. The expression of GL2 at the heart stage requires WERfunction. WER and CPC are transiently expressed throughout the root epidermal layer in the torpedo stage embryo when the cell-specific pattern of GL2 expression is being established in the epidermis. We also show that WER positively regulates CPC transcription and GL2 negatively regulates WER transcription in the mature embryo. We propose that the restriction of GL2 to the future non-hair cells in the root epidermis can be correlated with the activities of WER and CPC during torpedo stage. In the embryonic hypocotyl we show that WER controls GL2 expression. We also provide evidence indicating that CPC may also regulate GL2 expression in the hypocotyl.

JACKDAW controls epidermal patterning in the Arabidopsis root meristem through a non-cell-autonomous mechanism

“…Our data show that proper GL2 expression in the embryo requires JKD action. GL2 expression in the embryo depends on WER and CPC (Costa and Dolan, 2003), but not on the action of the receptor kinase SCM because no changes in GL2 expression were found in either scm embryos or in triple mutants of scm with srf1 and srf2, encoding the two members most closely related to SCM (Kwak and Schiefelbein, 2006). Therefore, the embryonic function of JKD must be independent from SCM.…”

“…In this model, SCM negatively regulates WER in T cells, which enables these cells to adopt the H cell fate, whereas in the A cells, WER abundance becomes relatively high, resulting in activation of the non-hair fate differentiation pathway. However, the epidermal cell pattern is set up during embryogenesis (Costa and Dolan, 2003), where SCM action is not required. This suggests that other factors perceive the initial signals that pattern root epidermal cell types.…”

The bHLH genesGL3andEGL3participate in an intercellular regulatory circuit that controls cell patterning in theArabidopsisroot epidermis

“…The position-dependent patterning of root epidermal gene expression is known to be established during early stages of embryogenesis (Costa and Dolan, 2003;Lin and Schiefelbein, 2001). To explore further the unexpected expression pattern of GL3 and EGL3, we examined the GL3::GUS and EGL3::GUS activity during embryogenesis.…”

Histone acetylation affects expression of cellular patterning genes in the Arabidopsis root epidermis

“…Previous studies have shown that the position-dependent cellular pattern of root epidermal cells is determined by interactions of six patterning genes: CPC, ETC, GL2, GL3͞EGL3, TTG, and WER (5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16). CPC, GL2, and WER are preferentially expressed in N position cells upon seed germination (6,(9)(10)(11)(12), and regulate the preferential expression of GL3͞EGL2 at H position cells (15). Therefore, their appropriate expression is essential for accurate regulation of root epidermal patterning.…”