A subset of Svb binding sites corresponding to functional enhancers. Svb-dependent trichome enhancers were identified by transgenic reporter gene assays, from a systematic scanning of the (a) singed (sn) and (b) shavenoid (sha) genes and (c) regions predicted by cisTargetX. (a,b) Vertical black lines represent evolutionarily conserved OvoQ6 clusters (at least two motifs in a 1 kb window), as predicted by cisTargetX. Horizontal boxes summarize regions tested by transgenic assays, using immunostaining of the lacZ reporter (green). Negative regions (pink) do not drive specific expression in the embryonic epidermis. Regions in cyan display enhancer activity reproducing endogenous expression in trichome cells (as assayed by mRNA in situ hybridization, purple). The snE1 and sha3 enhancers are under the control of Svb, as demonstrated by reduced expression in svb mutants. (c) Putative enhancers (CRMs) predicted by cisTargetX, from clustering and/or evolutionary conservation of OvoQ6 sites. Pictures show expression of positive enhancers (cyan) in wild-type (wt; top) and svb mutant (bottom) embryos. Additional regions (pink) showed no detectable activity during embryogenesis.
Menoret et al. Genome Biology 2013 14:R86 doi:10.1186/gb-2013-14-8-r86