Isolation of an Arabidopsis homologue of the maize homeobox Knotted-1 gene

Abstract

The shoot apical meristem (SAM) is responsible for forming most of the above-ground portion of the plant. We sought to isolate regulatory genes expressed in the Arabidopsis SAM by screening a Brassica oleracea (cauliflower) meristem cDNA library with the homeobox fragment from the maize Knotted-1 (Kn1) gene. We isolated and characterized the corresponding clone, Merihb1, from Arabidopsis. Analysis shows that the predicted MERIHB1 protein exhibits strong homology to KN1 and RS1 from maize, SBH1 from soybean, and KNAT1 and KNAT2 from Arabidopsis. Merihb1 is highly expressed in mRNA from cauliflower meristems and also accumulates in stem and flower mRNA. Based on the similarity of the Merihb1 and Kn1 sequences, expression patterns, and in situ hybridizations, we suggest that Merihb1 represents an Arabidopsis homologue of the maize Kn1 gene.

Expression ofMeis2, aKnotted-related murine homeobox gene, indicates a role in the differentiation of the forebrain and the somitic mesoderm

“…Furthermore, they show a high level of homology with the homeodomain of mouse TGIF protein, which represses the 9-cis retinoic acid receptor-dependent transcription activation (Bertolino et al, 1996), and with the Saccharomyces cerevisiae metallothionein cup9 (Knight et al, 1994). Meis homeodomains also show high level of conservation with the homeodomains of Zea mais Kn1 (Vollbrecht et al, 1991), and Arabidopsis thaliana Kn1 (Granger et al, 1996), Kn2 , h1 , and Knox3 (Mü ller et al, 1995). In Figure 1, we show the important identities between the homeodomain of Meis2 and the ones of the Kn protein family, conserved in plants, with particular attention to the alpha-helical structures.…”

Leaf Development

“…Six KNAT genes have been identified in Arabidopsis (Lincoln et al, 1994;Granger et al, 1996;Serikawa et al, 1996;Semiarti et al, 2001;Fig. 3B).…”

Cell wall invertase expression at the apical meristem alters floral, architectural, and reproductive traits in Arabidopsis thaliana

“…The KNOTTED‐1 gene has been reported to confer meristem‐specific expression in case of corn (Smith et al ., 1995), and the transcript of the A. thaliana homolog (KnAT1) could be detected in meristematic tissues (Granger et al ., 1996). Therefore, the KnAT1 gene promoter seemed a suitable candidate for meristem‐specific gene expression.…”