Functional conservation and maintenance of expression pattern of FIDDLEHEAD-like genes in Arabidopsis and Antirrhinum

Abstract

In Arabidopsis, loss of function of the epidermis-specific FDH gene coding for a putative b-ketoacyl-CoA synthase results in ectopic organ fusions in mutants. Corresponding mutants are not available for Antirrhinum majus, however, organ fusions can be induced in both species by chloroacetamide inhibitors of b-ketoacyl-CoA synthases using a chemical genetics approach. We isolated the ortholog of FDH from Antirrhinum majus, the ANTIRRHINUM FIDDLEHEAD (AFI ) gene, and showed that AFI complements fdh when expressed in the epidermis under control of the FDH promoter. Like FDH, the AFI gene exhibits protodermis-and epidermis-specific expression, and its promoter directs the expression of reporter genes to the epidermis in transgenic Antirrhinum and Arabidopsis. We demonstrate down-regulation of the FDH promoter in the epidermis of the ovary septum, thereby supporting the assumption that FDH-like genes may directly facilitate the cell-cell interactions that need to occur during carpel fusion and pollen tube growth. Up-regulation of FDH in the stomium, on the other hand, provides evidence for its possible involvement in cell separation during anther dehiscence. Down-regulation of the FDH and AFI promoters in the septum is observed in transgenic Arabidopsis but not in Antirrhinum plants. This probably reflects differences in the ontogeny of the ovary septum between the two species. We also show that epidermis-specific FDH-like genes may not be able to efficiently elongate fatty acid chains when misexpressed in seeds.

Apoplastic Diffusion Barriers in Arabidopsis

“…Organ fusions and the rapid leaching of chlorophyll were well phenocopied by transgenic Arabidopsis plants expressing a fungal cutinase, supporting the hypothesis that the fusion phenotypes are associated with a defective cuticle (Figure 10) (Sieber et al, 2000). Although FDH has been identified as member of the KCS family based on sequence similarity, the biochemical role of this protein in cutin formation has not yet been elucidated (Yephremov et al, 1999;Pruitt et al, 2000;Efremova et al, 2004). Similar to the fdh mutant, a link between cutin deposition and organ fu- 2006a; Bessire et al, 2007;Voisin et al, 2009;Bessire et al, 2011).…”

Apoplastic polyesters in Arabidopsis surface tissues – A typical suberin and a particular cutin

“…The molecular characterization of the corresponding genes as fatty acid elongase (FIDDEL-HEAD (FDH); Pruitt et al, 2000;Yephremov et al, 1999;Efremova et al, 2004), fatty acid x-hydroxylase (LACER-ATA (LCR); Wellesen et al, 2001), oxidoreductase (HOT-HEAD (HTH); Krolikowski et al, 2003), desaturase (WAX2; Chen et al, 2003; YRE; Kurata et al, 2003) and long-chain acyl-CoA synthase (LACS2; Schnurr et al, 2004) suggests these genes are probably involved in the biosynthesis of functionalized aliphatics. However, a direct effect on the amount or composition of leaf cutin could not be established because methods for the analysis of Arabidopsis cutin were not available at the time.…”

Misexpression of FATTY ACID ELONGATION1 in theArabidopsisEpidermis Induces Cell Death and Suggests a Critical Role for Phospholipase A2 in This Process

“…One explanation may be that cell type-specific processes for channeling FAs to particular metabolic fates may define the mechanism by which PCD is activated (Listenberger et al, 2001). Since the FDH promoter is active in all epidermal cells (Yephremov et al, 1999;Efremova et al, 2004), differences in key molecular and cellular processes in diverse cell types are likely to be the causes for the observed trichome death in FDH:FAE1 plants, in turn mediated by differences in the metabolic configuration of acyl-exchange pathways in different cells. It is reasonable to hypothesize that GL2 or other trichome-specific genes play some role in eventual manifestation of the death process.…”

“…To investigate the effects of VLCFA biosynthesis in the epidermis, Arabidopsis (Columbia ecotype) plants were transformed with a construct expressing the FAE1 cDNA from the epidermisspecific FDH promoter (Efremova et al, 2004). All 27 independent FDH:FAE1 T1 transgenic plants were clearly distinct from the wild type in that they showed a glabrous phenotype in rosette and cauline leaves, stems, and sepals ( Figures 1A to 1F).…”

“…The epidermis not only offers a model to study cell-type differentiation and provides the major physical barrier to invading pathogens and water permeation but also mediates a broad set of defense responses. The epidermis-specific FIDDLEHEAD (FDH) gene encodes a putative KCS (Yephremov et al, 1999;Pruitt et al, 2000), and its promoter shows strong expression in vegetative and floral meristems (Yephremov et al, 1999;Efremova et al, 2004). The fdh mutation has a deleterious effect on cuticle quality, plant morphology, and aspects of trichome differentiation.…”