Developmental Regulation of Cell Interactions in theArabidopsis fiddlehead-1Mutant: A Role for the Epidermal Cell Wall and Cuticle

• Published in: Developmental biology Vol. 189; no. 2; pp. 311 - 321
• Main Authors: Lolle, Susan J., Berlyn, Graeme P., Engstrom, Eric M., Krolikowski, Katherine A., Reiter, Wolf-Dieter, Pruitt, Robert E.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.09.1997
• DOI: 10.1006/dbio.1997.8671
• ISSN: 0012-1606

Although the plant epidermis serves primarily a protective role, during plant development some epidermal cells specialize, becoming competent to interact not only with pollen but also with other epidermal cells. In the former case, these interactions mediate recognition, germination, and pollen growth responses and, in the latter case, result in interorgan fusions which, most commonly, alter floral architecture in ways that are thought to promote reproductive success. In either case, all of the initial signaling events must take place across the cell wall and cuticle. InArabidopsis,mutation of theFIDDLEHEADgene alters the shoot epidermis such that all epidermal cells become competent to participate in both types of interactions. Infdh-1mutants, epidermal cells manifest not only a contact-mediated fusion response but also interact with pollen. Since carpel epidermal derivatives manifest both of these properties, we postulated thatfdh-1epidermal cells were ectopically expressing a carpel-like program. In this report we demonstrate that manifestation of thefdh-1phenotype does not require the product of theAGAMOUSgene, indicating that the phenotype is either independent of the carpel development program or thatfdh-1mutations activate a carpel-specific developmental program downstream of theAGgene. Furthermore, we demonstrate that plants bearing mutations in thefdh-1gene show significant changes in cell wall and cuticular permeability. Biochemical analyses of the lipid composition of the crude cell wall fraction reveal thatfdh-1cell walls differ from wild-type and manifest significant changes in high-molecular-weight lipid peaks. These results suggest that cell wall and cuticular permeability may be important determinants in developmental signaling between interacting cells and implicate lipids as important factors in modulating the selectivity of the permeability barrier presented by the epidermal cell wall and cuticle.