Poster: Signaling, cell-to-cell

Abs # 432: Characterization of epidermal cell dedifferentiation during carpel fusion in Madagascar periwinkle

Presenter:	Durbak, Amanda R, amanda.durbak@ncf.edu
Authors	Durbak, Amanda R (A)   Clore, Amy M (A)
Affiliations:	(A): New College of Florida

In some species, organ fusions occur during normal floral development. In Madagascar periwinkle (Catharanthus roseus), two carpels undergo postgenital fusion, resulting in the dedifferentiation of approximately 400 epidermal cells into parenchyma cells. Dedifferentiation and fusion are triggered by an unknown factor(s), which appears to be soluble and is able to pass through the plasma membranes, walls, and cuticles of the carpel epidermal cells. In order to find better ways of collecting factor for later identification, factor was both trapped in porous polycarbonate barriers placed in between the carpels (as has been previously reported) or in agar-solidified medium into which cultured carpels secreted factor. The trapped factor was applied to the abaxial surface of different sets of carpels, and dedifferentiation was induced in areas where it was not normally seen. In addition, agar blocks that had been in contact only with prefusion carpels appeared to induce epidermal cell walls on this surface to become wavy, perhaps indicating a wall modification effect. Also, RNA was extracted from carpels at different stages of fusion, and double-stranded cDNA was generated using BD SMART^TM PCR. The resulting cDNA populations were then subjected to suppressive-subtractive hybridization PCR, and fragments were amplified that should correspond to genes that are being differentially expressed between the pre-fusion and fusing stages. Subsequent purification, sequencing, and comparison of these fragments to known sequences should provide better knowledge as to how the dedifferentiation process works in this system. Future work will also focus on the identification of the molecules secreted by both pre- and fusing stage carpels.