Poster: Vegetative Development

Abs # 446: Regulation of Dieffenbachia idioblast cells containing calcium oxalate crystals

Presenter:	Coté, Gary G., gcote@radford.edu
Authors	Coté, Gary G. (A)   Gowdy, Christopher C. (A)   Brooks, Natasha L. (A)   Ryan, Matthew  (A)   Bowling, Lisa D. (A)
Affiliations:	(A): Department of Biology, Radford University

We are investigating the development of a particular kind of plant cell, the idioblasts that produce calcium oxalate crystals. The physiological roles of crystal idioblasts are not completely understood; calcium storage, oxalate sequestration and herbivore deterrence have all been suggested. We are focusing on the toxic aroid Dieffenbachia, in which the idioblasts have been suggested to play a role in toxicity and therefore in resisting herbivores. At least four kinds of crystal idioblasts are present in the leaves of this plant: raphide idioblasts, which have bundles of long, pointed crystals which they can eject; giant idioblasts which have a larger bundles of similar, but larger crystals; druses, which have small, flower-like crystals, and small idioblasts with bundled crystals. We have found that the numbers per unit leaf area of each kind of idioblast decreases as leaves age, consistent with their providing maximum protection against herbivores in tender young leaves. However, we have found no evidence of any change in the number or kinds of idioblasts in response to simulated herbivory. We are currently examining the effects of herbivory- and other stress-related signaling compounds, such as jasmonic acid and salicylic acid. To facilitate study of the cells in vitro, we have developed a method to isolate live idioblasts in suspension, and to separate idioblasts from photosynthetic and epidermal cells. We are attempting to separate the different kinds of idioblasts from each other. Supported by the Radford University Foundation and the Thomas F. and Kate Miller Jeffress Memorial Trust.