Developmental and Structural Section
Amponsem, Ohene , Weston, Erica , Ingram, Brian , Cote, Gary .
Regulation, Histochemistry, and Structure of Crystal-Producing Idioblast Cells in Dieffenbachia seguine (Araceae).
Many plants, especially in the Araceae, have idioblast cells which produce crystals of calcium oxalate. Some aroid species, including Dieffenbachia seguine, have an unusual type of crystal idioblast, termed the biforine,which is able to forcibly expel the crystals. It has often been proposed that these crystals, particularly those in biforines, might play a role in defending against herbivory. If this is true we would hypothesize that plants regulate the number of crystal idioblasts in foliage, producing more if the plant is under threat from herbivores. To test this we have examined the abundance of crystals in leaves of plants treated with simulated herbivory or with plant hormones that signal various kinds of stress. We found that crystal abundance drops with age; this is consistent with the hypothesis, since younger leaves are often more tempting to herbivores. However, none of the experimental treatments had any effect on the abundance of crystals, contradicting the hypothesis. We are extending this work by maintaining leaf pieces in peel culture so that leaf cells are directly in contact with the test substances. We are also studying the cell walls of biforines, which are noticeably thicker and more robust than those of other leaf cells, to the point that they survive blending or grinding with a mortar and pestle, which destroy all other leaf cells. Histochemical studies indicate the cell walls are remarkably free of lignin and other phenolics. We have also begun scanning electron microscopy studies of the structures of the crystals themselves.
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1 - Radford University, Biology, 501 Stockton Street,, Radford, VA, 24142, USA
2 - Radford University, Biology, 501 Stockton Street,, Radford, VA, 24142, USA
Presentation Type: Poster:Posters for Sections
Location: Khorassan Ballroom/Chase Park Plaza
Date: Monday, July 11th, 2011
Time: 5:30 PM