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Twinned Raphides of Calcium Oxalate in Grape (Vitis): Implications for Crystal Stability and Function
International Journal of Plant Sciences
|January 29, 2000
Summary
Plant raphides, needle-shaped calcium oxalate crystals, exhibit rotational twinning. This unique crystal structure may enhance mechanical strength and stability, aiding plant defense mechanisms against herbivores.
Area of Science:
- Plant biology
- Biomineralization
- Crystal structure
Background:
- Higher plants often accumulate crystalline calcium oxalate, with many taxa producing needle-shaped raphides.
- Raphides are implicated in plant defense against herbivory, with their shape crucial to proposed defense mechanisms.
- Previous studies noted twinned crystals in Vitaceae raphides, but the nature of this twinning was unclear.
Purpose of the Study:
- To investigate the fine structure of raphides in Vitis species.
- To determine the specific nature of crystal twinning in Vitis raphides.
Main Methods:
- Isolated raphides were rotated under cross-polarized light to observe extinction patterns.
- Cross-sections of raphides were analyzed.
- Etched crystals were examined to study dissolution patterns.
Main Results:
- Extinction patterns indicated that Vitis raphides are twinned along their length.
- The twin plane was observed to extend across the raphides, parallel to their surfaces.
- Dissolution patterns suggested a rotational type of twinning.
Conclusions:
- Vitis raphides exhibit rotational twinning, a characteristic that may enhance mechanical strength.
- This twinning could be vital for crystal stability and persistence, enabling the production of raphide morphology.
- Understanding raphide twinning provides insights into plant defense strategies and biomineralization processes.