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Calcium oxalate crystals in plant communities of the southeast of the pampean plain.
OSTERRIETH, MARGARITA; ALTAMIRANO, STELLA MARIS; BORRELLI, NATALIA; FERNÁNDEZ HONAINE, MARIANA; BENVENUTO, MARIA LAURA
Simposio; 14th International Symposium of Biomineralization; 2017
Calcium oxalate crystals (COC) are one of the most prevalent and widely distributed biomineralizations in plants. COC were analyzed in vegetative organs and fruits of vegetal species from forests, wetlands and agroecosystems of the southeast of the Pampean Plain. Diaphanization, clearing of tissues with 50% sodium hypochlorite and cross sectioning of the plant organs were realized. The material was mounted with gelatin-glycerin and COC were identified and described with optical, polarization and scanning electron microscopes. Crystal density was calculated and the composition of the crystals was analyzed by X-ray dispersive spectroscopy (EDS). Calcification mainly occurred in parenchymatous tissue. Generally, single crystal morphology was observed per organ. Druses, prisms, raphides and crystal sands were observed in the different vegetative organs of the plant species. In fruits, only prismatic crystals were observed, being smaller (5-11μm) than the vegetative organs (14-210μm). The COC density let to grouped together the tree species and the fruits of the species analyzed given their greater COC density: 9167-28308 and 1112-18531 crystals/mm2, respectively. The aquatic community (7-250 crystals/mm2) and the crop (340 crystals/mm2) were not differentiated for the crystal density, but by the COC morphology. The description and quantification of COC allowed to distinguish among different plant communities, species and organs. COCs in vegetative organs have structural and defense functions among others, ensuring the normal growth, development and reproductive success of the species. At death, plant material become part of the organic horizons, where its transformation allows the availability of calcium from COC promoting soil fertility and plant nutrition, both in natural and agroecosystems.