Publication details
Mineralogy of calcium oxalate hydrates in plants of the Araceae family
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| Year of publication | 2025 |
| Type | Appeared in Conference without Proceedings |
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| Description | Mineralogy of calcium oxalate hydrates in plants of the Araceae family INTRODUCTION Biominerals in plants include calcium oxalate hydrates (whewellite (CaC2O4 H2O; COM), weddellite (CaC2O4 2H2O; COD), and caoxite (CaC2O4 3H2O; COT)), calcium carbonate, and amorphous silica. These compounds regulate calcium levels, detoxify heavy metals, aid pollen release and germination, alleviate stress, regulate ionic reactions, detoxify oxalic acid, and protect plants from herbivores and pathogens (He et al. 2014).Methodology Based on previous exploratory research (Horáková, 2022), 10 plant species from the Araceae family were selected. The main part of the research was focused on the identification of CaOx in plant sections using Raman spectroscopy. Quantification of separated CaOx crystals was subsequently performed using the powder X-ray diffraction method. Using a polarizing microscope, CaOx crystals were observed in 5 sections of the plant body of each species from the Araceae family. Three sections from the plant leaf (leaf margin, middle part of the leaf and part of the leaf next to the main vein) and two from parts of the petiole (upper part of the petiole and lower part of the petiole) were used. Results The most common morphological types in plants of the Araceae family are raphides and druses, which are mainly of COM. Other, less common types, such as dipyramids and round or square aggregates, are typically COD. The least frequently represented types were calcium oxalate trihydrate (COT) structures, including crystalline sand and round or square aggregates. In plant leaves, calcium oxalate morphological types, such as raphides and druses (COM), were the most prevalent. In plant petioles, which were studied in two different cross-sections in each plant, raphides and druses (composed of COM) were the most abundant, along with smaller crystalline sand and round/square aggregates (all COM, COD and COT). In transmitted light under a polarizing microscope, only idioblasts with raphides, druses and crystalline sand were identified – on the contrary, dipyramids and square aggregates were not observed. Therefore, the variability of morphological types is lower than in data from a reflected light microscope coupled to a Raman spectrometer. CONCLUSION In plants of the Araceae family, the morphological types of calcium oxalate (CaOx) varied among species, with each species producing its own distinct combination of types. The most frequently observed types were raphides, druses, and crystalline sand. Raphides were more abundant than druses in the leaves of most plants, but the number of druses was slightly higher in some species (notably Monstera deliciosa). Druses were observed more in the central part of the leaves and in almost the same amount as raphides in the part next to the main vein. Crystalline sand was found in minimal amounts in the leaves of the plants. In contrast, the petiole mostly produced druses in the upper part (almost the same amount as raphides), followed by the greatest production of raphides in the lower part of the petiole, and then crystalline sand with similar proportions in both parts. When comparing the occurrence of leaves and petioles, druses were more frequently found in leaf parts, while raphides predominated in the petiole. In two members of the same species, a specific morphological form may be present only in one member and absent in the other. This discrepancy could stem from various factors, the most obvious of which are environmental differences (Eco and Belonias, 2017; Coté et al., 2012). |