Calcium Oxalate Crystals in Plant Communities of the Southeast of the Pampean Plain, Argentina

Stella Maris Altamirano,Natalia Borrelli,María Laura Benvenuto,Margarita Osterrieth,Mariana Fernández Honaine

doi:10.1007/978-981-13-1002-7_32

Abstract

Calcium oxalate crystals (COC) are one of the most prevalent and widely distributed biomineralizations in plants. The aim of this work is to analyze and compare the data previously reported about the presence and production of COC in leaves of plant 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 leaves were realized. The material was mounted with gelatin–glycerin, and COC were identified and described with optical, polarization, and scanning electron microscopes. Crystal size and density were calculated. Calcification mainly occurred in leaf mesophyll. In terrestrial species, crystals were closely associated with vascular bundles, while in aquatic species, they were associated with aerenchyma. Druses, prisms, and raphides were observed in the leaves of all species analyzed. Average crystal size was smaller in terrestrial species than aquatic ones (12 and 80 μm, respectively), but average crystal density was higher (246 and 23 crystals/mm2, respectively). These different patterns in COC production and distribution may be related to taxonomical characteristics, the types of cells where crystals precipitate, their function, and the differential transpiration rates, among other factors.

Highlights

Biomineralizations in plants are called phytoliths (Coe et al 2014), and calcium oxalate crystals (COC) are one of the most common (Metcalfe 1985)
The aim of this work is to analyze and compare the data previously reported about the presence and production of COC in leaves of plant species from forests, wetlands, and agroecosystems of the southeast of the Pampean Plain, Argentina
The material was mounted with gelatine–glycerine, and calcium oxalate crystals were identified and described with a petrographic (Olimpus BX 51P) and optical microscope (Leitz Wetzlar D35780) at 400× magnification

Summary

Introduction

Biomineralizations in plants are called phytoliths (Coe et al 2014), and calcium oxalate crystals (COC) are one of the most common (Metcalfe 1985). COCs serve as a Ca+2 sink and source, preventing Ca accumulation and ensuring the normal cells functions, protect against herbivory and chewing insects, and play structural functions (Ilarslan et al 1997; Prychid and Rudall 1999; Molano-Flores 2001; Braissant et al 2004; Franceschi and Nakata 2005; Korth et al 2006; Bauer et al 2011). They have taxonomic importance since their morphology and distribution in plant tissues and organs are characteristic of taxa (Franceschi and Horner 1980; Franceschi and Nakata 2005; Lersten and Horner 2008). Once in the soil, oxalotrophic bacteria promote COC oxidation because they function as a carbon, energy, and electron source, influencing the carbon and calcium cycle in soils (Braissant et al 2004; Verrecchia et al 2006)

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