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ARS Home » Southeast Area » Auburn, Alabama » Soil Dynamics Research » Research » Publications at this Location » Publication #358534

Research Project: Enhancing Production and Ecosystem Services of Horticultural and Agricultural Systems in the Southeastern United States

Location: Soil Dynamics Research

Title: Spatial distribution of structural elements in leaves of Ilex paraguariensis: Physiological and ecological implications

item BARBOSA, JULIERME - Uninga University Center
item MOTTA, ANTONIO - Universidade Federal Do Parana
item DOS REIS, ANDRE - Sao Paulo State University (UNESP)
item CORREA, RODRIGO - University Of Brazil
item Prior, Stephen - Steve

Submitted to: Trees
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/12/2019
Publication Date: 8/22/2019
Citation: Barbosa, J.Z., Motta, A.C., Dos Reis, A.R., Correa, R.S., Prior, S.A. 2019. Spatial distribution of structural elements in leaves of Ilex paraguariensis: Physiological and ecological implications. Trees. 34:101-110.

Interpretive Summary: Yerba mate leaves (Ilex paraguariensis) have been used in various products (food, beverage, cosmetic, and pharmaceutical) and contain elements that are of interest to human health. Leaf composition can vary due to environmental factors and farm practices, but the distribution of elements and crystal formations in yerba mate leaves is not well known. This work used standard chemical composition methods along with microscopy-spectroscopy analyses to examine where elements accumulated in leaves. Findings where related to possible physiological and/or ecological roles in yerba mate plants.

Technical Abstract: The concentration, form and location of elements in the leave tissue can impact on their release during the infusion such as used yerba mate (Ilex paraguariensis St., Hil.) leaves beverage and element remobilization. The spatial distribution of elements and characterization of crystals formation in I. paraguariensis is still not elucidated. Thus, this study aimed to use microanalysis technique to generate an initial understanding of elemental accumulation in yerba mate leaves. Spatial distribution of elements in yerba mate leaves from native-grown conditions were performed using scanning electron microscopy with dispersive energy spectroscopy (SEM-EDS). Chemical composition of leaves confirmed the high concentration of K and Mn as macro and micronutrients, respectively. Cell walls were predominantly composed by carbon (C) and oxygen (O). Compartmentalization of silicon (Si) occurred on the external surface of the upper epidermis between the cell wall and the cuticle of the leaves. Precipitation of calcium (Ca), O, and C was higher in the midrib than in the blade leaf. The mesophyll and the palisade mesophyll being the main accumulation sites. These precipitates probably are Ca oxalate crystals that also contained other elements (K, Mg, S, Mn, Na, Si, Al) in very low proportion. Microscopy-spectroscopy analyses revealed that there are differences in mechanisms of elements accumulation in leaves, which propose a physiological and ecological implications for yerba mate plants. Additionally, the abundance of Ca oxalates could explain the low Ca solubility from infusion.