Amaranth calcium oxalate crystals are associated with chloroplast structures and proteins

Calcium oxalate (CaOx) crystals in plants are formed in crystal idioblasts cells and have specific geometric shapes. Their proposed functions include calcium homeostasis and carbon source, among others. Amaranth is a plant that presents high tolerance to abiotic stresses and accumulates considerable...

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Bibliographic Details
Published in:Microscopy research and technique 2022-11, Vol.85 (11), p.3694-3706
Main Authors: Cerritos‐Castro, Ivan Takeshi, Patrón‐Soberano, Araceli, Bojórquez‐Velázquez, Esaú, González‐Escobar, Jorge Luis, Vargas‐Ortiz, Erandi, Muñoz‐Sandoval, Emilio, Barba de la Rosa, Ana Paulina
Format: Article
Language:English
Subjects:
Amaranth
Amaranthus
biomineralization
Calcium
Calcium homeostasis
Calcium oxalate
calcium oxalate crystals
Carbon
Carbon sources
Cell walls
chloroplast degradation
Chloroplasts
Crystal structure
Crystals
Electron microscopy
Homeostasis
Immunohistochemistry
Leaves
Mesophyll
nLC–MS/MS
Oxalic acid
Parenchyma
Proteins
Ribulose-bisphosphate carboxylase
RuBisCO
Thylakoid membranes
Ultrastructure
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Summary:Calcium oxalate (CaOx) crystals in plants are formed in crystal idioblasts cells and have specific geometric shapes. Their proposed functions include calcium homeostasis and carbon source, among others. Amaranth is a plant that presents high tolerance to abiotic stresses and accumulates considerable amounts of CaOx crystals; however, few studies have focused on characterizing the crystals ultrastructure and none is related to identifying proteins bound to them. This information is of great interest to understand the mechanisms related to CaOx crystal formation and to support their proposed functions. Thus, this work aimed to characterize CaOx crystals in amaranth leaves. Crystals were purified and the proteins bound to them were isolated and identified by nLC–MS/MS. Leaf sections were analyzed by light and electron microscopy. The identified proteins were related to the chloroplast such as ATPb synthase, RuBisCO large subunit, and cell wall‐related proteins, which were validated by immunohistochemistry and immunogold labeling. In addition, it was observed that CaOx crystal idioblasts were formed from parenchyma cells associated with mesophyll and veins, in which the thylakoid membranes of degraded chloroplasts turned into crystal chambers. These results significantly advance our understanding of the mechanisms of CaOx crystal formation and the potential function as an alternative carbon source in leaves. Plants form calcium oxalate crystals with particular geometric shapes. These crystals grow in crystalline chambers within specialized cells. It has been hypothesized that these chambers may control crystal shape. Our results support this hypothesis and further suggest that the crystalline chambers are formed from degraded chloroplast thylakoids.
ISSN:1059-910X
1097-0029
DOI:10.1002/jemt.24221