Confocal Volumetric μXRF and Fluorescence Computed μ-Tomography Reveals Arsenic Three-Dimensional Distribution within IntactPteris vittataFronds

Abstract

The fern Pteris vittata has been the subject of numerous studies because its extreme arsenic hyperaccumulation characteristics. However, information on the arsenic chemical speciation and distribution across cell types within intact frozen-hydrated Pteris vittata fronds is necessary to better understand the arsenic biotransformation pathways in this unusual fern. While 2D X-ray absorption spectroscopy imaging studies show that different chemical forms of arsenic -As(III) and As(V)occur across the plant organs, depth-resolved information of arsenic distribution and chemical speciation in different cell types within tissues of Pteris vittata have not been reported. By using a combination of planar and confocal µ-X-ray fluorescence imaging and fluorescence computed µtomography, this study reveals the localization of Arsenic in the endodermis and pericycle surrounding the vascular bundles in the rachis and the pinnules of the fern. Arsenic is also accumulated in the vascular bundles connecting into each sporangium, and in some mature sori. The use of 2D X-ray absorption near edge structure imaging allows for deciphering arsenic speciation across the tissues, revealing arsenate in the vascular bundles and arsenite in the endodermis and pericycle. This study demonstrates how different advanced synchrotron X-ray microscopy techniques can be complementary in revealing, at tissue and cellular levels, elemental distribution and chemical speciation in hyperaccumulator plants.

Size- and Ligand-Dependent Transport of Nanoparticles in Matricaria chamomilla as Demonstrated by Mass Spectroscopy and X-ray Fluorescence Imaging

“…This approach also was able to show differential spatial accumulation of Zn and Ni depending on the area of Noccaea tymphaea (a Ni hyperaccumulator) tissues studied, as the metals were localized in different types of leaf cells, but the same areas of the seeds of the plant . XFI was also used to determine the distribution of toxic contaminants within several plants, revealing that As was accumulated around vascular conducts in fern leaves or Pteris vittata , while La an Ce were found in necrotic areas of the leaves of Dicranopteris lineariz . In addition, XFI has been used more recently to study the interaction between plants and engineered nanomaterials. − Specially, XFI studies have provided insight into issues caused by NPs present in the environment during plant growth.…”

“…with different spatial resolution (μm or nm), − as well as exogenous environmental elements present as contaminants accumulated by plant species ( i.e ., La, Ce, As, etc . ). , For example, XFI mapping and tomography were used to demonstrate a correlation between Zn and Fe homeostasis, as Zn can be found in the chloroplasts and mitochondria of leaf cells in Fe-deficient plants . This approach also was able to show differential spatial accumulation of Zn and Ni depending on the area of Noccaea tymphaea (a Ni hyperaccumulator) tissues studied, as the metals were localized in different types of leaf cells, but the same areas of the seeds of the plant .…”

“…Alternatively, contamination with CeO 2 NPs may be of concern for the food chain, , as these NPs can be found in and alter the quality of corn and soybean seeds. However, normally, most plants analyzed by XFI in these examples are fixed and sectioned, or studied under cryogenic conditions, resulting in a static snapshot of the exposure scenario. ,,,− Others have evaluated hydrated or live plants at room temperature, although the irradiation must occur quickly. Furthermore, unwanted self-absorption by the samples of the X-ray emissions from the elements examined means that it is difficult to study whole plants, and samples others than leaves and seedlings (which are not very thick) are normally prepared as sections.…”

Atomic Spectrometry Update: review of advances in elemental speciation

“…The study demonstrated that two closely-related As-accumulating ferns had distinct mechanisms for As uptake, modulating As cycling in As-rich environments. In the second study looking at Pteris vittate , van der Ent et al 72 combined planar and confocal μXRF imaging and fluorescence computed μ-tomography to study the localisation of As in the endodermis and pericycle surrounding the vascular bundles in the rachis and the pinnules of the fern. Arsenic was also accumulated in the vascular bundles connecting into each sporangium, and in some mature sori.…”

Preparation of CdS@C Photocatalyst Using Phytoaccumulation Cd Recycled From Contaminated Wastewater

“…Phytoextraction is considered as a feasible and cost-efficient in situ remediation strategy for slightly or moderately contaminated environments with heavy metals, including Cu, Mn, As, Cd, and Zn ( Hou et al, 2017 ; Li et al, 2018 ; Ent et al, 2020 ). In fact, phytoextraction has been applied for achieving a substantial removal of arsenic (As) and cadmium (Cd) from environments at large-scale field trials in China ( Li et al, 2018 ; Zhou et al, 2020 ).…”