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Title: Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods

Abstract

The organ-specific accumulation, spatial distribution, and chemical speciation of selenium (Se) were previously unknown for any species of cactus. We investigated Se in Opuntia ficus-indica using inductively coupled plasma mass spectrometry, microfocused x-ray fluorescence elemental and chemical mapping ({micro}XRF), Se K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). {micro}XRF showed Se concentrated inside small conic, vestigial leaves (cladode tips), the cladode vasculature, and the seed embryos. Se K-edge XANES demonstrated that approximately 96% of total Se in cladode, fruit juice, fruit pulp, and seed is carbon-Se-carbon (C-Se-C). Micro and bulk XANES analysis showed that cladode tips contained both selenate and C-Se-C forms. Inductively coupled plasma mass spectrometry quantification of Se in high-performance liquid chromatography fractions followed by LC-MS structural identification showed selenocystathionine-to-selenomethionine (SeMet) ratios of 75:25, 71:29, and 32:68, respectively in cladode, fruit, and seed. Enzymatic digestions and subsequent analysis confirmed that Se was mainly present in a 'free' nonproteinaceous form inside cladode and fruit, while in the seed, Se was incorporated into proteins associated with lipids. {micro}XRF chemical mapping illuminated the specific location of Se reduction and assimilation from selenate accumulated in the cladode tips into the two LC-MS-identified C-Se-C forms before they were transportedmore » into the cladode mesophyll. We conclude that Opuntia is a secondary Se-accumulating plant whose fruit and cladode contain mostly free selenocystathionine and SeMet, while seeds contain mainly SeMet in protein. When eaten, the organic Se forms in Opuntia fruit, cladode, and seed may improve health, increase Se mineral nutrition, and help prevent multiple human cancers.« less

Authors:
; ; ; ; ; ; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
Advanced Light Source Division
OSTI Identifier:
1048282
Report Number(s):
LBNL-4932E
TRN: US201216%%860
DOE Contract Number:  
DE-AC02-05CH11231
Resource Type:
Journal Article
Journal Name:
Plant Physiology
Additional Journal Information:
Journal Volume: 155; Journal Issue: 1; Related Information: Journal Publication Date: January 2011
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES; 59 BASIC BIOLOGICAL SCIENCES; ABSORPTION; CROPS; DISTRIBUTION; EMBRYOS; FLUORESCENCE; HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY; LIPIDS; MASS SPECTROSCOPY; NUTRITION; PLASMA; PROTEINS; SEEDS; SELENATES; SELENIUM; SPATIAL DISTRIBUTION; SPECTROSCOPY

Citation Formats

Banuelos, Gary S, Fakra, Sirine C, Walse, Spencer S, Marcus, Matthew A, Yang, Soo In, Pickering, Ingrid J, Pilon-Smits, Elizabeth A.H., and Freeman, John L. Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods. United States: N. p., 2011. Web. doi:10.1104/pp.110.162867.
Banuelos, Gary S, Fakra, Sirine C, Walse, Spencer S, Marcus, Matthew A, Yang, Soo In, Pickering, Ingrid J, Pilon-Smits, Elizabeth A.H., & Freeman, John L. Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods. United States. doi:10.1104/pp.110.162867.
Banuelos, Gary S, Fakra, Sirine C, Walse, Spencer S, Marcus, Matthew A, Yang, Soo In, Pickering, Ingrid J, Pilon-Smits, Elizabeth A.H., and Freeman, John L. Fri . "Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods". United States. doi:10.1104/pp.110.162867. https://www.osti.gov/servlets/purl/1048282.
@article{osti_1048282,
title = {Selenium Accumulation, Distribution, and Speciation in Spineless Prickly Pear Cactus: A Drought- and Salt-Tolerant, Selenium-Enriched Nutraceutical Fruit Crop for Biofortified Foods},
author = {Banuelos, Gary S and Fakra, Sirine C and Walse, Spencer S and Marcus, Matthew A and Yang, Soo In and Pickering, Ingrid J and Pilon-Smits, Elizabeth A.H. and Freeman, John L},
abstractNote = {The organ-specific accumulation, spatial distribution, and chemical speciation of selenium (Se) were previously unknown for any species of cactus. We investigated Se in Opuntia ficus-indica using inductively coupled plasma mass spectrometry, microfocused x-ray fluorescence elemental and chemical mapping ({micro}XRF), Se K-edge x-ray absorption near-edge structure (XANES) spectroscopy, and liquid chromatography-mass spectrometry (LC-MS). {micro}XRF showed Se concentrated inside small conic, vestigial leaves (cladode tips), the cladode vasculature, and the seed embryos. Se K-edge XANES demonstrated that approximately 96% of total Se in cladode, fruit juice, fruit pulp, and seed is carbon-Se-carbon (C-Se-C). Micro and bulk XANES analysis showed that cladode tips contained both selenate and C-Se-C forms. Inductively coupled plasma mass spectrometry quantification of Se in high-performance liquid chromatography fractions followed by LC-MS structural identification showed selenocystathionine-to-selenomethionine (SeMet) ratios of 75:25, 71:29, and 32:68, respectively in cladode, fruit, and seed. Enzymatic digestions and subsequent analysis confirmed that Se was mainly present in a 'free' nonproteinaceous form inside cladode and fruit, while in the seed, Se was incorporated into proteins associated with lipids. {micro}XRF chemical mapping illuminated the specific location of Se reduction and assimilation from selenate accumulated in the cladode tips into the two LC-MS-identified C-Se-C forms before they were transported into the cladode mesophyll. We conclude that Opuntia is a secondary Se-accumulating plant whose fruit and cladode contain mostly free selenocystathionine and SeMet, while seeds contain mainly SeMet in protein. When eaten, the organic Se forms in Opuntia fruit, cladode, and seed may improve health, increase Se mineral nutrition, and help prevent multiple human cancers.},
doi = {10.1104/pp.110.162867},
journal = {Plant Physiology},
number = 1,
volume = 155,
place = {United States},
year = {2011},
month = {7}
}