Identification of Metabolites in Basil Leaves by Desorption Electrospray Ionization Mass Spectrometry Imaging after Cd Contamination

Abstract

In this study, basil (Ocimum basilicum L.) seedlings were intoxicated with Cd2+ and cultivated using a 5% v v–1 Hoagland nutrient solution. Desorption electrospray ionization mass spectrometry imaging (DESI-MSI) was used to identify different compounds on basil leaves (without and with 10 μmol L–1 Cd2+). DESI-MSI analysis identified 28 images of ions with high accuracy (mass deviation < 1.8 ppm) in contaminated and uncontaminated leaves. The biomarkers formed due to Cd external stress under controlled laboratory experiments were putatively identified in contaminated leaves as jasmone, hexose sugars, salvigenin, flavonoids (C18H14O7 and C21H22O10), and fatty acyl glycosides (C18H28O9). The accumulation of Cd occurred preferentially in the roots but also on the stems and leaves. The methodology to quantify Cd in basil organs was optimized and validated using an ultrasound-assisted micro-extraction procedure. Limits of detection and quantification were 6 and 17 μg L–1, respectively, with a precision better than 7.5 %, obtained by fast sequential flame atomic absorption spectrometry (FS FAAS). The standard reference material of spinach leaf (SRM NIST 1570a) presented a recovery of 101 ± 8 %. DESI-MSI was for the first time employed to examine the behavior of metabolites in plants maintained under stress conditions by the exposure to high levels of cadmium.

Influence of Silicon and Selenium and Contribution of the Node to Cadmium Allocation and Toxicity in Rice

“…Rice feeds more than 50% of the world’s population . Cadmium (Cd) contamination of soil is a serious environmental and agricultural issue and widely occurs in paddy soil around the world. − Cd contamination of soil is widespread and usually caused by anthropogenic sources, including industrial smelting and mining, sewage sludge, application of Cd-containing pesticide and fertilizer, waste disposal, and vehicle exhaust . Soil Cd can readily accumulate and be transported in a soil–crop system because Cd is more mobile than other heavy metals and then potentially accumulate throughout the food chain, posing a public health risk .…”

Mapping Molecular Signatures in Plant Leaves, Flowers, and Fruits by a TiO2 Nanotube-Based Plasmonic Chip for Imprint Mass Spectrometry Imaging

“…Mass spectrometry imaging (MSI) has emerged as a labelfree and untargeted detection technique for simultaneously capturing chemical recognition and spatiotemporal distribution information. 9 Among the available techniques, matrix-assisted laser desorption/ionization (MALDI), 10−12 secondary ionization (SI), 13,14 desorption electrospray ionization (DESI), 15,16 and laser ablation electrospray ionization (LA-ESI) 17,18 have become the most routinely used ionization sources of choice for mapping diverse metabolites in plant tissues, including sugars, amino acids, alkaloids, flavonoids, glucosides, and lipids. 4,19 Despite being widely adopted, conventional MALDI-MSI techniques remain challenging due to the intrinsic background interferences at the low mass range that originated from organic matrices and potentially altering native localization caused by inhomogeneous cocrystallization.…”

“…Mass spectrometry imaging (MSI) has emerged as a label-free and untargeted detection technique for simultaneously capturing chemical recognition and spatiotemporal distribution information . Among the available techniques, matrix-assisted laser desorption/ionization (MALDI), − secondary ionization (SI), , desorption electrospray ionization (DESI), , and laser ablation electrospray ionization (LA-ESI) , have become the most routinely used ionization sources of choice for mapping diverse metabolites in plant tissues, including sugars, amino acids, alkaloids, flavonoids, glucosides, and lipids. , Despite being widely adopted, conventional MALDI-MSI techniques remain challenging due to the intrinsic background interferences at the low mass range that originated from organic matrices and potentially altering native localization caused by inhomogeneous cocrystallization. , To overcome these limitations, emerging advances in nanostructured materials (e.g., silicon-based, , metallic-based, , carbon-based, , semiconductor-based, , and covalent organic frameworks) have enabled matrix-free LDI for MSI analysis, termed surface-assisted laser desorption/ionization (SALDI), to be used in a rapid, high-throughput, and sensitive manner. Recently, atmospheric-pressure infrared/ ultraviolet laser desorption and plasma post-ionization have been shown to be a promising method for matrix-free MSI analysis of biological tissues under ambient conditions. , More importantly, the choice of proper sample preparation method is crucial for the MSI analysis of various plant tissue materials .…”