Raman Spectroscopy Enables Non-invasive and Confirmatory Diagnostics of Aluminum and Iron Toxicities in Rice

Abstract

Metal toxicities can be detrimental to a plant health, as well as to the health of animals and humans that consume such plants. Metal content of plants can be analyzed using colorimetric, atomic absorption- or mass spectroscopy-based methods. However, these techniques are destructive, costly and laborious. In the current study, we investigate the potential of Raman spectroscopy (RS), a modern spectroscopic technique, for detection and identification of metal toxicities in rice. We modeled medium and high levels of iron and aluminum toxicities in hydroponically grown plants. Spectroscopic analyses of their leaves showed that both iron and aluminum toxicities can be detected and identified with ∼100% accuracy as early as day 2 after the stress initiation. We also showed that diagnostics accuracy was very high not only on early, but also on middle (day 4–day 8) and late (day 10–day 14) stages of the stress development. Importantly this approach only requires an acquisition time of 1 s; it is non-invasive and non-destructive to plants. Our findings suggest that if implemented in farming, RS can enable pre-symptomatic detection and identification of metallic toxins that would lead to faster recovery of crops and prevent further damage.

Diagnosing arsenic-mediated biochemical responses in rice cultivars using Raman spectroscopy

“…The Raman spectra collected from rice leaves contained several peaks that corresponded to different biomolecules, such as carotenoids (1003, 1155, 1185, 1213, 1525 cm -1 ), phenylpropanoids (1604, 1632 cm -1 ), cellulose (917, 1048 cm -1 ), carbohydrates (1155 cm -1 ), and pectin (747 cm -1 ) ( Sanchez et al., 2020 ; Higgins et al., 2022a , Higgins et al., 2022b ) ( Figure 1 ). The peaks at 1286, 1326, 1386, and 1440 cm -1 could be assigned to CH and CH 2 vibrations, which are present in nearly all classes of biological molecules.…”

“…Presidio is a Southern U.S. tropical japonica rice cultivar while the rest were indica cultivars. The plants received nutrients via a Yoshida solution mixture consisting of macronutrients (114.30 mg/L NH 4 NO 3 , 50.40 mg/L NaH 2 PO 4 ·2H 2 O, 89.30 mg/L K 2 SO 4 , 108.25 mg/L CaCl 2 and 405 mg/L MgSO 4 ·7H 2 O), and micronutrients [1.875 mg/L MnCl2·4H2O, 0.093 mg/L (NH 4 ) 6 Mo 7 O 24 ·4H 2 O, 1.09 mg/L H 3 BO 3 , 0.038 mg/L CuSO 4 ·5H 2 O, 9.62 mg/L FeCl 3 ·6H 2 O, 14.88 mg/L C 6 H 8 O 7 ·H 2 O and 0.043 mg/L ZnSO 4 ·7H 2 O] ( Higgins et al., 2022a ). The water and solution for the crops were completely replaced every 3 days, and the hydroponics were maintained at a pH of 5.…”

“…The water and solution for the crops were completely replaced every 3 days, and the hydroponics were maintained at a pH of 5. Experimental growth conditions were controlled in a growth chamber set to a day/night cycle of 12h/12h, humidity to 55%, and day/night temperatures to 29°C/26°C ( Higgins et al., 2022a ). Rice was grown in such conditions for two weeks before initiation of arsenic stress.…”

“…For example, a study in 2022 showed that RS could detect Fusarium head blight in wheat kernels due to the spectral changes in bands associated with lignin, carotenoids, pectin, cellulose, protein, and starch ( Qiu et al., 2022 ). It was also recently demonstrated that RS could be used to diagnose nutritional deficiencies, salinity stress, and aluminum and iron toxicities with high accuracy in rice crops ( Sanchez et al., 2020 ; Higgins et al., 2022a ). Based on these previous findings, we hypothesize that RS can be used to detect changes caused by arsenic stress in rice.…”

Understanding the Mechanics of the Temporomandibular Joint Osteochondral Interface from Micro- and Nanoscopic Perspectives

“…Raman spectroscopy is a noninvasive spectroscopic analysis technique using the inelastic scattering phenomenon caused by molecular vibrations in tissues. − Since different molecules of substances have specific vibration and rotation energy levels, spectral peaks appear at specific positions on the spectrum, and the intensity of spectral peaks reflects the relative content of the substance . As suggested by the Raman spectral results in regions i, ii, and iii, the main peak of PO 4 3– ν1 symmetric stretching at 960 cm –1 and the weak peak of CO 3 2– ν1 in-plane vibration at 1071 cm –1 indicate that the inorganic substance present in the osteochondral interface is carbonate-substituted HAP .…”