Determination of the fatty acid composition of the oil in intact-seed mustard by near-infrared reflectance spectroscopy

Near-Infrared Hyperspectral Imaging Pipelines for Pasture Seed Quality Evaluation: An Overview

Near-infrared (800–2500 nm; NIR) spectroscopy coupled to hyperspectral imaging (NIR-HSI) has greatly enhanced its capability and thus widened its application and use across various industries. This non-destructive technique that is sensitive to both physical and chemical attributes of virtually any material can be used for both qualitative and quantitative analyses. This review describes the advancement of NIR to NIR-HSI in agricultural applications with a focus on seed quality features for agronomically important seeds. NIR-HSI seed phenotyping, describing sample sizes used for building high-accuracy calibration and prediction models for full or selected wavelengths of the NIR region, is explored. The molecular interpretation of absorbance bands in the NIR region is difficult; hence, this review offers important NIR absorbance band assignments that have been reported in literature. Opportunities for NIR-HSI seed phenotyping in forage grass seed are described and a step-by-step data-acquisition and analysis pipeline for the determination of seed quality in perennial ryegrass seeds is also presented.

Molecular basis for the sensitivity of TRP channels to polyunsaturated fatty acids

Transient receptor potential (TRP) channels represent a superfamily of unselective cation channels that are subdivided into seven subfamilies based on their sequence homology and differences in gating and functional properties. Little is known about the molecular mechanisms of TRP channel regulation, particularly of the “canonical” TRP (TRPC) subfamily and their activation by polyunsaturated fatty acids (PUFAs). Here, we analyzed the structure-function relationship of Drosophila fruit fly TRPC channels. The primary aim was to uncover the molecular basis of PUFA sensitivity of Drosophila TRP-like (TRPL) and TRPgamma channels. Amino acid (aa) sequence alignment of the three Drosophila TRPC channels revealed 50 aa residues highly conserved in PUFA-sensitive TRPL and TRPgamma channels but not in the PUFA-insensitive TRP channel. Substitution of respective aa in TRPL by corresponding aa of TRP identified 18 residues that are necessary for PUFA-mediated activation of TRPL. Most aa positions are located within a stretch comprising transmembrane domains S2–S4, whereas six aa positions have been assigned to the proximal cytosolic C-terminus. Interestingly, residues I465 and S471 are required for activation by 5,8,11,14-eicosatetraynoic acid (ETYA) but not 5,8,11-eicosatriynoic acid (ETI). As proof of concept, we generated a PUFA-sensitive TRP channel by exchanging the corresponding aa from TRPL to TRP. Our study demonstrates a specific aa pattern in the transmembrane domains S2–S4 and the proximal C-terminus essential for TRP channel activation by PUFAs.

Mid-infrared spectral characteristics of lipid molecular structures in Brassica carinata seeds: relationship to oil content, fatty acid and glucosinolate profiles, polyphenols, and condensed tannins

The objectives of this study were to quantify lipid-related inherent molecular structures using a Fourier transform infrared spectroscopy (FT-IR) technique and determine their relationship to oil content, fatty acid and glucosinolate profile, total polyphenols, and condensed tannins in seeds from newly developed yellow-seeded and brown-seeded Brassica carinata lines. Canola seeds were used as a reference. The lipid-related molecular spectral band intensities were strongly correlated to the contents of oil, fatty acids, glucosinolates, and polyphenols. The regression equations gave relatively high predictive power for the estimation of oil (R² = 0.99); all measured fatty acids (R² > 0.80), except C14:0, C20:3n-3, C22:2n-9, and C22:2n-6; 3-butenyl, 2-OH-3-butenyl, 4-OH-3-CH3-indolyl, and total glucosinolates (R² > 0.686); and total polyphenols (R² = 0.935). However, further study is required to obtain predictive equations based on large numbers of samples from diverse sources to illustrate the general applicability of these regression equations.

Quantification of fatty acids in forages by near-infrared reflectance spectroscopy

Near-infrared reflectance spectroscopy (NIRS) was evaluated as a possible alternative to gas chromatography (GC) for the quantitative analysis of fatty acids in forages. Herbage samples from 11 greenhouse-grown forage species (grasses, legumes, and forbs) were collected at three stages of growth. Samples were freeze-dried, ground, and analyzed by GC and NIRS techniques. Half of the 195 samples were used to develop an NIRS calibration file for each of eight fatty acids, with the remaining half used as a validation data set. Spectral data, collected over a wavelength range of 1100-2498 nm, were regressed against GC data to develop calibration equations for lauric (C12:0), myristic (C14:0), palmitic (C16:0), stearic (C18:0), palmitoleic (C16:1), oleic (C18:1), linoleic (C18:2), and alpha-linolenic (C18:3) acids. Calibration equations had high coefficients of determination for calibration (0.93-0.99) and cross-validation (0.89-0.98), and standard errors of calibration and cross-validation were < 20% of the respective means. Simple linear regressions of NIRS results against GC data for the validation data set had r2 values ranging from 0.86 to 0.97. Regression slopes for C12:0, C14:0, C16:0, C18:0, C16:1, C18:2, and C18:3 were not significantly different (P = 0.05) from 1.0. The regression slope for C18:1 was 1.1. The ratio of standard error of prediction to standard deviation was > 3.0 for all fatty acids except C12:0 (2.6) and C14:0 (2.9). Validation statistics indicate that NIRS has high prediction ability for fatty acids in forages. Calibration equations developed using data for all plant materials accurately predicted concentrations of C16:0, C18:2, and C18:3 in individual plant species. Accuracy of prediction was less, but acceptable, for fatty acids (C12:0, C14:0, C18:0, C16:1, and C18:1) that were less prevalent.

Nondestructive NMR determination of oil composition in transformed canola seeds

Magic-angle spinning (MAS) 13C nuclear magnetic resonance (NMR) spectroscopy is a convenient method for nondestructive, quantitative characterization of seed oil composition. We describe results for intact hybrid and transformed canola seeds. The MAS 13C NMR technique complements and agrees with gas chromatography results. The spectral resolution approaches that of neat, liquid oils. MAS 13C NMR data allow quantitative analysis of major oil components, including saturates and oleic, linoleic, and linolenic acyl chains. 13C NMR directly and quantitatively elucidates, triglyceride regiochemistry and acyl chain cis-trans isomers that cannot be quickly detected by other methods. MAS 13C NMR can serve as the primary method for development of near-infrared seed oil calibrations. These NMR methods are nondestructive and attractive for plant-breeding programs or other studies (e.g., functional genomics) where loss of seed viability is inconvenient.