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Bulk Carbohydrate Grain Filling of Barley β‐Glucan Mutants Studied by 1 H HR MAS NMR
Author(s) -
Seefeldt Helene Fast,
Larsen Flemming Hofmann,
Viereck Nanna,
Wollenweber Bernd,
Engelsen S⊘ren Balling
Publication year - 2008
Publication title -
cereal chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.558
H-Index - 100
eISSN - 1943-3638
pISSN - 0009-0352
DOI - 10.1094/cchem-85-4-0571
Subject(s) - chemistry , glucan , starch , amylose , carbohydrate , magic angle spinning , hordeum vulgare , analytical chemistry (journal) , nuclear magnetic resonance spectroscopy , polysaccharide , nuclear magnetic resonance , food science , crystallography , chromatography , biochemistry , poaceae , stereochemistry , botany , physics , biology
Temporal and genotypic differences in bulk carbohydrate accumulation in three barley genotypes differing in the content of mixed linkage β‐(1→3),(1→4)‐D‐glucan (β‐glucan) and starch were investigated using proton high‐resolution, magic angle spinning, nuclear magnetic resonance ( 1 H HR MAS NMR) during grain filling. For the first time, 1 H HR MAS NMR spectra of flour from immature barley seeds are analyzed. Spectral assignments are made using two‐dimensional (2D) NMR methods. Both α‐ and β‐glucan biosynthesis were characterized by inspection of the spectra as well as by calibration to the reference methods for starch and β‐glucan content. Starch was quantified with very good calibrations to the α‐(1→4) peak (5.29–5.40 ppm) and the region 3.67–3.83 ppm covering starch glycopyranosidic protons from H5 and H6. In contrast, the spectral inspection of the β‐anomeric region 4.45–4.85 ppm showed unexpected lack of intensity in the high β‐glucan mutant lys5f at seed maturity, resulting in poor calibration to reference β‐glucan content. We hypothesize that the lack of β‐glucan signal in lys5f indicates partial immobilization of the β‐glucan that appears to be either genotypic dependent or water/β‐glucan ratio dependent.