Phenolic content variability and its chromosome location in tritordeum

Abstract

For humans, wheat is the most important source of calories, but it is also a source of antioxidant compounds that are involved in the prevention of chronic disease. Among the antioxidant compounds, phenolic acids have great potential to improve human health. In this paper we evaluate the effect of environmental and genetic factors on the phenolics content in the grain of a collection of tritordeums with different cytoplasm and chromosome substitutions. To this purpose, tritordeum flour was used for extraction of the free, conjugates and bound phenolic compounds. These phenolic compounds were identified and quantified by RP-HPLC and the results were analyzed by univariate and multivariate methods. This is the first study that describes the composition of phenolic acids of the amphiploid tritordeum. As in wheat, the predominant phenolic compound is ferulic acid. In tritordeum there is great variability for the content of phenolic compounds and the main factor which determines its content is the genotype followed by the environment, in this case included in the year factor. Phenolic acid content is associated with the substitution of chromosome DS1D(1H(ch)) and DS2D(2H(ch)), and the translocation 1RS/1BL in tritordeum. The results show that there is high potential for further improving the quality and quantity of phenolics in tritordeum because this amphiploid shows high variability for the content of phenolic compounds.

Keywords: antioxidant; chromosome sustitution; flour quality; healthy; nutritive; plant breeding; variability; wheat.

Figure 1

RP-HPLC chromatograms of the bound (A), conjugated (B), and free (C) phenolics fractions from tritordeum grain.

Figure 2

Principal components analysis. (A) The quantitative variables are represented. (B) The individuals lines and the centroids of levels factors “Year,” “Sustitutions,” “1RS/RL,” and “Cytoplasm” are represented.x “B.FA,” “F.FA,” “C.FA,” “Total.FA” are bound, free, conjugated and total ferulic acid; “B.VA,” “F.VA,” “C.VA,” “Total.VA” are bound, free, conjugated and total vanillic acid; “B.pCA,” “F.pCA,” “C.pCA,” “Total.pCA” are bound, free, conjugated and total p-coumaric acid; “B.CA,” “F.CA,” “C.CA,” “Total.CA” are bound, free, conjugated and total caffeic acid; “B.SA,” “F.SA,” “C.SA,” “Total.SA” are bound, free, conjugated and total syringic acid; “Total.B,” total bound phenolic; “Total.F,” total free phenolic; “Total.C,” total conjugated phenolic; “Total.phenolic,” total phenolic; “Total.Dim,” total dimer phenolic.

Figure 3

Content of phenolic compounds with a significant effect of the translocation 1RS/RL (p-value < 0.05; Table 4). N, no translocation; R, translocation 1RS/RL.

Figure 4

Phenolic acid content and multiple-comparison results of the different substitution lines. Gray bars are significantly different (p-value < 0.05) compared to the no substitution (N). Comparison of means (Tukey contrast) between levels of factor “Substitutions” took place only when the ANOVA table of Model 2 (Table 4) showed a significant effect of this factor. Figure shows only those compounds where any substitution level showed differences with respect to no substitution level (N).