Techniques for intrinsically labeling wheat with 65Zn

Several techniques of intrinsically labeling wheat with 65Zn were compared: stem injection of 65Zn, stem injection of 65Zn + ZnSO4, foliar application of 65Zn, and the addition of 65Zn to a hydroponic solution. Incorporation levels of 65Zn into the grain were 62.6% stem injection, 45.2% stem-injected 65Zn + ZnSO4, 57.5% foliar application, and 2.3% hydroponic solution. Four protein fractions were extracted from fat-free whole wheat flour. Distribution of 65Zn into the protein fractions for all treatments, was 8.5-20.3% in albumins and globulins, 47.4-60.3% in glutenins, 1-2.6% in gliadins, and 9.8-28.3% in the remaining proteins. Separation of the fractions by gel chromatography showed that protein and Zn distributions were similar among the treatments and when compared to the controls. Zinc-65 distribution was similar to the natural Zn distribution. These data illustrate that stem-injected 65Zn is incorporated in the same manner and ratios as Zn naturally utilized by wheat