Changes in the Element Composition of Globoids in Wheat Grains (Triticum aestivum L. cv. A. C. Reed and Celtic) During Seed Set and Early Seedling Growth

Abstract

In wheat grains, mineral nutrients are stored in spherical particles called globoids. Globoids are located within the protein bodies of cells from the aleurone layer, scutellum and embryonic axis of the wheat grain. Composed of phytate, globoids contain an essential source of myo-inositol, P, K, Mg, Ca, Mn, Fe and Zn which are used by the growing seedling during early seedling growth. Changes to the element composition within the globoids from the aleurone, scutellum and embryo axis, during seed set and early seedling growth were examined in two cultivars of wheat through the use of energy dispersive X-ray analysis. During seed set and early seedling growth the composition of the globoids within all tissues changed. In each of the tissues in both cultivars the P levels decreased during seed set and remained relatively constant during early seedling growth. K levels increased during seed set and decreased during early seedling growth. Mg and Ca levels generally decreased during seed set and increased during early seedling growth. Mn and Zn were detected only within globoids within the embryonic axis and no changes were noted for these two elements. Energy dispersive X-ray analysis showed that A.C. Reed and Celtic grains both followed the same general trends during seed set and seedling growth indicating that the differing protein content of the two cultivars had little effect on the timing of mineral nutrient accumulation and utilization within the globoids. Atomic absorption analysis of whole grain tissue for P, K, Mg and Ca revealed that Celtic grains had higher concentrations of P and K while being grown in identical conditions to that of A.C. Reed grains. These results indicate that mineral nutrient levels within the grain seem to be influenced by the cultivar, and possibly the protein content of the particular cultivar.