Arabidopsis, which has very small seeds, contains inside its protein bodies mineral nutrient reserves located in electron dense spheres called globoids. Globoids are generally believed to be phytate, a store of myoinositol, P, K, Mg and perhaps Ca, Mn, Zn and Fe. Energy-dispersive x-ray analysis and transmission electron microscopy was used to measure the elements present in globoids in nine different organ/tissue regions of dry seeds. We used seeds of wild type as well as the mutant lines pho-1 (phosphate in seeds reduced to 20% of wild type), pho-2 (phosphate accumulator with 1/4 more total P in seeds) and man-1 (manganese accumulator with increased seed Mn, Fe, Cu and Zn). Globoids of wild type seeds contained substantial P, K, Mg and Ca in all organs/regions, traces of Fe and Zn, and virtually no Mn. Compared to seeds of many other plants we have investigated, the Ca levels in globoids were very high and the Mg, levels were lower. The radicle and shoot apex regions had globoids with higher P, K and Mg levels and lower Ca. When the mutants were compared to wild type, for a given organ and tissue type, the peak-to-background values for P, K, Mg, Ca and Fe were remarkably similar. On average the man-1 mutant did not significantly accumulate more Mn than the wild type but one globoid did have a higher peak-to-background for Mn than occurred in all the rest. It thus appears that if a globoid was formed in the seeds of these three mutants it had concentrations of elements that were very similar to the wild type.

Key words: Arabidopsis, globoids, mineral nutrient reserves, mutants, phosphorus, seeds