Nutritionally relevant parameters in low-phytate barley (Hordeum vulgare L.) grain mutants

Nutritionally relevant parameters in barley low-phytate mutant grains were analyzed in order to assess the potential value of these lines for future f eeding trials. Phytate (myo-inositol 1,2,3,4,5,6-hexakisphosphate) levels i n grains from A- and B-type low-phytate mutants corresponded to 25% and 66% of those of the parent line content, repectively. These relative decreases in phytate were accompanied by proportional increases of inorganic phospha te amounts. Apart from phytate, A-type grains also contained substantial qu antities of myo-inositol 1,3,4,5-tetrakisphosphate. Phytate levels in straw and root material from mutants were similar to parent line controls, indic ating that low-phytate mutations were grain specific. Analysis of K, Mg, Ca , and Zn revealed normal or slightly increased mineral cation levels in gra ins from all low-phytate lines, suggesting that mutationally impaired phyta te accumulation did not affect mineral storage capacity. Other nutritionall y important parameters such as starch and protein contents were similar to parent line controls. Finally, dynamic changes in the phosphorus compositio n during kernel development suggested that A-type mutations directly affect ed phytate synthesis, whereas B-type mutations seemed to act on regulation of synthesis.