Variability in Phytic Acid Content in Barley Grain

Around 65 % of phosphorus (P) in barley grain is in the form of phytic acid (PA) and phytates (PA salts), both forms negatively affect the usability of mineral substances and other important nutrients, thus participating in mineral deficiencies in human as well as livestock nutrition, and contributing to the pollution of the environment. Detection and creation of new varieties with a changed rate of both P forms in favor of digestible phosphate (Pi) is one of possible solutions. The submitted study dealt with the evaluation of variability in contents of PA and Pi in grains of selected spring and winter barley varieties, genetic resources and new spring barley lines created by hybridization with so-called "lpa" chemo-mutants - donors of low PA content (M422, M1070, M635, and M955). Variability in the content of both P forms in spring barley was affected by year and only if the assessed set included lpa mutants also by a genotype. In spite of high year variability, Pi/PA rate in lpa mutants remained nearly the same (from 138.4 % in M422 to 772.1 % in M955), while in the standard varieties it was on average only 31.3 %. The comparison of winter and spring barley varieties proved that winter varieties have a strong tendency to a higher accumulation of P in grain in the PA form (12.42 mg.g(-1) vs. 10.94 mg.g(-1)). The screening method developed for the evaluation of free P content in grain using the colorimetric test (CT) allowed to perform a more extensive selection of materials with different PA and Pi contents. A strong positive correlation was calculated between the results obtained by the CT and classically determined Pi (r = 0.85**, P <= 0.01). On the other hand, the use of existing molecular markers (SCAR marker ABC153) for the detection of crosses with reduced PA content in grain was not very effective. Crossing with lpa mutants and following selection using the CT led to creation of new lines of spring barley with reduced PA content, increased Pi rate and comparable total P content in a caryopsis, which can be used in breeding or further research. A new line KM2881.622.2.07 where an increased content of free P is connected with a waxy starch character (reduced portion of polysaccharide amylose) can be a new interesting gene resource for the development of food barley varieties.