Identification of two low-phytate barley (Hordeum vulgare L.) grain mutants by TLC and genetic analysis

Barley grains mutagenized with sodium azide were screened for high levels o f free phosphate in order to identify low-phytate mutants. Approximately 20 00 M2 half-grains were analyzed by molybdate staining and high free phospha te contents were scored positive for low phytate mutants. Plants were grown from embryo-containing halves of positive samples. Subsequent TLC analysis of positives was used to display free phosphate and phytate simultaneously , and two characteristic low-phytic acid phenotypes (A and B) could be dist inguished. A-type grains, which were found for seven plants, contained very high levels of free phosphate, low levels of phytate and trace amounts of other phosphate-containing compounds not observed in wildtype samples. Migr ation of these novel P-compounds on TLC plates was similar to that of inosi tol phosphates other than phytate. In grains from the two B-type plants the increase in free phosphate and the decrease in phytate relative to wildtyp e levels were moderate and additional P-compounds were absent. Genetic test s showed that at least three recessive alleles caused low-phytic acid pheno type A, whereas a separate, recessive locus was responsible for phenotype B . The importance of these findings with respect to the development of new b arley varieties with an improved nutritional and environmental value is dis cussed.