Impact of Cross-Breeding of Low Phytic Acid MIPS1 and IPK1 Soybean ( Glycine max L. Merr.) Mutants on Their Contents of Inositol Phosphate Isomers

The knowledge on consequences of cross-breeding of induced low phytic acid ( lpa) soybean ( Glycine max L. Merr.) mutants on the contents of phytic acid (InsP₆) and lower inositol phosphate isomers (InsP₂-InsP₅) in the resulting progenies is limited. Therefore, MIPS1 and IPK1 lpa soybean mutants were crossed with wild-type (WT) cultivars or among themselves to generate homozygous lpa and WT progenies and double lpa mutants. The lpa trait of the MIPS1 mutant was not altered by cross-breeding with a WT cultivar; lpa progenies had InsP₆ reductions of about 44% compared to WT progenies. IPK1 progenies showed pronounced accumulations of specific InsP₃-InsP₅ isomers (up to 12.4 mg/g) compared to the progenitor lpa mutant (4.7 mg/g); the extent of InsP₆ reduction (43-71%) was depending on the WT crossing parent. Double mutants exhibited the most pronounced InsP₆ reductions (up to 87%), accompanied by moderate accumulations of InsP₃-InsP₅ (2.5 mg/g). Cross-breeding offers the potential to modulate the amounts of both InsP₆ and InsP₃-InsP₅ contents in lpa soybean mutants and thus to improve their nutritional quality.