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 (InsP(2)-InsP(5)) 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 Ipa mutants. The lpa trait of the MIPS1 mutant was not altered by cross-breeding with a WT cultivar; lpa progenies had InsP(6) reductions of about 44% compared to WT progenies. IPK1 progenies showed pronounced accumulations of specific InsP(3)-InsP(5) isomers (up to 12.4 mg/g) compared to the progenitor Ipa mutant (4.7 mg/g); the extent of InsP(6) reduction (43-71%) was depending on the WT crossing parent. Double mutants exhibited the most pronounced InsP(6) reductions (up to 87%), accompanied by moderate accumulations of InsP(3)-InsP(5) (2.5 mg/g). Cross-breeding offers the potential to modulate the amounts of both InsP(6) and InsP(3)-InsP(5) contents in lpa soybean mutants and thus to improve their nutritional quality.